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Old January 22, 2013, 06:10 AM   #1
oldandslow
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223 primer blow-by?

Greetings all, 1/22/13

I just got my LMT CQB .223 carbine in about a month ago after a six month wait. Fit and finish and function seem great. Twist is 1:7.

The only problem is that I'm getting powder blowing past parts of the primer causing bolt face erosion with about 10 % of my loads.

The reloading particulars- cases- new RP or once fired PMC, LC and FC. All are full length resized on my Rockchucker single stage press (even the new RP cases). Primers are Wolf Small Rifle primers, lot # 5-09.

Powder- IMR 4064 at 22-24 grains trickled or through a Dillon 650 (weighed charges are all close to the desired setting).

Bullets- Sierra 65 grain Spitzer Boat Tail.

Coal- 2.264" which just fits into my PMags and Brownells mags but is still about 0.020" off the lands.

Velocities- 22grains- 2320 ft/sec
23 grains- 2427 ft/sec
24 grains- 2528 ft/sec

I'm getting dark powder blowing past a part of the primer regardless of which powder charge I use. The powder charges seem to be below the max charges of my reloading manuals (Speer, Lyman) and there are no overpressure signs on the primers and the cases are not sticking in the chamber. The primers are seated below the case head and are still there after firing.

So any ideas on the cause of my primer blow-by? I normally reload a lot of pistol and rifle ammo (30/30. 270 Win, 30-06) and this is a new problem for me. I'm thinking a bad batch of primers but can use any ideas? Thanks.

best wishes- oldandslow
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Old January 22, 2013, 07:35 AM   #2
hoffbill
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Don't know but I have seen several comments on various threads about Wolf primers causing problems in 223. The gist of it was they are not hot enough so you end up with poor ignition too slow a burn. So perhaps try CCI, Fed, or Win primers and see if anything changes. Those velocities seem kind of low for 223 as well which I believe can be caused by insufficient primer. Plan B for me would be try a different powder. H335 works very well for me, and seems to be the most popular with AR guys.
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Old January 22, 2013, 08:42 AM   #3
243winxb
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If all brass is doing it, primer undersize problem? 24gr is maximun for autos. Have some primer pockets been swaged or reamed to remove the crimped in primer? Maybe over done? Barrel length has a large effect on velocity. Sierra is getting 2600 fps with a colt 20" bbl with 24.1gr (69gr bullet) Subtract about 35fps per inch of barrel. http://accurateshooter.net/Downloads/sierra223ar.pdf
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Old January 22, 2013, 04:07 PM   #4
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Are you cleaning primer pockets?

What tool/method are you using to seat the primers?

Have you tried a faster powder?

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Old January 22, 2013, 04:21 PM   #5
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I believe Wolf recommends using their small rifle magnum primer for 5.56 loads. They even make a step up above the magnum primer for .223 with "Hard to ignite powders".
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Old January 22, 2013, 04:34 PM   #6
243winxb
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Quote:
Wolf small rifle primers are now available in types.

SMALL RIFLE PRIMER (part # QQQSR) - Used as a standard small rifle primer. Perfect for the 30 carbine and 223 standard loads. Many people use this primer in bench and other loads for the 223. This primer is a copper colored primer.

SMALL RIFLE MAGNUM PRIMER (part# QQQSRM) - This is the primer we had before for use in the 5.56 loads and hot 223 loads. A thick cup for the higher pressure. We sold a lot of these primers earlier this year. The new lot is brass colored instead of nickel.

SMALL RIFLE 223 (part # QQQSR223) NEW NEW This is the newest primer available in the Wolf line. It is ever so slightly hotter than the small rifle magnum primer and it comes with a brass or copper colored thick cup. This primer can be used in place of the SRM primer or used when a different powder is used that is hard to ignite.
http://www.wideners.com/itemdetail.c...ir=278|284|737 3, when one would do.
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Old January 22, 2013, 04:41 PM   #7
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Not sure why 3 are produced or needed either? I bought 5k of the Magnum primers and although I have not shot all that many yet (150) they all worked great with the military surplus 844t powder I loaded them up with.
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Old January 22, 2013, 05:18 PM   #8
oldandslow
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Greetings, 1/23/13

Answers to questions-the gas blow-by is occurring in all brands of cases (RP, LC, PMC, FC) The primer pockets are reamed if they had crimped primers. The primer pockets are all clean- the RP cases were new and the once fired I ran through a SS pin rotary tumbler to clean the cases and primer pockets. I'm seating with either the RCBS Rockchucker single stage press or my Dillon 650 progressive.

I think the next logical step is to try a different brand of primer unless there are any other suggestions.

best wishes- oldandslow
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Old January 22, 2013, 05:52 PM   #9
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Yep. I would recommend you hold out for a military sensitivity spec primer. The AR type firing pin mechanism is designed to hit these less sensitive military types primers pretty hard, so I wouldn't be surprised to run into potential issues with lighter, softer cups. I know many don't, but not point in tempting fate either for slamfires or for gas cutting of your bolt face.

That new Wolf primer mentioned by 243winxb is apparently the latest contribution to the type. The other three are:

CCI #41
TulAmmo KVB556M
Federal GMM205MAR (don't confuse with GMM205M; the AR suffix is required)

Of those three, the first two are magnum, while the last is not, so you may want to favor the first two for the older spherical powders like H335. For the newer deterrent chemistry in Ramshot powders it is not necessary.
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Old January 22, 2013, 07:17 PM   #10
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Stainless steel media removed brass from the primer pockets? Would seem possible to me.
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Old January 22, 2013, 07:50 PM   #11
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It should be easy to tell if the primers are too small for the primer pocket in the brass by how if feels when they are seated.
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Old January 22, 2013, 07:55 PM   #12
Xfire68
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I have never had a issue with loose primer pockets from using brass that was tumbled in stainless steel media. I have 5.56 LC brass that has been reloaded no less then 4 times and each time was cleaned using SS media.

I have 9mm brass that has been reloaded at least 15x and each time cleaned in SS media.

Seeing how he used some new brass and some once fired and both had issues I would point at the primers first.
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Old January 23, 2013, 01:48 PM   #13
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If the pockets are loose, the stuff's been overloaded. Not hard to tell. The pockets on new cases are 0.1740" ±0.0005". So they are pretty close to right on. Measure a primer with a micrometer (a caliper won't have enough resolution or precision for this measurement), it should be at least 0.1746" and as much as 0.1756", so 0.0001" to 0.0011" interference by mil spec (not sure about commericial in-house specs, but they shouldn't be too different). If it has the right OD and it essentially falls into the pocket or can be pushed in with your thumb, the cases have been loaded to too high high a pressure at some point. A good rule of thumb is that any load that loosens primer pockets in five loadings or fewer should be backed down 5%. May be some exceptions, but .223 isn't one of them.
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Old January 23, 2013, 07:01 PM   #14
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My only observation is; why are you using 4064 powder? It's too slow for .223, I think you're seeing signs of way TOO low pressures. Especially when you consider the very slow velocities. Might just be lack of pressure NOT creating a good seal around the outside of the primer cup.
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Old January 23, 2013, 11:43 PM   #15
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Old & Slow, I feel your pain!
unclenick sure knows his stuff. Overpressure can change dimension of primer pocket. But you say that it is happening on all loads, even low pressure? Now assuming that you are getting blow by on once fired LC or the like, on your low pressure loads, it is not likely that the cases have been overstress by pressure. I find it more likely that your primer pockets were reamed too aggressively and cause a loose enough fit that it did not act as a gas check. I recommend swaging your primer pockets instead to remove the crimp. I also prepare my 5.56 brass with stainless steel pins. It makes for a genuinely clean case. I have found on occasion that two SS pins can get stuck side by side in the primer pocket....so inspect, inspect, inspect.
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Old January 24, 2013, 01:50 PM   #16
Jimro
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Quote:
My only observation is; why are you using 4064 powder? It's too slow for .223, I think you're seeing signs of way TOO low pressures. Especially when you consider the very slow velocities. Might just be lack of pressure NOT creating a good seal around the outside of the primer cup.
IMR4064 should be ok with a 69gr SMK, I didn't have any problems using 4064 with 68gr Hornady's. Now I'm using Power Pro 2000-MR which has an even slower burn rate, but with 75 and 80 gr bullets.

But I think a faster powder would be smart with such a short barrel.

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Old January 24, 2013, 01:52 PM   #17
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Pastor Shawn,

That's an excellent point. If you are using a hand reamer and it is wobbling in the hole or tending to bear to one side as you ream, that could easily leave the primer pocket elliptical.
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Old January 26, 2013, 06:12 AM   #18
oldandslow
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Update on .223 primer blow-by, 1/26/13

I tried a few things to decrease the blow-by. I tried a medium load in 3031 powder- 22 grains. Velocity 2417 ft/sec, 2 of 19 cases with primer blow-by. I tried a really light load of 4064 just to make sure it was not an overpressure problem- 20 grains yielding 2223 ft/sec. One of 10 cases with blow by. I even tried lowering the hammer spring tension thinking that the really deep primer hits might be deforming the primers causing the blow-by. No luck. All the cases were new RP cases full length sized. My prior cases were once fired LC, PMC, FC. A few had the crimped primer and the sharp edge was gently knocked off with a few twists of a hand reemer. Still had blow by with uncrimped and crimped cases.

In summary- there is primer blow-by with all four case headstamps. Same with different powders and loadings from light loads up to medium high loads. The only constant is the Wolf Small Rifle primer. With the current hysteria I am unable to buy any different primers. I've only put 197 rounds through this LMT AR and already have significant flame cutting in the bolt face. If anyone has any other suggestions I'm all ears.

best wishes- oldandslow
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Old January 26, 2013, 02:29 PM   #19
243winxb
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Case saver primer pocket swage

Never used one. Here are 2. R W Hart Case Saver Swage for Small Primer Pockets http://www.midwayusa.com/product/339...primer-pockets and another CASE SAVER PRIMER POCKET SWAGE - SMALL PUNCH ONLY http://www.mwgco.com/ar-15_accessori...S-SMP-000.html There are 2 common diameters of flash holes, some 223 brass has the smaller. Dont know if this could be a problem??
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Old January 26, 2013, 08:39 PM   #20
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Oldandslow,

Try upping the powder charge, if you are using a milspec primer you probably need to get closer to milspec pressures to make the primer cup fully expand into the cavity.

I've been using Wolf primers for a while now, and blow by hasn't been a problem with Lake City, PMC, Rem, or Winchester for me, using 24.4 grains of PowerPro 2000-MR which is slower than IMR4064. I would try 24 to 25 grains of 4064 under the 69 SMK.

Have you checked firing pin protrusion?

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Old January 26, 2013, 09:07 PM   #21
Law Dog
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223 primer blow by ?

Try using IMR 4895 I have loaded thousands of rounds with no problems !
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Old January 27, 2013, 03:46 AM   #22
oldandslow
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jimro,

Interesting thought about trying a heavier powder charge. Nothing else has worked short of finding different primers so that may give me something to do until different primers become available. Usually Wolf primers are pretty hard so this blow-by was unexpected for me. Thanks.

best wishes- oldandslow
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Old January 27, 2013, 07:06 AM   #23
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If you can find them. Fiocchi primers should resolve you problem. If those here can remember how tight the old Alcan primers were. Fiocchi resembles Alcan's to a T. Otherwise maybe a sealer may help. Which is something I don't use myself. Just Fiocchi's only. If my reloads were to leak a little I don't care. Because I reload over current listings and in doing so it is expected but hardly ever seen. So long as my rifle stays accurate fellers. I'm happy.

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Old January 27, 2013, 05:35 PM   #24
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Oldandslow,

Some other random thoughts:

You mentioned deep primer strikes. In addition to checking firing pin protrusion as Jimro suggested, check your headspace. If for some reason it is long, then when the primer fires it will back out until not much primer pocket is still supporting the sides of it.

Have you checked your primer pocket reamer's profile? If it's cutting too much shoulder at the perimeter of the primer pocket, again, you may be left with too little brass to properly contain the primer cup.

When shooting low pressure loads, like wax bullets, it is often necessary to open flash holes up a bit so the primer doesn't back itself out so hard. The normal spec for a flash hole is 0.080" ± 0.010". So you could try opening a few of them up to 0.090", and still be in spec. A number 43 drill or a 2.3 mm drill will do that.

Can you get hold of a flat bottom small hole gauge and an OD thimble micrometer to measure the inside diameter of your primer pockets with? If not, waxing one and pushing some JB Weld in to get a cast you can measure will tell you if the hole is out of round or has been too aggressively profiled.
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Old January 27, 2013, 05:49 PM   #25
Jimro
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The "deep primer strikes" got me thinking that maybe someone had put in a 7.62x39 firing pin instead of a milspec firing pin. Hoever on an AR the firing pin protrusion can be changed by shaving the rear of the bolt (to increase protrusion).

Normally a deep pin strike would cause a failure to the impact site, not necessarily the sides of the primer. But I guess some blow by is to be expected, I've got a lot of old Mauser's with a perfect ring of scoring around the firing pin from blow by.

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