Primer Cratering

[henry1]

Well hello guys, I have been working on trying to figure out my primer cratering issue with my left handed savage short action-accutrigger, with A and B bbl....little bit of background info....it started life as a .223 and is now a .223 AI. I have changed the bbl, the stock and bolt handle, scope bases ect. but that is it....no changing the firing pin or boltface... Gotcha-a member here and really great guy has been assisting me over the past couple months to help me figure out what is goin on.... I loaded up 5 shells about a week ago, CCI 400 SR primers, 55 gr Varmint Nightmare, 25.5 gr BLC-2 (this load was found by reducing the max load by 10% for regular .223 Remington) The brass was fireformed in my chamber, and then partial f/l sized. Im guessing to solve my issue, i will have to pick up a new bf but who knows for sure. That being said, i dont feel like this is a super dangerous issue??? correct me if i am wrong, but i have prob put close to 1000 rnds through this gun since i built it. before that it prob had 250 rnds through it (handloads and factories). She still shoots decently, .5 being common, depending on the load. hope you guys can help me, i will be posting pics soon. sorry for the run-ons and pauses :o

Henry.

http://IMG_1082.JPG

[stangfish]

Do you full leght size? Are your primer pockets tight? Have you tried another brand of primers?

[243LPR]

Did you go with a faster twist barrel? That can increase pressures. How is bolt lift after firing?

[henry1]

I do full length size once in a while, but the brass that i used this time was partial/neck sized. primer pockets are tight, but i have not tried another brand so that might be an option to try. Twist is 1/12, and bolt lift is the same as it is with or without a fired brass in the chamber.

[henry1]

Also, how do i post pictures from a mac? I see the attachment deal here but it doesn't seem to work for me. I also tried to search for a how to but didn't come up with anything.

[stangfish]

Get an account with PhotoBucket online. Upload. Take link and place the url in between the brakets.

[henry1]

ok hope this works.

http://i1205.photobucket.com/albums/bb423/hunter8734/IMG_1082.jpg

[243LPR]

The primers themselves aren't flattened at all. Doesn't seem to be a pressure problem. My guess is excessive headspace or too light of a load,probably something you've already looked at.

[ShaneG.]

I'd look at firing pin protrusion length and fit,it might need to have a bushing job done on it if the firing pin is sloppy in the boltface.

[henry1]

Yup, i dont think it has much pressure issues, I set the headspace with AI Headspace gauges, and have recently checked it to make sure its good. all the loads i have used over the years have had cratering, this one in particular is half a grain over min sug. load. Hopefully Gotcha (Dale) will join in after bit, I measured firing pin Protrusion for him a few months ago....anyways, he will be measuring his bolt today so that i can compare to what mine is. Thanks for all the replies guys! Keep em rolling!
Henry.

[243LPR]

Ever try different brass or primers? Maybe the brass is too hard and not expanding like it should. I use PMC in my AR's and never had a problem.Just thinkin out loud here.

[henry1]

I have tried different brass, however, If i have used different primers i have no data or recollection of it. So using a diff primer would be a valid experiment... i will have to buy some and try it out.
H.

[MatthewUSMC8791]

To me it looks like a firing pin issues. Suggest double checking your head space. At that time i'd double check your chamber length with an actual chamber length guage.

Try some US brass, not the PMC crap from south Korea.. JMTC

[Smokey262]

CCI small rifle primer cups can do this. I would buy a hundred of another brand and try them

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

[stangfish]

By looking at the lines on the brass I would say you were FLSing. You might be bumping the shoulder back to far... or any of the other ideas. Try the cheapest and simplest things first. If you dont have a headspace measuring tool to check your cases then use some tape on the primer end of the FLR case and see how much space you have. Measure your FP hole and compare to the FP. Keep notes. Read them. It will come.

[jo191145]

henry

First thing you need to do is get rid of the CCI 400's.
Try Rem 7.5
CCI-450
CCI BR4
even Fed 205Match will do better. Gotta say Match tho.

Just like listed on Calhoons chart smokey linked for you.

So far the biggest problem your having is using a primer thats not designed for high pressure cartridges.

Once you switch primers then and only then can you determine if theres a firing pin/boltface issue that needs to be addressed.

FWIW I've never heard of excessive headspace causing cratering. Premature flattening of the primers yes but not cratering.
But like everyone else I haven't seen or heard it all ;) ;D

On any AI your headspace should be fireforming with a crush fit on virgin brass.

[gotcha]

Hi Henry! Have you been AWOL again? ;) These measurements on my Mod. 12, .223 Rem. firing pin tip .065", Firing pin shaft .095". Used a set of precision drills to chk firing pin hole in B/F. .068" slides in snugly..... .071" starts to go in then stops. My guess is hole is .068" to .069" If your hole is substantially larger shimming B/F hole would make sense. A local machine shop should be able to meas. the hole for you. Don't really know what "spec" should be on the hole. Someone w/ more knowledge then me might help out. If not, Savage tech should be able to help. I think a shimmed hole should be .002" larger than F/P........... Changing primers might help but I don't think it will cure problem. STANGFISH whaddaya think???? Note: I use fed. 205m (cause I've got 4 bricks 8) ) and get some primer flow around F/P but its almost non existant. Keep on keepin' on. there's an answer here somewhere ;D Dale

[Blue Avenger]

no change to the bolt spring pressure or lift kit added?
How many times have these brass been fired? looking like they are starting to thin above the web.

[GaCop]

ok hope this works.

http://i1205.photobucket.com/albums/bb423/hunter8734/IMG_1082.jpg


The primer edges are rounded so it doesn't look like a hot load but the FP hole appears to need a bushing. JMHO

[henry1]

By looking at the lines on the brass I would say you were FLSing. You might be bumping the shoulder back to far... or any of the other ideas. Try the cheapest and simplest things first. If you dont have a headspace measuring tool to check your cases then use some tape on the primer end of the FLR case and see how much space you have. Measure your FP hole and compare to the FP. Keep notes. Read them. It will come.


Ok, we have some great ideas coming forth here....these brass were FL sized for all the firings that they endured before this last one....Yes these cases are not brand new, but....they were partial sized/neck sized for this last loading/firing. I will try the tape on the shell to see what we have for headspace....maybe my gauges are off, again thanks so much guys! Keep it all coming!
H