X2
The 243 AI gains at most 100 fps at the same pressure as a 243 (which no-one employs....), along with the mirage of increased case life (try partial F/L with the 243 first) at the cost of custom dies and fireforming.
.243 to .243AI
- Thread starter slug1977
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The 243 AI gains at most 100 fps at the same pressure as a 243 (which no-one employs....), along with the mirage of increased case life (try partial F/L with the 243 first) at the cost of custom dies and fireforming.
ACKLEY ABE
Regular
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- ST ALBERT, ALBERTA
I totally agree. There are more benefits to an A. I. cartridge other than just an increase in velocity. And yes my comment was sarcastic clued partly by my name.... I have several A.I's from 22.250AI and up and I have no reason to make any part of my anatomy bigger. There are certain carts that really don't benefit from it but no reason to insult someone at any time for that matter.
Yes, I caught that. Just pointing out that no one claims it is magic. It has many great qualities though.
The 243benefits a ton from an AI conversion. I run 105s at 3250 from a 24" barrel, pressures aren't over max, usually hard pressed to get a sammi 243 much over 3000 with a 105 in my experience. 243AI is the second dirtiest trick in rifle cartridges there is.
Most people don't run 243 chambered rifles with barrels longer than 22 inches, which is just about standard length for most off the shelf rifles.
There are a lot of reasons why you are getting 3250fps other than a barrel that's appx 10% longer.
For instance, a tight chamber on the low side of mean dimensions and a shorter throat.
Then again, it may just be you have a rifle that shoots a bit faster, no matter what.
I have two Winchester Mod 70 rifles chambered for the 30-06 Springfield. One of them, the older one shoots just about everything from 150 grain to 200 grain at least 100fps faster than the newer rifle. Both chambers can swap out hand loads and it doesn't have any affect on feeding or accuracy. Just 100fps difference in velocities.
This alone would take care of at least 150fps of your increased velocities.
The older rifle has a much shorter throat and both are factory, off the shelf, rifles.
The AI improvement is beneficial for almost any cartridge a person will hand load. In most cases that's it
I also have a Remington Model 700 chambered in 243Win as well as an identical Model 700 chambered in 6mmRemington. With 105 grain bullets, the 6mm Rem has a definite velocity advantage. The same can't be said about lighter weight bullets.
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In the examples I've owned, this has been the case. - dan
With lighter bullets it seems they will get up around 4k but that seems about it no matter how much powder
You're throwing some miraculous velocity figures out there.
The 243AI version as developed by PO Ackley has an appx 10% powder capacity increase (5 grains). It takes close half of that just to get the same pressure/velocity as a standard 243Win.
I'm wondering if your case is actually a 243AI or another version that's been blown out to to allow even more powder capacity increase, say with a neck that's less than one bullet diameter in length,25-30 degree shldr angle and the sidewall with a 1 degree taper?
I've seen rifles with similar chambers but never shot any of them.
Powder/pressure and velocity increases are not proportional and get further apart as the charge increases.
You don't mention loads but your pressures must close to or way over maximum. Throat/leade erosion is likely very aggressive.
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Mine is a standard ai, never run light bullets out of it. I used to run 55 ballistic tips about 3800 in my 243 sammi. Hard on hide hard on barrels. i more meant a 55g 6mm bullet is hard to get past 4 k period. Ive read of guys running 55s out of a 243ai as fast as 4100.
I see where you're coming from.
IMHO, those velocities are optimistic at best. Doesn't mean it isn't happening though and I would really like to see the pressures being generated doing it.
A chamber and bore will only burn so much powder, until it reaches a saturation point. The smaller the bore the lower the saturation point.
We used to make jokes about necking down the 50BMG to shoot phonograph needles. Possible to do it, but a KABOOM waiting to happen.
IMHO, those velocities are optimistic at best. Doesn't mean it isn't happening though and I would really like to see the pressures being generated doing it.
A chamber and bore will only burn so much powder, until it reaches a saturation point. The smaller the bore the lower the saturation point.
We used to make jokes about necking down the 50BMG to shoot phonograph needles. Possible to do it, but a KABOOM waiting to happen.
