Bullet movement during chambering (ar-15)

[DLT]

This shouldn’t take long to get a remedy for. I have drug out the 6.5 grendel gas gun from the back of the safe to give another go at reloading for it and remembered why I put it in the back of the safe to begin with. For those who shoot the Grendel cartridge and who run the 120gr class bullets what method do you use to keep the coal from moving while being cycled into the action ? I don’t see it much with light bullets or single feeding them. Do you use a light crimp or more neck tension ? Thanks in advance

 

[GLShooter]

I use 0.003 neck tension with good results in my ARs.

 

[SeabeeKen]

You can use either depending on what your rifle likes

 

[Larry Koch]

Have you tried a lee crimp rifle die.?

 

[6Creed73]

I use the Lee Factory Crimp die for my AR's

 

[ZenArchery]

1/8 Turn LFCD.
Confirm COAL is jammed.

 

[DLT]

1/8 Turn LFCD.
Confirm COAL is jammed.

Do what ? I can’t reach my lands using magazine

 

[Mark611]

I don't know if I had a problem with the bullet moving backwards upon chambering? but I have not checked for that either, all I shoot are hand loads loaded to mag length and I also single feed them thru the magazine, I also run the 120 or 123gn ELDM's or the 120gn SMK's, My sizing die is a Redding body die followed by a Lee collet die the mandrel is .262dia 2k neck tension, after I set the bullet I use the Lee FCD, with a light crimp just enough to feel it touch, my accuracy is outstanding, so I would think the bullet is moving during the loading process, went and measured the outside neck DIA, it was .290 on an unturned neck on a recently loaded new Starline case with a 120gn SMK, I also took a new SL case out of the box it measured .287 OSD, then ran it thru the LCD, it came out at .288, my COAL 2.260 mag length, I don't know if this helps but next time I get a chance to shoot I will check to see if I'm getting a set back from the loading, I hope not! 27.1gn of comp is a little crunchy when seating the bullet!

 

[DLT]

I don't know if I had a problem with the bullet moving backwards upon chambering? but I have not checked for that either, all I shoot are hand loads loaded to mag length and I also single feed them thru the magazine, I also run the 120 or 123gn ELDM's or the 120gn SMK's, My sizing die is a Redding body die followed by a Lee collet die the mandrel is .262dia 2k neck tension, after I set the bullet I use the Lee FCD, with a light crimp just enough to feel it touch, my accuracy is outstanding, so I would think the bullet is moving during the loading process, went and measured the outside neck DIA, it was .290 on an unturned neck on a recently loaded new Starline case with a 120gn SMK, I also took a new SL case out of the box it measured .287 OSD, then ran it thru the LCD, it came out at .288, my COAL 2.260 mag length, I don't know if this helps but next time I get a chance to shoot I will check to see if I'm getting a set back from the loading, I hope not! 27.1gn of comp is a little crunchy when seating the bullet!

Ok. I have the redding body die, and the collet neck die. I anneal every firing and the bullet seating force feels the same on my press.

 

[jepp2]

collet neck die

I use LCD's on many of my cartridges. If you are using the standard mandrel that came with the die, I find they typically only provide 0.001" neck tension. I use undersize mandrels on many of my LCD's. Probably me, but I never had much luck reducing the diameter on them as suggested.

 

[DiffEQ]

I have a Lee FCD for every semi-auto bottle necked rifle that I shoot, and a roll crimp for the levers.
I had bullet setback on a pistol once and the associated KB - I'm OCD about that now as a result.

 

[dellet]

You might also check your base to shoulder length after chambering, if it has shortened, the neck length will increase causing overall length to increase.

Dialing back the gas and or tuning the buffer and spring weights to slow down the cycling can help.

 

[DLT]

I use LCD's on many of my cartridges. If you are using the standard mandrel that came with the die, I find they typically only provide 0.001" neck tension. I use undersize mandrels on many of my LCD's. Probably me, but I never had much luck reducing the diameter on them as suggested.

I have tried it. I have only been able to gain about .001 more on a couple I have tried it on Once the petals/collet closes up and touches each other that’s as small as it’s going to go no matter how small the mandrel is

 

[marazzi59]

Light to medium crimp with lee die for any semi auto. If you need more crimp, there might be something a little out of spec on your gun. How much is your coal charging?

 

[DLT]

Light to medium crimp with lee die for any semi auto. If you need more crimp, there might be something a little out of spec on your gun. How much is your coal charging?

It varies between .005 and .010 on the rounds I have checked

 

[Larry Koch]

Lee 223 Remington Factory Crimp Die

The Lee Precision Factory Crimp Die is designed to give reloaders the perfect crimp on each round of reloaded ammunition. The Factory Crimp Die crimps...

www.midwayusa.com

12 dollars and your problem is solved. I always use these on a magazine fed rifle. Unless I shoot it single shot.

 

[Mark611]

You can also order a Mandrel from LEE small or bigger then the 1 that came with the LCD, if you want tighter neck tension get 1 smaller from them, I also checked my crimp at the mouth of a loaded round and it was 1k smaller than the center of the neck area, crimp area was .289 center .290.

 

[DLT]

You can also order a Mandrel from LEE small or bigger then the 1 that came with the LCD, if you want tighter neck tension get 1 smaller from them, I also checked my crimp at the mouth of a loaded round and it was 1k smaller than the center of the neck area, crimp area was .289 center .290.

Thank you for the measurements

 

[marazzi59]

If you rechamber a already chambered round does it set back further?

 

[DLT]

If you rechamber a already chambered round does it set back further?

That will be for me to test and let you know what I find. I can’t pinpoint if it happens while getting in the chamber or the sudden stop once it’s in or could be both. I have had rounds get shorter and longer