New Starline 38SC and Once Fired Starline Giving Different OAL...?

[Ssanders224]

Guys,

I just started loading 38SC not to long ago, and so far, Ive been loading all brand new Starline brass. Everything has been perfect.

However, last night I started loading with my first batch of my once fired Starline brass, and my OAL is coming out about .005" shorter consistantly. I have made no changes to the press, and it is the same lot of bullets.

Is this normal? Ive never loaded much brand new brass, so I wanted to get some opinions before I adjust my seating die.

[BSeevers]

Pistol brass shrinks but it shouldn't affect the OAL.

.005? that really isn't that much. I guess if you want to figure it out run some new brass through today and verify if its still happening. I have seen switching out to different seating stem help inconsistent seating problems but what's confusing is that new brass works fine.

Could there be a shoulder or something inside the seating die "hitting" the brass? Never heard of that but that's all I can figure.

Edited March 18, 2014 by BSeevers

[3gungeezer]

Check to make sure you haven't got gunk in your seating die. I am assuming that you didn't tumble the new brass but did the once fired could be a build up of residue from your media. doesn't take much to equal .005"

[Ssanders224]

No gunk in the die.

I can mix and match the new and once fired brass, and the results are the same. Once fired end up shorter.

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[Blankenhole]

I know it has only been fired once but I would just attribute some of it to wear in the brass and the rest to an acceptable deviation (either in seating, measuring, etc). I would be more worried about .05 then .005. I would say keep on chugging personally. Other than that make sure if you are on a progressive press your shell plate is tight, keep all the stations full, so on and so forth.

[Ssanders224]

I know it has only been fired once but I would just attribute some of it to wear in the brass and the rest to an acceptable deviation (either in seating, measuring, etc). I would be more worried about .05 then .005. I would say keep on chugging personally. Other than that make sure if you are on a progressive press your shell plate is tight, keep all the stations full, so on and so forth.

I'm definitely going to keep chugging, bumped the die to get it back where I wanted.

However, this wasn't a matter of measuring or loading deviations. There was something very specific going on, I'm just not sure what was causing it.

I can load 5 brand new brass in a row with scary accurate OAL. Variations of no more than .001 in either direction (much better than my .40 loads for some reason ).

Then load 5 of the once fired with ought changing anything. The results are still very consistent (+/- .001) but .006" shorter.

Not sure how that happens.

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[kineteks]

Since the brass length shouldn't affect OAL it may be a difference in case diameter between "fresh" brass and what your sizing die produces (or possibly material hardness). If the unfired brass offers more resistance to the bullet when seating you could be seeing the effect of very slight deflection in the mechanism of your press that doesn't occur with a little less seating force.

[Steve RA]

Shoot up all the new brass and then it'll be all used and should give you the same result then.

[Cavy]

It most likely has to do with a slight shift in the ram and shell holder due to the different amount of force needed to resize new or fired brass. You will notice a difference in oal if you leave the sizing position empty and seat a bullet also.