Bandhunter

When seating bullets does the pressure increase/decrease when not seating according to charts. Example: recommended OAL is .235 but seat bullet at OAL of .240. I am shooting an Encore so I don't have to worry about cartridges fitting into a magazine. Any info would be helpful.

Thanks, Rick

eldeguello

OAL variation will not cause pressure problems in HP rifle ammo. In pistol loads, it can be dangereous to seat the bullet too deeply.....

stubblejumper

Seating closer to the lands usually results in increased chamber pressure.There is a good example at the link below.

http://www.shootingsoftware.com/pressure.htm

bigcountry

I have done some tests with this, and found both. When I say that I mean seating too deep take more area away from the powder being burned, and increases pressure, and seating towards the lands increases pressure even though the powder has more room. Its give and take. From SAAMI specs, I find it usually in the middle.

eldeguello

Since maximum pressure in rifle bores occurs when the bullet is already 4"-5" up the bore enroute to the muzzle, I see little problem with variation is seating depth of the bullets.......Take a look at charts showing the comparison of chamber pressures and bullet travel.

This phenomenon is what accounts for people being able to fire significantly oversize bullets safely if the case neck can expand sufficiently to freely release the bullet. An example is firing Mauser7,92mm S bullets in 7,8mm J-bored barrels after the chamber neck portionswere bored larger. (OR, firing .308" bullets in a 6.5mmArisaka that was rechambered onlyfor .30/'06 with no change in the bore of the rifle!)