its a AI AE 260... doing load tests, mild loads, if you look at the edge of the primers you see they are nice and round..
yet the pin hit is popping up and out...
yet the pin hit is popping up and out...
Gunsmithing what would cause primer hits like this?
- Thread starter Ring
- Start date
can that cause accuracy deficiency?
I would vote headspace.
to much?............
Last edited:
Not sure if your firing pin protrusion is right but I believe the poster who told you your FP hole is too large was giving some good advice. And plowing primers is making it bigger.
also, on a wilson case gauge, a fired case is measuring .006, my savage and Rem-Age700 are normally .002 for head space
Are you sure it's not the primers? I had the exact thing happen but on an AR-15. Everything was the exact same except for the primers. I had 20 Fiocchi, 20 CCI 400 and 20 CCI #41. The Fiocchi were all pierced but about 7 of them and all of the CCI were perfectly fine. I know were taking apples to oranges here considering I have a semi auto and he's talking about a bolt gun but the exact same thing happened to my reloads.
Possible contributing factors
-Large FP hole for reliable ignition under all conditions.
-Primer Cups a bit too soft.
-Load too hot for above conditions.
Possible solutions
-Bush FP hole and reshape tip.
-Switch to harder primer
-Reduce Load
You state your loads are "mild" but how do you know they are in your rifle? Can you give details on your load?
I see at least three different headstamps and some .260Rem and some reformed .308Win. That is going to change pressures.
Have you chronographed the loads?
-Large FP hole for reliable ignition under all conditions.
-Primer Cups a bit too soft.
-Load too hot for above conditions.
Possible solutions
-Bush FP hole and reshape tip.
-Switch to harder primer
-Reduce Load
You state your loads are "mild" but how do you know they are in your rifle? Can you give details on your load?
I see at least three different headstamps and some .260Rem and some reformed .308Win. That is going to change pressures.
Have you chronographed the loads?
Their still soft. With head space the primer would back out and flatten out making it look like high pressure.
I'd check both firing pin protrusion and firing pin spring. You could also have a bolt that's filled with crud not just keeping the firing pin from properly protruding but also gumming the spring up enough to keep it from giving the primer a full strike.
Strangely enough, Remington has had some good results with the chamfer they put on the firing pin hole in the bolt face. It gives a "false cratering" look but it also prevents the "blanking" shown in the second picture.
Strangely enough, some case/powder/bullet combinations can show pressure signs in mid/mild loads. I recently shot some .308 175 SMK's in a matched set of cases, starting from published minimum to maximum in .4gr increments. Right in the middle of the charge weight spread I had cases that had ejector marks and flat primers. Loads above that, right up to max, showed NO pressure signs. Sometimes it's not any ONE thing, it can be the combination.
Strangely enough, Remington has had some good results with the chamfer they put on the firing pin hole in the bolt face. It gives a "false cratering" look but it also prevents the "blanking" shown in the second picture.
Strangely enough, some case/powder/bullet combinations can show pressure signs in mid/mild loads. I recently shot some .308 175 SMK's in a matched set of cases, starting from published minimum to maximum in .4gr increments. Right in the middle of the charge weight spread I had cases that had ejector marks and flat primers. Loads above that, right up to max, showed NO pressure signs. Sometimes it's not any ONE thing, it can be the combination.
Weak firing pin spring and a light load. Headspace could be off, too.
all the test loads were rem bress... the mixed was my varmit ammo...
the 140 tests was 42.3 42.5 42.8 43 gr h4350
according the lowlight, this is a known issue with 260 AE's due to large FP hole... he said to bushing it...
any ideas what that would cost?
Look up Gre'-Tan Rifles or you can order a oversized firing pin from Pacific Tool and guage.
PTG dont make AI pins...
and Gra says they dont work on AI's
trying to get ahold of SAC.. since he is down the road from me
Last edited:
it was 100% spotless when i took it out.... full carbon and copper removed.. from chamber to crown..
shot 5 fouling shots , then my tests
I actually meant disassemble and clean the firing pin and bolt. My bad. You probably got the chamber. Clean the lug recesses. What do primers on factory ammo look like? Factory ammo is always a good place to start when working up handloads. If you've got something on the tight side of SAAMI, out of spec or plain broken, it should show with factory ammo.
Last edited:
upate:
changed COL to 2.81, from 2.84
got some CCI BR2 primers to test
the CCI seams tad better in the same loads, a bit harder then the Rem.
the COL chance also seamed to help, still some protrusion, but not as bad.
but im getting dog slow FPS
42.5 H4350 123amax 26" kriger =2775fps
43gr h4350 140 Amax = 2678
changed COL to 2.81, from 2.84
got some CCI BR2 primers to test
the CCI seams tad better in the same loads, a bit harder then the Rem.
the COL chance also seamed to help, still some protrusion, but not as bad.
but im getting dog slow FPS
42.5 H4350 123amax 26" kriger =2775fps
43gr h4350 140 Amax = 2678
got my 123 speeds up, and good accuracy... the CCI primers are definitely harder...
need to see what i can do with my 140's... they are still 150fps slower then my r700
need to see what i can do with my 140's... they are still 150fps slower then my r700
Did you happen to go with a light spring and light firing pin in your build? I've seen light springs or weak springs cause this type of thing. Also, decock your bolt and have a look at your firing pin protrusion.
You have a clear overpressure issue. Your firing pin dent is blowing back out into your firing pin hole. These are not cratered pockets with a loose pin hole, it's over pressure. You don't always have to have flattened primers etc to display pressure. I'm trying to reattach a marked up picture of our first picture but I'm not sure if its attaching. Anyway... Couple things are the blown out primers more of the reformed 308 brass that you have in the first picture or are they Fed brass. There is an FC 308 case in the top row - middle that even has soot around the primer pocket where the gases leaked out. Possible case head expansion/loosening of the primer pocket. Deprime the brass and try reseat a primer in those pieces. Have they loosened up? Bet they have. I hate Fed brass for the fact that every bit of it I've ever have is all heavier and has less case capacity that the others. That leads directly to overpressure. I've wrecked more Fed brass years ago than I care to remember. If you ever feel less resistance when seating the same primers, it means the case head is expanding and that it where you need to stop and back it off a little. If you have a good caliper, you can measure the case head diameter before and after firing your hot loads to monitor any changes. Might be surprised.
I personally think Remington and Winchester LR primers are softer than CCI and Feds, so if you running near the hot edge, you may want to switch to them.
I personally think Remington and Winchester LR primers are softer than CCI and Feds, so if you running near the hot edge, you may want to switch to them.
Attachments
Last edited:
The CCI's are definitely harder than the Fed's. I recently solved a pressure sign problem by merely changing from Fed 210M to CCI BR-2, leaving all other parameters the same. No more pressure and only a 3 fps average reduction in speed (10 rounds ea over chrony).
Add me to the "No More Fed Brass" list. I'm now just leaving any Federal Brass I have already loaded at the range when I shoot it. Winchester and Lapua are the only ones I'm keeping.
No ejector marks. No shinyness on the brass. No flattened primers. Do yourself a favor and grab a micrometer. Check the diameter of the case base, just north of the extractor groove. Take measurements of several cases, and any unfired ones if you have them. See if you find a correlation between permanent expansion at the "web" of the case, and those blown primers.
I had the same issues with primer piercing and primer pockets blowing out when I had a 260 barrel on my AI Aw .kept getting worse and I ended up screwing up the boltface. Try using CCI military primers white box they have a harded cup from what I've heard. Good luck , I hope you get the issue resolved.
same load, shorter COL, and CCI primers... no issue
No issues... baloney. There are 4 fired cases in the bottom row alone which exhibit a poor characteristic. Now, you might now know how to do this, and so I'd encourage you to take this rifle to a competent gunsmith. In all likelihood, you've got either a short firing pin spring, a broken firing pin spring, a weak firing pin spring, a short firing pin, a broken firing pin, a dragging firing pin, or some reason why you're getting flow-back into the firing pin hole. This is NOT a high pressure sign, it's a sign specifically related to your bolt.
I mean no disrespect by this message, but I'll bet my paycheck that you don't have a pressure problem, and that you DO have a bolt related problem.
I mean no disrespect by this message, but I'll bet my paycheck that you don't have a pressure problem, and that you DO have a bolt related problem.
according to this
http://www.snipershide.com/shooting/snipers-hide-reloading/141446-ai-ax260-pierced-primer.html
its vary common for it to flow like that in AI's... the only 100% fix is to have the face bushing installed...
as long as im not punching holes in the primers, im not worried about it
http://www.snipershide.com/shooting/snipers-hide-reloading/141446-ai-ax260-pierced-primer.html
its vary common for it to flow like that in AI's... the only 100% fix is to have the face bushing installed...
as long as im not punching holes in the primers, im not worried about it
I'm having the same issue. Did you resolve it or did you go back to your .308 barrel?
Check the pin protrusion and replace the spring maybe even an extra strength spring if you can get one. I don't see any pressure signs in those pictures. Everyone thinks a spring lasts for ever but in a comp rifle it should probably be replaced every five years and don't store anything cocked!
I agree with Scout on this. Wolf primers will help. The firing pin is loose on the AI's for reliability. In the last pic of your fired rounds you can still see a slight cratering ridge around the pin impression on the primer. A common symptom with this rifle with soft primers.
good luck
R
good luck
R
I quit using CCI primers completely, too many clicks, not enough booms LOL. SeriouslyCCI's were manufactured for the Military SAW and were designed hard on purpose, had too many misfires during IPSC comps, and later with the AR-15. I quit using them altogether.
That really sucks, I was wanting a .260 barrel for my AI but don't want to deal with primer issues.
I recently experienced nearly identical abnormalities like these shown and it was a weak firing pin spring in a factory installed new bolt from Remington.
Looks like a hard striking firing pin. All the dimples in primers made by my weapons are smooth from the face of the primer, around the rim of the dimple made by the strike all the way down to the deepest point. It looks like your pin is hitting too hard and deep stretch in the primer metal in the impact spot to stretch too thin weakening it to where it blows back out as a raised nipple or blows all the way through. Look at it like this, take a pice of metal- set a punch and lightly strike it. You will end up with a nice smooth rimmed dimple. If you smack it hard you end up with that raised rim edge. I've seen this a few times with weapons in the army so my money would have to be with firing pin hitting too hard. I don't think you would get that raised rim if the primer was too soft...
I had a similar problem rifle wouldn't even set off win primers but would federal. I put in a new spring and it fixed it. The rifle had less than 100 rounds but I did bake the bolt for gunkote and wonder if that didnt mess up the spring.
Similar threads
