Not resizing enough

cryogenic419 · March 22, 2014, 02:46 PM

At the range recently, a guy who I sometimes run into and talk to was there with his AR. He says he has less than 1000 rounds through it, says has burned through a firing pin already and the new one doesn't look to be faring much better as the indentation seems really shallow on the primer. His bolt looks like he has pierced ALOT of primers. He shows all this to me, tells me what hes loading it up at which I check out later on and doesn't seem to be high powered or overloaded, 53gr SMK with 25 gr Varget with CCI primer. My initial thought was his scale or something was off and he was overloaded, he gave me 2 rounds which I pulled and measured the powder and it was what he said it should be. The only other thing I can think of is that he isn't sizing his brass down far enough...but the question is would that cause these kinds of problems or just crappy accuracy and really short brass life. Is there something else that would cause this?

F. Guffey · March 22, 2014, 03:02 PM

Quote:

The only other thing I can think of is that he isn't sizing his brass down far enough...

I could think of a different problem, setting the shoulder back far, then there is the firing pin striking the primer and driving the case, powder and bullet forward until the shoulder stops when it hits the shoulder of the chamber etc., etc.. I am sure everyone has that memorized by now, anyhow, it is possible the firing pin is poking a hole in the primer or there is not enough pressure against the firing pin to prevent the pressure inside the primer from from removing the dent in the primer.

I have seen M1 Garands cut the bolt face in 60 rounds.

F. Guffey

Bart B. · March 22, 2014, 04:14 PM

Can you get close up photos for us to see?

Is his firing pin tip round and not pencil point shaped? Spring strength correct?

Without measuring his cases and with normal firing pin parameters, my guess is he's sizing his fired cases too much.

cryogenic419 · March 23, 2014, 06:04 AM

I think I'm actually going to have to head over there and see what all his stuff is measuring out to. He doesn't have any case or headspace gauges, just calipers for measuring OAL. I would have measured the 2 loaded rounds he gave me but I don't have a bullet puller so I used vice grips to get the bullet out of the case. Would rather measure unmolested rounds.

The firing pin looked pointy.

As far as I know the rifle is stock.

Forgot to mention, the other thing I noticed on the fired cases is they were sooty all the way down past the casehead. I know with mine they are never that bad.

F. Guffey · March 23, 2014, 08:43 AM

Quote:

I think I'm actually going to have to head over there and see what all his stuff is measuring out to. He doesn't have any case or headspace gauges, just calipers for measuring OAL. I would have measured the 2 loaded rounds he gave me but I don't have a bullet puller so I used vice grips to get the bullet out of the case. Would rather measure unmolested rounds.

The firing pin looked pointy.

As far as I know the rifle is stock.

Forgot to mention, the other thing I noticed on the fired cases is they were sooty all the way down past the casehead. I know with mine they are never that bad.
cryogenic419 is offline Report Post

I am the only member that believes a reloader is capable of measuring chamber length, case length and the difference between the two without purchasing a boat (reloading bench) load of tools. The most elementary, basic and fundamental tool is the hole, the (shop) skill lever required to drill a hole is drilling perpendicular and be able to control the diameter. Once the reloader has drilled a hole they are able to make a datum, then 'what it is' they do with a datum.

Simple answer: Measure from.

Actually, sooty and pointy": New problem, sooty, low pressure, the case is not expanding to seal the chamber, it is possible the case can not seal the chamber.

I would first make sure the bolt is closing on the case as in stop reloading and purchase new, over the counter, factory loads for a test group. I would not use Wolf ammo, I would splurge and get some good stuff.

F. Guffey

steve4102 · March 23, 2014, 08:59 AM

Quote:

Originally Posted by Bart B.

Without measuring his cases and with normal firing pin parameters, my guess is he's sizing his fired cases too much.

^^^This would be my guess as well.^^^

Not sizing the case enough would cause feeding and chambering issues.

As to the soot, most likely from his weak load. Hodgdon list 24gr -27gr. His 25gr load is at the bottom end.

Jim243 · March 23, 2014, 11:25 AM

Quote:

I noticed on the fired cases is they were sooty all the way down past the casehead.

Low pressure rounds, his neck is not sealing the chamber and he is pushing the case back away from the throat. (under sized cases, trimmed back too far) He is fire cutting his throat and chamber which is adding to his problems.

Light hits on the primer most likely do to short cases or excessive head space. Who made his gun?? A DIY or factory made one?? Should take the gun to a good gunsmith to check it out now that he has had these problems.

Good luck and shoot straight.
Jim

243winxb · March 23, 2014, 12:36 PM

Dont use CCI 400 primers (thin cups) in an AR is the first thing i would change. 2nd would be see that he is removing the crimp from the primer pockets. You dont want high primers. [IMG]

[/IMG] [IMG]

[/IMG] Pierced or Blanked Primers.

--------------------------------------------------------------------------------

1. Check the firing pin, it should have no gas cutting or deformities. 2. Firing pin protrusion should be checked. Internet search shows .055" to be about right for an AR15. Check with a gun smith as each firearm IS different. 3.The firing pin must stay in contact with the primer on firing. A weak hammer spring on an AR or a weak firing pin spring like on a Rem 700 bolt action will let the firing pin rebound on primer piercing when the hot gas pushes the pin backwards. 4.If the hole the pin sits in is to larger in diameter, the primer flowes back into this hole till the center of the primer separates and fall into the action or travels into the firing pin area. Bushing the firing pin hole will fix this. Or you may want to try a magnum primer with a thicker cup. Military ammo may have a crimp that needs to be removed before seating a new primer. The crimp is removed by reaming or swaging the primer pocket. Swaging may be needed here so the prime can be seated lower in the pocket. High primer = misfires & pierced primers. There is also a high pressure sign visible. The reloader was using a "starting" load and CCI 400 primers. The CCI 400 is thin & soft, change to a mag. or Rem. 7 1/2 primers. The pressure sign may have formed on firing the factory ammo. I just shot some XM193F factory, the web area expanded .0015" on firing. This is a sigh of a "hot" load.

cryogenic419 · March 25, 2014, 04:19 AM

Got a chance to swing over there and actually measure his ammo, fired cases, etc. His fired cases drop into the Wilson cases gauge without issue, his loaded rounds however were well above the upper shelf on the gauge. Measured his fired cases with my Hornady gauge and helped him dial in his sizing die to .003below what the fired ones were measuring. He insists on keeping his powder charge and everything else the same.

Says he's going to shoot this weekend so I guess we'll see how this goes.

243winxb · March 25, 2014, 09:38 AM

Remington 6 1/2 primers should be avoided for a 223/5.56mm also.

March 22, 2014, 02:46 PM	#1
cryogenic419 Senior Member Join Date: March 29, 2009 Location: NW Ohio Posts: 569	Not resizing enough At the range recently, a guy who I sometimes run into and talk to was there with his AR. He says he has less than 1000 rounds through it, says has burned through a firing pin already and the new one doesn't look to be faring much better as the indentation seems really shallow on the primer. His bolt looks like he has pierced ALOT of primers. He shows all this to me, tells me what hes loading it up at which I check out later on and doesn't seem to be high powered or overloaded, 53gr SMK with 25 gr Varget with CCI primer. My initial thought was his scale or something was off and he was overloaded, he gave me 2 rounds which I pulled and measured the powder and it was what he said it should be. The only other thing I can think of is that he isn't sizing his brass down far enough...but the question is would that cause these kinds of problems or just crappy accuracy and really short brass life. Is there something else that would cause this?

March 22, 2014, 04:14 PM	#3
Bart B. Senior Member Join Date: February 15, 2009 Posts: 8,927	Can you get close up photos for us to see? Is his firing pin tip round and not pencil point shaped? Spring strength correct? Without measuring his cases and with normal firing pin parameters, my guess is he's sizing his fired cases too much. Last edited by Bart B.; March 22, 2014 at 04:26 PM.

March 23, 2014, 12:36 PM	#8
243winxb Senior Member Join Date: July 26, 2011 Location: USA Posts: 1,730	Dont use CCI 400 primers (thin cups) in an AR is the first thing i would change. 2nd would be see that he is removing the crimp from the primer pockets. You dont want high primers. [IMG][/IMG] [IMG][/IMG] Pierced or Blanked Primers. -------------------------------------------------------------------------------- 1. Check the firing pin, it should have no gas cutting or deformities. 2. Firing pin protrusion should be checked. Internet search shows .055" to be about right for an AR15. Check with a gun smith as each firearm IS different. 3.The firing pin must stay in contact with the primer on firing. A weak hammer spring on an AR or a weak firing pin spring like on a Rem 700 bolt action will let the firing pin rebound on primer piercing when the hot gas pushes the pin backwards. 4.If the hole the pin sits in is to larger in diameter, the primer flowes back into this hole till the center of the primer separates and fall into the action or travels into the firing pin area. Bushing the firing pin hole will fix this. Or you may want to try a magnum primer with a thicker cup. Military ammo may have a crimp that needs to be removed before seating a new primer. The crimp is removed by reaming or swaging the primer pocket. Swaging may be needed here so the prime can be seated lower in the pocket. High primer = misfires & pierced primers. There is also a high pressure sign visible. The reloader was using a "starting" load and CCI 400 primers. The CCI 400 is thin & soft, change to a mag. or Rem. 7 1/2 primers. The pressure sign may have formed on firing the factory ammo. I just shot some XM193F factory, the web area expanded .0015" on firing. This is a sigh of a "hot" load. Last edited by 243winxb; March 23, 2014 at 12:45 PM.

March 23, 2014, 06:04 AM	#4
cryogenic419 Senior Member Join Date: March 29, 2009 Location: NW Ohio Posts: 569	I think I'm actually going to have to head over there and see what all his stuff is measuring out to. He doesn't have any case or headspace gauges, just calipers for measuring OAL. I would have measured the 2 loaded rounds he gave me but I don't have a bullet puller so I used vice grips to get the bullet out of the case. Would rather measure unmolested rounds. The firing pin looked pointy. As far as I know the rifle is stock. Forgot to mention, the other thing I noticed on the fired cases is they were sooty all the way down past the casehead. I know with mine they are never that bad.

March 25, 2014, 04:19 AM	#9
cryogenic419 Senior Member Join Date: March 29, 2009 Location: NW Ohio Posts: 569	Got a chance to swing over there and actually measure his ammo, fired cases, etc. His fired cases drop into the Wilson cases gauge without issue, his loaded rounds however were well above the upper shelf on the gauge. Measured his fired cases with my Hornady gauge and helped him dial in his sizing die to .003below what the fired ones were measuring. He insists on keeping his powder charge and everything else the same. Says he's going to shoot this weekend so I guess we'll see how this goes.

March 25, 2014, 09:38 AM	#10
243winxb Senior Member Join Date: July 26, 2011 Location: USA Posts: 1,730	Remington 6 1/2 primers should be avoided for a 223/5.56mm also.