10mm Primers Blown-Backing Out

[Sal1950]

Tanfoglio Witness Match purchased as a 40 S&W.

I bought a 10mm barrel from EAA, a 20LB spring from Wolff.

Originally barrel wouldn't go into battery, hood was too long.. Mounted barrel in my surface grinder and removed about .010 from the hood,. Seems to lock-up correctly now.

Been shooting the gun for a number of years with fairly light to midrange loads with no noticed issues.

Decided to build something a little warmer,  but not crazy, and loaded up some of these,

 

Various brass but I don't consider it old or shot loose

Precision Delta 180g  FMJ

AA #9 powder 13.4g  (Lyman says max at 13.9)

Federal 155 LPM primers

OAL 1.250

Chrono Beta Master at 15 feet,  L 1210,  H 1256,  A1236

 

Shot about 30 rounds or so down range, report was brisk but didn't seem too unusual. Chrono numbers seem about as expected maybe just slightly faster.

Gun was jamming quite a bit so I stopped to look at things and pick up my brass.

They all showed the primers protruding at least  ..010  or more,  3 or 4 were missing their primers completely!

 

Went back to my prior lighter loading of 6.0g of Universal, with all else the same.

They chrono'd at  L 1063,  H 1091,  A 1081

No issues with primers with this load.

 

Does anyone have any ideas on what might be the issue here?

Any help would be appreciated.

TIA

 

Edited July 27, 2017 by Sal1950

[GrumpyOne]

Pics of the protruding primers? 

 

You might try a harder primer than Federal and see if that helps. 

 

If the primers came out completely,  it sounds like the primer pocket was loose. How difficult (or not difficult) was seating the primers?

[DougM]

Gotta agree with GrumpyOne.  I'm running an almost exact setup as you and having no issues what-so-ever with primers backing out - even with loads as hot as you are using.  I'm loading AA-7, though, but speeds and weights are in the same range.  I'm using CCI primers, which are harder than Federals, and that may be the difference.  I'm also using brass that has only seen a few firings and I can tell seating the primers that the pockets aren't loose.  Just for grins, you may try hand seating the primers (other than Federal)  in a small batch to see if you can detect loose pockets.  If everything seems OK, try shooting them and see if the problem has gone away.  I'm betting it has.

[Sal1950]

Thanks for the input guys.  GrumpOne, I haven't taken any pictures but yea they were all proud with 3 or 4 out of thirty completely blown out.

I'll have to run some experiments on the various suggestions here. My brass is from various sources that I haven't kept separated, none of it has been loaded excessively?

Maybe I'll buy a batch of new brass,  Top Brass has some good prices and see what happens with it and Federal primers and some others.  I have both CCI and Winchester on the shelf to try but most of my range weapons are tuned for Federal.    Very strange to me that this should occur all of a sudden with this new (to me) load.  I wouldn't consider it hot?

Thanks again,  when I learn something solid I'll report back.

Edited July 27, 2017 by Sal1950

[Sal1950]

Thought I'd update this thread with what I'd learned so far.

First to settle any question in my mind that there was some issue with the gun like headspace or cycle timing I bought a box of Bullalo Bore's Heavy 10mm 180 JHP's.  There were no issues at all firing this ammo rated to run about 1350 fps in a 5" barrel. Wanted to chrono my Tanfo but it was raining that day, saved some rounds to clock in the near future..

 

Loaded 30 rounds with the same P-D 180's and 13.4g of A#9 but this time using CCI 330 LPP,  no issues were observed with the primers backing out.

Loaded 30 the same way using Winchester LPP with the same result, no backing out there either.

 

Going back to the Federal 155's but backing the load down to 12.7 of A#9 the primers all remained in place except for one I noticed to be about .010 proud.

 

This situation still has me scratching my head a little. Been loading using Federal primers almost exclusively for many years now and never noticed any issues like this before. But in the end the solution is easily at hand since the Tanfo has a beautiful trigger at 3.5 lbs stock so never played with lighter springs here.

 

When I can I'll chrono those BB's and a few more of my builds and post the results here for peoples info.