22br bullet seating depth question...

[jefo65]

Kinda new to the BR's,..got a 6br barrel & 22br barrel from the Thompson Custom Shop for my Encores. So far in the early stages of the starting point reloading for the 22br, with 40gr Vmax's, 50gr Sierra Varminter's or 50gr Speer Varmint bullets, it seems impossible to use the old rule of hand, the bullet has to be seated into the case neck at least the same distance/diameter of the bullet/caliber used. If I want to achieve the .010 jump into the lands, on average the bullets mentioned are only seated approx 0.140" or 3.6mm into the case neck. I'm not so much worried about this being safe as I am about inconsistency in pressures. With the limited load data I can find on the 22br with these bullet choices I've seen variances of 1.995" COL to 2.090" COL. I know rifle chambers vary,..but isn't there a standard rule of hand? Any thoughts are greatly appreciated.

 

[fdshuster]

jefo65: Since you left the throat depth decision up to those who cut the chamber, you're stuck with whatever they decided to give you. If you have a really deep throat with a slow twist (like a 1-14) then you're between a rock and a hard place. You'll never be able to seat the bullet to touch ( where all my 6ppc's, 22BR, and 6BR's are) for the best accuracy. You'll have to determine the longest/heaviest bullet that the twist will stabilize and try seating it to touch. You will gain some bullet .224" diameter for more case neck contact if you choose a flat base bullet over a boatail. Yours is a classic example of why I spec out my chambering reamers, to the dimensions I want, with a particular bullet that I intend to use, and my 'smith cuts the chamber with my reamer. I've never had pressure problems with any or all of the various seating depths I've used, but that's one of the reasons to start load development with a powder charge that is well under maximum and slowly work up, watching for pressure signs. The loading manuals provide bullet seating depth information for their listed loads to show that pressures were safe, and when changing to a different depth, with that same powder charge, you're on you own. This is all part of load development for your (emphasis on "your") firearm.

 

[jefo65]

Definately not the end of the world for me. Played around with some 55gr Vmax's & some Hornady 55gr SP's & the math on both of those seems perfect. The sp's are seated at .230" into the neck and the Vmax's are at .245" with a .008 - .010 jump. Gives me somewhere to start anyway. The 1-12 twist running around 3600-3700fps should do just fine with these I'd imagine. I really don't plan on this becomming a bench gun, just high hopes of it being the primary 'yote rifle this fall. ;D