PTG Bolt Head and Bolt Body: What Fitting is Required?

michaelnel · October 30, 2014, 07:14 PM

Hi Folks

I have a Savage 12 Benchrest in 6mm BR. I have ordered the following and will receive them early next week:

Criterion 30" Bull Barrel in 6mm BR
PTG bolt head
PTG bolt body

PTG makes vague references to a need for gunsmithing to install the bolt head. I believe they just mean that I must do the headspace measurement with this assembled bolt, but I am not sure if I need to do more. I have emailed them, but no response.

I do understand that I need to set the headspace with the new barrel and bolt, and I have the GO gauge (and will use the tape trick for NO GO). I have installed a Criterion barrel before, successfully, on my .308.
'
Anything else I need to do for this job other than setting the headspace with the new barrel and the bolt with the new body and bolt head? I would think that with the floating bolt head design that lapping the lugs should not be necessary, but I am often wrong.

Thank you!
Michael

Bart B. · October 30, 2014, 08:17 PM

If best accuracy is your goal.......

First slug the barrel bore and verify groove diameter is a few .0001"s smaller in diameter than the bullets you'll use. Check for tight spots indicating uneven groove diameters. Otherwise it may not be a tack driver

Second, lap the lugs to full and even contact, then square the receiver face followed by squaring the bolt face to the tenon thread axis, and then headspace the barrel on a 1.630" GO gauge.

michaelnel · October 31, 2014, 05:46 AM

That's great info Bart, thank you.

tobnpr · October 31, 2014, 07:32 AM

I did a lot of scrounging on the net regarding the benefit of lapping lugs on the Savage bolthead before installing my barrels.

Consensus seemed to be that the floating bolthead design allows it to self-align with the lug abutments, and lapping serves no useful purpose.

This seems to make sense to me, though I'd like to hear arguments proving otherwise. Simple enough to do before replacing a barrel, and I'll take every advantage I can get...

**4V50 Gary** · October 31, 2014, 07:43 AM

The key issue is headspace.

The barrel, bolt and receiver must be fitted. If the bolt doesn't close on the go gauge, this is not a lap the lug type project but a remove the barrel from the receiver and increasing the chamber depth. If the bolt closes on the no-go guage, then the barrel shank must be shortened as well as the shoulder. Then the headspace must be checked and if insufficient, the chamber reamed out.

Take the two week NRA machine shop class at Trinidad St JC. During the second week, you should be fitting a barrel to a receiver (first week you learn how to use the lathe and make some tools for practice).

Bart B. · October 31, 2014, 08:06 AM

If bolt lugs are lapped to full and even contact with their respective receiver lugs, the bolt face can then be squared up and it will stay there as there'll be no uneven wear on the lug mating surfaces. If they get unevenly worn, that floating bolt head will not lock up in battery with its face square to the chamber axis.

Dixie Gunsmithing · October 31, 2014, 08:11 AM

Whether the bolts head floats or not has not a lot to do with the fit against the lug abutments. For that to happen, it would have to have zero headspace, so that the rear of the cartridge would push the lugs flat on both sides. At that, it would be according to haw accurate the machining process was.

In other words, for the lugs to mate 100% with the abutments, the abutments must be at 90 degrees to the center line of the bore, and be the same on both sides. The bolt head would also need to be in line with the bore, and it's lugs be at 90 degrees to the bore. Generally, the bolt is easy to machine, and achieve this, but a milling cutter has to be passed down into the receiver, as the receiver is turned in a chuck which is gripping it's OD, while the cutter cuts both abutments. If the ID of the receiver is not concentric with the OD, you can have problems. There's a good shot of this in the 1960's Remington manufacturing video on YouTube. Last, if you have tapered abutments and lugs, that is a horse of a different color.

So, to be accurate, the barrel has to seat square to the receiver, so the bores center and the receivers center match and are in line, the abutments have to be at 90 degrees to the bore, and the lugs have to be at 90 degrees to the bore. Every measurement has to be taken from and match the bores centerline.

**4V50 Gary** · October 31, 2014, 10:15 AM

DG - now you're talking blueprinting.

Michael - you may also want to take the two week blueprinting class at TSJC. You must take machine shop I & II first. You'll need them for blueprinting.

Bart B. · October 31, 2014, 10:36 AM

DG, if you're a gunsmith, I though you would know there's no such thing as zero headpace. The bolt face cannot touch the chamber datum reference. Instead, I think what you're referring to is called head clearance; it can be zero.

I don't think bolt and receiver lug mating surfaces need to be squrare with the chamber axis; just lapped to full and even contact. Nor does the receiver bolt way axis have to be perfectly aligned with the bore/chamber axis. To many actions with a small amount of out of square and alignment issues in these areas have been used to shoot as accurate as those with everything fit on the exact same axis. As long as it's repeatable, that's fine. A small angle between bolt axis and chamber/barrel axis is not a big deal. But many people think it is.

Doesn't most cocked bolt's firing pin springs push the bolt lugs back hard against the receiver when a round's chambered? If I push and pull on an uncocked closed bolt, it's got a few thousandths back and forth slop. When it's cocked, the bolt is hard back with its lugs against the receiver abutments.

Dixie Gunsmithing · October 31, 2014, 11:09 AM

It just technical terms, as its neither here nor there. Anyhow, the headspace or clearance comment just means that everything would have to be square and fit tight, with a cartridge in the chamber, for everything to be forced into mating flat, in a perfectly machined action, and of course there is no such thing as zero headspace or clearance in a gun that works. You have to have clearance for the bolt to open and close easily. The squareness does matter when its fired, in that the lugs are contacting the abutments as much as possible.

The blueprinting of an action is always measured off the bores center, and everything else is supposed to be done to match that as close to possible. If you have errors on every axis and fit, then they all can count up to be a lot (total error), thus it is why we do blueprinting. However, you can just try to lap the lugs so they make the most contact, but in reality, things can still be off everywhere else, if that is all you do. It could shoot just as well this way too. However, if I went to the trouble of squaring the front of the receiver for the barrel, I would do the rest of the blueprinting, and get all the fits as close as possible.

Nathan · October 31, 2014, 11:28 AM

Do people recut threads on a Savage, or just cut the action face square to the threads? Then bolt face parallel to action face?

Dixie Gunsmithing · October 31, 2014, 12:07 PM

Nathan,

Below are two good videos on blueprinting an action and bolt, in two parts. After this is done, the barrel is fitted to it.

Part 1:

https://www.youtube.com/watch?v=pGn9qWJIM9M

Part 2:

https://www.youtube.com/watch?v=UmMSeBAGV0M

Bart B. · October 31, 2014, 01:04 PM

I don't think bolt and receiver mating surfaces have to be exactly 90 degrees from bore axis. Barrel tenon threads aren't and they pull the tenon shoulder evenly straight back against squared up receiver faces. Just like firing pin springs do pushing the bolt lugs back against the receiver abutment lugs.

Even if the lug's mating surfaces are a small angle out of square with the bore axis. Properly lapped to full contact, they'll both be at the same very small angle to the bore axis.

Dixie Gunsmithing · October 31, 2014, 02:39 PM

Bart,

I do them about the same way as the guy in the videos. First, you find the exact center of the receiver and indicate that in. When you get that, then you can make the first cut on the receiver, to square it to the barrel. Then, since you are already set up, its easy to machine the abutments square to this center, and true up the threads for concentricity. However, you will end up with a slightly off standard internal barrel thread diameter, by a few thousandths, and you have to turn the barrel shank to match that. If you do it this way, and turn the shank on the barrel concentric to it's bore, then everything should line up as close as possible, once the bolts lugs and face are squared up to its center. Though the videos don't show the barrel fitting, I use the barrels bore to indicate to for turning and threading the shank, since the barrels OD can be eccentric to the bore. That way, everything should follow the same center line when you're done, and everything that needs to be square, should end up that way.

Bart B. · October 31, 2014, 04:41 PM

I know lots of smiths do all that detail wherever they can, but I'm one of the group that feel it's not all needed. But those of us who feel it's all not needed have rifles just as accurate as those who do.

tobnpr · November 1, 2014, 10:21 AM

Not a smith (but, I am self-teaching a bit thanks to Steve Acker)- but seems to me the Savage is a different animal in some respects than the typical 700, or Mauser type bolt action receiver.

There is no shoulder on the barrel to mate with the receiver, therefore, truing the receiver face serves no purpose. Truing the threads of the receiver, barrel, and barrel nut would seem to make sense to keep them all concentric to the bore.

But I can't help but ponder...in a "typical" bolt receiver it's the receiver face that holds the barrel/bore centerline perpendicular to it. So, if "blueprinting" a Savage, what do you indicate, "off-of"?

I agree that it needs to be an entire "package" of square and concentric. But, is truing lugs overrated? Supposedly...if you indicate a Rem 700 bolt when cocked, the sear raises the rear of the bolt enough so that there is no longer even/full contact with the lugs and abutments. I guess this would resolve itself assuming the case has expanded, the case head contacted the bolt face, and 50K psi of pressure forces the lugs into full and even contact before the bullet leaves the case. Anyway, a lot to consider.

Savages, like 'em or not, are usually more accurate out of the box than most other production bolt guns. I attribute it more to the floating bolthead design, more than anything else. There are some BR shooters placing Savage boltheads onto modified 700 bolts.

Bart B. · November 1, 2014, 10:41 AM

tobnpr, your lug-lapping issue is typically unknown, ignored or not understood by so many folks some of which are gunsmiths. Good to see you're one of the few who acknowledges and understands it. I was hoping someone would bring that issue up.

Which is why lapping lugs with a complete bolt and chambered case and action plus trigger (so the extractor pushes the bolt head to its firing position) ensures the lugs will have full contact when the bolt's closed in its normal "in battery" position with a thousandth or more case head clearance. That ensures best accuracy as the bolt face is square with the bore in its firing position. The action's parts have to fit and be in battery repeatably when the round fires, nothing else counts. Doesn't matter how much slop and clearance there is between parts; as long as its the same for each shot fired.

Don't forget; the bolt's pulled back so its lugs bear hard against the receiver by the firing pin spring pushing back on the bolt sleeve with its cocking piece is stopped against the sear. It stays there as the sear releases the firing pin and it flies forward.

Jim Watson · November 1, 2014, 12:14 PM

I know that Larry Racine, a leading Savage-smith, laps lugs and otherwise "tunes" the action; and Fred Moreno of Sharpshooter Supply "trues and times" the action.

Racine will also omit the barrel nut and fit a barrel with a shoulder, too.
A friend has one set up that way on its third barrel.

Dixie Gunsmithing · November 1, 2014, 05:34 PM

tobnpr,

Blueprinting one is more of making one mechanically correct or mechanically sound, than actually increasing its accuracy by a huge amount. Of course, having the barrels bore and the center line of the receiver match, does help. That's why I said above that when just lapping the lugs, that it could shoot just as well this way too. If you don't have to take too much off, when lapping, then there's no worry, but it can increase headspace. In the video, you'll notice he took off about 0.001" from the bolt lugs, and about that much from the bolt face, which will increase the headspace that much, or about 0.002", and then add to that what he removed from the abutments. Of course, he was fitting a barrel, so that would be accounted for when he was finished. If your gun was good with headspace, then I doubt lapping would be any worry.

tobnpr · November 2, 2014, 01:43 PM

After pondering it a bit more, I think I missed something...
Even though there's no barrel shoulder to mate with the receiver, the recoil lug certainly bears on it- and I guess it would make sense that if you're going to use a precision-ground lug (I use Holland's), that you'd still need to true the receiver face- and use a precision barrel nut- to ensure the bearing surface is perpendicular to the bore, right?

I don't see the point in setting back and re-chambering a new barrel to provide a shoulder to bear on the receiver, it defeats the whole purpose of owning a Savage- unless it's purely to realize the benefit (?) of the floating bolthead.

Bart B. · November 3, 2014, 12:18 PM

tobnpr, the point in shouldering a barrel directly on the receiver means there's one less part whose mating surfaces needs to be squared up with all else. Some folks have squared up their Remington round receiver faces only to find out the recoil lug's surfaces were not plane with each other; top part against the receiver was a few thousandths different than the bottom part.

Which is why David Tubb's custom Remington recoil lugs' front and back surfaces are ground plane with each other. They're thicker, too, as some Remington magnum rifles would bend them if they contacted the lug abutment only at the bottom of the lug recess in the stocks.

October 30, 2014, 07:14 PM	#1
michaelnel Junior Member Join Date: January 24, 2013 Posts: 12	PTG Bolt Head and Bolt Body: What Fitting is Required? Hi Folks I have a Savage 12 Benchrest in 6mm BR. I have ordered the following and will receive them early next week: Criterion 30" Bull Barrel in 6mm BR PTG bolt head PTG bolt body PTG makes vague references to a need for gunsmithing to install the bolt head. I believe they just mean that I must do the headspace measurement with this assembled bolt, but I am not sure if I need to do more. I have emailed them, but no response. I do understand that I need to set the headspace with the new barrel and bolt, and I have the GO gauge (and will use the tape trick for NO GO). I have installed a Criterion barrel before, successfully, on my .308. ' Anything else I need to do for this job other than setting the headspace with the new barrel and the bolt with the new body and bolt head? I would think that with the floating bolt head design that lapping the lugs should not be necessary, but I am often wrong. Thank you! Michael

October 30, 2014, 08:17 PM	#2
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	If best accuracy is your goal....... First slug the barrel bore and verify groove diameter is a few .0001"s smaller in diameter than the bullets you'll use. Check for tight spots indicating uneven groove diameters. Otherwise it may not be a tack driver Second, lap the lugs to full and even contact, then square the receiver face followed by squaring the bolt face to the tenon thread axis, and then headspace the barrel on a 1.630" GO gauge. Last edited by Bart B.; October 30, 2014 at 08:24 PM.

October 31, 2014, 07:32 AM	#4
tobnpr Senior Member Join Date: August 1, 2010 Location: Tampa Bay Posts: 4,556	I did a lot of scrounging on the net regarding the benefit of lapping lugs on the Savage bolthead before installing my barrels. Consensus seemed to be that the floating bolthead design allows it to self-align with the lug abutments, and lapping serves no useful purpose. This seems to make sense to me, though I'd like to hear arguments proving otherwise. Simple enough to do before replacing a barrel, and I'll take every advantage I can get... __________________ Remington 700/Savage Rebarreling /Action Blueprinting 07 FFL /Mosin-Nagant Custom Shop/Bent Bolts Genuine Cerakote Applicator www.biggorillagunworks.com

October 31, 2014, 07:43 AM	#5
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,845	The key issue is headspace. The barrel, bolt and receiver must be fitted. If the bolt doesn't close on the go gauge, this is not a lap the lug type project but a remove the barrel from the receiver and increasing the chamber depth. If the bolt closes on the no-go guage, then the barrel shank must be shortened as well as the shoulder. Then the headspace must be checked and if insufficient, the chamber reamed out. Take the two week NRA machine shop class at Trinidad St JC. During the second week, you should be fitting a barrel to a receiver (first week you learn how to use the lathe and make some tools for practice). __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

October 31, 2014, 10:15 AM	#8
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,845	DG - now you're talking blueprinting. Michael - you may also want to take the two week blueprinting class at TSJC. You must take machine shop I & II first. You'll need them for blueprinting. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

October 31, 2014, 05:46 AM	#3
michaelnel Junior Member Join Date: January 24, 2013 Posts: 12	That's great info Bart, thank you.

October 31, 2014, 08:06 AM	#6
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	If bolt lugs are lapped to full and even contact with their respective receiver lugs, the bolt face can then be squared up and it will stay there as there'll be no uneven wear on the lug mating surfaces. If they get unevenly worn, that floating bolt head will not lock up in battery with its face square to the chamber axis.

October 31, 2014, 08:11 AM	#7
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	Whether the bolts head floats or not has not a lot to do with the fit against the lug abutments. For that to happen, it would have to have zero headspace, so that the rear of the cartridge would push the lugs flat on both sides. At that, it would be according to haw accurate the machining process was. In other words, for the lugs to mate 100% with the abutments, the abutments must be at 90 degrees to the center line of the bore, and be the same on both sides. The bolt head would also need to be in line with the bore, and it's lugs be at 90 degrees to the bore. Generally, the bolt is easy to machine, and achieve this, but a milling cutter has to be passed down into the receiver, as the receiver is turned in a chuck which is gripping it's OD, while the cutter cuts both abutments. If the ID of the receiver is not concentric with the OD, you can have problems. There's a good shot of this in the 1960's Remington manufacturing video on YouTube. Last, if you have tapered abutments and lugs, that is a horse of a different color. So, to be accurate, the barrel has to seat square to the receiver, so the bores center and the receivers center match and are in line, the abutments have to be at 90 degrees to the bore, and the lugs have to be at 90 degrees to the bore. Every measurement has to be taken from and match the bores centerline.

October 31, 2014, 10:36 AM	#9
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	DG, if you're a gunsmith, I though you would know there's no such thing as zero headpace. The bolt face cannot touch the chamber datum reference. Instead, I think what you're referring to is called head clearance; it can be zero. I don't think bolt and receiver lug mating surfaces need to be squrare with the chamber axis; just lapped to full and even contact. Nor does the receiver bolt way axis have to be perfectly aligned with the bore/chamber axis. To many actions with a small amount of out of square and alignment issues in these areas have been used to shoot as accurate as those with everything fit on the exact same axis. As long as it's repeatable, that's fine. A small angle between bolt axis and chamber/barrel axis is not a big deal. But many people think it is. Doesn't most cocked bolt's firing pin springs push the bolt lugs back hard against the receiver when a round's chambered? If I push and pull on an uncocked closed bolt, it's got a few thousandths back and forth slop. When it's cocked, the bolt is hard back with its lugs against the receiver abutments. Last edited by Bart B.; October 31, 2014 at 12:48 PM.

October 31, 2014, 11:09 AM	#10
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	It just technical terms, as its neither here nor there. Anyhow, the headspace or clearance comment just means that everything would have to be square and fit tight, with a cartridge in the chamber, for everything to be forced into mating flat, in a perfectly machined action, and of course there is no such thing as zero headspace or clearance in a gun that works. You have to have clearance for the bolt to open and close easily. The squareness does matter when its fired, in that the lugs are contacting the abutments as much as possible. The blueprinting of an action is always measured off the bores center, and everything else is supposed to be done to match that as close to possible. If you have errors on every axis and fit, then they all can count up to be a lot (total error), thus it is why we do blueprinting. However, you can just try to lap the lugs so they make the most contact, but in reality, things can still be off everywhere else, if that is all you do. It could shoot just as well this way too. However, if I went to the trouble of squaring the front of the receiver for the barrel, I would do the rest of the blueprinting, and get all the fits as close as possible. Last edited by Dixie Gunsmithing; October 31, 2014 at 12:41 PM.

October 31, 2014, 11:28 AM	#11
Nathan Senior Member Join Date: July 1, 2001 Posts: 6,334	Do people recut threads on a Savage, or just cut the action face square to the threads? Then bolt face parallel to action face?

October 31, 2014, 12:07 PM	#12
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	Nathan, Below are two good videos on blueprinting an action and bolt, in two parts. After this is done, the barrel is fitted to it. Part 1: https://www.youtube.com/watch?v=pGn9qWJIM9M Part 2: https://www.youtube.com/watch?v=UmMSeBAGV0M

October 31, 2014, 01:04 PM	#13
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	I don't think bolt and receiver mating surfaces have to be exactly 90 degrees from bore axis. Barrel tenon threads aren't and they pull the tenon shoulder evenly straight back against squared up receiver faces. Just like firing pin springs do pushing the bolt lugs back against the receiver abutment lugs. Even if the lug's mating surfaces are a small angle out of square with the bore axis. Properly lapped to full contact, they'll both be at the same very small angle to the bore axis. Last edited by Bart B.; October 31, 2014 at 01:11 PM.

October 31, 2014, 02:39 PM	#14
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	Bart, I do them about the same way as the guy in the videos. First, you find the exact center of the receiver and indicate that in. When you get that, then you can make the first cut on the receiver, to square it to the barrel. Then, since you are already set up, its easy to machine the abutments square to this center, and true up the threads for concentricity. However, you will end up with a slightly off standard internal barrel thread diameter, by a few thousandths, and you have to turn the barrel shank to match that. If you do it this way, and turn the shank on the barrel concentric to it's bore, then everything should line up as close as possible, once the bolts lugs and face are squared up to its center. Though the videos don't show the barrel fitting, I use the barrels bore to indicate to for turning and threading the shank, since the barrels OD can be eccentric to the bore. That way, everything should follow the same center line when you're done, and everything that needs to be square, should end up that way.

October 31, 2014, 04:41 PM	#15
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	I know lots of smiths do all that detail wherever they can, but I'm one of the group that feel it's not all needed. But those of us who feel it's all not needed have rifles just as accurate as those who do.

November 1, 2014, 10:21 AM	#16
tobnpr Senior Member Join Date: August 1, 2010 Location: Tampa Bay Posts: 4,556	Not a smith (but, I am self-teaching a bit thanks to Steve Acker)- but seems to me the Savage is a different animal in some respects than the typical 700, or Mauser type bolt action receiver. There is no shoulder on the barrel to mate with the receiver, therefore, truing the receiver face serves no purpose. Truing the threads of the receiver, barrel, and barrel nut would seem to make sense to keep them all concentric to the bore. But I can't help but ponder...in a "typical" bolt receiver it's the receiver face that holds the barrel/bore centerline perpendicular to it. So, if "blueprinting" a Savage, what do you indicate, "off-of"? I agree that it needs to be an entire "package" of square and concentric. But, is truing lugs overrated? Supposedly...if you indicate a Rem 700 bolt when cocked, the sear raises the rear of the bolt enough so that there is no longer even/full contact with the lugs and abutments. I guess this would resolve itself assuming the case has expanded, the case head contacted the bolt face, and 50K psi of pressure forces the lugs into full and even contact before the bullet leaves the case. Anyway, a lot to consider. Savages, like 'em or not, are usually more accurate out of the box than most other production bolt guns. I attribute it more to the floating bolthead design, more than anything else. There are some BR shooters placing Savage boltheads onto modified 700 bolts. __________________ Remington 700/Savage Rebarreling /Action Blueprinting 07 FFL /Mosin-Nagant Custom Shop/Bent Bolts Genuine Cerakote Applicator www.biggorillagunworks.com

November 1, 2014, 10:41 AM	#17
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	tobnpr, your lug-lapping issue is typically unknown, ignored or not understood by so many folks some of which are gunsmiths. Good to see you're one of the few who acknowledges and understands it. I was hoping someone would bring that issue up. Which is why lapping lugs with a complete bolt and chambered case and action plus trigger (so the extractor pushes the bolt head to its firing position) ensures the lugs will have full contact when the bolt's closed in its normal "in battery" position with a thousandth or more case head clearance. That ensures best accuracy as the bolt face is square with the bore in its firing position. The action's parts have to fit and be in battery repeatably when the round fires, nothing else counts. Doesn't matter how much slop and clearance there is between parts; as long as its the same for each shot fired. Don't forget; the bolt's pulled back so its lugs bear hard against the receiver by the firing pin spring pushing back on the bolt sleeve with its cocking piece is stopped against the sear. It stays there as the sear releases the firing pin and it flies forward.

November 1, 2014, 12:14 PM	#18
Jim Watson Senior Member Join Date: October 25, 2001 Location: Alabama Posts: 18,545	I know that Larry Racine, a leading Savage-smith, laps lugs and otherwise "tunes" the action; and Fred Moreno of Sharpshooter Supply "trues and times" the action. Racine will also omit the barrel nut and fit a barrel with a shoulder, too. A friend has one set up that way on its third barrel.

November 1, 2014, 05:34 PM	#19
Dixie Gunsmithing Moderator Emeritus Join Date: April 27, 2013 Location: Ohio Posts: 1,923	tobnpr, Blueprinting one is more of making one mechanically correct or mechanically sound, than actually increasing its accuracy by a huge amount. Of course, having the barrels bore and the center line of the receiver match, does help. That's why I said above that when just lapping the lugs, that it could shoot just as well this way too. If you don't have to take too much off, when lapping, then there's no worry, but it can increase headspace. In the video, you'll notice he took off about 0.001" from the bolt lugs, and about that much from the bolt face, which will increase the headspace that much, or about 0.002", and then add to that what he removed from the abutments. Of course, he was fitting a barrel, so that would be accounted for when he was finished. If your gun was good with headspace, then I doubt lapping would be any worry.

November 2, 2014, 01:43 PM	#20
tobnpr Senior Member Join Date: August 1, 2010 Location: Tampa Bay Posts: 4,556	After pondering it a bit more, I think I missed something... Even though there's no barrel shoulder to mate with the receiver, the recoil lug certainly bears on it- and I guess it would make sense that if you're going to use a precision-ground lug (I use Holland's), that you'd still need to true the receiver face- and use a precision barrel nut- to ensure the bearing surface is perpendicular to the bore, right? I don't see the point in setting back and re-chambering a new barrel to provide a shoulder to bear on the receiver, it defeats the whole purpose of owning a Savage- unless it's purely to realize the benefit (?) of the floating bolthead. __________________ Remington 700/Savage Rebarreling /Action Blueprinting 07 FFL /Mosin-Nagant Custom Shop/Bent Bolts Genuine Cerakote Applicator www.biggorillagunworks.com

November 3, 2014, 12:18 PM	#21
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	tobnpr, the point in shouldering a barrel directly on the receiver means there's one less part whose mating surfaces needs to be squared up with all else. Some folks have squared up their Remington round receiver faces only to find out the recoil lug's surfaces were not plane with each other; top part against the receiver was a few thousandths different than the bottom part. Which is why David Tubb's custom Remington recoil lugs' front and back surfaces are ground plane with each other. They're thicker, too, as some Remington magnum rifles would bend them if they contacted the lug abutment only at the bottom of the lug recess in the stocks.