6BR charge weight test results / input

[Lefty Trigger]

The first test is 107gr Sierra Match King. This was shot over two days with reduced loads after the upper end found pressure signs at 30.0gr. 28 inch Criterion barrel, Lapua brass, Varget powder, Rem 7 1/2 primers. Test is 4 shot groups all shot at 200 yds.
Numbers,...
Varget
27.5gr / vel 2707 / ES 8 / SD 3.8
27.8gr / vel 2742 / ES27 / SD 11.3
28.1gr / vel 2764 / ES 5 / SD 2.2
28.4gr / vel 2796 / ES 12 / SD 5.3
28.5gr / vel 2798 / ES 10 / SD 4.1
29.1gr / vel 2847 / ES 7 / SD 3.3
29.4gr / vel 2866 / ES 10 / SD 4.6
29.7gr / vel 2893 / ES 14 / SD 6.2 very slight cratering of primer
30.0gr / vel 2914 / ES 46 / SD 19 STOP! worse cratering of primer



Second test is using Sierra 85gr HPBT AND Spitzer bullets and Benchmark Powder. Same as above but with powder and bullet change.
Numbers,...
Benchmark
26.4gr / vel 2846 / ES 25 / SD 11.2 (HPBT)
26.4gr / vel 2807 / ES 14 / SD 5.7 (Spitzer FB)
26.6gr / vel 2852 / ES 14 / SD 7.5 (HPBT)
26.6gr / vel 2824 / ES 15 / SD 6.3 (Spitzer FB)
26.8gr / vel 2852 / ES 18 / SD 7.7 (Spitzer FB)
26.8gr / vel 2873 / ES 13 / SD 6.9 (HPBT)
27.8gr / vel 2948 / ES 13 / SD 6.5 (HPBT)
28.8gr / vel 3026 / ES 15 / SD 6.5 (HPBT)
29.3gr / vel 3064 / ES 7 / SD 3.9 (HPBT)

 

[memilanuk]

Something that might be worth checking, if you're getting cratered primers with the 6 BR... get that firing pin hole bushed. Makes a *huge* difference on Savage bolts.

 

[Mark W]

I sent the Savage bolt from my new 6BR Improved to @Grimstod for bushing and bolt lift kit. The results were remarkable! I will be sending more for sure.

 

[JFrank]

How much headspace are you currently running

 

[Falfan2017]

Honestly none of those look super promising. If I had to pick one today to compete with it would be the 28.4 or 28.5 with Sierra 107.

Have you tried the Berger 108? If that is a 1-8 twist barrel I’d be willing to bet it will work well with around 30 grains of varget. Also a different primer like fed 205m might be worth trying. I think I settled on 30.2 gr of varget with the 108 Berger jumping 20 thousandths in my criterion 6br. They should be capable of .5” groups at 200 yards

 

[beemanjohn]

I will second that thought on getting your bolt done by @Grimstod. He does fantastic work on Savage bolts for a very reasonable price. It makes a HUGE difference. (tried to get him to do my Howa bolt, but no luck, darn it!)

 

[KenOath]

Personally I’d test powder charges with Sietra 107s between between your 28.5 and 29.1... so 28.6-28.7-28.8 28.9 and 29 @ 10 jump and possibly change to a CCI450 or CCI BR primer..

 

[Lefty Trigger]

How much headspace are you currently running

The fired brass measures 1.118 and after full length sizing with the Whidden die it measures 1.117

 

[Lefty Trigger]

I have some more loads setup for tomorrow at the 300yd line. They are 28.4gr of Varget and the 107's loaded with both the Rem primer and some CCI 450's. Also made some up using the 85gr bullet at 26.6gr of Benchmark also trying both primers. I think what shocked me the most is how well this pound of Varget shot as compared to the last two pounds I gave away cause it shot like crap in everything I tried it in.

 

[JFrank]

I like Varget

 

[group therapy]

I like Varget

me too LOL

 

[group therapy]

The fired brass measures 1.118 and after full length sizing with the Whidden die it measures 1.117

if you are only bumping the shoulder back 1k, try bumping 2k. small difference but it might matter

 

[Grimstod]

I will second that thought on getting your bolt done by @Grimstod. He does fantastic work on Savage bolts for a very reasonable price. It makes a HUGE difference. (tried to get him to do my Howa bolt, but no luck, darn it!)

Actually started doing those now. I now have the tooling for it.

 

[Lefty Trigger]

if you are only bumping the shoulder back 1k, try bumping 2k. small difference but it might matter

Curious what you think this might change? I thought our goal was to move the shoulder as little as possible, I actually set the die to that spec because I read that on the 6mmbr.com site.

 

[JFrank]

I run about.003
My curiosity was regarding the possibility of too much headspace

 

[group therapy]

Curious what you think this might change? I thought our goal was to move the shoulder as little as possible, I actually set the die to that spec because I read that on the 6mmbr.com site.

I don't know what I don't know but more than one world class shooter/record holder has said to bump the shoulder back around 2k, maybe more, NOT LESS. almost all my rifles shoot really well (especially considering the driver) and it has been a rule of mine that if someone I consider to be a great shot gives me advice that doesn't contradict my version of common sense, I go with it. if I were you I would certainly post a question about how far to bump shoulders, I can't say that I'm the Kinda person to take advice from,lol. good luck, bryant

 

[beemanjohn]

I will send you my bolt after the season is over. Thanks!!

 

[Ccrider]

Shoulder bump will vary depending on where you are measuring from.

 

[mike a]

About pressure. With 30 Varget and the 107 I can shoot a quick 5 shot group. But, I cannot shot a 20 shot string without getting hard bolt lift. Even with around 45 seconds between shots at around 10 it gets tight. That's ok because at 29.4 I get zero pressure and awesome accuracy. 6BR ROCKS!!! Cheers Mike

 

[Texas10]

Been watching this thread because my new Shilen 6BR barrel seems to hate the 105 HPBT Hornaday that my X-Caliber barrel had an affinity for. So bought several boxes of 107MK to try out.

My results were very similar to yours. Best accuracy was 29.0 Varget and 30.2 cratered the CCI 400 severely. I didn't chrono it, but simply can't beat the results on paper. As best as I could measure it, the 3 shot group measured .08 (100 yds), so I'll go with that and reaffirm it with at least 20 rounds before putting the tuner back on.

Wish I still had access to a 500+ yard range, but developers nearby got a judge to shut it down.

Edit to correct primer used, CCI 400, not the Fed 205