Any testing with the 6BR 40deg shoulder?
- Thread starter Changeling
- Start date
SHall
Silver $$ Contributor
Jim, that would work if you have your reamer made with the same dimensions as a Dasher at the body/shoulder junction which is about .460 diameter. Most Dasher dies resize to .459. My reamer has a .463 body/shoulder junction diameter. My die resizes to .462 there. I will have to admit the easiest most economical thing to do would be to have a 6BR-AI reamer made with the same dim. as the Dasher-.460. But my original "prototype" chamber made with 2 reamers was already bigger than that at .463, so I stayed with that dimension on my reamer. Mine also has has less body taper and maybe slightly more powder capacity. Probably wont make a hill of beans (or powder) difference in the real world, but sounds good on paper! Samuel
Phil
Gold $$ Contributor
Funny thing about all this is I asked about doing this exact thing years ago, I was really new to all this at the time, and all I received was the standard negativity.......special dies, case forming....etc.
I am really glad that Samuel decided to try it out, it resurrected the project for me, I think it would also be interesting to see it in .22 and .20 Cal.
I built a .22 BRDX for varmints but I think the 22BR 40* would have been a really good one too, maybe better............
Can`t wait to hear more results and ideas from this..
Phil.
I am really glad that Samuel decided to try it out, it resurrected the project for me, I think it would also be interesting to see it in .22 and .20 Cal.
I built a .22 BRDX for varmints but I think the 22BR 40* would have been a really good one too, maybe better............
Can`t wait to hear more results and ideas from this..
Phil.
Sam, just had a JGS Dasher reamer reground to 6mm imp. same specs .460 shoulder so it is a D3 Harrells die it was made for to start with. So i just have to cut a little off the bottom……… in fact it is on the way now …….jim
SHall
Silver $$ Contributor
Guys, I am still happy and shooting the AI. Shot it a 600 yard match this month. I had a few groups in the "1's" but not consistent enough. I could tell it was out of tune right away. Temps were much higher than they were when i when I tuned it back in the winter. I shot yesterday over a chrno at 500 yards. My velosity was lower than it was prior, probably due to bearrel getting broken in. Vel was 2920 with same load that was shooting 2980- in cold weather. i bumped the R-15 load from 32.3 to 32.7. Velosity was 3003fps. I messed with the seating depth as I was still getting a little vertical. I was 10 thou off rifling with Hybrids, the groups shrunk up at 30 thou off. After tuning groups went from 1.7 inches to 0.765! I was satisfied! Samuel Hall
Hi All
Last week I rechambered my BRDX to a 6BR AI using a BR and BRDX reamers. I managed to get the range yesterday and was very pleased with it's performance, only had a chance to shoot 2 x 5 shot groups at 800M, it held around 3.5" in elevation, velocity using 108 Bergers with 31.8 of Varget gave 2980 and 32 gave 3002 both had single digit ES. The big thing for me was the case forming, you can produce excellent quality brass with out all the hassel, every time.
Matt P
Last week I rechambered my BRDX to a 6BR AI using a BR and BRDX reamers. I managed to get the range yesterday and was very pleased with it's performance, only had a chance to shoot 2 x 5 shot groups at 800M, it held around 3.5" in elevation, velocity using 108 Bergers with 31.8 of Varget gave 2980 and 32 gave 3002 both had single digit ES. The big thing for me was the case forming, you can produce excellent quality brass with out all the hassel, every time.
Matt P
I did some testing with my own designed reamer today basically fireforming and barrel break in. My reamer numbers are different than those here shooting but still with same 40* shoulder angle.
Below are results only of fireforming and now I have enough formed cases to actually load develope. If load developing is any indication as fireforming I may have something here.
First picture are 3 five shot groups at 100 yards fireforming cases.
Next photo is a six shot group fireforming as well.
Here is a chronograph snapshot of a fireform load shot today. Yes velocity is down and that's ok I didn't want to blow out the primer pockets on my first shot thru the case. Goal is to achieve 2900-2950 accuracy node.
Shot cycle was I used one each of the five previous fireform loads to use as a fouler and then I shot five fireforming loads and then cleaned. And started over for the four groups posted.
Powder used was Varget at 30.3 CCI 450 primer a brux 1-8 twist barrel at 30" and a Sierra 107 jammed .010
Tomorrow's test loads will start at 32 grains and work up to 32.6 in .2 grain increments.
Below are results only of fireforming and now I have enough formed cases to actually load develope. If load developing is any indication as fireforming I may have something here.
First picture are 3 five shot groups at 100 yards fireforming cases.
Next photo is a six shot group fireforming as well.
Here is a chronograph snapshot of a fireform load shot today. Yes velocity is down and that's ok I didn't want to blow out the primer pockets on my first shot thru the case. Goal is to achieve 2900-2950 accuracy node.
Shot cycle was I used one each of the five previous fireform loads to use as a fouler and then I shot five fireforming loads and then cleaned. And started over for the four groups posted.
Powder used was Varget at 30.3 CCI 450 primer a brux 1-8 twist barrel at 30" and a Sierra 107 jammed .010
Tomorrow's test loads will start at 32 grains and work up to 32.6 in .2 grain increments.
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Well now I have enough cases fire formed, today I started load work up and still dong barrel break in waiting on it to either speed up or slow down once it hits it's seasoned point.
Today's loads start at 32.0 of Varget and go up to 32.8 in .2 grain increments using a CCI 450 primer and a Sierra 107 bullet.
Here are my 100 yard results testing today what I call the 6 JDP cartridge.
After testing I cleaned the barrel good and decided I wanted to shoot five more fire form loads so I shot one fouler shot and then five fire form loads. The one shot is the bottom bullet hole and the top group are the five shots.
Tomorrow I'm going to 600 yards and do a test with the top 3 loads using the CCI 450 and a Fed 205m primer and will post those results as well.
Today's loads start at 32.0 of Varget and go up to 32.8 in .2 grain increments using a CCI 450 primer and a Sierra 107 bullet.
Here are my 100 yard results testing today what I call the 6 JDP cartridge.
After testing I cleaned the barrel good and decided I wanted to shoot five more fire form loads so I shot one fouler shot and then five fire form loads. The one shot is the bottom bullet hole and the top group are the five shots.
Tomorrow I'm going to 600 yards and do a test with the top 3 loads using the CCI 450 and a Fed 205m primer and will post those results as well.
Hi James, that is some nice shooting. How did the pressure look at 32.6 and 32.8gr Varget? You broke your goal (and then some). I can't help but wonder if the full cartridge potential has been reached or not!
This is more exciting then waiting for a series Zombie episode on TV. Good luck Wednesday
I hope Tim and Sam Hall see this and comment.
This is more exciting then waiting for a series Zombie episode on TV. Good luck Wednesday
I hope Tim and Sam Hall see this and comment.
What pressure? Really primers where still rounded no cratering no extractor marks. Primer pockets are tight. 32.8 is at bottom of the neck with a moderate slow pour with a long drop tube. I'm considering testing a 33.0 charge tomorrow as well as the 32.4, 32.6 and 32.8 charges.
tclaunch
Silver $$ Contributor
I have a front row seat....lol. I chambered this new barrel.Hi James, that is some nice shooting. How did the pressure look at 32.6 and 32.8gr Varget? You broke your goal (and then some). I can't help but wonder if the full cartridge potential has been reached or not!
This is more exciting then waiting for a series Zombie episode on TV. Good luck Wednesday
I hope Tim and Sam Hall see this and comment.
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.
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could you stop the BRDX reamer short then run a BR reamer in to get the neck length back?? I assume you would have to shorten my BRDX FL dies to size such a round??
tclaunch
Silver $$ Contributor
Starting from scratch, I'd chamber the 6BR first if you didn't want to shorten the OAL. Then run the BRDX in like Sam explained. Initially I was in the dark about being able to use a BR gauge since the angle was different on the 2 reamers.
I would like to hear from Sam on how long the OAL is on the 6BR Improved 40* case after fire forming,,myself I like as long a neck as I can get,,if you can get the chamber neck length .010 longer than Sams fireformed BR40* Improved I just might try that with the zero freebore project,,
I wonder what a 6BR Improved 40* with zero freebore and a 14 twist 28 inch 1.250 straight cylinder bbl would do with the 58 VMax or 60 Sierra Vraminteer,,or maybe Barts 65 BTs,,60 class bullets shooting ones at 3800+ fps sounds interesting,,
I wonder what a 6BR Improved 40* with zero freebore and a 14 twist 28 inch 1.250 straight cylinder bbl would do with the 58 VMax or 60 Sierra Vraminteer,,or maybe Barts 65 BTs,,60 class bullets shooting ones at 3800+ fps sounds interesting,,
SHall
Silver $$ Contributor
Guys, I have learned a few important things about this BR AI case since I started this experiment last October. Most importantly the true AI case's headspace is 4 thousands less than the parent case! This is so you get a "crush" on the neck shoulder junction of the parent case, to eliminate any headspace issues when fireforming. There were three of us that ordered reamers from Dave Kiff, we recieved "go-Gauges" that were 6 BR's with 30 degree shoulders instead of the AI's 40 degree. Dave explained to us the go gauges for the AI are designed like the pareent case ,but 4 thou shorter for the reason I stated above. The original barrel I experimented with using 2 reamers (BR and BRDX) actually headspaces 8 thou more than the true AI should. It shoots great! I just have to run my Whidden FL resizing die out a little and check shoulder bump everytime I resizes cases for it. I don't recommed the 2 reamer chambering. It was just for an initial test to see if I actually wanted to go all out with reamers, dies, and all on this case. And yes, I still love it. I plan on my future barrels being chambered for it. It is a no turn and saves so much time and effort over the Dasher and shoots great for me! Now, if I can just make some more matches! Samuel Hall
tclaunch
Silver $$ Contributor
The beauty of this to me is the crush fit, so no more false shoulder or jamming to fireform. James made me a video, as I was so curious how the standard BR case fit the new chamber. I was pleased, but will make an adjustment and not go the full -.004" in the future, more like -.002" This crush fit cannot be taken advantage of using 2 reamers like Sam explains. To answer your die question, yes it would need more taken off the bottom.
awesome stuff,,the pic of James`s case is exactly what I been wanting or at least something very close,,just a straight BR case Ackleyiezd with a 40* shoulder kinda like PO Ackley would have done it,retaining the long neck,,
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