Sierra Match King in an AR - jamming


November 30, 2009, 09:17 PM
I am hand-loading a 55 gr. Sierra BlitzKing for my AR 15. I have sized the case and the load according to my Sierra manual. The manual has a COAL of 2.250" and I have seated bullet a tad deeper to COAL of 2.200" (I did this as 55 gr. Remington FMJ factory loads ran great ... this is their COAL). My problem, the hand-load is picked up from the magazine but the bolt lacks closing by about an 1/8 of an inch. I am unable to assist the round (into battery) and the charging handle requires considerable effort to extract the case. I see no visible signs of problems on the case or the bullet. All I can determine is the action prefers the full metal jacket load versus the plastic tipped BlitKing. Anyone have experience with this issue? Thanks!

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November 30, 2009, 09:55 PM
BNAllen, Are you full length sizing? Are you using .223 or 5.56 brass. If you are using 5.56 and AR is chambered for .223 that is the problem.

November 30, 2009, 10:56 PM
Allen, I have used a RCBS small base dies for many years and do not have a problem. There should be no difference in military vs. commercial brass when run through the sizing die. That difference would be military ammo vs commercial ammo not the fired case.
Have you been using Wolf that that coats the steel case? That could have caused some sticking. Give the chamber a thourgh cleaning using the chamber brush. Byron

November 30, 2009, 11:04 PM
Take a black marker to the bullet and brass. Find out where your problem is.
Can you load different bullets in the same brass without problems?
Can you chamber the resized brass?

Questions lead to questions which lead to answers that may lead to more questions.
It can be a fun process.


November 30, 2009, 11:29 PM
Sounds like a sizing die adjustment issue.
BTW, .223 Remington and 5.56X45mm NATO have the same external dimensions.

November 30, 2009, 11:51 PM
There are many ways you can wind up with handloaded brass dimensions greater than Remington FMJ Factory load brass in the wrong places (and still have a smaller OAL).

Seating force can be excessive causing bulging at the shoulder/body intersection.
Trim length can be excessive causing case neck to jam into chamber relief.
Resizing can cause case to grow lengthwise from shoulder to rim face.

Your AR chamber is now acting as a case gage and rejecting your reloaded case.

December 1, 2009, 01:09 AM
I will work up dummy loads with different bullets to see if they feed correctly. And, I will work up dummy loads with the BlitzKing bullets just to see how they seat into chamber. Thanks for the help ... Ill let you know what I learn ... maybe someone else will also benefit from my endeavors.

December 1, 2009, 01:11 AM
Yes full-length resizing .223 cases

December 1, 2009, 06:49 AM
I will work up dummy loads with different bullets to see if they feed correctly
As noted repeatedly above, it's not the bullets - it's the cases.

Do you have the sizing die down far enough that the press 'cams over' at the top of the stroke? Put felt marker on some cases and hand cycle them ... also, brush out the chamber really well.

December 1, 2009, 12:43 PM
It sounds to me like the sizing die is not fully sizing the cases. Make sure that you turn it down a quarter turn past the point where it engages the shell holder when the press is in the full up position.


December 1, 2009, 12:54 PM
Sound advice on the sizing die.
Your press has to "bump" or cam over at full ram travel in order to get the case shoulder back where it came from.

The other leading cause of your problem is excess crimp.

Make sure your seating die is not screwed in so far as to crimp the case neck on the bullet.
That will buckle the shoulder imperceptibly, but the rounds will not chamber.


December 1, 2009, 01:56 PM
If you are using 5.56 and AR is chambered for .223 that is the problem.

I disagree. I've used headstamps from the 70's through '06 without issue in bolt and gas guns.

This problem is usually due to insufficient shoulder setback. The best advice I ever got for sizing dies was to throw out the factory directions. You can use a tool that measures head space via a fired case. Set the die to reduce by .001" to .003" depending on application (I like .002" for semis). I use RCBS case mics. In a pinch you can use your chamber by turning in the size die until you get a case that will just barely chamber. Turn the die an additional 1/16 to 1/8 turn and you should be set. Good luck.


December 1, 2009, 02:07 PM
Turn the die an additional 1/16" to 1/8 inch and you should be set.Inch?

Don't you mean an additional 1/16 to 1/8 turn? (.004 - .009")

You most certainly do not want to screw the die in another 1/16" to 1/8" inch (.0625" - .125") after the case will just barely chamber.


December 1, 2009, 06:06 PM
Yes, I did mean turn. Good catch.

December 1, 2009, 06:35 PM
Do you crimp the case? I had a similar problem when I overcrimped a few rounds. They more looked like a .223 Ackley ( ) and I didn't notice until after the AR wouldn't go into battery.

December 1, 2009, 07:35 PM
I just had the same problem. I got advice from this forum anf fixed the problem. I had to screw the sizing die in another 1/8 of a turn, and that fixed the problem.

December 2, 2009, 03:22 PM
Thanks everbody ... I am looking forward to hitting the bench tonight to see what happens. I'll post my findings!

Regards, Brad

December 2, 2009, 03:35 PM
Limit yourself to one variable at a time.

First question, is this brass that has been fired in your chamber before? If so I would think it would be a crimping issue, ie cases too long or too heavy a crimp. Honestly you shouldn't need to crimp the rounds anyway....eliminate that variable for now.

If this is brass not from your rifle, I would assume a sizing die issue. Work with just the sizing die until you are sure that the sized cases will chamber smoothly. It is possible that your dies are out of spec, I had a redding die that would not set the shoulder back far enough, solution was to face off the base of the die in a lathe. Also make sure your cases are well lubed. A lubed case will see the shoulder set back further than a case with insufficent lube, given the same die setting...this can be a significant ammount...upwards of .003" that I've personally measured.

December 2, 2009, 04:19 PM
been there done that, Trim, small base sizing die has solved my problems both with My AR and M1a

December 2, 2009, 04:23 PM
Measure or fail.

December 2, 2009, 04:51 PM
For a quick and dirty measure of head space, make one of these...except for use as a head space gauge. Use something along the lines of a 3/4" nut, heat it up to soften it, drill, then heat and oil quench. You want roughly .330" for the .223 Slip it over the shoulder and use your caliper to measure. Compare a case fired in your rifle with the cases you sized.

December 2, 2009, 05:31 PM
+1 for W.E.G. I have a head space micrometer and I use it whenever I size cases. It will tell you in a couple of seconds if your die is properly adjusted.


December 3, 2009, 09:43 AM
Update ... I've sized three fired cases making certain that the press noticeably cams over. I then seated three bullets. I placed the three dummy loads into the magazine and worked the action. All three went into battery and then ejected properly. I believe the problem was truly the sizing of the cases (as most pointed out) ...

Thanks everyone!


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