R700 5R .223 cratered/blown primers with factory ammo

[Gtek]

I would not put another round in it until the head space was checked. Then I think a known good chamber reamer and confirm nose fits in muzzle then light chamber spin to check for throat removal. Next would be firing pin protrusion, a little suspect marking at base of firing pin stem, internal forward bolt?

[Peregrine]

Measure the protusion of the the firing pin through the bolt .give everything a good clean then try it again it might be OK .a little crud in the wrong place can cause havoc.

The firing pin protrusion is .054"

I did give the firing pin channel a good clean and found one blown out piece of brass in there I was able to blow out, and I soaked the whole bolt in some solvent overnight and it doesn't appear anything more is in there. But again, the problems with light strikes occurred right from round 1 with this rifle, and generally only happens with ammo that has harder primers.

What is the firing pin extension from the bolt face?

A possibility for the blown primers is the chamber neck is cut a bit short, and/or the factory ammo was not trimmed properly. The case mouth pinching the bullet in place can send pressures sky-high. I would check the case length of the cases with blown and cratered primers, compare to other cases, and post the info here.

Alright, I decided to measure the Sako and the PPU (which were problematic), and the White box and Nosler (which look perfectly fine).


Sako => 1.761, 1.759, 1.758
PPU=> 1.762 (neck not square, extreme measure), 1.756, 1.768
Winchester White Box=> 1.754, 1.759 (neck not square, extreme measure), 1.758
Nosler=> 1.756, 1.758, 1.759

So that's not our smoking gun, but it was interesting to see how much more square the necks on the premium ammo was, even the ones I didn't comment on with the PPU/Winchester were off.

I'm seeing the cratered and pierced primer. But don't see a flattened radius on the primers or extractor imprint on the case. Aside from the cratered/blown primer, the pressure doesn't look high. Is the bolt sticky when opened? Try the cheap stuff first, I'd replace the firing pin spring to see if a weak spring is the problem. I'd measure the case head expansion, you should have about .007 increase from new, on a normal fired case.

No bolt stickiness. I have a couple boxes of unfired Sako up where I shoot, i'll check a couple of those with my Hornady Headspace comparator compared to these fired cases and get back to this thread.

I would not put another round in it until the head space was checked. Then I think a known good chamber reamer and confirm nose fits in muzzle then light chamber spin to check for throat removal. Next would be firing pin protrusion, a little suspect marking at base of firing pin stem, internal forward bolt?

I don't have a reamer, what do you mean by the suspect marking? Do you mean the pictures of the galling on the firing pin I posted up in my third post in the thread? I'm not sure what's up with that.


I couldn't find my preferred Tipton rods locally, so I got the LGS to see if they can special order me one. If the distributor has one in stock it shouldn't take much more than a week or two, i'll give the bore a really good cleaning and then we'll go from there.

[Larry Gibson]

"The firing pin protrusion is .054""

That's within spec but the piercing of the primer indicates the protrusion when firing is too long. The dry fire collar may not be in contact with it's stop surface in the bolt with that protrusion measurement. If it still can go forward under inertia that indicates something else is amiss.

The cratering may be caused by something as simple as a weak firing pin spring or weak firing pin strike. The misfires also indicate either. That may have been caused by the fouling in the firing pin channel. Have you fired it since the cleaning and removal of the "chip"? I see no sign of any "pressure" problem.

[Gtek]

^^^ Referring to what Mr. Gibson better explained in more detail. Just pushing forward with finger pressure vs strike protrusion. Yes the marks at base of pin stem, pin possibly going farther than intended post release. Without another identical weapon to compare/mic parts, I think I would buzz pencil very small identifiers on bolt components and give big green a call, hopefully someone still knows how the 700 works there.

[McFred]

Reading material RE full pressure and excessive headspace blanking primers:

http://forum.accurateshooter.com/thr...#post-37402552

2¢

[tomme boy]

GET a new firing pin spring. It will go away. Get a wolf brand one. Preferably a extra power one if available. If this does not fix the problem then you will need to have the bolt head bushed. These are the two very common problems with remington 700 bolts. It is not a headspace issue. That shows up in a different way not like this.

[Peregrine]

^^^ Referring to what Mr. Gibson better explained in more detail. Just pushing forward with finger pressure vs strike protrusion.

Pushing forward with finger pressure? I might be missing something, I just pulled back the striker and rotated the bolt to the cut where the striker is allowed to fall when the rifle is in battery, then measured.

"The firing pin protrusion is .054""
The cratering may be caused by something as simple as a weak firing pin spring or weak firing pin strike. The misfires also indicate either. That may have been caused by the fouling in the firing pin channel. Have you fired it since the cleaning and removal of the "chip"? I see no sign of any "pressure" problem.

That's reassuring but still strange. I have not fired it yet, i'll likely wait until I get a new spring in at this point.

GET a new firing pin spring. It will go away. Get a wolf brand one. Preferably a extra power one if available. If this does not fix the problem then you will need to have the bolt head bushed. These are the two very common problems with remington 700 bolts. It is not a headspace issue. That shows up in a different way not like this.

That's an easy enough proposition.
I can see on the Wolff website that there are several strengths of spring available; 24lbs, 28lbs, and 32lbs. Can someone talk me through the logic of the different strengths of spring? It mentions that 24lbs is the factory standard, are the higher strengths simply for harder primer milspec type ammo or is there any other benefit or effect to consider (other than force require to cock naturally)?

In any case I found a sole retailer (Canada) with a single 28lbs short action spring in stock, unless someone has anything pertinent to add i'll probably order that and go from there. I could order direct from Wolff but they have a $25 minimum for international orders and I can't think what else I could use from them.

[HangFireW8]

If firing pin overextension is still an issue, it will get worse with a stronger spring.

The rifle may have had two or three issues. Spring strength. Primer disc inside bolt. Overextension. Don't despair if you don't solve all of them at once with the new spring. A fresh spring won't hurt the rifle.

[Bigslug]

A lot of stuff could be going on there. . .

Once you pierce a primer for whatever reason, your firing pin gets a dose of hot plasma jetted onto it's tip, which stands a good chance of pitting it, leaving a rough surface, which stands a good chance of creating a place for another primer to pierce at, pitting the firing pin further, and so on. Get a magnifying glass and look hard at the tip of your firing pin for this kind of damage.

Then you get into 5.56 NATO vs. .223 Remington issues. 5.56 is loaded hotter to meet various gun functioning requirements and goofy military things such as the distance at which Soviet body armor must be pierced. Guns chambered for 5.56 ammo have a longer throat cut into the rifling to deal with this added pressure. SAAMI spec .223 Remington throats are tighter. The fun begins when you shoot 5.56 or loads cooked up for a longer throat in a tighter spec barrel - which your 5R tube undoubtedly is.

CCI makes both large and small military spec primers which are thicker. They're a nice safety net against this sort of thing. The puckering around your firing pin strikes seems to indicate that the loads are a little toasty for the throat, the primers are a bit thin, or both.

700 light strikes: YMMV, but I just got done dealing with one that had some form of factory goo between the firing pin and cocking piece that was gumming up the works. The gun was audibly "not right" when dry firing. Rather than dismantle the whole striker assembly, it got a generous hosing with brake cleaner followed by a dousing of Break Free. All is now right with the world.

[DCM]

Light strikes could be a sign of long headspace. Same for the primer appearance. The primer backs out with the case forward than get reseated under pressure.

My vote is This.

[tomme boy]

CCI SR primers are also thinner than everyone else's. So that can be a issue. They were not meant to be used in 223 Remington according to some older data. They were made for the Hornet and others in its class. Here is a chart that shows the thickness of some primers and I have run into the same thing he has. But the problem the OP has is SOMETHING else.

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

[samari46]

Don't know if Remington still makes them but they had a 7 1/2 primer with a copper colored shell that was made spefically for warm loads. used many thousands for a few 222 Remington chambered rifles. This was way before the 22 ppc and 6mm ppc benchrest cartridges came out. Still remember the load, 19.0 grains IMR 4198, Rem case,Rem 7 1/2 primer and a rem 52 grain match bullet. Frank

[Lloyd Smale]

its tough to gauge a rifle problem on primer appearance especially when you start running imported ammo. Ive seen ammo loaded to the same pressure with cci and fed primers and get completely different looking fired primers. Ive seen ammo loaded with wolf primers using the same exact load with some primers looking normal some looking flattened and some even pierced with loads that are right out of a load manual. My guess is your looking at more of an ammo problem then a gun problem. It still wouldn't hurt to buy a new pin and spring but I woundnt go with a weight other then factory. Millons of 700s are out there running just fine with a factory weight spring. I seriously doubt its a headspace problem either. that's pretty rare in factory guns. quick check to see if its might be even possible is to take a piece of fired brass and see if it chambers in another 223. Don't take that as absolute proof though because even if it doesn't it could be just that the gun your trying it in has a slightly tighter chamber. You should be able to measure your fired case and see how much its lengthened after being fired. Full length size and Trim a couple pieces of brass to minimum trim length and load one and shoot it in the gun and measure it. Youd also be seeing case separation after 2 or 3 firings if headspace was letting that case stretch. Ive found more problems through the years with out of spec dies causing this kind of trouble then headspace. Not that it cant happen. I had a 300 H&H model 70 that was on the iffy side with headspacing. If I full length sized brass I was lucky to get 3 firing out of it even with milder loads. I saw case separation firing once fired brass with that gun. If I neck sized the problem went away.

[Fernando]

Polish the tip without changing the radius.
The cratering is probably due to pin fit - some have them bushed.
You could try a different pin that may have a better fit.

[DCM]

Ok here is why IMO this is a headspace issue. Some of the primers look normal, some look like light strikes, some are blown, some cratered, many different brands, not just the brand(s) with soft primer cups. So it seems that the cases are not being held close to the bolt face all of the time, pointing to loose headspace IMO.

I would check the headspace first, if it is safe then I would neck-size some of the once fired brass from this rifle, insert CCI Mil. primers, load up some safe loads and re test.

Just my 02, YMMV

[tomme boy]

Nope. I have had numerous 223 rifles from several brands. Went through this with several makes. HS issues would be showing a belt around the case and the primer would be completely flat and flowing around the face of the case. None of his cases are showing any signs of HS problems. Like I said before there are two thing that can be going on.

One, Remington rifles are famous for having oversized firing pin holes. Thus needing to have them bushed.

Two, the firing pin spring is weak. If it is weak, the pin is pushed back upon firing and that is how the hole is punched. It also will cause misfires as the piece of the primer can clog up the firing pin inside the bolt. Usually you just cock it again and it will fire the second time.

Throwing mil spec primers in the cases will just cover up the actual cause not fix it.

[DCM]

Yeah why bother?




V V V V V

[Forrest r]

Nope. I have had numerous 223 rifles from several brands. Went through this with several makes. HS issues would be showing a belt around the case and the primer would be completely flat and flowing around the face of the case. None of his cases are showing any signs of HS problems. Like I said before there are two thing that can be going on.

One, Remington rifles are famous for having oversized firing pin holes. Thus needing to have them bushed.

Two, the firing pin spring is weak. If it is weak, the pin is pushed back upon firing and that is how the hole is punched. It also will cause misfires as the piece of the primer can clog up the firing pin inside the bolt. Usually you just cock it again and it will fire the second time.

Throwing mil spec primers in the cases will just cover up the actual cause not fix it.

Doesn't ptg sell an oversized fp tip for the 700's?

[Markopolo]

Start with the spring as many have recommended... springs are cheap. Step one. If your gunna keep the rifle, why not grab a couple different sizes. The stiffest to the factory stiffness. Buy all 3.

If that doesn’t fix it, then go with the other option that tommyBoy suggested. Pretty simple to get the thing bushed, even in Canada.

Play around with it a bit. The challenge is the exploration, and the most satisfying.

Marko