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Do you remember what velocity you ran the 22-250AI at?? How did the 75 grain A-Max perform on ground hogs??
Barrel wear was the main reason I did not go with the AI, and went with the standard 22-250. However if I thought I could have gotten 700 rounds with the AI-then I wish I would have chambered it for the AI.
Also I am leaning toward H-414. What do you think about that?? Tom.
Well... This is kind of a difficult subject for me to get into over a keyboard. Much easier to talk about it than type about it. What makes it difficult, is there are so many variables, and shades of gray in the definitions of the terms we use. I'll give you a real short version here, but realize, there are variables involved that make it entirely likely for someone else to get quite different results.
Some pertinent info about my setup - 29", 8T, Lilja 3 groove barrel. Length, twist, grooves, they all matter.
First, velocity and terminal effect on 'chucks with the 75 Amax... They were doing about 3400 fps MV, and were very effective on the terminal end on 'chucks. VERY effective!
BUT!!! I was only able to use the 75 Amax for about 250 rounds. At that point, full house loads started going "poof" as soon as the barrel got a bit warmed up and fouled. Started backing off the velocity and it helped some but was not really the answer.
Switched to the 80 gr. Berger, at about 3250 fps. Between lower velocity and an apparently stronger jacket they got me back in business again. But... Only for about another 300 rounds. Then they too, started going "poof". Again, I backed off the velocity, and again it helped some, but not really the answer.
So... I switched to the SMK 80 gr. at about 3100 fps. Poor terminal performance, lots of pencil throughs and crawl offs. Plus, they really didn't get me away from the "poofs" for very long either. After only about 150 rounds, I gave up on the barrel.
My opinion, the difference in barrel life between the standard .22-250 and the AI version, in an 8 twist barrel used for the application I just described, would be very little. The "problem", with large capacity, fast twist .22's, is that once the throat gets just a little bit rough, jacket integrity starts to become an issue. And before you know it, you've got "poofs". The problem being, that it really does not take much gator hide in the throat to cause it. It's just that at over 300,000 RPM, it doesn't take much damage to the jacket to cause it to come apart.
But! Like I said to begin, there are some really, really significant variables that can create really significant differences in how things will turn out. I went with a 3 groove on that barrel because my experience with them has been that they resist erosion a bit better than 6 grooves. But! That barrel was rendered pretty well useless long before any really significant erosion took place. With hindsight, I suspect that more, smaller lands would have caused less stress on the jacket and perhaps allowed longer service life. But, that's just speculation on my part. Another really large variable worth mentioning, I think, is the actual twist rate. That barrel of mine was an 8. The 8 is needed to shoot the longer 80's. But, a 9 would have sufficed for the 75 Amax. And the lower RPM of a 9, I am speculating again, would likely have contributed to significantly longer service life. Yet another variable worth mentioning, shot strings. The way I used mine, it routinely shot strings until the barrel got good and hot. Towards the end of it's life, it just would not tolerate being warm or dirty. It would still kill 'chucks all day, as long as it was kept cold and clean. For my hunts, that makes it about as useful as teets on a boar. But for a guy that only takes a few snipes in an evening, it might not matter at all. So I think the manner in which the rifle actually gets used can both accelerate wear, and accentuate what wear there is, or just the opposite, depending on rate of fire and length of string.
There's way more to it, of course. But like I said, it's not a subject I really like to get into over the keyboard. Too much typing, and still too much chance of not being understood.
Bottom line for me though, after messing with a few of them, large capacity fast twist .22's are more PITA than they are worth, to me. But! That 75 Amax sure has a place in the field on windy days. A 9 twist .22BR with a long barrel is what I'll build around that bullet next though. Enough capacity to get over 3000 fps, enough twist to stabilize, but not too much of either. I think it would outlast my 8T .22-250AI several fold.
Oh! Powder... H414 is worth trying. Mine liked RL-22 best though.
- DAA
