Chamber reaming, 2nd opinion

stephen b · November 1, 2018, 11:00 PM

Recently I had a 22 Hornet reamed into a K Hornet. Before reaming, the chamber had a radial runout of .0005". Post reaming the fire formed cases came out of the chamber with a .006" bulge just forward of the case web, in the same radial location each time. The bulge was such that the case would not rechamber unless it was indexed in the same position that it was shot. A number of fireformed cases were full length sized, reloaded, and fired resulting in the same condition. The gun smith's reply to my enquiry was, "That is part of the risk about going into an existing chamber". My question is, is this a reasonable risk to accept or did something go wrong that should not have been expected and is unacceptable?

Thank you for weighing in on this question.

Geezerbiker · November 2, 2018, 12:46 AM

Personally I think the guy screwed up and isn't owning up to it. This is a common conversion and this is the first one like this I've heard about.

Is it a rifle that the barrel can be set back and the chamber recut?

Tony

NoSecondBest · November 2, 2018, 08:35 AM

Geezerbiker got it right. It's a very common conversion. Not everyone working on guns should be working on guns. Way too many who try and don't mind ruining someone else's equipment.

tango1niner · November 2, 2018, 09:29 AM

I've always thought going from Hornet to K-Hornet to be a fairly simple re-chambering job.

What I am not getting is why the reamer was cutting at that end of the case. If I am not mistaken the shoulder of the chamber is modified, not the case head end. I believe the persons reamer handling technique leaves a little to be desired.

In any case I would probably not let him do any more work on my stuff.

stephen b · November 2, 2018, 09:43 AM

Thanks guys. I appreciate the second opinions. My thoughts exactly. I scoped the chamber and saw a deep gouge in the cylinder wall as well. Something went wrong.
Will probably contact a highly regarded and practiced gun smith to get another "professional" opinion. I will then contact the offending individual with having preformed my due diligence. Seems like the the reasonable thing to do.
Thanks again.

**4V50 Gary** · November 2, 2018, 10:18 AM

This is why you do it by hand very slowly. Sometimes it doesn't take much before it closes on the go gauge.

old roper · November 2, 2018, 11:13 AM

Headspace for 22 Hornet is off the rim.

https://saami.org/wp-content/uploads...-SAAMI_CFR.pdf

Click on above 22 Hornet (page 62)and lower picture give headspace on 22 Hornet.

FrankenMauser · November 2, 2018, 01:16 PM

old roper, I'm fairly certain that 4V50Gary was speaking in general about chamber reaming.
Even so, some rimmed wildcats, like the .22 K-Hornet and nearly any Ackley variant, get set up to headspace on the shoulder. Or, at the very least, must cut material out of the chamber for the new shoulder.

For any of the above, you're still cutting to maintain or achieve proper headspace.

Even though headspace was the topic he addressed, the concept also applies to general chamber reaming: Take it slow and keep control.
Doing dumb things or bringing in power tools when they aren't necessary can result in a ruined chamber - too deep, 'fish-bellied', etc., or chattered, rough, and unusable.

HiBC · November 2, 2018, 04:20 PM

I was not there.I don't know what happened..(I'm not recommending this procedure)

What CAN happen: Reaming under power in a lathe a wrench or tap wrench is used to hold the square end of the reamer.The end of the wrench is rested on a toolin the toolholder to keep the reamer from spinning.

The rotational torque on the reamer gets translated into a deflection force by the wrench. It can cause a reamer flute or flutes to scrape into the side of the chamber.
If you use this method,you might see your reamer jump as you engage the cut.

This can be aggravated by an excessive feed pressure.

The typical gunsmith lathe might have a tailstock that is light duty,old,and less than precise and rigid. A tailstock center in the reamer is not necessarily a solution.

What is needed is a way to hold and drive the reamer that puts no side loads on the reamer.A floating reamer holder might be the solution.The one I bought helps,but it still relies on a wrench.

I've cut some nice chambers by hand with a vise and a Starret tap wrench.The reamer wants to follow the bore.

While I do appreciate the debate over headspacing on the rim vs the shoulder,its a side trip into the weeds.
It has nothing to do with the OP problem.

Scorch · November 2, 2018, 07:28 PM

Quote:

The gun smith's reply to my enquiry was, "That is part of the risk about going into an existing chamber".

Weeeellllll, maybe. Yes, this is part of the risk going into an existing chamber, but a good smith knows how to deal with an existing chamber and make sure he doesn't "egg-shape" the chamber, My bet is that the smith took the K-Hornet reamer and re-cut the chamber using a hand-held reamer holder (instead of taking the barrel off, indicating the chamber, then cutting, then replacing the barrel and headspacing the barrel).

Quote:

My question is, is this a reasonable risk to accept or did something go wrong that should not have been expected and is unacceptable?

I wouldn't expect my customers to accept that kind of work, but maybe he does.

Quote:

If I am not mistaken the shoulder of the chamber is modified, not the case head end.

The whole chamber is recut. The K-Hornet is larger than the standard Hornet at every point ahead of the case web.

old roper · November 2, 2018, 08:47 PM

FrankenMauser, this is from Manson reamer on chambering AI.

How Are “Improved” Chambers Headspaced?

When “improving” a standard chamber, the barrel must be set back so that fireforming may be done safely and proper chamber length achieved. Headspace gages—made with the shoulder angle of the original chamber, but .004”/.006” shorter than standard–are used to check the headspace dimension. A “light touch” should be used when checking headspace of improved chambers.

“Improved” calibers work well when done properly and can offer real performance benefits when compared to factory cartridges. Once the principles of gaging these chambers are understood, cutting improved chambers is no more complex than cutting standard chambers. Please contact us if you have any questions about the principles or processes described in our article on Ackley Gaging. It’s better to ask a question than to ruin a job.

Here is gauges for 22 Hornet.

http://pacifictoolandgauge.com/saami...-go-field.html

Scorch · November 3, 2018, 12:30 AM

Quote:

Here is gauges for 22 Hornet.

Those are not gauges for a 22 Hornet, they are either just a generic picture for illustration purposes or someone got the picture of the wrong gauge. The Hornet is a tapered, slight bottleneck, rimmed cartridge, those are for a short, sharp bottlenecked rimless case like a Fireball or such.

FrankenMauser · November 3, 2018, 02:26 AM

Quote:

FrankenMauser, this is from Manson reamer on chambering AI.

Interesting link. But very few rimmed cartridge require a barrel setback for an AI conversion.
Rimmed AI conversions typically (there are always exceptions - especially for apocryphal "AI"s) require nothing more than reaming the new chamber and stopping when headspace is good - determined by maintaining existing headspace, but cutting the new body and shoulder geometry.

.30-06? Yep, barrel setback.
.280 Rem? Yep, barrel setback.
.243 Win? Yep, barrel setback.
.220 Swift? Yep, barrel setback. (Semi-rimmed, but it doesn't headspace on the rim.)

.303 AI? Nope. Ream and run it.
.22 Hornet? Nope. Ream and run it.
.22 K Hornet? Nope. Same deal.

The determining factor in 'true' AI or other 'improved chamber' conversions is generally whether or not the entire chamber will 'clean up' (get reamed out) by just running the 'improved' reamed in. If not, barrel setback is required. If so, then you're just chasing headspace.
The vast majority of rimmed cartridge "improved" chambers are designed for "ream and hit the range."

F. Guffey · November 3, 2018, 11:45 AM

Quote:

Interesting link. But very few rimmed cartridge require a barrel setback for an AI conversion.

The barrel must be set back if the smith is going to remove all artifacts of the original chamber. Meaning the case body/shoulder juncture on the Ackley Improved shoulder is ahead of the 30/06 case body/shoulder juncture but the shoulder/neck juncture is further back.

What does that mean? The shoulder of the case will not head space on the shoulder of the chamber at the shoulder/neck juncture and the fire formed case will have two different angles on the shoulder.

And there are difference in designs; I understand no one want to hear this but I fired 8mm57 ammo in one of my 8MM06 chambers. to save the few that could have an interest the 8MM57 shoulder was short of the 8mm06 chamber by .127"; and everyone knows if a shooter shoots a round in a chamber with .127" clearance they will experience case head separation.

I exaggerate; not everyone; I am the one that did not fall of that old saying about the firing pin driving the case to the shoulder of the chamber before the bang.

And then there is the reminder about my long chambered M1917, the chamber is .016" longer than a minimum length/full length sized case.

F. Guffey

November 1, 2018, 11:00 PM	#1
stephen b Member Join Date: August 15, 2002 Location: Vashon, WA. Posts: 27	Chamber reaming, 2nd opinion Recently I had a 22 Hornet reamed into a K Hornet. Before reaming, the chamber had a radial runout of .0005". Post reaming the fire formed cases came out of the chamber with a .006" bulge just forward of the case web, in the same radial location each time. The bulge was such that the case would not rechamber unless it was indexed in the same position that it was shot. A number of fireformed cases were full length sized, reloaded, and fired resulting in the same condition. The gun smith's reply to my enquiry was, "That is part of the risk about going into an existing chamber". My question is, is this a reasonable risk to accept or did something go wrong that should not have been expected and is unacceptable? Thank you for weighing in on this question. __________________ stephen b

November 2, 2018, 09:43 AM	#5
stephen b Member Join Date: August 15, 2002 Location: Vashon, WA. Posts: 27	Thanks guys. I appreciate the second opinions. My thoughts exactly. I scoped the chamber and saw a deep gouge in the cylinder wall as well. Something went wrong. Will probably contact a highly regarded and practiced gun smith to get another "professional" opinion. I will then contact the offending individual with having preformed my due diligence. Seems like the the reasonable thing to do. Thanks again. __________________ stephen b

November 2, 2018, 10:18 AM	#6
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,832	This is why you do it by hand very slowly. Sometimes it doesn't take much before it closes on the go gauge. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

November 2, 2018, 11:13 AM	#7
old roper Senior Member Join Date: June 11, 2007 Posts: 2,155	Headspace for 22 Hornet is off the rim. https://saami.org/wp-content/uploads...-SAAMI_CFR.pdf Click on above 22 Hornet (page 62)and lower picture give headspace on 22 Hornet. __________________ Semper Fi Vietnam 1965 VFW Life member NRA Life Member Last edited by old roper; November 2, 2018 at 11:22 AM.

November 2, 2018, 01:16 PM	#8
FrankenMauser Senior Member Join Date: August 25, 2008 Location: In the valley above the plain Posts: 13,424	old roper, I'm fairly certain that 4V50Gary was speaking in general about chamber reaming. Even so, some rimmed wildcats, like the .22 K-Hornet and nearly any Ackley variant, get set up to headspace on the shoulder. Or, at the very least, must cut material out of the chamber for the new shoulder. For any of the above, you're still cutting to maintain or achieve proper headspace. Even though headspace was the topic he addressed, the concept also applies to general chamber reaming: Take it slow and keep control. Doing dumb things or bringing in power tools when they aren't necessary can result in a ruined chamber - too deep, 'fish-bellied', etc., or chattered, rough, and unusable. __________________ Don't even try it. It's even worse than the internet would lead you to believe.

November 2, 2018, 12:46 AM	#2
Geezerbiker Senior Member Join Date: March 20, 2011 Location: Willamina, OR Posts: 1,908	Personally I think the guy screwed up and isn't owning up to it. This is a common conversion and this is the first one like this I've heard about. Is it a rifle that the barrel can be set back and the chamber recut? Tony

November 2, 2018, 08:35 AM	#3
NoSecondBest Senior Member Join Date: December 7, 2009 Location: Western New York Posts: 2,736	Geezerbiker got it right. It's a very common conversion. Not everyone working on guns should be working on guns. Way too many who try and don't mind ruining someone else's equipment.

November 2, 2018, 09:29 AM	#4
tango1niner Senior Member Join Date: March 5, 2009 Location: NY Posts: 317	I've always thought going from Hornet to K-Hornet to be a fairly simple re-chambering job. What I am not getting is why the reamer was cutting at that end of the case. If I am not mistaken the shoulder of the chamber is modified, not the case head end. I believe the persons reamer handling technique leaves a little to be desired. In any case I would probably not let him do any more work on my stuff.

November 2, 2018, 04:20 PM	#9
HiBC Senior Member Join Date: November 13, 2006 Posts: 8,283	I was not there.I don't know what happened..(I'm not recommending this procedure) What CAN happen: Reaming under power in a lathe a wrench or tap wrench is used to hold the square end of the reamer.The end of the wrench is rested on a toolin the toolholder to keep the reamer from spinning. The rotational torque on the reamer gets translated into a deflection force by the wrench. It can cause a reamer flute or flutes to scrape into the side of the chamber. If you use this method,you might see your reamer jump as you engage the cut. This can be aggravated by an excessive feed pressure. The typical gunsmith lathe might have a tailstock that is light duty,old,and less than precise and rigid. A tailstock center in the reamer is not necessarily a solution. What is needed is a way to hold and drive the reamer that puts no side loads on the reamer.A floating reamer holder might be the solution.The one I bought helps,but it still relies on a wrench. I've cut some nice chambers by hand with a vise and a Starret tap wrench.The reamer wants to follow the bore. While I do appreciate the debate over headspacing on the rim vs the shoulder,its a side trip into the weeds. It has nothing to do with the OP problem. Last edited by HiBC; November 2, 2018 at 04:48 PM.

November 2, 2018, 08:47 PM	#11
old roper Senior Member Join Date: June 11, 2007 Posts: 2,155	FrankenMauser, this is from Manson reamer on chambering AI. How Are “Improved” Chambers Headspaced? When “improving” a standard chamber, the barrel must be set back so that fireforming may be done safely and proper chamber length achieved. Headspace gages—made with the shoulder angle of the original chamber, but .004”/.006” shorter than standard–are used to check the headspace dimension. A “light touch” should be used when checking headspace of improved chambers. “Improved” calibers work well when done properly and can offer real performance benefits when compared to factory cartridges. Once the principles of gaging these chambers are understood, cutting improved chambers is no more complex than cutting standard chambers. Please contact us if you have any questions about the principles or processes described in our article on Ackley Gaging. It’s better to ask a question than to ruin a job. Here is gauges for 22 Hornet. http://pacifictoolandgauge.com/saami...-go-field.html __________________ Semper Fi Vietnam 1965 VFW Life member NRA Life Member Last edited by old roper; November 2, 2018 at 08:54 PM.