I have a model 70 in .243 Win. It had never been fired even though my research found it to be a 1991 model. Last weekend I decided to start working with it and it proceeded to rupture primers and spit stuff in my face. I tried several different brands of factory ammo and only found Hornady Custom 100 grain loads held the primers together and those were cratered pretty bad.

Anyone have any suggestions about what might be causing this problem?

Thanks in advance,

Ceyl

Holy cow!! Sounds like you've got a real pressure problem there. How do the rounds chamber? Is the bolt hard to close? Is or was the bore free of obstructions and clean? If you didn't clean it and it did just come out of the box it could have had some cosmoline in the bore. Does the barrel appear to be straight? How many rounds have you fired thru it?Probably stuff you already checked or did but we detcetives need some leads

You might want to take it to a reputable gunsmith and have the chamber and throat checked.

May be nothing more than a firing pin that's a little too long. Second the motion to take it to a quality gunsmith for full check - up and repair.

Rounds chamber fine, bolt closes easy, bore is clean. Shoots straight about 1.25" groups. I have put about 20 through it so far and it does't rupture every primer just about every 5th one, the rest are cratered but intact.

Could the firing pin be defective someway? Is it possible that the hole that the firing pin comes through the bolt is too big? Does any of this make any sense?

Ceyl

Someone may have replaced the firing pin with another and used one that is too long. Suggest you get a replacement firing pin, never a bad idea to have one, and compare them. If it were homeloads then could be other things but with different factory ammo it should be the firing pin.

Remove and break down the bolt. There can be gunk built up. Also check to see if the pin feels Sharp or pointed. You can polish the tip w/ a Dremel. Can
de-cock the bolt after it's removed? It can be a number of things. JP

A picture of one that fired, but did not rupture would be helpful.
I also suspect the firing pin.
Cheezywan

A picture of one that fired, but did not rupture would be helpful.
I also suspect the firing pin.
Cheezywan

Know this for a fact: just one really high pressure primer leak can erode a sizeable "pit" in the bolt face...usually right at the firing pin...and that rifle will often pop primers after that event simply becasue they ae unsupported at that "pit". Have had it happen...just one poped primer event, and forever after that bolt would let other primers either expand at that pit, or pop and leak gas.


So, yes...it is possible the firing pin or bolt face is part of this....and it's NOT going to self-heal; the more poped primers the more erosion to the bolt face or firing pin.

The best advice is to not shoot any load that produces poped primers....if foactory loads are doing it, would put that rifle aside until the casue si found and cured.

Broken firing pin? It may be unfired, but how many times was it dry- fired? Just a thought...

Broken firing pin? It may be unfired, but how many times was it dry- fired? Just a thought...
Yup! And a good one too?
Cheezywan

May be nothing more than a firing pin that's a little too long. Second the motion to take it to a quality gunsmith for full check - up and repair.

Good advise, get it to a good smith or send it to the manufacturer. Firing Pin Protrusion is easily checked provided you know what is proper for the rifle.

Thank you all for your advice. I'm taking it into Nagle's in San Antonio this weekend

Ceyl

I suspect excess headspace and low-pressure loads, rather than high-pressure.

Excess headspace allows the firing pin to move the cartridge case forward in the chamber before the primer/charge ignites. When it finally does ignite, the low pressure load is insufficient to "grab" the sides of the chamber. The firing pin might be too long, too.

In either case, good call to take it to a gunsmith.

Jaywalker

May be nothing more than a firing pin that's a little too long. Second the motion to take it to a quality gunsmith for full check - up and repair.
a rusty firing pin or lack of lube can do the same