Some time back I had a thread on my Hepburn and primers backing out.  I wasn't sure if it was a headspace problem or a rebounding hammer problem and got lots of suggestions for fixes but along come Covid 19 and my range closed.  I have a chamber that was cut for full length 405 brass with a 0.073 rim and all of my Hornady brass was 0.068.  I bought some Baco brass to try that is the correct 0.073.  Not being able to shoot much as the range is closed I loaded a few of all of my brass types with a 330 grain bullet and smokeless for this go-around and shot a few each with Winchester WLR and Federal Match.  It didn't seem to make any difference which case was used but I had more problems with the Federal primers than Winchester.  I believe that the firing pin is sticking in the primer and not allowing ejection.  Firing a second time does not always work either.  I need to look at the end of the firing pin closer but I am not sure that I want to tackle taking a Hepburn apart.  My next thought was to try CCI primers and also magnum primers.  The lower pressure loads seemed to have more problems.  So my quick question is this, what is the toughest primer known to man so that the angled firing pin of the Hepburn with the force to penetrate the armor of a light tank does not stick in it so far as to pull the primer back out when it rebounds?  Thanks.  Tom

John, I know one of the fixes suggested earlier was to put in a heavier extractor spring and to reshape the firing pin.  I have CCI LR and Magnum primers and am now going to experiment with black and paper patched bullets to see if I can find a reliable combination.  Most of the problems I had today were with Federal and I did not have any of the proper rim thickness cases loaded with anything but Federal.  Winchester worked 85% or so with the only problems with a light load of Buffalo Rifle.  When I used a heavier load of H4198 with a gas check bullet I had no problems except the recoil!  Tom

You might try CCI  number 34 primers they are made for use in semi auto military rifles to prevent slam fires.

I get my best results with a standard Winchester Large Rifle Primer.

40 Rod

Hopefully you get the issue resolved primers shouldn't be creating the problem it has to be related to something else.

Oldman1950 wrote on Apr 28^th, 2020 at 6:36pm:


I have a Marlin 336, 30-30 that does this - primers backing out of the case. It is most prevalent with starting loads, although I have seen it with factory ammo, too.  Never had a case head separation in this rifle, due to case stretching.

Primers nearly always back out of the case due to chamber pressure.  With low pressure loads the, case does not stretch and the primers stay backed out of the case.  The amount that the primer backs out is the difference between the thickness of the rim and the total headspace.  High pressure loads stretch the case and reseat the primer.

One question, can you rechamber one of the cases with the primer backed out.  It would be interesting to measure the amount of primer protrusion, rechamber the case, eject it and measure the protrusion again.  I have a feeling that you will find there is no difference.

Mike

I had this trouble when I used Remington 2 1/2 pistol primers in my .40-2 1/2 Rem. Hepburn (as I do with all of my other large primer calibers I deal with.)I changed to Remington Rifle primers and the problem was solved.

I believe that the problem is that he primer tip penetrates the softer primers so far that it sticks in the case as it is hitting on an angle and not inline with the bore.  The attached photo shows 10 cases fired with the identical load.  The cases on the left are 405 Winchester from Hornady and the rim thickness is such that there should be excessive headspace.  They were primed with WLR primers and did not experience any issues extracting.  The ones on the right were from BACO brass with the correct rim thickness to eliminate excess headspace.  Four out of five hung up with Federal Match primers.  You can see where the Federal primers have deeper craters.  I now have that same load with both types of cases loaded with CCI to see if the problem goes away.  If so, I might buy some CCI 34 primers to make sure that it stays away.  I have taken the firing pin out and cleaned everything and inspected the spring.  I would imagine a heavier return spring might lighten the pin impact and also give more effort to retract the pin.  Without better knowledge I was not able to see how the tip was shaped compared to the above pictured firing pin.  Tom