Reloaded some 223?5.56 ammo awhile back with LC brass, 55Gr FMJ , 24.5 gr H335, CCI #41 primers, also had a batch of the same with a CCI 450 primers. Had numerous misfires with the #41 primers 80% to be close, no misfires with the CCI 450 Small mag rifle primers. Don't know if its is a bad lot of primers of something I have done wrong. Pulled the bullets out of the shell and they  have powder. The primer has a punch mark indicating the firing pin is striking the primer which resembles the fired shells.  Any help would be greatly appreciated!

Did the misfire fire on the second attempt?

Did you remove the primer crimp?

Nine times out of nine, primer misfires to that degree are caused by improperly seating the primer.  A high or proud primer will dent, but not go bang as the anvil will not contact the primer pocket.  A second attempt will set the primer off as the firing pin completely seated the proud primer on the first attempt.

One thing jumps out real quick. The 41's are a mil-spec (harder cup) primer. What FCG are you using. Could it be you are getting lighter than "normal" hammer strikes form a after market FCG or a incorrectly installed hammer spring.

Thanks for the replies,will check little closer to see what my primer depth are, I seated them down till the press stopped, like I do with all my reloads. Hammer spring is installed properly

Gunrunr do you have pics?

Also, is there any chance the primers were exposed to long term moisture?

Have no pictures, but they have been in a cool dry place 50 to 60 degrees. I checked the depth with my dial calipers, about .012 fro the top of the brass case. But all my other reloads with CCI450 primers are the same depth and they shoot fine. I think I"ll pull a couple bullets from the case and dump powder and put the shell and primer in my rifle and see If the fire, and double check to see if they fire again. I swaged my brass before trimming or primming  so I know it is not the primer pocket. Thanks again guys for you help!

Are the LC cases new or once fired?

If they are once fired what do you do the clean out the crud left behind in the primer pocket after removing the spent primer?

How do you address the residual primer crimp ring in the case?

What trigger group are you using?

They are once fired LC brass. I clean the primer pocket with brush that is attached to the end of my case trimmer (lyman power case trimmer. I also Swage the primer pocket. I use  a tool with a flat nose to stick into the primer pocket   which  takes the crud out of the primer pocket. As for a trigger group, It is a lower parts set I bought from MA parts about 12 years ago. It  has shot fine all this time and everything I have reloaded, except for the CCI #41 primers. Only thing that is different in my reloads is the primer.  CCI 450 small rifle mag primer has always worked fine for my loads. Has me stumped!!!

my guess is the hard primer cups made for machine gun use to prevent slam fire

try a heavy hammer spring

I have heard of issues with some match triggers - IIRC it was Jewell, but have not heard of any problems with the M&A trigger.  I suspect it is a GI clone trigger but do not know for sure.

I shoot the WSR, CCI-450, and some recently finished up some old Alcan Max-Fire primers and all went bang.  No experience with CCI #41.

Good luck,
dcat

I am a little confused here.  You clean the pocket with a brush then use a "tool with a flat nose".  What is that "tool".  Is it a brush also?  

Thanks for the help guys, I'll get a new Wolff hammer spring and try it out.

CCW, I use a Lee primer pocket cleaner, and I also use a primer pocket brush that screws on the end of my Lyman power case trimmer. Most of the time I only use the Lee primer pocket cleaned.

I measured some of my CCI#41 cups (Lot L05P).  The cup height is .118".  It is not easy to make the measurement because the anvil support legs extend beyond the cup rim** and get in the way.  The MilSpec drawing for the case shows the primer pocket depth .118 +.004 / -.000.

SAAMI recommends .003 to .008 below case head face for the primer, tolerance stack ups considered.  The #41 cups are domed somewhat.  I have found if you use "On Press" insertion it is easy to flatten the dome of the cup with the ram force.  You reported .012 depth which is perhaps a little too deep.  

Until you get to the "bottom" of the primer problem, I would recommend you suspend use of the Lee Primer Cup Cleaner, and just use the brush.
Also, see if you can modulate the force on the ram handle until you can get the depth back in the SAAMI limits.

Finally, check your as-fired shoulder-to-casehead face against your sized shoulder-to-casehead face and determine that your sized cases are no less than .003 of your as-fired.   If you do not have a case gage to make that measurement you can easily make one, as suggested by AeroE.

Measurement = X - Y [ETA] **The support legs of the anvil are pushed back up into the cup upon proper insertion.

Dryflash3, I use a dillion super swage 600 to remove crimps in my military brass.

CCW, I do use a wilson case gage to check my reloads. I checked  a few otherloads on my primer depth, they are with the .003 to .005 tolerance.  I will start checking my primer pockets alittle closer before I process them and after I reload them. Thanks for your tips and you help.

Gunrunr,
You may be on the right track. You did say that FCG was 12 years old. It could be your hammer spring has lost some of it's punch. Do you store your rifle with the hammer cocked or relaxed?
Please report back after you try it with the new spring.

springs weaken from high amount of flex cycles not from being left under tension.  

In addition to the weak spring force, I'd also suspect primer seating issues (anvil legs not in contact with pocket bottom and the first firing pin blow is deadened by using power up to finish the primer seating) and or excess headspace on your reloads.  Excess headspace will just leave your primer and brass that much farther from the breachface, remember that the spring loaded ejector is pushing the case to the shoulder in the chamber, any slop will be between the primer and the breachface.  

Also might want to check your firing pin protrusion as a distant problem.  

Please report back on anything you find in regards to the problem and solution.

I can't disagree with that but have read at least one owners manual that suggested storing the firearm with the hammer down. I can't think of any other reason why other than spring fatigue. I store all by bolt action rifles and pistols with the firing pin relaxed. But yes my AR is usually in the bolt locked back position.

That's what the problem was (weak hammer spring) Installed a new Wolff spring and performed excellent. Noticed that the one I took out compared to the other one on my LMT was real weak . Shot a couple of 30 rnds mags thought it without any misfires. Thanks again my brothers!