SmallCaliberCentral

Hi, I am strugling with two things, 1st a high percentage of my 204 reloads don't chamber all the way even with the use of the forward assist resulting in a miss fire, usually if the first round chambers properly the rest do just fine. this never happens with factory or new brass.
the dies I'm using are rcbs.
2nd, This one is odd and not 100 % consistent, when i chamber the first round from the mag and dont shoot anything then eject the shell it will have a dent on the case body that goes almost half way around the case wich starts a 1/4 " below the shoulder. If i hand cycle 5 shells at least 2 will have this dent?

Any help will be appreciated, Thanks

I also had a problem with my reloads not chambering at first until I put a little more grip on the bullet. I use lee for my .204 just had to screw the body of my die in about a 1/4 turn at a time until the neck got small enough. that also stopped my bullets from pushing back inside the brass. On the dents I have not had that happen. I do get scratches on mine in that area when I have to eject unfired rounds. so sad when that happens

First off with the denting I had this trouble as well with my mags. I lightly filed edges of feed ramps to give a more rounded edge . This solved the denting. As far as reloads not feeding, you are using a full length sizing die and not a Kneck sizer? Being a autoloader full length sizing of brass is recomended. Maybe this will help?

This only happens with reloads? It sounds like the brass isn't sized correctly, you may try to fit them into the chamber before you load them or it could be a crimp issue. I've seen the crimp bulge the brass a little. I usually run all my loads through a case gauge if I'm going to shoot semi auto. this helps quickly catch the small problems before they show up on the range.

Are you trimming your brass?

i would also say its a sizing issue. i FL size for my 204 AR (and other calibers) with redding dies and never had one problem

Also, Dillion Precision makes a handy gauge to measure your ammo to make sure it will chamber. Hopefully they make one for 204.

I use cheap lee reloading dies and never have a problem. But I do trim brass and full length resize. In my bolt guns I neck size only.

in regaurd to the chambering issue, i do FL resize with rcbs dies. Yes the problem is only with reloads. never had a problem with new brass or factory ammo. The only variation in dementions i can find is the witdth at the shoulder, all my books spec 0.360 after resizing i have 0.359, my factory ammo and new brass are at 0.355. Is it possible that the chamber in my bushmaster 204 is smaller than the spec?

And as for as the denting goes my gunsmith, who i dont have to much confidence in says he has seen this a fair amount in the 308 but never in the small calibers, he sugested sending it back to bushmaster, he also sugested not reloading for an AR???? (not an option for me)
He was not much help.

Stien, my shell holder is touching the body of the die, I gusess i dont understand how lowering it any further would change anything?

Valar, Just to be clear, you are saying i should file the metal on the mag? Not the grooved ramp on the gun? In case there was any question this is my first AR and i have not been reloading very long.

Lead Lobber, All my 204 brass is still within case lenght specs i have not trimmed any yet.

Stonefly,
I always have problems with chambering if I do not use a small base resizing die, RCBS recently has come out with one for the 204, it cures all the chambering issues. I also saw a dent on most brass ejected and I found that a piece of Velcro on the shell deflector has cured all my denting issues, not sure if you are having the same dent issue, hope this helps
Dan

Stonefly, when reloading for an auto loader I always use a case gauge (http://www.sinclairintl.com/.aspx/pid=3 ... Case-Gauge) after i load the rounds i drop every cartridge into this gauge to make sure it fits. I do this for my semi auto rifle and pistols and often catch little stuff that will mess up the feeding. This will tell you right away if the case has been sized properly and if the case is to long. I have never used the small base resizing die but i'm sure if your not able to size your brass properly with your die then that would be the next step. Also watch out when seating the bullets to not over crimp.
I'm 90% sure your having a sizing issue though.

Stonefly,,,You are most likely not bumping the case shoulder back far enough when sizing your brass...Set your die so that it touches the shell holder when the ram is fully up....Then turn the die down another 1/4 turn so that the press handle will "Cam Over" when pressure is applied...Make up a dummy round without primer or powder and see if that doesn't cure your problem...

All of this is assuming that your chamber is really clean and your brass is properly spec'd as far as trim length and you are not trying to use a neck sizer die..I've never found a reason for a small base die and my AR has a custom cut chamber that is a little tighter than most production models...