Gun Smithing- 270 AI Chamber Question

[hankle]

I Just dropped my Rem 700 off at the smith for trueing, new barrel, and chambering. I'm going with 270 AI.

I hear some horror stories of Ackley chambers being cut too long and factory brass not head spacing properly for fire forming. Some have to jam the lands to fire form. My choosing of this cartridge was based on a surplus of factory ammo. It would be a terrible waist if my chamber turned out bad.

I'm renting the reamer and gauges from 4drentals.com Does this come with a print/schematic that will help guide my smith?

To be clear my smith is a very talented machinist. He is a full time machinist and has patents on suppressors. He did my target rifle and it turned out great. He just doesn't have experience with Ackley chambers.


What information should I get him to make sure everything goes well? Or am I worrying for no reason?

 

[budlight]

I can't find it on Saami https://saami.org/wp-content/upload...99.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

But my 270 win ai uses redding dies and it's a wonderful cartridge. I had mine throated an additional .300 for super long vld bullets 169.5 & 175 grain. It makes it a single shot. I use full powered 270 ai win loads to fire form. It's like 4 grains above max loaded 270 win. Using R-26 or retumbo

 

[Weaver93]

P.O. Ackley – His Work and Life.

ackleyimproved.com

Chambering for Ackley Cartridges – P.O. Ackley

ackleyimproved.com

Interesting site and book. I doubt your guy will have problems. 4D is the supplier listed on Ackley site.

I have several AI ctgs and like them all.

 

[lancetkenyon]

What is wrong with jamming the lands to fire form?

 

[Weaver93]

What is wrong with jamming the lands to fire form?

I think he is worried he can't do that with the pile of factory ammo he has.

 

[hankle]

What is wrong with jamming the lands to fire form?

It is my understanding that if the chamber is cut correctly the AI should have a .004-.006 crush fit to the neck/shoulder junction on the factory case.

If the chamber is too long, you can't head space factory brass. This negates the original intention of the improved cartridge.

 

[FEENIX]

I Just dropped my Rem 700 off at the smith for trueing, new barrel, and chambering. I'm going with 270 AI.

I hear some horror stories of Ackley chambers being cut too long and factory brass not head spacing properly for fire forming. Some have to jam the lands to fire form. My choosing of this cartridge was based on a surplus of factory ammo. It would be a terrible waist if my chamber turned out bad.

I'm renting the reamer and gauges from 4drentals.com Does this come with a print/schematic that will help guide my smith?

To be clear my smith is a very talented machinist. He is a full time machinist and has patents on suppressors. He did my target rifle and it turned out great. He just doesn't have experience with Ackley chambers.


What information should I get him to make sure everything goes well? Or am I worrying for no reason?

I have a .270 AI and never had any issues. I ended up with load development for a .270 Win and .270 AI.

 

[hankle]

I have a .270 AI and never had any issues. I ended up with load development for a .270 Win and .270 AI.

Yes sir, I trusted your PM, I just want as much info as possible.

 

[FEENIX]

I can't find it on Saami https://saami.org/wp-content/upload...99.4-CFR-Approved-2015-12-14-Posting-Copy.pdf

It's because it is still wildcat/non-SAAMI approved.

 

[lancetkenyon]

I am pretty well versed in AI and other Improved chambers. I have/had/shot numerous AIs (and other "Improved" cases).
.22-250AI
.243AI
.250AI
.25-06AI
.260AI
6.5-06AI
6.5-.270AI
6.5-.280AI
.280AI
.30-06AI

6.5SLR
6.5SS (long before 40° brass was available)
6.5PRC/SI
6.5 Sherman Max
7SS (before 40° brass was available)
7 Sherman Max
7-.300 Norma Mag Imp 35°
.300 Norma Mag Imp (33°, 35°, & 40°)
.338 NMI (35°)

Probably some more I can think of right now.

But my question still stands. What is wrong with seating to the lands for fire forming? Unless it is for the fact you want to shoot factory ammo for your fire forming loads. Then I understand why you can't do this.

Most "Improved" cartridges are a slight crush fit. Your .279AI should be .004" shorter. I know I can always feel significantly tight chambering of virgin larent case brass when fire forming.

As long as your gunsmith is competent, you will be fine. But good to verify, as you are doing here.

 

[hankle]

I am pretty well versed in AI and other Improved chambers. I have/had/shot numerous AIs (and other "Improved" cases).
.22-250AI
.243AI
.250AI
.25-06AI
.260AI
6.5-06AI
6.5-.270AI
6.5-.280AI
.280AI
.30-06AI

6.5SLR
6.5SS (long before 40° brass was available)
6.5PRC/SI
6.5 Sherman Max
7SS (before 40° brass was available)
7 Sherman Max
7-.300 Norma Mag Imp 35°
.300 Norma Mag Imp (33°, 35°, & 40°)
.338 NMI (35°)

Probably some more I can think of right now.

But my question still stands. What is wrong with seating to the lands for fire forming? Unless it is for the fact you want to shoot factory ammo for your fire forming loads. Then I understand why you can't do this.

Most "Improved" cartridges are a slight crush fit. Your .279AI should be .004" shorter. I know I can always feel significantly tight chambering of virgin larent case brass when fire forming.

As long as your gunsmith is competent, you will be fine. But good to verify, as you are doing here.

But my question still stands. What is wrong with seating to the lands for fire forming? Unless it is for the fact you want to shoot factory ammo for your fire forming loads.

Yes sir, a surplus of a factory ammo and brass is why I chose the cartridge. Not to mention the availability of 270 win ammo on the shelf.

 

[ButterBean]

Hog Wash, you will have no problem fire forming

 

[FEENIX]

But my question still stands. What is wrong with seating to the lands for fire forming? Unless it is for the fact you want to shoot factory ammo for your fire forming loads.

Yes sir, a surplus of a factory ammo and brass is why I chose the cartridge. Not to mention the availability of 270 win ammo on the shelf.

Nothing! And I believe that is also what Lance is saying in #4. BTW, I appreciate your PMs.

 

[xsn10s]

4D rental has the 270 Ackley go nogo gauges so your smith should be fine.