Savage .223 Primer Cratering

[Clucknmoan]

Gents-

Need some help in the worst way. I have an event this weekend and my rifle is not cooperating at all.

Savage Model 12 .223 with a 9 twist tube, B&C Comp stock...yada yada. About 350 rounds down the barrel thus far. Through the OCW process my load turned out to be 25.2 grains of Varget (Hodgedon says Varget and SMK's anywhere from 24 to 26) with 69 SMK's just off the lands, Winchester brass, CCI 400 primers. This load gave me about 3050 fps to begin with, then sped up to about 3089 after barrel settled in. Shoots very well, very consistent in the low 3's.

Thought everything was great, spent 3 weeks in San Antonio and when I got home to Idaho it had turned hot. Needed to run a tall target test on my new scope to make sure it was true with the bore and noticed that my loads were cratering more than before, some pretty bad cratering actually. I figured it was the heat, so I dropped clear from 25.2 grains down to 24.1 grains .1 grains at a time. Velocity followed to the low 3000's as it should have, but the cratering never really got better. So I then switched to CCI BR4, WSR and Remington primers at various low charges and although some were better than others, still cratered. I even shot a real light load from my AR, still cratered. Then I took some of my original loads and made sure they were nice and cool, still cratered. Timing of this problem says heat, but I sure can't seem to get it to go away by taking heat out of the equation.

The cratering is really the only sign of pressure. It is flattening primers somewhat, but nothing too terrible. No ejector marks, heavy bolt lift, nothing.

Checked everything I could think of. Cleaned the rifle, made sure primers were fully seated, double checked charges, made sure bullet wasn't jammed in the lands, checked case length,

Not sure what to do here. During workup, I did always notice the firing pin seemed to strike the primers very deep, so I checked the protrusion. It looks like its right around .065 which from what I can find is high. Could this have gotten worse with time?

I also understand that the firing pin is too sloppy in the hole and this can cause the cratering. Can this also get worse with time?

I guess tomorrow morning I will pull the copper out of it and check for a carbon ring, but I'm not sure this would cause these issues.

I'm stumped. It shoots like crazy, just craters the primers fairly bad now. I'm afraid if I shoot on a real hot day with more pressure it could pierce one.

Please help!!

 

[memilanuk]

Most likely a quick call to Gre-Tan Rifles will fix things easily enough. I'm guessing you probably have a small firing pin in a bolt head with a big firing pin hole. This results in a lack of support for the primer cup during firing, allowing it to flow back around the pin tip and into the hole. Gre-Tan does an excellent job of fixing this by reaming out the hole, soldering in a plug, drilling and reaming it to a precise size, then turning the firing pin to a corresponding diameter. Most gunsmiths could do it; Gre-Tan kind of specializes in it and has the tooling all set up and ready to go.

It's not a Savage specific problem, FWIW. I had the same issue on a Rem 700VS years ago, and then my first 'custom' action, used PTG bolts that copied the Remington design, right down to the big sloppy firing pin hole - resulting in cratered primers with multiple forms of factory ammo. My first Savage 6 BR, I could only get up to ~2700 fps with a S107MK because of the primer cratering. Pretty sure if I'd known then what I know now, and set that bolt off to get the firing pin hole bushed, that problem would have went away completely.

A word of warning... once you have that firing pin bushed, its takes some serious effort to get any cratering at all - so pay extra close attention to any *other* pressure signs!

 

[DirtySteve]

All of my Savages appear to crater primers. I believe you are below max so, since you have no other signs and are happy with the load. I say ignore it and keep shooting.

 

[Clucknmoan]

Some of them appear to be a little more than cratering. Some appear to flow up the firing pin. Supposed to be hot as hell where I'm going this weekend. A little worried that heat will put the pressure over the top.

 

[Anytime]

All of my savages crater too. My 12 in 223 will crater any round I put through it.

 

[Texas10]

If it bothers you, it's an easy fix. Just order a few firing pins from Savage. You'll have to sign a waiver, but they will sell them to an individual. Once in hand, measure carefully with a micrometer, not a caliper, and select the one with the largest pin diameter. You'll find them to be a bit out of round when you measure, so be sure to get an average.

When re-assembling the firing pin, you can set the pin protrusion to .045 if you like. Do a little polishing with 1000 grit on the pin body in the area of the top threads where the keyed washer slides upon cocking and release. Also the cocking sleeve. There is a lot you can do to make it work better and cock easier.

 

[memilanuk]

Gre-Tan's turn-around time is traditionally fairly quick... maybe two weeks tops. Definitely a better fix, IMHO, than playing mix-n-match with factory parts hoping to get the size you need.

 

[Clucknmoan]

Appreciate all the replies gents. Here's a little more to add to it.

I should have mentioned above that the AR load I shot out of this had a CCI 41 primer in it. I think they are pretty damn hard.

I put a bore scolding it this morning and there wasn't much to report. Maybe a very thin and faint carbon ring, but not much. Regardless I pulled the copper out and scrubbed the carbon ring.

I am going to run the bolt down to a gunsmith today and see what he thinks, maybe he can fix it real quick, at least adjust the Firing pin. From there I am going to try and see if it will shoot WSR primers, they seemed to hold up about the best and had low SD in load development.

I will get this fixed in the near future, but right now I'm just trying to make sure I have a rig to shoot this weekend, it's not something I can skip.

 

[Deleted old_dood]

I have 2 Savage 12's, a LRPV and a 6BR. the both cratered primers when new due to oversized FP holes. I put a new PTG bolt head on one and the other went to Gre-Tan for bushing. After many thousand of rounds, the one with the PTG bolt head has just started to crater again. The Gre-tan modified shows no hint of it.

 

[Clucknmoan]

Bit of an update here. Shot some over the LabRadar this morning after I pulled the copper and carbon out of the barrel.

First 5 shells were cool to the touch and they came in exactly what my load was to begin with, 3059 fps with an ES of 11. Still had some cratering, but I would say it's acceptable cratering. Primer isn't flowing up the firing pin really at all.

Put 5 shells in the sun to try and get them warmed up. These shot at 3057 fps, with an ES of 28. It would have been right at the 11 ES again if it hadn't been for one oddball shell. These shells were not hot, but just warm. I then shot a couple cool to the touch ones (now that the barrel was a little warmer) and got about the same, actually a little less speed for whatever reason.

So...I stuck my rifle in the sun to get my barrel good and hot. Put virgin and once fired shells in the sun to get hot. These gave me 3103 fps and an ES of 32. These primers cratered much worse and one was severe. Id say my culprit is most certainly heat and I'm sure I need to get the firing pin bushed ASAP.

So here is my question then for the weekend. I already have 400 shells loaded for this deal. Should I pull them all and drop a couple grains or should I figure out a way to keep my ammo cool?? It seems to shoot pretty well at both the 3050 range and the 3100 range. ES is better down around 3050 for sure, but I'm not sure it matters enough to pull 400 bullets and reload!

 

[GrocMax]

If you've never had piercing issues, what are you worried about?

 

[louielouie]

FWIW, I had a similar problem with the end of the firing pin being worn to a smaller diameter. Since protrusion is adjustable, I began shortening the pin (carefully radiusing the point) until the 'fatter' portion of the pin began filling the hole in the bolt head. It is a temp fix until I get a PTG bolt head and find some oversize pins.
Also, the WOLF magnum primers definitely have thicker cups and don't extrude very much at all.

 

[Clucknmoan]

If you've never had piercing issues, what are you worried about?

Never pierced one, just encountered heavy bolt lift a few times from it. If crater severity goes up as heat does, which is what it looks like, I very well may have a problem this weekend in 103 degrees and no shade. That's what I'm worried about, what will happen in very hot conditions.

 

[CharlieNC]

At the suggestion of a fellow shooter who had the same problem, replace the bolt head with one from PTG. Headspace and firing pin protrusion needed adjustment on my 223, but cratering is gone. Just ordered another from Bullets,com for $54 for a beater 308.

 

[Clucknmoan]

Thanks for all the input Gents. I will be dealing with this bolt issue after this weekend. In the mean time, I might have to carry a refrigerator with me to keep the heat and pressure under control.

 

[memilanuk]

Thanks for all the input Gents. I will be dealing with this bolt issue after this weekend. In the mean time, I might have to carry a refrigerator with me to keep the heat and pressure under control.

I've seen people keep their ammo in a lunchbox cooler i.e. "Lil' Igloo" or similar, with an ice pack in there to keep the temps down. Just make sure to keep a towel in there between the ice pack and your ammo, to absorb moisture from condensation. Putting wet ammo in a hot chamber will do worse than just crater your primers!

 

[Clucknmoan]

^^ This is the plan for now. After I deal with the bolt issue it looks like I will need to run another OCW. This node is really accurate but isn't that stable. From 60 to 100 degrees, it's increasing almost 1 fps per temperature degree. The top end of that the ES goes to crap too.