Matt3479, That is awesome !!!! That kind of accuracy would make me question if I had actually shot it. I did watch a guy in one of our matches shoot a 3 shot group alittle larger than that @500 yds, and I was awestruck.. Congrats on the incredible group and excellent shooting, because it's never just the rifle..rsbhunter
The 22bra Thread
- Thread starter urbanrifleman
- Start date
Trust me I hear you there! I’ve lucked out more the once in the past few builds and they make me look like I know what I’m doing!!
urbanrifleman
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I made myself a new barrel for my Kauger. I realized the 7 twist was way over spinning the bullets at the speeds are shooting.
Here is the first workup from the break in.
This is ts15 5 starting at 29.6 in .3 jumps to 31.4. Velocity went from 2955 to 3146. 75 ELDM. Jumping 15 thou.
30.2 and 30.5 had spreads of nearly nothing . Ones and twos. 3050ish.
Here is the first workup from the break in.
This is ts15 5 starting at 29.6 in .3 jumps to 31.4. Velocity went from 2955 to 3146. 75 ELDM. Jumping 15 thou.
30.2 and 30.5 had spreads of nearly nothing . Ones and twos. 3050ish.
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That’s good to know, I really wanted a 7.5 twist but Ibi only offered 7 or 8 twist. I’m glad I went with the 8.
We’re you tearing jackets or what makes you say you were over spinning them?
urbanrifleman
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Just do the rpm math 320k is 3100 RPM with a 7 twist.
You want to be closer to 280k to 290k.
The bullet really doesn't matter. It's just rpms.
urbanrifleman
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I'm not so sure that's true. I've shot both. 22xc is a honey. So easy to tune, and brass is cheap. Feeds from a regular mag too.
30.5 looks like it's money. Good shooting!
urbanrifleman
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I've really enjoyed working out the bugs in the 22 bra. Really there weren't any bugs to work out other than I made the wrong twist barrel. And because I make my own barrels I didn't really mind all the wasted bullets it was a good learning experience. I came out of the other side of 4 or 500 rounds of frustration with a bunch of new knowledge. So now I know what to tell my customers.
I think I'm going to make a 22XC 170 free bore and compare it directly to the 22 bra 150 fb after I get some more groups.
I tell customers everyday that right now with the shortage of 6BR Lapua brass which may never go away the 22xc and 6XC look better and better every day.
Lessons learned hard are lessons not forgotten...
Went through the same process with a faster twist on a Dasher barrel. Went back to an 8 twist and that's where I'm stayin'.
A .22 XC and 88 gr. ELDMs sounds like a winning combination. A .170 free bore should handle that bullet just fine in the XC. Both of my .22-.250 AI barrels are getting long in the tooth and a .22 XC sounds like a good direction to go.
6mm. I gave a 1:7 twist a look and went back to the 1:8. Better groups, better scores with the 1:8.
urbanrifleman
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The 22 BR Ackley is capable of it's fast enough that you don't need any additional twist over it. It really is just about the RPMs. Decide what speed you want to shoot the bullet you're going to shoot and then calculate the RPMs if you're shooting your standard 105s and whatnot at over 3,000 feet per second you don't need any more twist than an eight twist. Once the velocity start to drop with heavier bullets you might need more twist.
The seven twist is really only appropriate for 223 speeds. Everything else is overspun. There is absolutely nothing to be gained from overspending bullets. They don't shoot better they shoot worse.
urbanrifleman
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The most interesting thing is that spin is spin It doesn't matter what the bullet is or the caliber or the cartridge It's simply a calculation of muzzle velocity versus twist equals RPM. You want to shoot the bullets at optimum RPM.
padom
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I have extensive data in both 22BR and 22GT with 1-7 and 1-7.5.. I was getting inconsistent accuracy in both with 7 twist with the heavies....90smk, 90 vld, 88 eld, 95smk and 85.5 ... 80s shot great in the 7 twist in 22br
I changed both my 22BR and 22GT to 28" Bartlein 1-7.5... boring consistency.. stupid accurate..
Here a new load development I did today with my 7.5 twist 22BR with 90smk and 4166... shot a seating depth test as well today...
padom
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I guess your a believer now after letting you know about your RPMs being too high.. rule of thumb is stay under 320,000rpm... I find the sweet spot is in the 290,000rpm range....
urbanrifleman
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tac284
Gold $$ Contributor
Bulletin article from 08 about bullet rpm for those that might be curious like I was. Interesting stuff…
bulletin.accurateshooter.com
Calculating Bullet RPM — Spin Rates and Stability « Daily Bulletin
Most serious shooters can tell you the muzzle velocity (MV) of their ammunition, based on measurements taken with a chronograph, or listed from a manufacturer's data sheet. (Of course, actual speed tests conducted with YOUR gun will be more reliable.) <img src=http://accurateshooter.
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