Any testing with the 6BR 40deg shoulder?

[JamesnTN]

This am at 6:00 sharp I'm up and out the door. I packed the HG with the Brux 1-8 twist barrel at 30" with my new chambering. Today's testing was done at 600 yards using a Sierra 107 (old style) bullets seated -.015 and Varget powder. I tested 2 primers the CCI 450 and the F205m. The groups are four shot as I didn't have enough fire formed cases to do 5 shots for 4 different powder charges and two different primers.
Also note I circled the shots that are the 205m and numbered the CCI 450 primers.

Group sizes and charge weight are written on each Target.

Target 1

Target 1 stats

Target #2
Somehow I didn't get one of the shots in the photo sorry for that.

Target #3

Target #4

I decided to push it and upped my charge another .2 from yesterday so this one is at 33.0 and it showed a slight cratering on the primer.

Last I wanted to see how well my fire form load performed at 600 yards this was a load of 30.3 Varget CCI 450 primer Sierra bullet Jammed .010

Now if weather holds out tomorrow I'll test the Hybrids at 600 starting at -.030 from lands

 

[Eric Leonard]

on that 33.o target is where I am not good enough to tell if that one shot is the load the conditions or me,,

sure getting off to a good start,,

 

[Changeling]

Hi James. that last load (30.3gr V) looks awesome on the vertical, you might want to try that load some more playing with the seating. If it (seating) brings the shots back together in horizontal, maybe then some - and + 0.1gr load changes from the 30.3 charge to see if you can pin point what that barrel likes. Right now the barrel looks great and your shooting awesome. I really believe you are into a GOOD thing at this point.

Good luck again tomorrow

 

[Changeling]

I have a front row seat....lol. I chambered this new barrel.
The first suggestion I made was to actually shorten the neck to make the case more balanced to look at. Chamber OAL 1.570" could be adjusted back to 1.510" with an initial trimming of the brass to 1.500". I since have an idea to chamber a BRDX reamer held -.004 with a 6BR gauge. I believe that would take .039" off chamber length as well the case neck.
One thing for sure, if Sam Hall is excited about this 6BR imp it's well worth spending time and $ to investigate. With the initial testing James has done, I'm convinced it's a great case.

Hi Tim, LOL, I didn't know you were the Smith on James's rifle. After seeing the way Mr. Big has been shooting I should have guessed, I know you chambered his.
You better be careful, people start hearing about all this you won't have time to shoot because of the long line of rifles to be chambered going out the door and down the street

 

[JamesnTN]

Hi James. that last load (30.3gr V) looks awesome on the vertical, you might want to try that load some more playing with the seating. If it (seating) brings the shots back together in horizontal, maybe then some - and + 0.1gr load changes from the 30.3 charge to see if you can pin point what that barrel likes. Right now the barrel looks great and your shooting awesome. I really believe you are into a GOOD thing at this point.

Good luck again tomorrow

Thanks, tomorrow is a new day and new test. I'll be shooting the Berger Hybrids seated .030 off and work with loads once again. I have a base line now for those sierras and they did very well. But I'm hoping I can get the Bergers to shoot more so. The batch of Sierras I have once gone are gone for good as they are the old bullets from before when they made changes to their dies. Once I get a handle on the Hybrids, I'll jump into my Vapor Trails and hopefully I'll find something that'll win me matches.

 

[JamesnTN]

I was asked about pressure at 32.8 grains the case didn't show any signs.
This is a 330 grain and you can see slight cratering but still no ejector marks. Temps this am were at 60* so I'm guessing at 85-90 33.0 is going to be tops if not over just have to see

 

[Matt P]

James
Does this case use a standard BR headspace or is it a little longer ?? When I did mine I simply ran a tight neck BRDX reamer into a standard BR chamber until the standard BR case a 0.004" crush.
Do you have any velocity numbers ??
Matt P

 

[JamesnTN]

James
Does this case use a standard BR headspace or is it a little longer ?? When I did mine I simply ran a tight neck BRDX reamer into a standard BR chamber until the standard BR case a 0.004" crush.
Do you have any velocity numbers ??
Matt P

Matt

I'm using a standard BR go Guage with a crush fit. I believe it's .004 crush. Velocities are I think a page back on my 100 yard testing

 

[johara1]

Matt

I'm using a standard BR go Guage with a crush fit. I believe it's .004 crush. Velocities are I think a page back on my 100 yard testing

James, Perfect…………. jim

 

[Changeling]

Thanks, tomorrow is a new day and new test. I'll be shooting the Berger Hybrids seated .030 off and work with loads once again. I have a base line now for those sierras and they did very well. But I'm hoping I can get the Bergers to shoot more so. The batch of Sierras I have once gone are gone for good as they are the old bullets from before when they made changes to their dies. Once I get a handle on the Hybrids, I'll jump into my Vapor Trails and hopefully I'll find something that'll win me matches.

James I have no doubt winning matches will come your way this year. You started with a plan and have been executing that plan to perfection, people who do it that way usually come out on top regardless of the endeavour, so my money is on you. Good luck.

 

[JamesnTN]

James I have no doubt winning matches will come your way this year. You started with a plan and have been executing that plan to perfection, people who do it that way usually come out on top regardless of the endeavour, so my money is on you. Good luck.

Thanks for the kind words and encouragement. I hope your money makes a wonderful return

Now today started a bit earlier than yesterday as I wanted to beat the winds and rain so I was at the range this am at 6:00 sharp setting up and posting the targets down on the 600 yard berm.
Today's test was to work with the Berger Hybrids,Varget and primers F205m and CCI 450. I forgot the MS as my brain really doesn't function well with just 4 hrs sleep.

The targets posted with circles around the bullets holes are the 450 primers and they are also colored. The F205m didn't fair well today as they all shot verticle so I'm unsure what's going on on that. But clearly each target shows just that in a .2 grain increase in charge. Also group sizes are only noted on the 450 primed cases.

Here's the first target of 32.7 grains

Here's the 32.9 load and once again I somehow missed one shot in the photo.

Closeup of the 450 primer group

Now here's the 33.1 load test and again a missing bullet hole. My apologies as I'm trying to get close enough so the groups can be seen.

Closeup of the 450 primer load

Again all shots were done out to 600 yards and even though a couple targets didn't show it they are five shot groups. Today's wind was a head wind from 6-8 mph with temps 65-67*

This pretty much concludes all my load developing on my new case design. I will now test for consistency and go back and test when I get some 85* temps to know how much to adjust my powder charges. The barrel used now currently has 134 rounds thru it and this has been the quickest and easiest barrel to date to find a tune for.

A quick calculation showed a three 5 shot group agg of 1.599 with three different powder charges. Not too shabby

Comments and suggestions are welcomed.

 

[Changeling]

Hi James. Not to shabby at all! There really seems to be something going on at 29 to 33 gr Varget. I believe it would be beneficial (Hopefully) to load a few rounds in that charge area with .010 out, .000, and .005 in to the lands. I know that is not much but sometimes a little becomes a whole lot!
Whatever you do, I wish all the luck to you.

James I deleted the stupid sentence about the vertical.

 

[stretch257]

So my question is, do you think with having factory Dasher brass avalable you would still go with a 40 degree ai or just buy Norma brass?

 

[Jeff Conover]

I built a 6BR-AI on the 6 BR go gage, no crush, and 271 neck, same drawing as Sam Hall's. I also order the sizing die reamer at the same time from Dave Kiff. I fire formed brass the same as for a dasher and started load development. My barrel is a Krieger .236 bore. I cannot get the velocity you guys are getting, maybe my firing pin spring is weak and will have a new one next week, but at 30.8 gr of RL-15 and 30.8 gr of Varget seem just right. 31.3 grains for RL-15 dimpled one out five primers. After firing in a stock that flexed too much I moved the action into a Shehane stock and things came together. I can only test at 100 yards.

1. 30.8 grains of RL-15, CCI 450, Berger 108, 2875 fps will shoot under 1/4 MOA, but not consistently. I would get a .155 then a .290 inch groups. Pushing a patch through the barrel after firing is like cleaning a sewer pipe. Velocities seemed to jump around with fouling.

2. 30.6 grains of Varget, CCI 450, vapor trail 103 or Berger 108, 2905 fps will print under .2 inch a 100 yards and more consistent than RL-15. Velocity stayed more consistent as fouling built. My barrel shoots 30.5 to 30.8 grains of varget to the same point and velocity at 30.6 seemed to be more consistent.

3. Case sizing is critical. 40 degree shoulder case need a better fit to the chamber than a 30 degree shoulder so be cautious on shoulder bump. That is why I ordered a sizing reamer at the same time.

4. Conclusion from my testing. I believe the 6BR-AI case will stay in tune better than the dasher. I was hoping for 2950 fps but didn't get there, but case efficiency is better than the dasher, but not better than the BR case. Looking at the winner circle in 600 yard Benchrest the straight 6 BR is hard to beat, it stays in tune better than the dasher. Guys are pushing 2850-2880 fps with their BR's with 30.0 grains of Varget. The dashers are pushing 2940-2980 fps with 32.5 grains of Varget. I will see how mine shoots at Big Piney 600 match on July 9th and 10th match.

 

[saunaking]

4. Conclusion from my testing. I believe the 6BR-AI case will stay in tune better than the dasher. I was hoping for 2950 fps but didn't get there, but case efficiency is better than the dasher, but not better than the BR case. Looking at the winner circle in 600 yard Benchrest the straight 6 BR is hard to beat, it stays in tune better than the dasher. Guys are pushing 2850-2880 fps with their BR's with 30.0 grains of Varget. The dashers are pushing 2940-2980 fps with 32.5 grains of Varget. I will see how mine shoots at Big Pine 600 match on July 9th and 10th match.

I am finding similar results with mine. 31.2 grains of Varget, with 107 bullet gives me a average 5 shot group of 2920fps. I was as high as 31.6 grains, but started to get slight marks when the weather got over 80 degrees and higher humidity. Ladder tests early this year showed 31.2 - 31.6 was a good window.

 

[SHall]

Guys, for me, the BR-AI earned its keeping this weekend at the Piedmont NC, July 9th match. I shot it in HG. It opened with a 0.837! Despite not the best of condition in the afternoon. Followed by a 2.6, 1.8, 2.7. For a 2.009 four target agg. Interesting that all the targets only had less than an inch of horizontal (side to side). Groupes were all vertical! That means I should be able to tweek it and even shoot better! I worked this load up back in the winter and have not tweeked it in warm or hot weather. It was 95 degrees yesterday. Anyway, this performance proved the 6BR-AI is a keeper! Load was R-15, 31.7g/ Berger Hybrid 105 about 20 off rifling, CCI-450 primers. The barrel is chambered with a true 6BR-AI reamer from PT&G, , no turn .272nk and .125 freebore. Barrel was an old 4groove Lilja 1.250 straight fluted 30 inches long. It use to shoot great as a 6BR, but quit shooting. We set it back less than a quarter inch and rechambered it in the AI. It came back to life! Final verdict: All tests passed with flying colors. Now I am going to test Shiraz's new Norma Dasher brass. I am looking forward to that. I just had a BRUX HV barrel chambered for it with the correct reamer for the Norma brass. Samuel Hall 7/10/2016

 

[Phil]

Good to hear.............and can`t wait to hear your results with the new
dasher brass........


Phil.

 

[SteveOak]

.... case efficiency is better than the dasher, but not better than the BR case.....

Thank you for the informative post.

How are you quantifying case efficiency? Fps/grain of powder?

I'm surprised that the 30 deg shoulder would be more efficient than the 40 deg shoulder.

 

[Jeff Conover]

Steve, you are right..I miss spoke, using the 6 BR as a base line might of been worded better.

Yes, basing fps/grains of powder for efficiency, but also know barrels velocity vary, temp and humidity, and chronographs vary.

My match at Big Piney out 16 targets showed promise...had a 1.289 group and several 4 shot groups @ 1 inch or less with a flier for 1.7, 2.6 and a weather report of a 4.3. I shoot a little too slow and need to pick up the pace and suffer in the mirage.

 

[Grimstod]

Has there ever been a test comparing the BRX to the Dasher?