6BR load development

[Cody Richardson]

So last week I shot my new F-Open rifle, straight jane 6BR on a Remington 700 with 30' 1.250 Bartelin 1-8 twist. The load was 30.0 of Varget with CCI 400's behind a 105 Hybrid .010 off the lands. Shot a 196-6, not bad for the first 25 rounds out of the gun. It was roughy 84-86 degrees that day. Today, shot the same load, shot a 198-6 and 198-10, today was around 96 degrees. I had most rounds showing slight signs of cratering, but I had 3 rounds with a excessive crater and clear gas blow black causing the the crater to turn black. How much would you back off to start. I hate to lose a good load to over pressure but I needs to be backed off a bit I think.

 

[jr600yd]

.3 of a grain

 

[L.Sherm]

just a thought but have you tried CCI 450's

 

[Danley]

450's give great results for a lot of guys, plus harder cups.

 

[ShootDots]

Your load would not "normally" be excessive in Texas which is at least as hot as where you were shooting. If I had to guess, which is what anyone can do at this point, is that you have a 100 Freebore and a .236 barrel. Hybrids have a pretty long bearing surface and with a .236 bore you could end up with pressure. You basically have 3 options: 1.) go to a 105 Berger boattail, 105 Lapua Sceanr or a 107 SMK>>>all have MUCH SHORTER bearing surfaces than the Hybrid; 2.) back off the load or go to a bit of a slower powder; or get your 'smith to elongate the throat out to about a 120+ freebore if you still plan on using the hybrids.

Personal recommendation: Throat out the barrel and back off the load somewhat and work back up...

 

[Cody Richardson]

I checked my reamer print and it is a freebore of .100, so I think this winter I will have my smith throat it out to .120. However in the mean time I need to find a happy medium. The weather for next weekends match is a low of 52 and a high of 76 so I may try the same load in the milder weather and see if it still still has signs of pressure. Do you think the 450's would help reduce some of the pressure, even though they are magnum primers?

 

[L.Sherm]

I could be all wrong on this BUT my understanding is the 450's have just a harder cup and will take pressure a little better not saying it;s gonna fix your primer issue. Be on the safe side and back your load off, work up and try the 450's then you'll know.

 

[ShootDots]

I checked my reamer print and it is a freebore of .100, so I think this winter I will have my smith throat it out to .120. However in the mean time I need to find a happy medium. The weather for next weekends match is a low of 52 and a high of 76 so I may try the same load in the milder weather and see if it still still has signs of pressure. Do you think the 450's would help reduce some of the pressure, even though they are magnum primers?

Even if your gun does not exhibit pressure at those temps, you are STILL at the very top of that node. If you have time, revisit your loads by dropping it about 6tenths of a grain and work up in 0.2 increments. If you can find accuracy a bit below your 30.0grs node, shoot it.

 

[7.62X51]

Consider having your firing pin hole bushed and firing pin ground to suit.
I had a Remington that would pop primers with an even lesser load of Varget in 6BR, same bullet
and CCI BR primers. Way too much clearance the way the stock bolt was and a simple
bushing job fixed the problem for good.We often shoot in 100 degree plus weather at 2000 ft.during summer.

cheers,
Chris

 

[Cody Richardson]

I picked up some 450's today, Im going to drop the load by .4 and work it back up. Also, I emailed Gre-Tan about getting the firing pin hole bushed this winter. There website said they were a max 2 month wait, I still have some matches this year scheduled so a 2 month wait is out. From what I have read on here it seems to be a common issue with a BR.

 

[GeorgeSpringer]

I am shooting 30.5 grains of varget with 105 scenars and CCI450's out of a 8 twist Bartlien barrel. The reamer was no turn with .015 freebore. The Scenars are seated .015 into the lands. This shoots in the low .2's at 200 yards.

GSpringer

 

[2dogs]

If you haven't had Gre-Tan bush your firing pin hole I highly recommend it.

 

[Eric Leonard]

I had a bolt done by Gre-tan in July and from post office back to mailbox was 15 days,,

 

[Drop Port]

If you haven't had Gre-Tan bush your firing pin hole I highly recommend it.

+1

Don't change a thing, do this first. Rems have enough slop to crater or blank primers very early. A tight fit .062" pin will more than likely do the trick.

 

[Cody Richardson]

Talked to Greg today and he said the same thing. I'm sending my bolt his way when our season is over, I just switched to a 450 primer and just going to try that and see if the harder cup works until I can send my bolt off.

 

[FatBoy]

I love the 450Ms with Varget. Very low SDs and acceptable accuracy. (Average in the .3s with 107s) I use 29.5gr in both of my 30" 6BRs. I had to bush the m70 for piercing as low as 24 gr. Bushed I had no issues at 30.5 but 29.5 works better for me and 200 case will outlast the barrel.