Inconsistent OAL with 180 Rainier RNFP

[Lonnie]

I decided to try the Rainier 180 RNFP. I had been loading the Rainier 155 FP. The RNFP are giving me OAL variations from 1.133 to 1.143. My goal was to get 1.135. I never had more than .004 variation when loading the 155 FP. Has anyone else experienced this? The brass has not changed (Speer) and I'm using the same dies (Lee). Definitely not loading compressed loads either, testing with N320, WST, Titegroup and Universal; all below 4.1 grains. I checked the seating die stem for debris - none. I also made sure the bullets were set into the case as straight as possible before seating them. The die is not double side, so turning it over was not an option. I just don't get it. The Rainier RNFP appears to be very consistently constructed.

[Flexmoney]

You might try adjusting the seating when all the other stations on your progressive press are properly occupied.

Could be differences in brass.

could be looseness of the dies, tool head...shell-plate...etc

I don't think your variation is too far out.

You are geting a range of 1.133-1.143...whcih means you are likely set up in the middle of that range (even though you were shooting for 1.135...unless you set up with the other stations full, you won't get your 1.135)

[eric nielsen]

Like Flex says --

With my presses [Dillon] I usually find the first round through the shell plate is about .005" to .008" shorter than the rounds loaded off a full shell plate.

The last one off the shell plate is usually closer to the normal OAL.

Check that the shell plate doesn't have a big burr in one cartridge slot, then put it back in the press and make sure it's tight.

Check the O.D. of the bullets, try about 50 of them. They should be the same within .001" and within .0005" is better. The diameter of the flat point will affect the way the seating die puts them in - they should be consistent too. If not, change to Jacketed.

[Nolan]

A Lee Factory Crimp Die with plated or lead bullets can cause variances in the Overall length. When it sizes the case on the down stroke it squeezes the soft plated or lead bullet undersize, (less case pull) the brass case springs back a little bit after sizing. The bullet doesn't. Then on the up stroke the FCD can pull/squeeze the bullet out of the case a small amount.

Nolan

[Doggorloader]

FWIW I just opened a new lot of (45 Cal) FMC and started having the same problem. Up to .010 variation on overall which wasn't a problem with the old lot.

The bullet' OAL varied that same amount it appears throughout the lot but when checked with a bullet comparator on the oglive they were exactly the same. I was lucky I had a seating stem that contacted the bullet back almost at the same spot. The finished rounds now check exactly the same with the bullet comparator but still check varied with the COL up to the .010. That tells me the back of the bullet is in the same place in the case. They clear my magazine and feed perfectly.

Alot of screwing around but at least I feel better.

TW

[TonyT]

A Lee Factory Crimp Die with plated or lead bullets can cause variances in the Overall length.  When it sizes the case on the down stroke it squeezes the soft plated or lead bullet undersize, (less case pull) the brass case springs back a little bit after sizing.  The bullet doesn't.  Then on the up stroke the FCD can pull/squeeze the bullet out of the case a small amount.

Nolan

<{POST_SNAPBACK}>

I had the same experience with Rainier bullets and the Lee FCD. Switched to a normal crimping die.

Tony

[b_ionian]

I ran into this problem with RCBS dies. I got this answer from RCBS and it was confirmed by Speer. The problem is most liketly not with the bullets, and not a big problem in any case. What happens is that your seating plug in the seating die most likely contacts the bullet on the ogive (the curved portion of the bullet) as opposed to the nose of the bullet. Since bullets vary in the amount of curvature at the ogive, and there is variability in the way each individual bullet is formed, the OAL measured from the nose to the base of the cartridge can vary once it is seated in the shell.

This does not mean that the space under the bullet, and within the cartridge, is different. It is probably consistent even though your OAL is varying, because the seating plug contacts the ogive. What I do is look for an average OAL to be around my target (in my case, 1.120 for .40 cal). I don't worry about a few thousandths of an inch different from one cartridge to another. Keep in mind that it's not the OAL which causes excessive pressure, it is the amount of space within the case.

If you remove the seating plug from the die, and place it on top of a bullet, you can likely see just where the plug makes contact with the bullet. I hope I have been clear in my explanation- if not let me know and I will try to explain it better.

[mrapathy2000]

I never had much of a problem with Rainier plated RNFP in 40sw. then again I am carefull.

did have slight issues getting them to OAL but nothing more than +/- .005

[Lonnie]

I never had much of a problem with Rainier plated RNFP in 40sw. then again I am carefull.

did have slight issues getting them to OAL but nothing more than +/- .005

<{POST_SNAPBACK}>

Thanks, but I'm careful, too...

[mrapathy2000]

are you crimping at the same time as seating?

used lee seating die myself but I crimp with a lee taper crimp and also run through a lee FCD my last few loads of ammo have barely touched the FCD anymore.

how much bell and crimp you using. used 180gr RNFP myself.

not pulling the lever on the press just right gave me inconsistent OAL. anymore when I load a batch I sit and measure everyone till I get the die just right.