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Discussion in 'The Basics, Starting Out' started by summitsitter, Feb 21, 2008.
What is the difference between the regular 22-250 and the 22-250 40degree ackly improved
The Ackley improved has alot less body taper and the 40 deg shoulder which reduces bolt thrust under pressure , extends case life and less trimming due to less brass flow because of the steep shoulder and reduced body taper and also increases velocity because the internal capacity in increased.
I think that the 22-250 is one of the better cantidates for the Ackley improvment because it has so much body taper and steep shoulder , though it already pretty badly overbored the increased capacity realy bennifits the case with heavier bullet in longer barrels like 26-28 inches
Again I am very new to this. Do you have to rechamber your rifle or do anything special to it to make it shoot these Ackley rounds?
Yes, but when you rechamber you can still shoot factory rounds, and the brass comes out in the Ackley shape ready for hotter reloads.
Some smiths will not set the shoulder back when they recut the Ackley chamber adn if done improperly can cause serious headspace trouble and pressure problems when fireforming brass. Rechambering this way is fine so long as you understand the proper way to fire from the new cases and it will actualy give you a little more volume.
A true Ackley chamber causes a slight "crush fit" of factroy ammo, the bolt wil get slightly tight as the bolt closes , this allows you to shoot factory ammo without the trouble of having an excessive head space problem.
What kind of gain in FPS are you guys getting in this Ackley's compare to the regular cartridge, and usually what does it cost for a gunsmith to recamber a rifle.
I don't shoot a 22-250, but here is some info I found for you-
22-250 40 grain=4300 fps
22-250 AI 40 grain=4500+fps
22-250 50 grain=3800 fps
22-250 AI 50 grain=4100 fps
22-250 65 grain=3300 fps
22-250 AI 65 grain=3300 fps
22-250 80 grain=3350? (found these on reloadersnest.com)
22-250 AI 80 grain=3200? (don't ask me)
So it seems to ream it out to AI gains much more with lighter bullets.
My 250AI loves the 50 grainer out of all you listed that's all I shoot. Mine has a 26 in Douglas with a brake. What a gun shoot great groups will try to post loads and targets later today. Fireforming is easy....... Coreygun)
Actualy Tyler , if you were to take a 26" barrel chamber it in 22-250 and shoot a gamot of bullet from 40-90grs keeping an eye on presser signs then set the barrel back 1/4" and rechamber to 22-250 Ackley and shoot the same bullets running up to the same pressures you would see that the Ackley version realy starts to shine with the heavier bullets and slower powders. The added volume with the Ackley improved case along with the more effecient case desgine will push the heavier bullets faster , this is especialy true with older less effecient desgined cases like the 250 Savage (22-250's parent case) , 300 H&H , the good old 30-06 and many others where if you were Ackley improve say a 300 RUM or 300WSM your gain would be minimal in the velocity depertment.
I have a barnard action .22-250AI
and have settled on 55gr Noslers, i went with a 1-14 twist, as i wasnt interested in the larger pills, just flat shooting..... I have had with nosler brass, the 55gr up to 4225 fps, which was HOT in my rifle, the results I have found are on the average, 3990 fps with varget, 4050 with win760 and awesome groupings, I shot a ladder test with 760 at 300m 15 loads .3 up at a time all went in to a group of about .9 or so.....slight impact change to teh right for the last 6 shots..... And I also used IMR 3031 with good results and good velocity but settled on WIN 760, it seems to love it, i am running a pac-nor supermatch bbl on it...