I was just given an old, slightly sporterized, P-17 Enfield which has been re-barreled to 22-250. There are absolutly no markings on the 26" replacement barrel but careful measurements indicate it's a 22-250 chamber. But, after measuring 5 or 6 times with a tight patch and cleaning rod I get 1 turn in 16.5".
All of my reloading and reference books show 1 turn in 14" for the 22-250. I have no experience with "high powered" .22's. Will this rate of twist work? It seems like it would favor very light bullets.
It appears the work on this rifle was done many years ago as it came with an old, steel tube, Weaver K-6 scope, Redfield one piece base, and very unusual steel rings. Could this be a rate of twist that was tried years ago and dropped for the more efficient 1-14" twist?
Any comments appriciated...

Jon

It may be made from a blank made for the 22 LR or Hornet.

I have a High Wall barreled with an old blank made by Buhmiller thats 1-16" and .2228" groove diameter. It's shot the 50 gr .224" Sierra spitzer very well for many years and now also shoots the 40 gr Nosler just as good.

.22 Hornet...now that's an interesting possibility. The groove dia. is about the only thing I haven't measured. I'll slug/mic it today.
Thanks...

Jon

Ought to be a dandy for those little 35-40 grain zippers! I suspect 50 grains will be a good maximum weight, and that 55 grainers will marginally stable at best. My 1:12" .22-250 will shoot 60 grainers well (flat base spitzer), but that's about as far as I'd push it. If you want to play on the extra high velocity end with those very light bullets, you'll have an advantage with the bullets not being subjected to such extreme centrifugal force as they would be in a faster twist.

Good call Savage99!
The slug mic's .22295, .22300, .22303, etc.
My old Lyman manual shows the .22 Hornet's groove as .223 with a 1-16 twist, and all the other CF 22's have a .224 groove and 1-14.
The P-17 is a big, strong action so the slightly large .224 bullet shouldn't be a problem. The condition of the bore is perfect. It's going to be interesting to see how it shoots.
Thanks again for "heads-up" on the Hornet.

Jon

Ricochet...
Thanks for the info. I'll look for some 50g 22-250 factory ammo for the first "test's". If it shoots ok I'll be in the market for a set of dies and new brass. Thanks again...

Jon

You've got something cool and definitely different. Have fun with it!