Ogive measurement on .308

Glennster · July 25, 2006, 06:24 PM

I just got my rifle back from a gunsmith, he trued the action on my Remington 700 (.308 ) and squared everything up.

Is it strange to have the Ogive measure 3.370'' on a bullet loaded to touch the rifling at the back of the barrel?

It seems real long compared to a factory load.

**Bud Helms** · July 25, 2006, 07:00 PM

Ogive: The curved prtion of a bullet ahead of the cylindrical, or shank, section. Also the radius of this curve, usually expressed in caliber.

3.370'' isn't an ogive measurement. It sounds like you are describing the distance from the head of the loaded round (bolt face) to that point where the bullet first touches that rifling.

That's a lot of freebore. How did you make this measurement?

Quote:

... 3.370'' on a bullet loaded to touch the rifling at the back of the barrel?

You actually got a .308 Win cartridge to load out that far? Heck, that's a good bit of free bore for a .30-06!

Okay, this is starting to sink in ... I don't see how you got a .308 Win to touch rifling that's 3.370 inches away from the face of a closed bolt. Are you sure he didn't rechamber for .30-06?

Glennster · July 25, 2006, 09:08 PM

Bud,
Thanks for the reply.

You're right, the ogive measurement is 2.370", I forgot to deduct for the length of the tool that measures the lentgh of the bullet from primer to ogive.
The overall length is 3.004''

Did the gunsmith take too much out of there when he trued it up?

THANKS,
Glenn

**Bud Helms** · July 25, 2006, 09:42 PM

Well, that's better.

But I'm still confused:

"... the ogive measurement is 2.370" ..."

"The overall length is 3.004''"

Exactly what is it that measures 2.370 inches and exactly what is it that measures 3.004 inches? Be specific.

Remember the ogive is a fixed value for the shape of the bullet. So, what is it you're calling ogive? And the overall length of what?

A distance of 2.370 from the bolt face to the the point where the rifling begins doesn't seem overly long, but I'm not a .308 Win chamber expert.

[Edit: I think what I'm reading is 2.370 in from case head to rifling contact point on the bullet and 3.044 overall length for the loaded cartridge. Right? If you can get at least a caliber (approx .3 inches of bullet) in the case and still kiss the rifling with a loaded round, you're good. The overall length of the loaded cartridge is only a factor if it's too long for the magazine.]

Glennster · July 25, 2006, 10:49 PM

3.004'' is the TOTAL length of the cartridge, from the back of the case to the tip of the 150 Gr. Nosler.
This length was found by taking a fired case, then sizing the neck of the case a little, then we put the Nosler in the case ( no powder, no primer ). We then took the case with the bullet inserted just a liitle, and put it in the rifle. We gently ran the bolt forward and locked it up.
Then we pulled it back and removed the '' dummy'' round to be used as a guide to measure bullet length.
This should give us a case and bullet length where the bullet is just kissing the rifling.
At that point I use a ''Bullet Comarator'' to get the '' OGIVE'' measurement, which is ogive, as you describe it, to the back of the case.
Does this make sense???

Bullet94 · July 25, 2006, 11:23 PM

Glennster Quote – “This should give us a case and bullet length where the bullet is just kissing the rifling.
At that point I use a ''Bullet Comarator'' to get the '' OGIVE'' measurement, which is ogive, as you describe it, to the back of the case.
Does this make sense???”

Makes sense to me. One thing I would say is the distance to the lands when measured with a bullet comparator will probably change when using different bullets and the amount of neck tension can effect this also. With enough neck tension you will be into the lands not just the start of the lands. I believe most bullet comparators don’t really measure from the part of the bullet that will contact the lands first, but is a way to make comparisons.

I’ve read that the newer Remingtons have more freebore, enough that seating to the lands may not be possible. Make sure your in the case enough as Bud Helms mentioned.

L Puckett · July 25, 2006, 11:40 PM

Glennster,

I believe I'm following your measurements and yes that is a long throat (leade). The specs on a 308 is 2.1835 (Base to datum) which means you have a leade of .186. First realize that a bullet comparator is not a perfectly machined tool, but close enough. It is used for comparing, bullet to bullet, round to round, not for exact specifications.

Back to your question, it does sound like you have a long leade. For a Nosler that isn't all that important. Depending on the leade angle most bullets don't have a problem with "jump" in fact many prefer it. The "loading to the lands" is something that has become important to those who load VLD bullets (Bergers, etc). Those who use SMK's have found a given jump is better.

As Bud has suggested, always maintain at least the depth of your caliber (.308 of your bullet inside the neck). If you like single loading, load long but I have found with most long leades, load to "mag length" and play around with .010 short to .010 long in mag length and you can find a good spot.

A lot more can be gained just playing with your bullets, charge weights and primers to get you tight groups, then fine tune the length.

LP

Bullet94 · July 26, 2006, 12:02 AM

I agree with L Puckett that VLD’s seem to like the lands others don’t care so much. I read this on another forum –

“ONLY with a true-blue BR rifle capable of "shooting in the ones" will you EVER see a gain from "tuning" with seating depth (and even then it gets more play than mebbeso it should )
For regular stuff it's all about INTO the lands and OUT OF the lands (like ten thou out, or more, like to fit a magwell)”

Any comments on this?

Glennster · July 26, 2006, 05:58 AM

Please forgive my ignorance, BUT, define neck tension.
Is that how tight the bullet fits in the neck of the case, or how tight the bullet fits in the chamber lenght wise?

BTW - I sure do appreciate all of the input.
THANK YOU!!!

**Bud Helms** · July 26, 2006, 06:17 AM

Datum line or datum point is a generic term that is pretty useful in what we are discussing, but there are still two different uses in this discussion. There is a datum line that is used to measure headspace and that is the one I was referring to. That datum line is on the case shoulder. The other use of the term datum line is the distance from the cartridge case head to that point on the bullet where the caliber-diameter stops and the ogive begins. And that will be right at the point where the bullet begins to engage the rifling.

Here is a good explanation, with some practical suggestions on bullet seating depth from Rocky's Reloading Room.

L Puckett · July 26, 2006, 11:31 AM

Glennster,

Neck tension refers to the tension placed on the bullet by the neck of the case. A neck sized .002 smaller than the bullet will (generally) result in approx 55-65 ft lbs of tension. This is considered "normal" tension for a bolt gun, if you use a gas gun (semi-auto) the neck sizing is tightened to .003 to result in 85-95 ft lbs of tension.

Bud, you are correct on Datum lines, and dang if it isn't great to read comments from someone that really knows his stuff. To further Glennster's question, do you know the leade angle Remington is using ? It is only a guess on my part but I would expect a 3 degree, and for a Nozler bullet I would think that would "square it up nicely". I am interested in your thoughts on this.

LP

kingudaroad · July 26, 2006, 11:41 AM

Quote:

ONLY with a true-blue BR rifle capable of "shooting in the ones" will you EVER see a gain from "tuning" with seating depth

I think there is some scientific evidence out there to the contrary.

Try typing "bullet seating depth" into your google search engine.

Heck, some folks think it is more important than powder weight.

**Bud Helms** · July 26, 2006, 03:59 PM

L Puckett, thanks. It's been a long time since I was in a discussion about leade angle cut. but it wouldn't surprise me if you are right on the money. I've seen quicker angles than that, but Weatherby convinced me that in this case tighter isn't necessarily better.

Now you want to get in a conversation with someone that knows his stuff and gets practical too, ... get Art Eatman to open up on ya.

kingudaroad, I think I agree with you on that. Once you've trued your action, bedded it, start neck sizing, you eventually get to a point where you see less and less incremental gain. I think if you start with a really stiff, trued up action and go from some handloads with say, bulk Rem PSPs in full resized brass of unknown history and some load right in the middle of a load range for powder/bullet weight and go straight to new, once fired, neck size, primer pocket cleaned brass with a good load and get those bullets out to within 0.010 of the rifling, most of the time you'll see some dramatic repeatability. But just remember, David Tubbs will put a hex on you for saying that!

kingudaroad · July 26, 2006, 07:11 PM

Quote:

David Tubbs will put a hex on you for saying that!

I sure hope I don't find myself in his crosshairs.

July 25, 2006, 06:24 PM	#1
Glennster Senior Member Join Date: July 31, 2005 Location: Northern Indiana Posts: 226	Ogive measurement on .308 I just got my rifle back from a gunsmith, he trued the action on my Remington 700 (.308 ) and squared everything up. Is it strange to have the Ogive measure 3.370'' on a bullet loaded to touch the rifling at the back of the barrel? It seems real long compared to a factory load.

July 25, 2006, 11:23 PM	#6
Bullet94 Senior Member Join Date: September 8, 2004 Location: Kansas Posts: 723	Glennster Quote – “This should give us a case and bullet length where the bullet is just kissing the rifling. At that point I use a ''Bullet Comarator'' to get the '' OGIVE'' measurement, which is ogive, as you describe it, to the back of the case. Does this make sense???” Makes sense to me. One thing I would say is the distance to the lands when measured with a bullet comparator will probably change when using different bullets and the amount of neck tension can effect this also. With enough neck tension you will be into the lands not just the start of the lands. I believe most bullet comparators don’t really measure from the part of the bullet that will contact the lands first, but is a way to make comparisons. I’ve read that the newer Remingtons have more freebore, enough that seating to the lands may not be possible. Make sure your in the case enough as Bud Helms mentioned. __________________ PRO-SECOND AMENDMENT - Live Free or Die

July 26, 2006, 12:02 AM	#8
Bullet94 Senior Member Join Date: September 8, 2004 Location: Kansas Posts: 723	I agree with L Puckett that VLD’s seem to like the lands others don’t care so much. I read this on another forum – “ONLY with a true-blue BR rifle capable of "shooting in the ones" will you EVER see a gain from "tuning" with seating depth (and even then it gets more play than mebbeso it should ) For regular stuff it's all about INTO the lands and OUT OF the lands (like ten thou out, or more, like to fit a magwell)” Any comments on this? __________________ PRO-SECOND AMENDMENT - Live Free or Die

July 25, 2006, 09:08 PM	#3
Glennster Senior Member Join Date: July 31, 2005 Location: Northern Indiana Posts: 226	Bud, Thanks for the reply. You're right, the ogive measurement is 2.370", I forgot to deduct for the length of the tool that measures the lentgh of the bullet from primer to ogive. The overall length is 3.004'' Did the gunsmith take too much out of there when he trued it up? THANKS, Glenn

July 25, 2006, 09:42 PM	#4
Bud Helms Senior Member Join Date: December 31, 1999 Location: Middle Georgia, USA Posts: 13,198	Well, that's better. But I'm still confused: "... the ogive measurement is 2.370" ..." "The overall length is 3.004''" Exactly what is it that measures 2.370 inches and exactly what is it that measures 3.004 inches? Be specific. Remember the ogive is a fixed value for the shape of the bullet. So, what is it you're calling ogive? And the overall length of what? A distance of 2.370 from the bolt face to the the point where the rifling begins doesn't seem overly long, but I'm not a .308 Win chamber expert. [Edit: I think what I'm reading is 2.370 in from case head to rifling contact point on the bullet and 3.044 overall length for the loaded cartridge. Right? If you can get at least a caliber (approx .3 inches of bullet) in the case and still kiss the rifling with a loaded round, you're good. The overall length of the loaded cartridge is only a factor if it's too long for the magazine.]

July 25, 2006, 10:49 PM	#5
Glennster Senior Member Join Date: July 31, 2005 Location: Northern Indiana Posts: 226	3.004'' is the TOTAL length of the cartridge, from the back of the case to the tip of the 150 Gr. Nosler. This length was found by taking a fired case, then sizing the neck of the case a little, then we put the Nosler in the case ( no powder, no primer ). We then took the case with the bullet inserted just a liitle, and put it in the rifle. We gently ran the bolt forward and locked it up. Then we pulled it back and removed the '' dummy'' round to be used as a guide to measure bullet length. This should give us a case and bullet length where the bullet is just kissing the rifling. At that point I use a ''Bullet Comarator'' to get the '' OGIVE'' measurement, which is ogive, as you describe it, to the back of the case. Does this make sense???

July 25, 2006, 11:40 PM	#7
L Puckett Senior Member Join Date: March 2, 2002 Location: Mid-Tennessee Posts: 150	Glennster, I believe I'm following your measurements and yes that is a long throat (leade). The specs on a 308 is 2.1835 (Base to datum) which means you have a leade of .186. First realize that a bullet comparator is not a perfectly machined tool, but close enough. It is used for comparing, bullet to bullet, round to round, not for exact specifications. Back to your question, it does sound like you have a long leade. For a Nosler that isn't all that important. Depending on the leade angle most bullets don't have a problem with "jump" in fact many prefer it. The "loading to the lands" is something that has become important to those who load VLD bullets (Bergers, etc). Those who use SMK's have found a given jump is better. As Bud has suggested, always maintain at least the depth of your caliber (.308 of your bullet inside the neck). If you like single loading, load long but I have found with most long leades, load to "mag length" and play around with .010 short to .010 long in mag length and you can find a good spot. A lot more can be gained just playing with your bullets, charge weights and primers to get you tight groups, then fine tune the length. LP

July 26, 2006, 05:58 AM	#9
Glennster Senior Member Join Date: July 31, 2005 Location: Northern Indiana Posts: 226	Please forgive my ignorance, BUT, define neck tension. Is that how tight the bullet fits in the neck of the case, or how tight the bullet fits in the chamber lenght wise? BTW - I sure do appreciate all of the input. THANK YOU!!!

July 26, 2006, 06:17 AM	#10
Bud Helms Senior Member Join Date: December 31, 1999 Location: Middle Georgia, USA Posts: 13,198	Datum line or datum point is a generic term that is pretty useful in what we are discussing, but there are still two different uses in this discussion. There is a datum line that is used to measure headspace and that is the one I was referring to. That datum line is on the case shoulder. The other use of the term datum line is the distance from the cartridge case head to that point on the bullet where the caliber-diameter stops and the ogive begins. And that will be right at the point where the bullet begins to engage the rifling. Here is a good explanation, with some practical suggestions on bullet seating depth from Rocky's Reloading Room.

July 26, 2006, 11:31 AM	#11
L Puckett Senior Member Join Date: March 2, 2002 Location: Mid-Tennessee Posts: 150	Glennster, Neck tension refers to the tension placed on the bullet by the neck of the case. A neck sized .002 smaller than the bullet will (generally) result in approx 55-65 ft lbs of tension. This is considered "normal" tension for a bolt gun, if you use a gas gun (semi-auto) the neck sizing is tightened to .003 to result in 85-95 ft lbs of tension. Bud, you are correct on Datum lines, and dang if it isn't great to read comments from someone that really knows his stuff. To further Glennster's question, do you know the leade angle Remington is using ? It is only a guess on my part but I would expect a 3 degree, and for a Nozler bullet I would think that would "square it up nicely". I am interested in your thoughts on this. LP

July 26, 2006, 03:59 PM	#13
Bud Helms Senior Member Join Date: December 31, 1999 Location: Middle Georgia, USA Posts: 13,198	L Puckett, thanks. It's been a long time since I was in a discussion about leade angle cut. but it wouldn't surprise me if you are right on the money. I've seen quicker angles than that, but Weatherby convinced me that in this case tighter isn't necessarily better. Now you want to get in a conversation with someone that knows his stuff and gets practical too, ... get Art Eatman to open up on ya. kingudaroad, I think I agree with you on that. Once you've trued your action, bedded it, start neck sizing, you eventually get to a point where you see less and less incremental gain. I think if you start with a really stiff, trued up action and go from some handloads with say, bulk Rem PSPs in full resized brass of unknown history and some load right in the middle of a load range for powder/bullet weight and go straight to new, once fired, neck size, primer pocket cleaned brass with a good load and get those bullets out to within 0.010 of the rifling, most of the time you'll see some dramatic repeatability. But just remember, David Tubbs will put a hex on you for saying that!