shilen barrel and berger bullet success

[strut64]

I finally got weather good enough to get to the range. Have been getting a savage 110 with 6mmBR shilen prefit set up. Using Berger 105 hybrid, Lapua brass and CCI 400 primers, and Varget. The best group looked like less than .250" at 100. This is the first range session and still a lot of optimizing to do. I had the bullets set to what I thought was light touching but ended up so tight I couldn't extract. So I have backed off seating depth. Varget at 29.0 gr had some primer cratering. I am very pleased so far.

 

[dkhunt14]

Usually when you can't extract without pulling a bullet they are in really hard. I shoot a lot of guns at 10 to 15 in and can open my bolt without letting a bullet stick. They seem to shoot good when in. Matt

 

[Judd]

29g shouldn't be cratering primers. Is your firing pin brushed?

 

[gambleone]

Mine was cratering at 29.3. Sent it to Greg Tannel to be rebushed.
problem solved .Greg does very good work with quick turn around.

 

[Roarke]

Will you guys in the know explain how ambushed bolt prevents premature cratering? I've got a 6br tube gun built on a R700 and have only had it blueprinted. No other mods have been performed .... Yet.

Thanks in advance,
Roarke

 

[GrocMax]

Why worry about minor cratering from a slightly oversized firing pin hole in the bolt face on a high pressure cartridge design? Curious.

 

[jonbearman]

Minor cratering as you call it just gets worse over time.Bushing the bolt face is the smartest thing you can do with a factory rifle such as a remington. They are sloppy to begin with.

 

[dkhunt14]

Why worry about minor cratering from a slightly oversized firing pin hole in the bolt face on a high pressure cartridge design? Curious.

Eventually you will blank one. If it happens in a match the results are usually not a good thing. Matt

 

[dkhunt14]

Will you guys in the know explain how ambushed bolt prevents premature cratering? I've got a 6br tube gun built on a R700 and have only had it blueprinted. No other mods have been performed .... Yet.

Thanks in advance,
Roarke
They machine out the bolt and put in a bushing and then they drill a new hole in the center. Now there is not excess space around the firing pin for the primer to flow into. Matt

 

[strut64]

Cratering was not the only issue. 29.0 Gr was top of my test range and accuracy went to pot as well. Don't understand why the thread went off down a rabbithole with the bushing stuff. The big issue was the potential accuracy of the rig. That is the best group I ever shot and the potential is astounding at least to me.

 

[bsc4444]

I think part of your cratering problem is your hard "jam". This can cause a pressure increase. You might try a Seating Depth Gage to know where you are at depth wise and the lands. You said you were at the top of "your range". This might change when you figure out where you are at with seating depth. There may be another accuracy node above 29 gr. This is quite common as long as you see or figure out the cratering....Have you tried jumping .060 and working in .0.010 down to the lands. If I were you I would try your load you have and try it with a jump and see if you still have the cratering and how accurate it is. If it doesn't have the accuracy you want jump it .050 .
and see where your at. Let us know how things go.

Brad

 

[fdshuster]

strut64: Primer cup thickness on the CCI 400's is .020", and it's .025" on the BR4's and 450's. Try a few CCI 450 primers, a lot less cost than the BR4's.

Those are the only 2 primers I use with 30 grs. of Varget and have never had any problems.

 

[Tim Singleton]

Cratering was not the only issue. 29.0 Gr was top of my test range and accuracy went to pot as well. Don't understand why the thread went off down a rabbithole with the bushing stuff. The big issue was the potential accuracy of the rig. That is the best group I ever shot and the potential is astounding at least to me.

What do you mean by accuracy went to pot? Your .250" group was at what charge?
Are you shooting over a chronoghaph? As someone else said the extreme hard jam most likely caused the over pressure cratering

Give us an up date after you make the seating depth changes, Again as others have suggested find some BR-4 or 450 primers for 105's and 30 plus grains of Varget
that should make you Happy Happy Happy