6BR accuracy issues

[Gunner75]

I have been working with this rifle for over a year now, but have only been able to dedicate a little time here and there. Need to get this thing up and going.

I have worked up loads in this rifle using RL15 and Varget. The barrel seems slow as if I dip below 30.5gr, velocity drops a lot.

I have mostly ran 107's but have ran a couple 105's looking for a change in accuracy.

This rifle wants to shoot, it simply does not.

I know this is a very general question, but by posting I was hoping someone would mention something that I have looked over.

(***This rifle is the 4th of 5th I have had put together by a long time shooter/gunsmith. The others shoot lights out FWIW)

Typical 100yrd, 300yrd, 500yrd groups. Please look past the other groups as that is a completely different work of art.

My Load:
31gr Varget
107 SMK Moly
Lapua Brass
CCI 450 Primers
2835fps
2.802 to lands, running 2.790
(Added Redding Dies with .267 bushing)



Rifle:
Nesika S Right Bolt, Left Port
Bartlien 8 twist, 30" (1) T10225 - Barrel 30",1-8 Twist,1" Taper,.237/.243 ), Vias Brake
Jewell Trigger (bottom safety)
45X Leupold (Currently it supports 12-42 NXS)

 

[Forum Boss]

1. That's a slow barrel, with your load, in a Bartlein, you should be around 2900 fps.

2. If the barrel is a 0.236 land version I would definitely try some different bullets, such as the 105gr Scenar and the Berger 105 VLDs, and I would shoot them naked (no moly). (Note you will have to reduce your load to shoot naked bullets)

Stick the 105s 10-15 thousandths in the lands. From what I read in your report you are jumping. But you are kind of in "no-man's land", about .012 off. Again, for safety, with a load in the lands, naked, start low and work up. I would start at 29.5 varget.

3. I would take off the muzzle brake to eliminate that variable.

4. Run wind flags and try to shoot in same condition. The vertical on your 300yd groups isn't bad, suggesting wind is causing your problems.

5. Borrow a friend's scope to eliminate that variable.

6. If 1-5 doesn't help, I would consider slugging the barrel to find a tight point near the muzzle and I might have it cut back (from muzzle end) 3/4" - 2" and re-crowned. That's a drastic measure, but it's cheaper than a new barrel.

Q: when the bullet is seated into the lands, are the marks even all the way 'round? We've seen crooked chambers that only engage bullet on one side (you see 3 marks on a 5-groove barrel). These chambers will NEVER shoot really well.

 

[Gunner75]

.237" barrel. Sorry, forgot to mention.

The 45X Luepold that is in the pic has been replaced with a 12-42 NXS.

The Muzzle brake has been pulled off and shot 1,3,&500yrds two or three sessions w/o any real noticeable change.

I will double check and report back on your question.

Thank you very much for the help on this. I will be working with this much more starting this weekend to get this up and going.

 

[Gunner75]

What would be the suggested barrel length for the 6BR?

 

[Sully2]

What would be the suggested barrel length for the 6BR?

I ordered a 26"....got 22 inches???? So mine is laying here till the 26" barrel gets into the smith's and then mine is headed back for a barrel change

 

[Forum Boss]

Barrel length for a 6BR -- Take your pick...

Richard Schatz has won Nat'l championship with 26"

Sam Hall has won Nat'l Championships with 29" and 30"

Tim Claunch just shot a .981" screamer at 600yds with a 26"

I have a 27" Pacnor than can shoot in the high ones with flatbase bullets.

FYI, a couple years ago Jackie Schmidt did a 6BR cut-down barrel test, removing 1" at a time from a barrel that started at 33" and ended up at 28". We lost a TOTAL of 40 fps, pretty much evenly 8 fps per inch of reduction. So, between 26" and 30", I think you'd lose only 40-60 fps. Our test was with H4895 which burns faster than Varget. Possibly Varget would burn a bit longer which might raise the speed differential -- but still most of the "push" is achieved in less than 26".

Since you have 30" now, I repeat my advice -- try to see where the barrel naturally chokes between 27" and 30" and take off as little as possible to get a clean crown. But try everything else before cutting!!

 

[myelkmtn]

gunner, I also shoot a 6BR and I am using a 28.5 Shilen Match Select that loves 31 grains of Varget and 107 SMK's naked. Just this morning , I tested some new Berger 105 Hybrids and they looked mighty good at 100 yds. I am talking 1's and 2's easy. Good Luck with yours. Michael Brown

 

[Frankr]

here is a crazy idea, try a jewell trigger with out the bottom safety..see if it shoots any different.

 

[DCRYDER]

The first thing I would try is some stock tape and powder those leather ears (if you havent already). If the rifle doesnt slide smoothly you can forget shooting good groups!!!!! I like shooting off of nylon much better than leather.

Hope this helps,

Dave

 

[DCRYDER]

I would also recommend a rear bag with correct spacing between ears so you can get the heel of the stock down to the bottom.

 

[Gunner75]

Nylon bags have been on order. Hoping they show up this week. Thanks again for the suggestions fellas. I have some work to do and hopes are up.

Thanks,
Wade

 

[Gunner75]

Made some improvements today. Will try and doctor up a pic to explain my results and testing. Looks like this barrel likes to "jam".

 

[Gunner75]

Well, here it is. Naked 107's with .010" in the lands produce better 100yrd groups than anything else. That is with 29.5 and 30gr Varget. Will likely up the load on naked and run some moly to see what works best.

Thoughts?

 

[Hoier]

It is looking alot better! I had about the same luck with the Amaxs. Any reason why your hell bent running moly?

 

[Gunner75]

Not really dedicated to Moly especially now. Would like to just know if the 107 Moly jammed would shoot as well.

 

[rocketron]

don't be afraid to try a different bullet. mine liked the Berger 108 bt's better than the 107 smk and the 105 a-max.

 

[Gunner75]

Settled on 30.5gr Varget, 107 (naked) SMK for now, and went to a .266 bushing in my Redding Die. Was hoping for a touch tighter.
(These rounds were loaded using the Prometheus II)

 

[Gunner75]

Well, I think I could get this rig to tighten up a bit more, but am extremely happy with where it's at so far.
I shot out monthly VS Match this morning and beat my personal best of 37. I hit all 40 targets, but turned a rabbit at 500M. Little guy just hung on.
Thanks for the help fellas.

My rig:

My Score: Really only a 39

Tough Rabbit:

Ammo loaded yesterday using the Prometheus II:

http://forum.accurateshooter.com/index.php?topic=3783316.msg36057202#msg36057202

 

[fm1947]

I have 2 6brs one is a 24 the other 29 inch both would shoot sub 1/4 moa at 100 and 200 yards, I tried some moly at a match one Sunday , I bought them by mistake and I was out of bullets , I used them in my 24 inch shilen, the barrel never has shot the same since, now it is about .5 moa it was worse shooting 1 moa I have scrub and scrubed that barrel to get that moly out I will never shoot moly in anything again.

 

[DennisH]

Another crazy idea I didn't see mentioned!

My BRX loves CCI 450's with 107 smk's

My 6br likes Win small rifle primers with 107 smk's!

Made a difference with my gun when I tried different primers!

One of my 6.0x47L's likes Remmy 7 1/2's!

Just a thought!

I would also drop the Moly, give the barrel a good cleaning and get the Moly removed from the rifling.