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Old 08-02-2019, 01:23 AM
pertnear pertnear is offline
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Default Help diagnosing Ruger #3 firing pin/breech block problem.

I apologize for the pictures, but it is hard to get a close-up of a primer with my camera. My rifle is a Ruger #3 that has been rebarreled to a 6.8mm SPC. The firing pin has always been off center, even in its previous chambering. That’s no big deal, as far as I can tell. But the firing pin indentation kicks up a burr no matter what the load. On a minimum book load you can see it & easily feel it with a finger nail. As the load & pressure goes up the burr gets more pronounced & eventually it flows back so much that you can “feel” the burr being rubbed flat as you lower the breech block. The primers look curved on the edges, so still far from “flattening”.

My question is has anyone ever encountered such a problem with a Ruger #1 or #3? Is the firing pin sloppy? Is the breech block hole sloppy? Does the firing pin “float” so could it be a hammer/spring issue? Any ideas would be most welcome.

This primer show the burr with a min book load.

This load is .5 grain below book max. The primer indent flowed into the firing pin hole & was rubbed flat when the breech block was lowered. (The red is from a marker I used to separate my loads.)
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Last edited by pertnear; 08-02-2019 at 05:05 PM. Reason: trying to get pictures to work
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Old 08-02-2019, 02:34 AM
Bill K Bill K is offline
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I am finding no pictures ?? Bill K
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Old 08-02-2019, 05:08 PM
pertnear pertnear is offline
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I had problems getting pictures to load for some reason. Please click on the links to see the pictures. I got frustrated try to get pic's inline, which I've done before without problems. Definitely would like opinions & suggestions from the brain-trust of Saubier's.

Thank You,

Dave
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Old 08-02-2019, 10:54 PM
Nor Cal Mikie Nor Cal Mikie is offline
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Possible a head space problem?? NOT a chamber issue but brass too short for the chamber and when fired, get slammed back against the block/firing pin causing the problems?? Just thinking the first thing that comes to mind.
Once fired brass, reloaded WITHOUT pushing the shoulder back too far to cause the issue again.
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Old 08-03-2019, 06:48 AM
rick w. rick w. is offline
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Dave,

Did you have the chance to shoot the rifle before the converison to the new case? Did it have the primer flow characteristic then?

Ruger single shots being off center a little is not unknown, one only has to look at the top of the lifting arm to see perhaps a clue. I assume that the hit of the firing pin is either high or low; never saw one that was right or left.

One could run a set of headspace gages thru the rifle if available. I thought the SPC was on the SAAMI list now but kinda new to me.

The primers kinda suggest headspace issues in my opinion. Brass is too short(shoulder wise) or the chamber is too long. One could take a few brass, expand up to 6mm or 25cal, then insert into the rifle during sizing, until the brass seated with a bit of touch(resistance)(false shoulder routine). Then put in moderate load and bullet and see how those fired cases looked afterwards. I am not a big fan of running the bullet into the lands for headspace, I do not feel it is very consistent for the purpose, just my opinion there.

The basic firing pin of the No.1(no.3) is a smallish firing pin energized with a transfer bar in the breechblock. Hammer never strikes the firing pin, but rather the transfer bar. As I recall the nose is about 0.073" nominal and the ones I have examined are a nice fit to the firing pin hole of the block. I have never bushed a No.1 firing pin in the block; never had the need I guess. One can pull the breechblock out, hold a rod against the transfer bar to get the nose of the firing pin to protrude, looking visually for anything abbynormal...........like way loose fit of nose to hole; beat up nose(not nice and round).

Some smiths when rebarreling a Ruger single shot will decrease the factory gap space to 5 or less, and set the headspace on the low end of SAAMI numbers, so the case is pretty well confined during a breeching, ie does not fly around very far during ignition.

Last edited by rick w.; 08-03-2019 at 06:53 AM.
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Old 08-03-2019, 02:36 PM
pertnear pertnear is offline
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Thank you for your detailed response. Here is a little background on the rifle. I originally bought the rifle at a gun show & it had already been re-barreled to a .270 Win with a fly-weight 22” Apex barrel. Other than the barrel, the butt, forend & band were all original #3. With a scope it weighed less than 7lbs! To say it had a sharp kick is an under-statement! The .270 cases from this rifle exhibited the same cratering around the firing pin indention, but no flow into the hole & no flattening. Obviously I was using LR primers.

I had a new Shilen .277 barrel stashed away so after some research I settled on getting a varmint weight contour cut on the barrel & then fitted with a standard SAAMI 6.8mm SPC II chamber. I also fitted the rifle with Ruger #1 wood & had a tuning screw installed in the hanger. Rifle now weighs 10lbs with scope & I call it a Ruger #2. My gunsmith (who I trust) says he rented headspace gauges & checked the chamber.
  • For sure I’ll expand some necks & size a secondary shoulder for a “light-crush” fit on headspace. That should yield some interesting results.
  • I did determine that indeed the off-center firing pin indent is always high at 12 o’clock. Its effect is pretty much cosmetic, but can the lifting arm be adjusted or modified to correct this?
  • The firing pin doesn’t look like much but trying to find a new one is a problem. Numrich shows firing pins & breech-blocks, but they seem to be on perpetual back-order. I thought I’d try a new firing pin first. If the breech block hole is not elongated, could a new slightly oversized firing pin be fabricated?
As a note, all Mfg’s LR primers have a cup thickness of .027”. SR primers vary by Mfg from .019” to .025” in thickness. I don’t have any info on cup hardness. I’m only experimenting with SR primers that are .025” in thickness.

Thanks to everyone for their help!

Dave
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