How did gunsmiths typically Ackley a factory chamber?

[effendude]

Sorry if this gets long... An older buddy of mine has a Rem 700 25-06 that was ackley'd by a local gunsmith when he lived in Arkansas. Ackley is stamped under the factory 25-06 stamping on the barrel so I know it wasn't set back and rechambered fresh. He never shot the rifle for 20+ years until yesterday. We went to set up his Redding custom reloading dies and the fireformed brass is about .008 larger than unfired brass at the web. I darn near got it stuck in the body die and didn't even get all the way to the base with the stroke. I told him he can't shoot the rifle until we set it back or rebarrel. You can see how large the web and case body are compared to an unfired with the naked eye.

I suspect the smith just ackely'd the oversized factory chamber and didn't give it another thought. Only other way this could have happened is with the reamer was wobbling or something went wrong? Did smiths commonly just run the ackley reamer in by hand to modify the chamber or were the barrels removed and chucked up? I suppose both operations would work. Rifle is 30+ years old so there is no recourse other than setting back or rebarreling. This is driving my older OCD afflicted buddy crazy so I'm helping him get some answers.

Thanks,
Scott

 

[gunsandgunsmithing]

Since it's a wildcat, there really is no set in stone specification but the way Ackley designed his chambers is for the barrel to be set back to where the new chamber would give a .004 crush fit at the neck/shoulder junction of the parent case. More specifically, the Ackley chamber at the neck shoulder junction is .004 shorter than the parent. The amount of crush depends on brass tolerances but the idea was and is to have an interference fit at this area so that the case doesn't drive forward when the firing pin hit is, causing brass stretch at the web area. .004 is the common number used and is the difference between most if not all headspace go and no go gauges used for any Ackley I can think of. This is where and why using the parent case's go gauge as the AI no go comes from.

Lots were done without a setback. It can be done but is not the proper way to do it.

 

[PigButtons]

Since it's a wildcat, there really is no set in stone specification but the way Ackley designed his chambers is for the barrel to be set back to where the new chamber would give a .004 crush fit at the neck/shoulder junction of the parent case. More specifically, the Ackley chamber at the neck shoulder junction is .004 shorter than the parent. The amount of crush depends on brass tolerances but the idea was and is to have an interference fit at this area so that the case doesn't drive forward when the firing pin hit is, causing brass stretch at the web area. .004 is the common number used and is the difference between most if not all headspace go and no go gauges used for any Ackley I can think of. This is where and why using the parent case's go gauge as the AI no go comes from.

Lots were done without a setback. It can be done but is not the proper way to do it.

You sir, along with quite a few others, are truly an amazing knowledge base. Answers like this is why I'm proud to be a paying member here.

 

[jepp2]

Lots were done without a setback. It can be done but is not the proper way to do it.

I bought one of those. Tried to find out before I bought if the barrel had been set back when it was re-chambered. Seller didn't know, gunsmith deceased. So I took a chance. I could tell from my supply of cases I have in various case head to datums it was LONG. So I picked the longest cases, sized without a shoulder bump (which move the shoulder even longer). Fired 20 and 16 showed the stretch marks of incipient case head separation.

Off to my smith, instead of the -0.004" HS, it was + 0.016" HS. So I basically had 0.020" headspace that it shouldn't have. But the case at the web was fine.

 

[dakor]

Like stated above the case should be .004 shorter than the parent.

 

[effendude]

I measured my buddy's loaded unfireformed brass. He was loading them exceptionally long by mistake and was creating a hard jam. This allowed the cases to fire. His gunsmith just ran the reamer into the factory chamber, which sadly was oversized to begin with. Anyone need an Ackley'd tomatoe stake?

Scott

 

[wwbrown]

I measured my buddy's loaded unfireformed brass. He was loading them exceptionally long by mistake and was creating a hard jam. This allowed the cases to fire. His gunsmith just ran the reamer into the factory chamber, which sadly was oversized to begin with. Anyone need an Ackley'd tomatoe stake?

Scott

Just passing the Ackley reamer into the factory chamber does not allow for the crush on the shoulder that allow Ackley cartridges to fire the non-ackley ammo without a problem. Passing the ackley reamer in without setting the barrel back sometimes creates a need for fire forming like done for a Dasher, which your friend did when he seated the bullets long.

 

[cj8vet]

Curious, and just to possibly add some trivia-I had heard that it was OK to just run the ackley reamer in a hornet with no setback, true?/False?
Mark

 

[jackieschmidt]

Years and years ago, there were a lot of factory barrels that gunsmiths simply ran the Ackley reamer in, being careful to stop it before any serious consequences occurred when firing a true factor round in the Rifle.

Back in the ‘60’s and ‘70’s, there used to be a kit you could buy that included the reamer, a T handle, and a headspace gage that allowed shooters to ream their own ackley chamber by hand without even removing the barrel.

There was also a similar kit that allowed shooters to convert their 8mm surplus Mauser into a 8mm ‘06.

When I was in high school, a machinist friend of my Dad had several of these kits. He did quite a few rifles, the most popular being the 30/06 Ackley.

I doubt anybody markets anything like this now, the liability is simply too great.

Hey, they worked.

 

[ckrifles]

Curious, and just to possibly add some trivia-I had heard that it was OK to just run the ackley reamer in a hornet with no setback, true?/False?
Mark

The Hornet case is a rimed case and so HS off the rim. Chambering without setting the barrel back should not be a problem.