Sticky Bolt

[Twud]

I have a new 6BR with a BAT Action and Krieger barrel. I'm using Lapua Brass and 68 grain Hammonds bullets. I'm working up my first loads with some difficulty. The man who built the gun is using 34.5 grains of Varget with no problems.
I'm using 33 grains of Varget and getting a sticky bolt. I don't have to beat on it or use a lever. From a sitting position it's just sticky. I see no signs of pressure. The primers look fine and I have no extraction problems
Based on my 2 manuals 33 grains should be fine. I'm getting ready to load some more rounds. Should I go to 32 or 31 grains.
This gun was built as a hybrid varminter/benchgun so velocity is important on them far away whistlepigs.

 

[Twud]

I'm using new brass and extraction is as smooth as can be. The necks have been turned for a tight neck, but I don't see that as being an issue.

 

[tightneck]

Sounds as though the bolt is a little tight on closing? Sounds like the chamber was cut with zero headspace, or maybe even a little short. Nothing wrong with that. That little bit of a "crush" fit will actually help insure that your cases last longer, assuming that you don't set the shoulder too far back when FL sizing. When sizing your brass, the goal is to "bump" the shoulder back somewhere between .001" and .002", allowing for easy closing of the bolt. There are several tools available that will let you measure this shoulder bump. A FL sizing die from Harrell's Precision has a simple tool included that helps measure bum back...I feel the Harrell's die is one of the best bargains in the accurate rifle game.

 

[Preacher]

My last 6br die from Harrells was $70.00 and very well worth the price I paid.....
Can you slip a bullet into a fired case easily ?????

 

[longshooter]

Have you checked the calibration on your scale?

 

[Twud]

I calibrate my PACT digital scale everytime I use it.
A bullet slips right into a fired case.
A fired case slips right into the gun.
An unfired loaded round slips right in and the bolt closes with minimal effort. More effort than a factory action, but I would expect that.
Bullets are seated .010" off the lands.
If this gun is going to shoot with a tight action that's fine. I just don't want to damage anything or cause premature wear on the lugs.

 

[gunsandgunsmithing]

A fired case slips right into the gun.
An unfired loaded round slips right in and the bolt closes with minimal effort. More effort than a factory action, but I would expect that.



Based on the above statements, I'd say that the shoulders need to be bumped another thous. or so. The smith probably set it up with minimal headspace and may have even set it up with a piece of brass instead of a headspace guage. Not really a problem if you can bump the shoulder back a little to fit. Don't go too far. You need to be able to measure the amount of "bump" and allow for about .001"-.002" clearance here. ---Mike Ezell
p.s.--There is no reason that your BAT should feel any harder to close than a factory action.