Before switching to 22 Creedmoor & 22 Benchrest, you may want to read about RPM limits w/ heavy bullets, jacket failure, and bullet blow-ups.
- Thread starter Renomd
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I just started using a GT barrel (7.5-6.5 IIRC) on a 224V build. The thing shoots well...
Gain Twist Barrels work, end of the story,
The fact they are not more popular is an industry issue, very few companies are capable of doing them correctly.
I have at least 6 by my last count, they shoot better, handle multiple bullet weights better and basically have no downside beside availability.
Bartlein is killing it with them.
The fact they are not more popular is an industry issue, very few companies are capable of doing them correctly.
I have at least 6 by my last count, they shoot better, handle multiple bullet weights better and basically have no downside beside availability.
Bartlein is killing it with them.
I am running the 88gr ELDM out of a 26" 5R 1-7" Bartlein in 22BR with no issues. I have just over 1300 rounds out of it so far. Very happy with the performance, lack of recoil, and being able to spot hits and misses at matches.
Getting 3005 fps with H4895 and 3075 fps with Varget. Going to play with some Rl16 soon.
Getting 3005 fps with H4895 and 3075 fps with Varget. Going to play with some Rl16 soon.
Late last year I built a .224 for use with the 95 SMK. They blew up at velocities as low as 3150 in my 28" 7-twist 4-groove Krieger within the first 50 rounds. It's possible that it's made worse being that the bore is a little tighter than spec, I had to get a smaller removable pilot for my reamer for this one barrel. So far I've had better luck with the 88 ELDs through a 1:8" 6-groove that's compatible with my high-elevation (stable and less than 300k RPM).
Searching, Krieger 4-groove tight twists seem to come up in topic more than others. As mentioned, odd-number land configurations, 5R or polygonal style riflings might postpone blowing jackets.
Sure, flat trajectories, little recoil and minimal wind deflection is nice, but I'm discovering it's not worth the headache.
Searching, Krieger 4-groove tight twists seem to come up in topic more than others. As mentioned, odd-number land configurations, 5R or polygonal style riflings might postpone blowing jackets.
Sure, flat trajectories, little recoil and minimal wind deflection is nice, but I'm discovering it's not worth the headache.
<whisper> "gain twist"
Gain twist is a balancing act between jacket distortion and changing the rate of rotational acceleration.
I'm not saying GT doesn't have any merits-- I have a couple of them. However, I'm not totally convinced that the small amount of gain you're limited to with cup&core bullets is going to be the deciding line between blown and not blown bullets. As far as I know the only GT barrels out there are 5r, which doesn't seem to have near as much problems with blowing bullets as 4 or 6 groove barrels anyway.
I'm not saying GT doesn't have any merits-- I have a couple of them. However, I'm not totally convinced that the small amount of gain you're limited to with cup&core bullets is going to be the deciding line between blown and not blown bullets. As far as I know the only GT barrels out there are 5r, which doesn't seem to have near as much problems with blowing bullets as 4 or 6 groove barrels anyway.
To add some more data/experience to this issue.
I've used Hornady 75 gr HPBT bullet for 6-7 years now and over 40,000 of them in that time.
For the past couple years they were all shot through a 24" or 26" 1:8 barrels with a load of 23 gr of 8208 in an ar15 based 'spacegun'. The barrels were all either from WOA or Green Mountain [finished by a smith]. Never chrono'd the load, but it would probably be in the mid to high 2700. Never a blow up.
This winter I've started using a bolt action with 26" barrel and 1:7 twist. The barrels I've used so far are Shilen with 6 groove rifling. Chrono'd the load today - 2820. Through a little over 1000 bullets from a lot made in 2018, one disappears about every 20-30 rounds, sometimes several close together. Through a couple hundred bullets from a lot made in 2019, none have blown up [yet] - including ones with 23.4 gr of 8208 - which should be 2860 or so.
Over on the National Match forum, someone sectioned a H75 and a S77 - the jacket on the S77 was, as I remember, 20% thicker. I think the thinner jacket along with the jacket thickness varying from lot to lot causes the problems with Hornady's bullets - at least with the H75's.
I have two barrels with 5R rifling and am anxious to try them out as soon as my new action shows up.
I've used Hornady 75 gr HPBT bullet for 6-7 years now and over 40,000 of them in that time.
For the past couple years they were all shot through a 24" or 26" 1:8 barrels with a load of 23 gr of 8208 in an ar15 based 'spacegun'. The barrels were all either from WOA or Green Mountain [finished by a smith]. Never chrono'd the load, but it would probably be in the mid to high 2700. Never a blow up.
This winter I've started using a bolt action with 26" barrel and 1:7 twist. The barrels I've used so far are Shilen with 6 groove rifling. Chrono'd the load today - 2820. Through a little over 1000 bullets from a lot made in 2018, one disappears about every 20-30 rounds, sometimes several close together. Through a couple hundred bullets from a lot made in 2019, none have blown up [yet] - including ones with 23.4 gr of 8208 - which should be 2860 or so.
Over on the National Match forum, someone sectioned a H75 and a S77 - the jacket on the S77 was, as I remember, 20% thicker. I think the thinner jacket along with the jacket thickness varying from lot to lot causes the problems with Hornady's bullets - at least with the H75's.
I have two barrels with 5R rifling and am anxious to try them out as soon as my new action shows up.
Raising from the dead. I run a 16.5" Proof 7 twist sending the 95gr SMK 3095 fps with zero issues. And Proofs are known for their deeper grooving vs Bartlein, thus harder on jackets. Soft jacketed Berger hunting bullets? Maybe more of an issue, but target pills of any weight have not given me any trouble up to 3350 fps in the last 3 Proof barrels.
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