I just bought a used 77 MarkII SS 233.I shot some of my reloads for another 223 ( 25gr H335 50gr V-Max CCI 400 primer RP Brass CL 1.76 COL of2.255 ) It cratered the primers.I thought too hot so shot some White box winchester factory rounds same problem. The bolt face is not machined smooth otherwise the rifle appears shot very little. Would like to know if anyone else has had this problem?
Cratering primers
- Thread starter GaryinOh
- Start date
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The Preacher
Blackhawk
Not an expert here but an enlarged firing pin hole will cause primers to crater. The enlarged hole allows the primer cup to "flow" back into the bolt housing. If not that it could be a chamber issue (head space) as you shot factory loads and had the same problem.
The Preacher
The Preacher
1. Excess headspace can cause flattened or cratered primers with ammo that's nominally within normal pressure limits.
2. There's a chance here that we have a case of the difference between 5.56 and .223. 5.56 chambers and leade are a hair looser; .223 is tighter. The permissible max pressure for 5.56 is also higher than that for commercial .223. Most ARs, unless otherwise specified, are made with 5.56 chambers. If you were loading before for a 5.56 chamber, then that's why the primers didn't show up then. Also possible that the WWB was loaded to 5.56 specs instead of .223.
And then sometimes, stuff just happens. Couple months ago I shot a box of TZZ Israeli milspec .45ACP in a S&W M25-2 without using the snowflake clips. The primers were flattened much more than you usually see in .45ACP. They were flattened more than the same ammo fired in several 1911s. Some vagary of the ammo/headspace combination on that particular gun, I suppose.
2. There's a chance here that we have a case of the difference between 5.56 and .223. 5.56 chambers and leade are a hair looser; .223 is tighter. The permissible max pressure for 5.56 is also higher than that for commercial .223. Most ARs, unless otherwise specified, are made with 5.56 chambers. If you were loading before for a 5.56 chamber, then that's why the primers didn't show up then. Also possible that the WWB was loaded to 5.56 specs instead of .223.
And then sometimes, stuff just happens. Couple months ago I shot a box of TZZ Israeli milspec .45ACP in a S&W M25-2 without using the snowflake clips. The primers were flattened much more than you usually see in .45ACP. They were flattened more than the same ammo fired in several 1911s. Some vagary of the ammo/headspace combination on that particular gun, I suppose.
WOB
Bearcat
CCI 400 primers are not suitable for 50,000 + psi loads according to at least one expert. The primer cup is only .020" thick. He recommends CCI 450 ( magnum) as they have a .025" thick cup. His article is here:
http://www.jamescalhoon.com/primers_and_pressure.php
I have had CCI 400 primers crater in my .223 bolt action while CCI 450 do not with the same load. This seems to bear out Calhoon's experience.
I have checked the firing pin tip shape and fit in the bolt face in my rifle and it is normal, so I have to conclude he is on to something.
WOB
http://www.jamescalhoon.com/primers_and_pressure.php
I have had CCI 400 primers crater in my .223 bolt action while CCI 450 do not with the same load. This seems to bear out Calhoon's experience.
I have checked the firing pin tip shape and fit in the bolt face in my rifle and it is normal, so I have to conclude he is on to something.
WOB
45flattop
Single-Sixer
You might want, along with the other good advice others have given
here, to check the headspace with a set of go/field/nogo gauges, if
your local gunsmith doesn't have a set for that caliber you can get
some(good to have anyway if you shoot that caliber in other guns)
at Brownell's and possibly at Midway.
here, to check the headspace with a set of go/field/nogo gauges, if
your local gunsmith doesn't have a set for that caliber you can get
some(good to have anyway if you shoot that caliber in other guns)
at Brownell's and possibly at Midway.
