Cratering - Is this something to worry about?
- Thread starter jdbell2004
- Start date
What primer is being used?
The slightly THICKER,.. PETERSON Brass, IS causing, SOME, of, the "extra Pressure" !
Switch to, a thicker Primer,.. IF, this cratering, bothers you !
For SURE, Polish, the Firing Pin's, TIP, "Lightly", as IT's, rough and probably, slightly, too long .
Save your Money and live with, the Bolt face, as is !
It's NOTHING to Lose sleep over, as there's, NO,.. "Swipe" seen, on the Brass.
I use, Peterson Brass and Load, 6.5 Creed, myself !
Might, back off, a Tad ( 1/2 grain ) on Powder with, Peterson Brass !
Hope this, Help's !
Switch to, a thicker Primer,.. IF, this cratering, bothers you !
For SURE, Polish, the Firing Pin's, TIP, "Lightly", as IT's, rough and probably, slightly, too long .
Save your Money and live with, the Bolt face, as is !
It's NOTHING to Lose sleep over, as there's, NO,.. "Swipe" seen, on the Brass.
I use, Peterson Brass and Load, 6.5 Creed, myself !
Might, back off, a Tad ( 1/2 grain ) on Powder with, Peterson Brass !
Hope this, Help's !
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Higher outside Temps will cause hotter loads. Happened to me with H4350. Even when reducing charge. Over time lower loads were even cratering and piercing.I reached out to @carlsbad via PM about bushing but the more closely I look at things, the tip of the firing pin is troubling me. It does not feel smooth at all. It is rounded but seems "unfinished". I have reached out to Ruger, they want the entire firearm mailed in.
Anyway, I pierced two primers yesterday. I was shooting groups, the same load for all groups. I got through 17 rounds with only minor cratering then loaded up my last 5 rounds for the day. Pulled the trigger and smoke started rolling out of the receiver. I pulled the bolt and immediately saw the hole in the primer. Pulled the magazine, pulled the bolt apart, removed all debris, scratched my head, and loaded it up again. Next trigger pull, same thing so I packed up and went home.
Why would I start piercing primers all of the sudden with no change in load?
I've attached a couple of shots of the firing pin fit and protrusion. Measured at .048".
Also, my punctured primers
On a positive note, this rifle can shoot! Only one group greater than 1moa, most around .5-.7moa with 200 rounds through it!
I was piercing primers with loads below 40 with H4350 and 136 scenars.
After Carlsbad bushed my bolt I'm pushing 41.5 grains of H4350 at 2800 FPS without any cratering at all
Dusty Stevens
Shiner
That is an awful looking firing pin tip. Sending it back to ruger will be a waste of time- its already passed qc. Id send the bolt straight to carlsbad and get back to shooting
WSnyder
Silver $$ Contributor
In the picture of the primer indent I see the pin tip is likely very rough by how the primer indent looks. I'd pull the pin and polish to as fine a finish as possible (I smooth and polish all pins to a mirror finish). By polishing the tip you can eliminate a lot of cratering issues. When a pin tip is highly polished the indent in a primer will look the same (very smooth with a high gloss) and the flow (cratering) will be less.
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CCI BR2. All loads I've used these without piercing before these last two.
I did notice a pretty significant jump in velocity around the time I switched to Peterson brass. I'll have to go back and look a the data. I've been considering dropping the charge weight back to get a velocity the rifle seemed to like early on anyway.
I'm leaning that way at this point. It's frustrating that Ruger produces a rifle that needs additional work to function properly...
I'll give this a try first. Any tips for doing this successfully?
I agree, just send it to Carlsbad. My pin and bolt looked great prior to sending it to Carlsbad. So sending it to Ruger won't resolve anything even if they clean things up
WSnyder
Silver $$ Contributor
I do it on a lathe with stones, cratex and final polish with a felt wheel. If you don’t have access to a lathe maybe a drill press or even a drill motor would do. Doesn’t everyone have a cordless drill these days?
When they built the RPR, there was only large primer brass for the 6.5 creedmoor, and it doesn't crater large primers
Did you notice that the firing pin tip was rough before or after piercing the primers? The pressure and hot gasses will damage your firing pin nose upon piercing a primer. This can also open up the pin hole in your bolt head.
Either way have a decent smith bush your bolt and set the firing pin protrusion and fall correctly.
Either way have a decent smith bush your bolt and set the firing pin protrusion and fall correctly.
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