300BlkTalk

First I would like to say Hello!
While I am new to this forum I am not new to handloading, but definitely not a expert. That being said I haven't touched a reloading press in a few years, until this week. I decided I would fire up the ol Lee press to load some plinking ammo. I have been doing a lot of reading, mostly on this forum and found some very useful info.

So here is my problem. I was making a dummy round before I got into the actual loading and no matter what I try the bullet will creep forward .004-.010 when chambering from a magazine. According to my measurements I have .003-.004 of neck tension. I have removed the expander ball to try to get more tension. I have tried the FCD from a light crimp to so heavy it left a ring in the bullet. Is this forward creep normal for the 300blk?

I have two types of factory ammo on hand and tested those for creep just out of curiosity. PPU 125gr ammo didn't budge. I pulled the bullet and it looked like it had lacquer or some sort of sealer on the bullet. The other was Armscor, 147gr. This one also crept forward when chambering, about .010. Any thoughts or suggestions would be greatly appreciated.

Almost forgot...the firearm is AR, bullets are Speer 125gr TNT, the dies are Hornady, bullet seating 2.060 and the brass is new Jagemann brass trimmed to 1.358. Haven't had a chance to get around to converting LC brass yet.

Thank you in advance!

How do you know neck tension? Just dropping the bolt? Try pushing a dummy on the bench to check tension.

I was able to push the bullet back into the case by pushing it on the bench. That was after chambering it. I didn't wright down that measurement, I was pretty much done at that point. But if I remember correctly it was somewhere in the 2.040 range.

I use a Lee collet die after a F.L. resize die for the 300 Blk. Then depending on bullet type ( cast/coated, lead/plated, jacketed ) I have notes on varying crimp for each bullet. .004" C.O.L. growth is what I measure after 4 chamberings, I have turned down the Lee collet die mandrel on other calibers to tune a neck tension. A heavy crimp is not a solution for sloppy neck tension with the 300Blk it becomes ugly at subsonic velocity.

Thanks for the suggestion. I was thinking I would try a bushing die after FL sizing but the collet die might be a good option also. Looks like I have some research to do.

The only brass I have been able to use with bullets that don’t have a cannelure is converted LC brass. All other brass I have tried has bullet creep when chambering in an AR.

Bgd wrote: ↑Fri Apr 05, 2019 9:30 pm The only brass I have been able to use with bullets that don’t have a cannelure is converted LC brass. All other brass I have tried has bullet creep when chambering in an AR.

thank god converted LC brass is so cheap.

might explain why i havent had any trouble. most of my brass is converted LC.

There is a company in the western part of my state that sells converted 300blk brass and will also convert brass that you send him. Blueridgebrass.com, he will convert 1k peices of LC for 70.00. I have 1,200 peices set aside to send him just haven't done it yet. Guess i should hurry up and do it!

or you can order some from sages and forgoe paying shipping both ways.

by the time you send him and get it shipped back you're within spitting distance of this stuff


https://sagesreloadingsupply.com/index. ... uct_id=125

just a happy customer, but one of many on this forum who've bought brass from him over the years. at 12¼ cents per delivered (if you buy 1k anyway) you're gonna have a hard time beating the quality you get from him.

That sounds like a good deal on the brass. I'll have to give it a try.

I did order the Lee collet die, it should be here Wednesday. I'll post results after giving that a shot.

Thanks for all the replies!