Why the difference in OAL when seating

luv2shoot · #1 02-22-2011, 05:02 PM

Why do I not get the same OAL , I set it for 1.225 this is for a 40sw. I get any where from 1.220-1.227. Once the die is set I don't move it I'm using a Lee single stage press and Lee dies.
Is that much difference Ok. Thanks for any help.

anomad · #2 02-22-2011, 05:45 PM

Variations in brass, bullet and measuring could easily give that kind of spread. Not a bad spread at all.

Key thing is, make sure they are on the long side more than short. You don't want to short seat a .40.

I load mine on the long side, obviously still fitting in the magazine and cycling in my pistol.

Rule3 · #3 02-22-2011, 05:52 PM

Every bullet and case would have to be exactly the same and your caliper would have to cost a gazillion dollars.

Set it to .007 and see how much 7/1000 is.

Don't worry about the 1000th's

luv2shoot · #4 02-22-2011, 06:15 PM

Ok I get it Thanks.

Pisgah · #5 02-22-2011, 06:23 PM

Yet another factor in addition to bullet/case variations -- you. It is mighty hard to make your stroke of the press handle EXACTLY the same EVERY time, and this, all by itself, can cause minor variations from cartridge to cartridge.

Skip Sackett · #6 02-22-2011, 08:10 PM

I bought a used SDB from a guy that hated it. That should tell you something about his reloading ability!

All kidding aside, I noticed that if I ran only one round through at a time, I got one OAL. If the shell plate was full, then I got a totally different and ALWAYS longer OAL.

Now being a bit OCD, not to be confused with OCD1, (

) I started to look into why I was getting the difference. What I found surprised me. It was a broken frame that would "flex" when more force was exerted! I cannot remember the difference in OAL at the present time, .010" seems to stick in my mind.

Sent the press back, the frame is the only part they won't send out as part of the warranty, and son #1 is loading on it now. Works just fine!.

nofishbob · #7 02-23-2011, 01:32 PM

How are you measuring the OAL?

Variations in the tips of bullets sometimes make this measurement more difficult to do consistently.

Look at bullet comparators that measure the length to a reference diameter on the ogive rather than the tip.

Here's one:

Graf & Sons - HORNADY COMPARATOR SET w/6 INSERTS (224-308cal)

Good luck!

Bob

ImprovedModel56Fan · #8 02-23-2011, 01:43 PM

Nofishbob nailed it. OAL is to the farthest point on the bullet. Seating is from wherever the seater touches the bullet. Except with flat-point bullets and seaters, this is usually NOT the same. You end up measuring differences in bullet shape, plus other variables mentioned in earlier posts. Seven thousandths doesn't sound to me like a basis for worrying.