20 BR Improved

[L.Sherm]

I wouldn't be afraid to try H4895 either, RL16 was the same as H4350 no speed.

 

[martini]

Shot the 20 BRAI for groups for the first time Wednesday. I'm got about 1.5" at 200 yards with 40g Vmax bullets and 8208 or RamShot TAC (four shots in 3/4" first shot was 2" away from the group). Need to increase the powder charge a bit as the hottest loads showed the best accuracy. I haven't chrono'd loads yet so I don't know what velocity I'm looking at.

 

[martini]

What is the velocity, barrel length in your experience with RL15, thanks

About 3600 fps out of a 27" barrel with a muzzle break.

thanks,

Randy

 

[chuckshooter]

I'm going to build one of these 20 br's and need a little help with the free bore dimensions . If anyone has a copy of their print they could share with me and tell me what bullet you shoot would be helpful. My goal is to shoot the 40 grain V-Max because I have over 10,000 on hand. Thanks Jim

 

[L.Sherm]

Zero freebore would work fine with the long neck of a BR case, .020 max.

 

[Terry]

Zero is the right answer. Had a reamer maker tell me .068 he was wrong. Reground to Zero.
Places the base of a 55 gr. Berger in the middle of the neck on a BR case.

 

[moorepower]

Last fall I ordered a 20 BR prefit 1:10 barrel for my custom Savage M12. I already shoot 55g Bergers in my 1:9 20 BR custom Remington and I intended the Savage to shoot 40 - 50g bullets. When I shot the 20 BR Savage barrel using Lapua brass formed for my fast twist 20 BR, I got case ruptures at the shoulder to neck transition. When I measured the brass I found that the shoulder had been moved forward and the shoulder angle was sharpened. So what I believe I have is a 20 BR improved chamber of some variant in the Savage barrel (comparing the cases to my 6mm Dasher it is not a 20 Dasher). So far the barrel maker has ignored my emails to correct this problem so I may end up using the barrel.

The top case is a 20 BR case fired in my fast twist Remington. The second case is a 20 BR formed case. The 3rd from the top is a case annealed and fire formed in the Savage chamber while the bottom case illustrates the issue I had with firing a formed case in the Savage barrel.

Does anyone shoot a 20 BR Improved. If so what do you do for a full length resizing die? I have dies for 22 BR, 6mm BR, 6mm Dasher, and 20 BR.

Any insight would be appreciated.

Randy

That case looks kind of like the 5mc2 or whatever they called it with the round shoulder. Probably isn't but it shure looks rounded to me.

 

[martini]

That case looks kind of like the 5mc2 or whatever they called it with the round shoulder. Probably isn't but it shure looks rounded to me.

I don't believe it is rounded like the McPerson cartridges. Regardless, I shot a 1.1" five shot 200 yard group with the barrel (IMR 8208 and 40g Vmax) and like it well enough so that I ordered a second barrel cut with the same reamer for a heavier Savage project. Given that I have a custom sizer die, I don't see the downside to a second barre.

Randy

 

[CdnHotshot]

My experince with 4350 was the same as Sherms , low velocity. However with 8208 I was pushing the 50 grain Bergers 3,800 fps with my 20 Nitro (20 BR ai). RL15 is capable of pushing the 55 Berger up into the mid 3,700 fps range.

Using IMR8208 with the 50's > what is the min. & max. powder charge for that combination ?

 

[martini]

Using IMR8208 with the 50's > what is the min. & max. powder charge for that combination ?

Unfortunately, I don't have any source for non-custom 50 caliber bullets. I'm not aware of any published data for 8208. I would like like to shot 45-50 grain bullets in my 1:10 barrels but bullets in that weight range are not readily available as far as I know.

 

[CdnHotshot]

20BR IMPROVED > 50gr Bergers and IMR8208 which was very promising for accuracy and velocity.
29.2 grains avg. 3646 fps ES30.0 SD12.00 1.384" group @ 200 yards
29.5 grains avg. 3670 fps ED21.0 SD 9.00 1.004" group @ 200 yards

Compared to:
32.0 RL15 avg. 3658 fps ES35 SD12.0 .835" group @ 200 yards
33.9 H4350 avg. 3640 fps ES65.0 SD25.0 .982" group @ 200 yards

IMR8208 ...is the fastest powder of the three and yielded the lowest ES and SD and will be my focus as I move toward choosing a pet load.
This goes against the thoughts of some who preferred slow burning powders for this calibre.