Lee seating die....

[texasgunhand]

I was reloading the 9mm for the first time tonight. I was trying for 1.140...
I set the die on the first round at 1.150 and worked down till i got to 1.140 and when i seated the next round my oal was like 1.138 it seemed to jump around alot.

I thought once it was set it should be at the 1.140 and stay there. I finaly just backed the seater off abit and would just work it down to 1.140 for every round after that. Iam i doing something wrong? Like i said iam new and this is the first time ive ever done it. A little info on the stuff i was using.

Range p/u brass resized and then checked in a wilson pistol max gauge,,passed
Remington green bag of 100... 124gr FMJ RN i picked up at academy. Definitely not as pretty as the hornady fmj....

My dies aren't moving btw,, i was keeping an eye on them. The good news is i got some loaded,not many,,enough to test,,but it took forever.

My test loads will be 4.3gr Win231 with a COAL of 1.140 iam also gona try some 1.135 per speer manual.

[williejc]

I've got a couple ideas. Press linkage might be a factor. Try bringing handle down each time with same amount of force. Linkage with cam over action seen in RCBS and other presses has been cited as a cause. Measure your projectiles length ways to see if you notice variation. With cast bullets lube accumulation in seater stem will definitely cause variation during seating. Try this. Start over by cleaning inside(including stem)of seater die. Next, set aside several bullets verified to have exact length. Back die out far enough to seat bullets without die touching side of case. Then adjust depth using a loaded round with verified o.a.l. Next seat several but do not use crimping feature. Then measure. As a final step, adjust die to crimp and then crimp this little batch and measure again. Write down data by step. Can you identify sources of variation?

[texasgunhand]

I use a lee carbide FCD, I dont crimp with the seating die. But ill look at some of those suggestions tomorrow. I cant honestly say i cleaned the seating die, its the first time its been used and i dont see anything in there.

btw, i am using a rcbs rock single stage press

[texasgunhand]

I use a lee carbide FCD, I dont crimp with the seating die. But ill look at some of those suggestions tomorrow. I cant honestly say i cleaned the seating die, its the first time its been used and i dont see anything in there.

btw, i am using a rcbs rock single stage press

[mattieb]

Unless you trim your pistol brass that's your variation there. I don't trim pistol I just go with the few thou +\- it's not that big of a deal to me for blaster ammo. Ymmv.

[Onyx Z]

None of the bullet dimensions are EXACTLY identical. What you are seeing is the variation in length of the bullet. For my pistol, I typically see .002-.003 difference in OAL. For my rifle, I've seen up to a .007 difference in seating depth with Sierra MK's from the same lot, but they are still very accurate.

A few thousandths here and there is not going to make a difference...

[bigedp51]

None of the bullet dimensions are EXACTLY identical. What you are seeing is the variation in length of the bullet. For my pistol, I typically see .002-.003 difference in OAL. For my rifle, I've seen up to a .007 difference in seating depth with Sierra MK's from the same lot, but they are still very accurate.

A few thousandths here and there is not going to make a difference...

I agree 100% with Onyx Z and it is the best answer given here even though he is a Texacan I must admit he must be almost as smart, good looking and modest as I am. :sarcastic:

[texasgunhand]

I measured some today iam sure your right.i didnt trim the brass,but that shouldnt effect COAL.
These are just bagged factory Remington fmj i bought a while back so i wouldnt have to open a 500 box of hornady fmj. I loaded up some to go to the range in the morning.

So if you dont hear from me again i messed up..lol I guess that time arrives for every reloader when you pull that trigger the first time. The small powder measure for my uniflow will be here in a couple of days,were i dont have to scoop and measure, but by doing it that way you can get it exactly the same,,just takes forever. A good learning experience though. I just hope i got powder in all of them.
I checked it so much i probably made a mistake trying to be to carefull. I can already tell this is a rythem thing.