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Old 05-07-2012, 05:12 PM
Kevin Gullette Kevin Gullette is offline
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Post Of Primer, Boltface, and Firing Pin.

In light of a recent subject, I thought I'd start this thread.

A few days ago there was discussion on the issue of bushing boltface firing pin holes to a smaller diameter. It seems, to me, that a "good thing" may also have it's limits.

In two rifles, that had primer blanking issues, I had added extra power firing pin springs........in theory, to help reduce the blanking/cratering effect. The 32lb. and 28lb. springs did help a little bit, but did not cure the problem. Also, the bolt cocking effort was increased.

Later, both bolts were "bushed".......and the blanking/cratering disappeared.

BUT...........I later found an occasional problem. Once in a while, in both rifles, a primer(Fed 205M) would pierce at the BOTTOM of the firing pin indentation. A nice little tiny round hole(I'll add a pic of the 17Jav case, from the other computer, later). Note that both firing pins had perfectly smooth, round ends.

I had left the extra power firing pin springs in the bolts. I wondered if the now 0.060" firing pins were moving a little TOO fast. So, I went back to 24lb. and 22lb. springs.........and the little holes have not reappeared. Also, the ease of bolt cocking has returned.

Sure.....other primers may have made a difference, but I long ago had mostly standardized on 205M's due to their thicker cup, that would withstand more measureable "cratering" before blanking. Also, they are pretty much THE benchrest standard.

I can't prove it.......but, whatever works.....huh??

Anyway........anyone have similar experiences......or different experiences, for that matter?? All input is welcome......as we're all looking for the truth....right??

Friend Of The 17
Kevin

Last edited by Kevin Gullette; 05-07-2012 at 05:39 PM. Reason: add pic
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Old 05-10-2012, 12:58 AM
montdoug montdoug is offline
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I don't know how this thread slipped past me but threads seem to be cycling through to the next page a lot faster anymore. Actually I was on the second page looking for that thread you mentioned on "bushing the bolt" to find that PS magazine issue you'd posted Kevin cause I had a little time to go digging.
This is an interesting thread as well cause I sure can't figure how a heavier spring would cause primer piercing as you mentioned but obviously it was??
I guess if a guy ever figures it all out completely he'd lose interest and be on to a new hobby . Won't ever happen in my case so I'm safe .
Did you happen find that pierced primer picture??
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Old 05-10-2012, 02:19 AM
Kevin Gullette Kevin Gullette is offline
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Smile Doug.......

The pic is of one of my 17 Javelina cases. Kevin
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Old 05-10-2012, 03:20 AM
dcloco dcloco is offline
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Been through this dilemma as well. I only use CCI Magnum and Rem 7.5's.

http://www.jamescalhoon.com/primers_and_pressure.php

Chart lists primer cup thickness.

Of note, I have never seen a rockwell hardness scale for primer cups. As is the case with 205M's, they are in the middle of the thickness scale, but have often wondered with they were not on the soft side. I have had the same problems as you. Switched primers and the problem went away.
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Old 05-10-2012, 04:43 AM
montdoug montdoug is offline
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I read it wrong Kevin, I thought you'd said a hole at the bottom of the primer?? I reread it as see it is in the bottom of the firing pin dent . Still strange?
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Old 05-10-2012, 10:06 AM
K22 K22 is offline
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I've been through this dilemma also, well sorta. A Rem. with a firing pin hole that needed a bushing and then some bad Rem. primers that required having 3 bolts repaired by putting in bushings. What I noticed was how loads that used to crater the primers, didn't any more, plus I could up the load and sometimes significantly. For instance, my load of 20.9 H322 in a 17 Rem. is now 21.5. both using a 25gr. bullets. Accuracy is much more consistent also.
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Old 05-10-2012, 02:06 PM
SmokinJoe SmokinJoe is offline
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Have seen this once with my Cooper 38 in 22 K-Hornet using Rem 6 1/2 primers. All I can think of is cup softness/hardness vs the combination of firing pin spring & shape, plus maybe anvil shape & hardness inside the primer. It didn't seem to cause any problems at the time, but not a comforting thing either. I changed back to Wolf SR primers & have had no more signs of that problem. Have not seen this problem using 205M primers, and I use lots of them anymore in my Dakota Predators, as those rifles have shown a problem with harder primers not firing consistently.
On the primer blanking issue, I had a Savage LRPV in 204R that made nasty looking cratered primers, even with moderate loads. Examining the firing pin hole, it looked as though the hole was actually beveled or radiused. I think that bolt head is an investment casting, so maybe that was the problem. Sent it to Greg Tannel for a bushing job & that fixed all issues with that rifle.
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Old 05-13-2012, 03:12 PM
Kevin Gullette Kevin Gullette is offline
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Smile I guess I should clarify......

.....the above picture.

The primer has NOT blanked, or even slightly cratered. There IS a very tiny hole at the very bottom of the "dent", that was made by the firing pin.

I should also say that the bolt's firing pin protrusion was measured at 0.045".

I guess that I was proposing that a firing pin tip "can" be too "pointy" AND too "fast".

Now.......THAT should be as clear as mud.....huh??/

Kevin
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Old 05-13-2012, 04:56 PM
drewh drewh is offline
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Kevin,
I experienced the exact same thing on a Rem VS 17 Rem. When I bought this rifle it had the j-lock shroud on it, I sent it off to have the firing pin hole bushed and firing pin mechanism replaced. When I got the bolt back I loaded up some mild loads to start working up and was having the same problem - a little pinhole pierce at the bottom of the firing pin strike. I never tried reducing the spring as this one had the added complication of a very tight bore. After the rifle was re-barreled I never had the problem again. So it seem that higher pressure cartridges add to the equation too. I wonder if it is possible, in your rifle, that the higher power spring caused the fp to extend a little farther? I checked the protrusion on mine when I was trying to figure things out, but I believe that the rem is at a mechanical stop when the pin is down.
Drew
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  #10  
Old 05-13-2012, 11:49 PM
dcloco dcloco is offline
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Almost forgot the obvious.

With a good magnifying glass, look at your firing pin. If this firing pin/bolt has had other pierced primers, then there is probably some damage to the face of the firing pin.

The shape of the firing pin should be round, but not a half round, but a blunt round. Like this: (
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