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Old 05-07-2017, 12:07 PM
Harold M Harold M is offline
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Default Primer Piercing / Blanking

OK. In all these years, I never paid any attention to the causes of primer piercing, mainly because I never had it happen.

Here's the story. In the Springfield '03 converted to 223 ... I increased the velocity by about 100 fps (according to the manuals) by switching from H-4198 to N-133. Same 52 grain match bullet, same 205M primers, same Remington cases. Measured head space by comparing fired and in-fired cases - the difference in length to the shoulder datum is only 0.001; maybe another half mil. I figure I just went over the edge for this rifle by moving the peak pressure up by about 12%. The firing pin hole is a little on the large side. The end of the pin is nicely rounded.

I set up the bolt in a vice and put a magnetic base dial indicator on the firing pin hole, and eased the striker down, and measured the firing pin protrusion to be 0.070, not to put too fine a point on it.

I read that the protrusion on more modern rifles is, nominally, 0.055. I don't have a spare firing pin front part (Springfield uses a unique two-part firing pin) and don't want to make a mistake.

Do I suck it up and file the point of the firing pin down maybe 0.010? I can always go back to the old load.

Harold
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Old 05-07-2017, 12:51 PM
Bill K Bill K is offline
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Default Primer Piercing/ blanking

I may be missing the point of something, but if you have no issues and your rifle is shooting, with the accuracy you want, than why do anything, at this point ? If it works don't get picky and try to fix it.. Bill K
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Old 05-07-2017, 01:03 PM
Nor Cal Mikie Nor Cal Mikie is offline
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Like Bill says, "don't fix it if it ain't broke".
Could be something as simple as the brass being too short for the chamber, (headspace issue from pushing the shoulder back too far, not a barrel spacing problem) round gets pushed forward in the chamber by the firing pin, fires, then gets slammed back onto the firing pin piercing the primer??? I go for the simple stuff first.
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Old 05-07-2017, 01:04 PM
Hog Patrol Hog Patrol is offline
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Filing it down, are you going to make the end a radius? Squared off firing pin, I would imagine, would increase the likelihood of blanking. As a previous post stated, if it ain't broke, don't fix it.
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Old 05-07-2017, 01:49 PM
gzig5 gzig5 is offline
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Primer blanking is normally caused by the FP hole being too large. The increased pressure is pushing back harder and shearing the primer cup on the unsupported region between the FP and hole. The normal corrective action is to bush the FP hole in the bolt to be a close fit to the FP diameter. You can do this on a lathe or Greg Tannel does FP bushing for a pretty nominal fee. The other option is to make the FP diameter match the hole in the bolt by making a new front FP. On the Springfield this would be an easy task on the lathe. I don't think that shortening the FP .015" will make a difference but you can try. Springfield FPs are cheap and readily available if you mess up. If you don't have a lathe, chuck the FP in a drill and run against a bench grinder stone. You will want to go slow and keep that nice radius. Leave it a touch long and finish by running against a fine stone or crocus cloth to leave a smooth finish. A rough FP point can cause piercing too. Besides that, drop the powder charge to the original pressure level and live with it.
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Old 05-07-2017, 05:29 PM
L.Sherm L.Sherm is offline
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Harold you could also try 7.5 or 450's I believe the cups are thicker than a 205.
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Old 05-07-2017, 07:45 PM
Larry in VA Larry in VA is offline
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Like some have suggested a change to a tougher primer may be the easiest solution. The Springfield being an old military weapon CCI No.41 primers would be the easiest solution me thinks.
http://www.cci-ammunition.com/produc...ers.aspx?id=30
https://www.midwayusa.com/product/13...ary-primers-41
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Old 05-07-2017, 08:58 PM
Stevo Stevo is offline
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Quote:
Originally Posted by L.Sherm View Post
Harold you could also try 7.5 or 450's I believe the cups are thicker than a 205.


They are. I use them when the 400's start too get loose in the pockets.
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Old 05-07-2017, 10:18 PM
TinMan TinMan is offline
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I recall that Rem 7.5 and CCI BR4 are the same thickness.
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Old 05-07-2017, 10:41 PM
Bill K Bill K is offline
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Default Primer Piercing/ blanking

Harold.. Even sporterized the old Springfields and Enfields are fine actions and make good rifles. Bill K
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