Primers backing out?

[dfrosch]

Built a 223 a few years ago, but didn't get to shoot it much at the time. Just recently pulled it out of the safe and ran a few rounds through it. It's a heavy 24" factory barrel with a 1 in 9 twist.

The loads were made with 55 grain Nosler BTs, LC 09 brass, CCI 400s and either 25, 25.5 or 26 grains of H4895. According to my Stoney Point, the loads were about .010 from the lands. The brass was bought from Midway a few years ago and I think it was new, but was discolored and spent a lot of time in the tumbler just to get it looking kinda shiny. All the brass was run through a FL sizer before starting, but that didn't take much effort.

Shooting went well with the 25.5 grain load. Four shots in one hole and the fifth one just outside. Maybe around 3/8" for the five shots. the other groups looked to be about 3/4".

Didn't have any trouble lifting the bolt, but it looked like all the primers had backed out a few thousandths. Measured the fired rounds with the primers still in them and, sure enough, they checked about .005" longer than the deprimed rounds - 1.762 vs. 1.757.

Checked the rifle with a no go headspace gage. While I couldn't completely close the bolt, it did seem to be near maximum. Only had a little bit left on the bolt throw.

So, I'm kinda guessing that this brass might have started a little small. With my rifle being near max headspace, the firing pin pushed the round to the front of the chamber, the brass grabbed the chamber wall and the slop at the back of the chamber allowed the primer to back out .005 past the brass.

Should I:
A) Not worry so much?
B) Jam some bullets until this brass fits my chamber good?
C) Go ahead and adjust the headspace just a little bit tighter?


Thanks in advance,
Dana

[DanSavage]

I think you're right Dana, if it were me,, having the tools already I'd tighten up the head space. I would first buy some factory rounds and compare. You could pull down a factory round and add tape to the back of the cartridge layer after layer until the bolt closes with resistance, then you would know how far that case is able to stretch.

Dan

[MacDR]

I think you're right Dana, if it were me,, having the tools already I'd tighten up the head space. I would first buy some factory rounds and compare. You could pull down a factory round and add tape to the back of the cartridge layer after layer until the bolt closes with resistance, then you would know how far that case is able to stretch.

Dan

+1 on this advice. I was going to suggest possibly a rough chamber that was preventing the brass from stretching backwards but after rereading your post, headspace combined with some short brass is more likely. Have you measured case stretch of fired cases versus the new unfired ones?

[GunDog72]

Not sure if this will have any effect or not but I have a Model 11 in a .243 and I load anything that goes in the chamber. I have found that if I use Remington primers that they fit really lose and if I do a hot load with a heavy bullet they will back out a few thou. but I have always had really good luck with the CCI's.

[dfrosch]

Measured the brass and couldn't really tell the difference. The ones that held the heaviest charge might have been about .002 longer.

The barrel has a matte finish, so the chamber could have some roughness to it.

My bolt head looks a little concave and that could add to the issue. Gonna order a new one and recheck the headspace. If it's still near max, I'll screw it in a little.

Thanks.

[Nor Cal Mikie]

Sounds like the OAL of the case is a little short? Round gets fired, case moves forward in the chamber. Primer backs out a little before the case has a chance to form to the chamber. Pull the bullets out to a jam "into" the lands. Once brass is fireformed to the chamber, no more primers backing out. (been there, done that)
Could also be loose primer pockets. Fireform first and double check headspace with factory loaded ammo. Make sure you're not pushing the shoulders back too far when resizing. (causing the same problem again)

[stangfish]

I think the problem is in the headpspace and the sizing process. You either need to close the chamber some by reducing headspace or back off on the die. Either way a good thing to do is inspect the case in the chamber. Reisize tight and bump in .001increments untill the bolt closes easily. I had some lee dies when set up per Lee, it sized .015 short.

[dfrosch]

The brass is all new. Bought it a couple years ago and ran it through the tumbler, but got sidetracked on other projects. Ran it through a FL sizer a couple weeks ago, but don't think that did more than round the mouths. Pretty sure I didn't touch the shoulder.

While the headspace is near maximum, the dimensions laser etched in my go and no go gages are only .003 apart. I only measured .0025 difference, but probably checked it at a different diameter on the shoulder with a cheap caliper. The bolt will start to close on the no go, but won't quite go all the way down.

I really think the issue is a combination of the dished bolt face, a firing pin that's sharp and has the protrusion at minimum(.035) and the new brass being short. Found my old magnifying glass and the primers look a little domed and a little cratered too, but not pierced. The outer edge might be past the brass, but my old eyes can't see that close. Dug up some Winchester brass that was run through this rifle a few years ago when it was built. It showed some of the same symptoms, but to a lesser degree. The LC brass is part of it.

Got the bolt head on order from Midway(needed a new mag box too). Hopefully, this one will be flat. When it comes in, I'll tighten the headspace , move the pin protrusion out a little and jam some bullets about .020. Might even try dulling the firing pin. It might take a few weeks to get to the range, but I'll let you know.

Thanks.

[stangfish]

Dfrosch, Where do you shoot?

[dfrosch]

Been going to Bailey's lately, but keep thinking I need to join Bayou Rifles. Had a BR membership a few years ago. Let it lapse when I didn't have any spare time.

[stangfish]

There is a waiting list now.

[M_Trivette]

55 gr Nosler b/t
lake city bbrass
cci 400 primers
25.5 grains of H-4895

this load shoots 1/2 inch groups in my LAR-15 all day
and also if you sub the 60 gr. Nosler b/t and drop the powder to 25 gr. the accuracy AND point of impact is the same (100 yards)

[GunDog72]

55 gr Nosler b/t
lake city bbrass
cci 400 primers
25.5 grains of H-4895

this load shoots 1/2 inch groups in my LAR-15 all day
and also if you sub the 60 gr. Nosler b/t and drop the powder to 25 gr. the accuracy AND point of impact is the same (100 yards)

I've been wanting to try some of these in my Model 11 .243 but haven't been to a store that has them in stock. Right now my gun will shoot a 5/8 group all day long and a couple of times I've shot a 1/4 inch at 100yrds. The best load I've found so far is 44gr of H4831 capped by a 60gr sierra vaminter.

[dfrosch]

There is a waiting list now.

Thanks. Went ahead and filled out the online request form. You shoot there?

[dfrosch]

55 gr Nosler b/t
lake city bbrass
cci 400 primers
25.5 grains of H-4895

this load shoots 1/2 inch groups in my LAR-15 all day
and also if you sub the 60 gr. Nosler b/t and drop the powder to 25 gr. the accuracy AND point of impact is the same (100 yards)

Thanks M. I was a little surprised by the 55 grain load. Kinda remember my first attempt at reloading for this rifle, not very impressive. Probably why it sat in the safe for a while.

[scratcherky]

If I had the problem you describe, I would fire some factory rounds to see if they exhibit the same problem. Low chamber pressure can cause primers to back out a little. Just another thing to think about.

[dfrosch]

Didn't try factory ammo. Got some kind of mental aversion to paying for it. All the loads were up near book max, but the OAL was longer than the book. Don't think low pressure was the issue.

Got the new bolt head and finally put it together. The new bolt head is definitely flatter. Reset the headspace tighter. Can barely feel the go gage at the bottom of the stroke. The bolt closes fine on the LC brass, but has resistance when a piece of .003 tape is added. Really think the old bolt head was the problem.

Still gotta find time to load and get to the range.

[dfrosch]

Finally got back to the range today. No more issues. I think my load is on the warm side in my rifle. The primers now look kinda flat.

My guess is that the warm load and the dished bolt head made the primers look like they were backing out.