Pressure

[Jumpin4Joy]

Will seating a bullet too deeply in the case increase its pressure or contribute to inconsistent accuracy?

 

[Walkalong]

It can and it can, depends.

What caliber, load, etc. and we can be more specific.

 

[Jumpin4Joy]

This is what I loaded last week. My rounds where all over the freaking place. Thought at first it might be the Colt Detective Special I was using, however, consistency was not improved with my 4" Security Six at bench rest. 158 Grn swc, HS-9 5.8 grn, seated 1/64" too deep.

 

[Bullet]

In revolvers, the free run through the cylinder is always relatively great, and increased seating depth always increases the chamber pressures.

 

[Walkalong]

HS-9 ?

I do not believe the rounds being seated deeper than you wanted them caused horrible accuracy. I believe it is something else. More info?

Seating depth can effect accuracy in revolvers for sure. The jump to the forcing cone is changed, but I haven't seen it go from good to horrible with a seating change, just make a small difference.

 

[strat81]

How does it shoot with factory ammo? I assume the gun itself is in fine condition.

Have you mic'd the bullets? Inconsistent lead bullets aren't uncommon.

 

[1911NM]

Crimp?

 

[bhawkeye]

Is the brass all the same headstamp? Have you checked the neck tension?