Gun Smithing- 270 AI Chamber Question

[FEENIX]

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

I do not think Fred Zeglin provides the reamer blueprint. You can, however, request reamer blueprints from reamer manufacturers such as https://mansonreamers.com/, https://www.jgsprecision.com/, https://www.clymertool.com/chambering-reamers/, etc.

 

[lancetkenyon]

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.

Good deal. Makes it easy.

But, make sure you stick with like brass after you form and start handloading. I would personally not mix headstamps/brands/brass weights. Do you have 100 (or more) loaded rounds of the same factory ammo?

Like others have mentioned, when fire forming to an improved chamber, I usually quickly find an accurate fire forming load and use it to bang steel and have fun, all while getting that first 100 (or more) rounds down the bore to smooth things out. I have even hunted with fire forming loads.

I can't wait to see that first picture of a virgin round next to a fired case! I have always like the idea of a .270AI, especially a fast twist to push the 165/170/175. I think those really bump up the .270 in punching power.

 

[sable tireur]

Just because pictures are usually best suited to explain some processes:

Standard cartridge case in Ackley Improved chamber:

Ackley Improved cartridge case fireformed in Ackley Improved chamber:

The headspace is controlled by the neck and shoulder feature of standard cases minus a .004" shorter chamber to create crush. That's the premise of the Ackley cartridges, factory ammunition or cases fired in an Ackley Improved chamber.

Here is the drawing and explanation for the Ackley Improved process by PTG. Simple and clear.

Enjoy!

 

[59FLH]

The headspace is controlled by the neck and shoulder feature of standard cases minus a .004" shorter chamber to create crush.

This.

 

[59FLH]

I hear some horror stories of Ackley chambers being cut too long and factory brass not head spacing properly for fire forming

I have seen shoulders cut forward to AI with no set back. And I have seen chambers cut with the formula ""backwards" using the parent no go as the go. Both conditions will create a chamber too long.

Sables post is the word

 

[hankle]

Good deal. Makes it easy.

But, make sure you stick with like brass after you form and start handloading. I would personally not mix headstamps/brands/brass weights. Do you have 100 (or more) loaded rounds of the same factory ammo?

Like others have mentioned, when fire forming to an improved chamber, I usually quickly find an accurate fire forming load and use it to bang steel and have fun, all while getting that first 100 (or more) rounds down the bore to smooth things out. I have even hunted with fire forming loads.

I can't wait to see that first picture of a virgin round next to a fired case! I have always like the idea of a .270AI, especially a fast twist to push the 165/170/175. I think those really bump up the .270 in punching power.

Yes, multiple factory loads over 100count. Yes, I'm not a real hi volume shooter, so I nerd out on the reloading. I separate head stamps and group brass by weight.

This one will have 1-8 Douglas premium barrel. I am pumped to see what it will do.

Judging from the few people that have modern 270AI's they seem to be pretty awesome. I discounted the 270AI because the original literature said it wasn't worth it. With fast twist barrels, modern powder, and VLD type bullets; the cartridge reads to be a monster, but time will tell.

 

[26Reload]

Ask MuddyBoots.....let him roar...

 

[hankle]

Just because pictures are usually best suited to explain some processes:

Standard cartridge case in Ackley Improved chamber:

View attachment 450831

Ackley Improved cartridge case fireformed in Ackley Improved chamber:

View attachment 450833

The headspace is controlled by the neck and shoulder feature of standard cases minus a .004" shorter chamber to create crush. That's the premise of the Ackley cartridges, factory ammunition or cases fired in an Ackley Improved chamber.

Here is the drawing and explanation for the Ackley Improved process by PTG. Simple and clear.

View attachment 450836

Enjoy!

Dude thank you for the post! This is the info I needed!

 

[59FLH]

Hankle,, to clarify a bit, the chamber is not shorter it's where the parent go gauge contacts the neck and shoulder junction is .004" shorter. I just went through this on another forum. The few AI chambers I have cut have all been 280AI and I have SAAMI go gauges for that caliber. Im going to cut a non SAAMI 7-08AI later this week and I'm going to do one of a few things

1. If my Manson 7-08AI go gauge arrives in time, use it

If not

2. Grind .004" off the bolt face of a std 7-08 go gauge

or

3. Close the bolt on a minimum chamber with an unmodified std 7-08 go gauge and then face .004" or what's needed off the barrels shoulder and breech face(s) to get the recommended .004" crush at the NSJ.

I hope you and you friend find this advice helpful. Just substitute 270 Win for 7-08

 

[FEENIX]

Just because pictures are usually best suited to explain some processes:

Standard cartridge case in Ackley Improved chamber:

View attachment 450831

Ackley Improved cartridge case fireformed in Ackley Improved chamber:

View attachment 450833

The headspace is controlled by the neck and shoulder feature of standard cases minus a .004" shorter chamber to create crush. That's the premise of the Ackley cartridges, factory ammunition or cases fired in an Ackley Improved chamber.

Here is the drawing and explanation for the Ackley Improved process by PTG. Simple and clear.

View attachment 450836

Enjoy!

Agreed! The pictures speak for themselves in many words.

@hankle check your PM. I have an old .270 Win barrel for your gunsmith to practice on that I can send you if that helps.

 

[nksmfamjp]

I hear some horror stories of Ackley chambers being cut too long and factory brass not head spacing properly for fire forming

I have seen shoulders cut forward to AI with no set back. And I have seen chambers cut with the formula ""backwards" using the parent no go as the go. Both conditions will create a chamber too long.

Sables post is the word

This is only similar to the smith in question as he doesn't "know" Ackley chambers. The pictures above should help him understand and telling him he needs an AI GO gage. Renting from a single source like 4d should help.

 

[VinceMule]

Properly set up, the Headspace gauge used is a Go gauge, minus .004-.006. Go minus .006 is about .010 less than using the No go gauge as the headspace gauge on the AI chamber, which did not work worth a darn in one barrel that I had done this way. He can do the calculations on your action on the headspace gauge protrusion from the back of the barrel. I have used a Redding body die to bump back shoulders on loaded ammo in more than one caliber.

I fire form with 14.6g of Bullseye powder and cream of wheat, and you may forgo the cream of wheat, once fired brass turns out great. Federal brass is soft, don't use it. This method saves you a lot of money and bullets down the barrel. I cool and brush the barrel every 25 rounds.

I like my Ackley chambers set up for a crush fit on the fire-forming case, you will feel slight resistance when closing the bolt. If a case is too tight, I bump the shoulder back just a tad with the full-length sizer....no case stretching.

You can work up a very accurate load for fire forming your brass and hunt with it if you wish.
17 Ackley Hornet, 223 Ackley, 22/250 AI, 6/250 AI, 243 AI, 6 Rem AI, 280 AI were all exceptionally accurate with "forming" loads. I always fire-formed the smaller cases on varmints.

I wish you would forget the "ammo on the shelf" concept, lots of once-fired brass out there in the Winchester brand. If you lose a case now and again, no big deal. A lost case would be where it was work hardened and split at the shoulder with an incomplete fire form, which would be rare unless you used a light fire-forming load with the bullseye.

Forming the cases is nowhere near rocket science.

Tell the gunsmith that he should set up the headspace "tight" on an AI go gauge, NOT loose.

 

[hankle]

Yes sir, I will most likely be using Peterson brass, once I get settled into the rifle. The factory option is really nice, especially if my kids don't reload.

Properly set up, the Headspace gauge used is a Go gauge, minus .004-.006. Go minus .006 is about .010 less than using the No go gauge as the headspace gauge on the AI chamber, which did not work worth a darn in one barrel that I had done this way. He can do the calculations on your action on the headspace gauge protrusion from the back of the barrel. I have used a Redding body die to bump back shoulders on loaded ammo in more than one caliber.

I fire form with 14.6g of Bullseye powder and cream of wheat, and you may forgo the cream of wheat, once fired brass turns out great. Federal brass is soft, don't use it. This method saves you a lot of money and bullets down the barrel. I cool and brush the barrel every 25 rounds.

I like my Ackley chambers set up for a crush fit on the fire-forming case, you will feel slight resistance when closing the bolt. If a case is too tight, I bump the shoulder back just a tad with the full-length sizer....no case stretching.

You can work up a very accurate load for fire forming your brass and hunt with it if you wish.
17 Ackley Hornet, 223 Ackley, 22/250 AI, 6/250 AI, 243 AI, 6 Rem AI, 280 AI were all exceptionally accurate with "forming" loads. I always fire-formed the smaller cases on varmints.

I wish you would forget the "ammo on the shelf" concept, lots of once-fired brass out there in the Winchester brand. If you lose a case now and again, no big deal. A lost case would be where it was work hardened and split at the shoulder with an incomplete fire form, which would be rare unless you used a light fire-forming load with the bullseye.

Forming the cases is nowhere near rocket science.

Tell the gunsmith that he should set up the headspace "tight" on an AI go gauge, NOT loose.