40sw oal .007 - .01 variance

[Sixshot87]

Hi all, is a variance in oal between 1.130-1.140 in the same batch of reloads acceptable?

How badly will it effect the chronograph?

I have a lee single stage press and ever since it was brand new, oal's varied on my 40 reloads.

Please advise

['ol shooter]

I load on a 1978 Rock Chucker, and run of the mill plinking fodder usually runs a variation of .000-.003, I think likely due to the slight variance of the bullet length vs. Ogive. More than that I would be making sure everything was correctly adjusted and tightened. Technique plays a role too, smooth press operation and consistency is a plus. Are you using a flat headed seating stem or one that indexes on the Ogive?

[Sixshot87]

is the seating stem the inside of the seating die? If so, I believe it indexes. I always load with flat headed bullets.

[jimmythebrain]

what type of bullets are you using? plated, lead, hollow point...
mixed head stamp brass?

are your primers all set flush or below flush? if your calipers are hitting the primer on the case head, then any amount the primer that protrudes above the brass will add to your OAL. Different brass can have tighter or looser primer pockets so primer seating depth can vary.

['ol shooter]

is the seating stem the inside of the seating die? If so, I believe it indexes. I always load with flat headed bullets.

Yes it's inside the die. Some die sets come with more than one stem, the flat stem is usually used for flat faced tapered bullets like semi-wadcutters, but you can use it or a concave stem if the bullet profile is curved, which your .40 bullets probably are. Whatever you are using, make sure it's clean before you start seating rounds.