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Thread: Primers Backing Out

  1. #1
    Boolit Master
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    Primers Backing Out

    Had an odd occurrence yesterday when using my 03A3 with the NOE copy of the 311291 and 13 grs of Red Dot. Fired 25 of 50 I had with me and all the primers backed out of the case, some more than others. Have used this load and rifle for years with no issue, probably over 1K rounds. The brass was once fired from a member here and was FL sized in with Hornady dies, tumbled, expanded and loaded. Only difference from past brass processing is the Hornady die, in the past used an RCBS FL die. Expected the brass to fire form to the chamber and then just neck size on subsequent loadings (keep brass for my 06's separate). Think the firing pin blow is pushing the case forward and when fired the case is seizing to the chamber walls and letting powder gas push the primer back to the bolt face. Will clean the chamber before next firing and see if this helps, but otherwise am at a loss to what is happening.

  2. #2
    Boolit Master
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    My guess is (for how ever little that is worth!) that the Hornady die has to be setting the shoulder back too far for your rifle in the sizing operation. Dies always try to return fired cases to minimum dimensions or slightly below, and our rifles are more likely to be somewhere toward maximum. So I never screw a FL die all the way down -- back the die off a ways and keep trying until you get a perfect fit for your rifle.

  3. #3
    Boolit Master
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    earlmck, thought about that too. I usually FL size brass first time if not fired in my rifles to ensure it will chamber, and start with a uniform lot of brass. I had used the die with some brass from another of my 06's that I was repurposing for the A3 and did not have any issues. Did clean the chamber on the A3 last night and was surprised at how dirty it was, although probably shouldn't have been as my normal routine is to just wipe out the barrel after each range session. If it warms a bit will fire off the remaining rounds and see it it makes a difference.

  4. #4
    Boolit Mold
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    The primer always backs out when a round is fired, then the recoil of the case reseats it. When primers don't reseat it usually means the load is too light to drive the case back to reseat the primer or as you stated the cases may have hung in the Chamber and not slammed back against the bolt and reseated the primer.

  5. #5
    Boolit Master Baltimoreed's Avatar
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    Double ck your powder measure to make sure nothing has changed. Bull Skinner is correct about the primer moving during firing. This is where you get cratered primers from as they can ‘flow’ back into the firing pin hole around the firing pin when firing overly high pressure loads. Looks like a moon crater, not a good sign. Sounds like light loads.

  6. #6
    Boolit Master

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    Also check your case dimensions. If the shoulder has been set too far back for your chamber and you are using low pressure loads, the primers can back out too. High pressure loads in that case can cause head separations, so be careful.

  7. #7
    Boolit Master
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    Fired the remaining 25 after cleaning and they all backed out. When I processed this batch I loaded 100 rounds. Shot the next 50 and only three or four primers backed out. Did realize that one difference was I seated the bullets a bit deeper on these, no slight resistance closing the bolt. Wonder if that little extra resistance was enough to make a difference. Have neck sized all of them and will seat the bullets like normal (slight resistance) and see what happens.

  8. #8
    Boolit Buddy Old Coot's Avatar
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    Rich, Is all the brass the same make? If not check the ones that the primers backed out in.
    Also, I don't full length resize anything unless it is going to need it. ie. Heavy revolver loads, brass meant for several rifles where one or more may have a tight chamber, as mentioned straight cased pistol ammo. When loading for one rifle I only neck size (assuming that the cases will chamber easily). It is easier on the brass, and centers the case in the chamber better. Brodie

  9. #9
    Boolit Grand Master uscra112's Avatar
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    Your primer is driving the cases forward in the chamber, setting the shoulders back, before the powder lights. The light load of Red Dot isn't sufficient to drive the case backward again, reseating the primer and pushing the shoulder back where it belongs. This has been a classic problem with light loads in rimless cases ever since rimless cases were invented.

    Three things:

    One, use PISTOL primers, which don't drive the case forward as energetically.

    Two: Make up a set of cases with the flash hole drilled out to about .090". This reduces the pressure in the primer pocket, and thus the force driving the case forward. Use these for your light loads. Do NOT use for full power loads.

    Three: Seat your bullet out far enough to contact the lands firmly, and crimp the case.

    The cases you are getting primer setback in are now too short to headspace properly. Do NOT load any of these with a fullpower load. Head separations will occur.

    You can recover these by loading that Red Dot load and then lightly greasing the outside of the cases before you fire them. The case will slide back in the chamber when fired, blowing the shoulder forward to where it should be. Once this is done, clean your rifle's chamber of ALL TRACES of the grease.

    Personally, I long ago quit shooting light loads in my .30-06, .35 Remington, or any rimless cartridge rifle. Rimmed cases do not suffer this problem.
    Cognitive Dissident

  10. #10
    Boolit Buddy
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    Quote Originally Posted by earlmck View Post
    My guess is (for how ever little that is worth!) that the Hornady die has to be setting the shoulder back too far for your rifle in the sizing operation. Dies always try to return fired cases to minimum dimensions or slightly below, and our rifles are more likely to be somewhere toward maximum. So I never screw a FL die all the way down -- back the die off a ways and keep trying until you get a perfect fit for your rifle.
    This is a good place for an RCBS Precision Mic. I use one to set most of my sizing dies. Using one you can set sizing dies right spot on. the cost is one that has proven to me to be one of the best expenditures I have made for good accurate amo!

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Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check