I'm working with a Ruger 77 Mark II. Factory ammunition works well but when testing reloads, the primer has to be hit twice before going off (both CCI and WSR). The brass is Winchester from above mentioned factory tested loads, full length resized. Bullets are Hot-Core 7.62 (.310) 123 Gr HCSP. Any thoughts or advice, please.

Nine times out of nine if you have to fire twice to go boom your primers are not seated deep enough. Seat them till they bottom out and are below flush.

BTW Winchester x39 takes a Large primer not a Small primer. Hope this is just a typo and you are not actually trying WSR in a Large primer pocket.

Thanks Steve3102; typo indeed. WLR

That ought to fix it.
I have to look a little closer at the primers when loading this brass,why? Don't have a clue,maybe tighter primer pockets in the brass.

It is possible that your full length sizing die may be somewhat smaller than your chamber. If you are pushing the shoulder back too far then the excessive headspace caused by this would allow the shell to rest far enough forward in the chamber to reduce the firing pin strike to less than is required to set off the primer.

Since this is a bolt action rifle which is firing a cartridge that is normally loaded to only around 45-48,000 PSI, there is no need to full length size. Run your sizing die into the press only as far as necessary to allow your resized brass to freely re-enter the chamber. Your brass will last much longer this way and you'll avoid the dreaded case head separation.

Thanks guys. I checked the primer seating and they are seated fully to the bottom of the pocket.

Measured as much as capable, and the only difference between the factory once fired and the reloaded fired brass is the factory is <0.050 longer; measuring from ogive (Lock and Load).

I'll try less than full length sizing next (although I've used full length almost exclusively for 50 years). Don't let the new member label fool you; I've been here a while but had to change ID's when I retired. Thanks all!

Oooops...2nd paragraph refers, of course, to loaded ammo. (This senility is getting om my nerves)

Try cleaning the firing pin and ID of the bolt.
The last 3 ruger boltguns I purchased had some rust colored gunk that was there from the factory. With out starting a riot the guns were new in box, thier top of the line RSM models and this should not have happened. I replaced all 3 firing pin spring with wolf and problems went away.
hth
Don

clean out the firing bolt and bolt 1st - then if that doesn't do it replace the spring

OK, How does the bolt come apart?

overly resizing your brass - if facotry works, and reloads don't, it is NOT likely to be a small issue like primer depth ..

Got a chance to go the the range today. Tried some reloads that were neck sized only; failed to fire. Further checking of my shooting notes revealed that some factory cartridges (Highland Sports by PPU mfd in Yugoslavia)had also needed 2 primer hits to fire. Going to take to smith and have bolt/firing pin/head-space checked. Thanks all. (any other thoughts?)

It's been so long since I looked at the firing pin assembly on a model 77 that I can't recall.... IS the firing pin protrusion adjustable on that rifle assembly?

If so, sounds to me as if you may need just a few thou more protrusion. Somewhere just shy of .060" beyond the bolt face seems to ring a bell in my mind as a figure an awfully lot of rifles do very well with.....

quote:

Originally posted by Mike Michalski:
Got a chance to go the the range today. Tried some reloads that were neck sized only; failed to fire. Further checking of my shooting notes revealed that some factory cartridges (Highland Sports by PPU mfd in Yugoslavia)had also needed 2 primer hits to fire. Going to take to smith and have bolt/firing pin/head-space checked. Thanks all. (any other thoughts?)

What does the indentation look like after the first hit? Normal, or just a slight ding?

Personally, I doubt the problem is rifle headspace. It could be artificial excess headspace caused by setting the case shoulder back too far when re-sizing, but I doubt that too, as new Winchester ammo seems to be working okay in it and factory ammo has to be made a little short to make sure it fits in any rifle of that designation.

(That's why SAAMI standard maximum factory specs for ammo are usually about .003" shorter than SAAMI mimimum specs for chambers of the same name.)

I have had to adjust firing pin protrusion on a number of rifles of various makes where this very same thing was happening. If you don't know how to check it yourself, the first thing I would ask the 'smith to do is to check firing pin protrusion for you.

We have had the same problem with a Ruger .257 Roberts Varmint circa 1972 when my cousin uses #34 primers which were, I understand, designed to eliminate slam firing. Of all our rifles this is the only one exhibiting this problem. From all the info we figure it was a slightly weak spring or firing pin portrusion. What ever, he doesn't use the #34s in that rifle and the situation is non existent.
Had a 340, 30-30 that had that problem till the fouling was removed inside the bolt and around the firing pin . Goes bang every time now every time. roger

Been to the smith (twice) and he says the bolt is clean and firing pin protrusion is ok. Still having fails to fire on reloads but not on some cheap, non reloadable stuff from Dunham's. Hmmmm?

quote:

Originally posted by Mike Michalski:
I'm working with a Ruger 77 Mark II. Factory ammunition works well but when testing reloads, the primer has to be hit twice before going off (both CCI and WSR). The brass is Winchester from above mentioned factory tested loads, full length resized. Bullets are Hot-Core 7.62 (.310) 123 Gr HCSP. Any thoughts or advice, please.

I use to own a Ruger M-77 in 7.62 X 39 m/m and found that if you use .308" bullets you'll need to kneck-size only. If you use .310" dia. bullets then you can full-length size your cases. I found that the Ruger has a long throat in this caliber and is slightly tapered. I also believe the bore diameter is .309" so it can handle both .308 & .310 bullets.

quote:

Originally posted by Mike Michalski:
Been to the smith (twice) and he says the bolt is clean and firing pin protrusion is ok. Still having fails to fire on reloads but not on some cheap, non reloadable stuff from Dunham's. Hmmmm?

I think the firing pin spring is weak.

BECoole, How would that work? I'm no smith but I thought the firing pin spring held the pin back(?). Maybe I'm confused.

mike - the firing pin spring does in fact hold the pin back, but when you pull the trigger the sear releases the pin. if the spring is weak the pin does not come forward with enough energy to set off the primer. If you replace the spring, take a look at the old and new together. the new one will be visably better

butchloc, Yes, of course. I was thinking of a hammer gun....another brain fart.