The 22bra Thread

[padom]

What made you choose the 28.7gr load over the 30.2gr load? The 30.2gr load produced a smaller group in your initial test.

The speed. I was trying to mimic my 90smk 220TB load as I sold my 220TB and switched to 22BR. Mainly for better dies availability and brass.

So I wanted to be in that 2950-3000 range. And the 30.2gr losd was starting to show pressure

Also, almost 3100 with a 90 in 22BR is cooking.

 

[papa]

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...

https://imgur.com/Q4oD1i2

https://imgur.com/MNGuMe4

Calculating bullet spin and comparing that to bullet stability on Berger's website gives conflicting data. 85.5 berger hybrid 3150FPS in a 1:7.5 twist barrel at 40 degrees temp at 200' above sea level results in a marginally stable bullet with a SG of 1.39. Drop the barrel twist to 1:7 you have a SG of 1.60 comfortably stable. Comparing same data as above the 1:7.5 twist has 302,400 rpm's vs 1:7 twist has 324,000 rpm's. To me this is conflicting data.

 

[CA48]

Calculating bullet spin and comparing that to bullet stability on Berger's website gives conflicting data. 85.5 berger hybrid 3150FPS in a 1:7.5 twist barrel at 40 degrees temp at 200' above sea level results in a marginally stable bullet with a SG of 1.39. Drop the barrel twist to 1:7 you have a SG of 1.60 comfortably stable. Comparing same data as above the 1:7.5 twist has 302,400 rpm's vs 1:7 twist has 324,000 rpm's. To me this is conflicting data.

85.5gr bergers have been shooting fine out of my 18” 22arc bolt gun at 2833fps so far with a 7.6” twist. DA 900ft 40*, SG is 1.38. It’s shoots the 88eldm well also at 2670fps with factory ammo.

 

[papa]

85.5gr bergers have been shooting fine out of my 18” 22arc bolt gun at 2833fps so far with a 7.6” twist. DA 900ft 40*, SG is 1.38. It’s shoots the 88eldm well also at 2670fps with factory ammo.

See, there is the conflict. Go to Bergers website and put those numbers into the bullet stability program and it will show that your bullets would be marginally somewhat stable at your muzzle velocity and twist rate. I'm building a long range prone rifle 30" barrel 7 twist 6BRX with the plan of using the 85.5 hybrids at 3050 to 3150fps. Bergers bullet stability calculation software says that this combination is good to go but using the RPM formula I will be over spinning these bullets at 40F even worse during the summer when temps reach 85-90F. I guess only testing will tell the real story.

 

[Matt_3479]

Calculating bullet spin and comparing that to bullet stability on Berger's website gives conflicting data. 85.5 berger hybrid 3150FPS in a 1:7.5 twist barrel at 40 degrees temp at 200' above sea level results in a marginally stable bullet with a SG of 1.39. Drop the barrel twist to 1:7 you have a SG of 1.60 comfortably stable. Comparing same data as above the 1:7.5 twist has 302,400 rpm's vs 1:7 twist has 324,000 rpm's. To me this is conflicting data.

I run the 85.5’s in a 1:8 with great results

 

[papa]

Well, if the 1:7 barrel doesn't work out I have ordered a Kreiger 1:7.7 barrel. I'll just have to chamber that one and use it. My current barrel is a straight 22BR so I may just try that 1st and see if I can find a good node in the 2950-3000FPS. If that doesn't work I may look into using the 90gr SMK or the 90gr VLD's. It's all a guessing game right now.

 

[Deputy819]

That Berger calculator has to be taken with a grain of salt. It told me that at my altitude, speed, twist, etc, etc that I’d only be moderately stable with the 80gr SMK at 3050fps in my 8-twist @urbanrifleman 22-BR-A barrel. I finished fire-forming my last 10 cases on Tuesday and had no trouble putting 10 shots into a half-minute at 200 yards. I’ll take that kind of “moderacy” all day. Oh, I was NOT adjusting for wind at all…which was 10-12mph and slightly cross.

 

[urbanrifleman]

See, there is the conflict. Go to Bergers website and put those numbers into the bullet stability program and it will show that your bullets would be marginally somewhat stable at your muzzle velocity and twist rate. I'm building a long range prone rifle 30" barrel 7 twist 6BRX with the plan of using the 85.5 hybrids at 3050 to 3150fps. Bergers bullet stability calculation software says that this combination is good to go but using the RPM formula I will be over spinning these bullets at 40F even worse during the summer when temps reach 85-90F. I guess only testing will tell the real story.

Honestly that Berger thing is a total piece of junk.

 

[urbanrifleman]

That Berger calculator has to be taken with a grain of salt. It told me that at my altitude, speed, twist, etc, etc that I’d only be moderately stable with the 80gr SMK at 3050fps in my 8-twist @urbanrifleman 22-BR-A barrel. I finished fire-forming my last 10 cases on Tuesday and had no trouble putting 10 shots into a half-minute at 200 yards. I’ll take that kind of “moderacy” all day. Oh, I was NOT adjusting for wind at all…which was 10-12mph and slightly cross.
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Doping for a cross that is a nickel or less.