Did you set the barrel back? Or was the head space longer than factory cartridge?

quote:

Did you set the barrel back? Or was the head space longer than factory cartridge?

If you are asking me my NORMAL procedure when building an AI was to set the barrel back.

There were a few times I had access to an old strain guage system then later the Oehler system and was attempting to get better data as to velocity gains from capacity.

So the test procedure was to take the barrel and chamber it for the std parent. I would cut it tight so the factory case I was using were a crush fit. Then run std loads up until I saw head expansion and recored the pressure data. It could have been 60,000 could have been 70,000 I was just looking for close to a max point that I could try and repeat. Then I would run the AI reamer in far enough to clean the chamber. No set back using the same brand & lott of brass I would increase the load until I reached the earlier pressure data and record both the difference in case capacity and velocity. Trying different powders trying to max velocity from the new capacity. Yes a STD case would have been a little short to headspace in my AI chamber. That was never my plan. I was interested in the capacity and velocity relationships. In the case of the 280 I went 280-280RCBS-280AI-7mmJRS then my 280PDK. Matter of fact that McGowan barrel is still on the 280PDK I took to Namibia in 2007.

I'm sure someone will find fault with my procedure but it did prove to me that the majority of AI gains were pressure (in my opinion from my testing)

As I've said my opinion and a $$ will get you a

I just noticed this thread, and looking for a little humor, my take on the title "Best Ackley Improved Rounds" just kinda struck me as a classic oxymoron.

Thanks for the humor.

KB

I'm surprised that no one mentioned the 22-250 AI. I have two of the 40 degree versions. I put the first one on a 760 Remington pump to make it feed properly. It was a rechambered .222 barrel. The factory case has too much taper to feed properly from the 760 magazine. Rechambering fixed all of the feeding issues. I made up a second barrel for my switch-barrel 700 Remington. An extra 200 fps is a bonus.

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An extra 200 fps is a bonus.
Posts: 378 | Location: Tennessee | Registered: 18 February 2007

I had a MKX factory 22-250 I shot for many years. As it neared it's life I took and ran a 55gr nosler up to case head expansion measured the velocity then took an AI reamer and simply recut the barrel and ran the same test. I saw around 50fI coversion.

Guys the AI's look cool heck I shoot mostly my own imp cases like a Gibbs. If you want one go for it but be realistic. Comparing your velocity to other barrels or posted data and old low pressure rounds tells you very little.