advice-soft seating bullets and jam measurement

[cognac jack]

I am shooting a 6BR, soft seating the bullets ( 105 berger hybrids ), and than letting the bolt push the bullet back in the case, jamming the bullet into the lands. My touching the land measurement is 1.820, the jammed measurement is 1.855 with .001 neck tension. My question is, Is .035 to much jam to start and then move to .030, .025 etc. I've read most of the articles and they all seem to be .020 or less jam. I have shot a few rounds with no pressure signs and very good velocity, also my ES was 9. Advice welcome.

 

[ShootDots]

It has been my experience that IF you could pull the entire loaded round out of the chamber without leaving the bullet in the barrel it usually measures to about a 8-12K "final jam" if you will... Since seating them WAY off actually means little IF they actually seat down to "about" 10K in, it would not matter. If you really want to know, try this: It would be nice to have someone help you but do this. Seat a bullet, like you normally would, in an EMPTY case. Then chamber the EMPTY round and just lift the bolt. Take a cleaning rod and just "reach / touch" the bullet "gingerly".. then with VERY slight pressure on the bullet from the cleaning rod, open the bolt all the way and slowly draw the bolt rearward KEEPING slight pressure on the bullet from the cleaning rod, continue in this fashion til you extract the entire round and measure the results.. That's what I did and that's how I found out, in a few rifles, where the bullets actually "end up"..

 

[Erik Cortina]

Seat a bullet into a case that you shoot with but don't load powder in it. Put die wax on the bullet or some kind of lube. Measure base to ogive before chambering round, then chamber it in your gun. You should feel the rifling seat the bullet. Now snap the bolt open and extract the round. Do this a few times, the new base to ogive measurement is your "jam" measurement. Anything past this point will stick the bullet in the lands if you try to extract it.

I find no reason to go past jam. I usually end up .020" short of jam (jam - 0.020") for the hybrids. If you still want to soft seat, load them .020" longer than jam (jam + .020") and you should be ok.

 

[cognac jack]

Thanks, With your help I got it done.

 

[tenring]

Many shooters find that hybrids work best when jumped. My 6mmBR likes them -.025 jump. Ya gotta experiment.

 

[rvn1968]

This sounds like another thread where we were discussing the value of a cerrosafe mold.FWIW. But I am not going to argue with Erik C.