Low Load with big over pressure signs???

Status
Not open for further replies.

alexmc

Member
Joined
Aug 31, 2014
Messages
4
Location
NC
So I went to the range today with a new set of development loads I was very hopeful for. I ended up getting to shoot ten of them, then driving home to the bullet puller. My rifle is self-built with a 20" 1:8" twist AR Stoner HBAR barrel with Wylde chamber and a syrac ordinance adj. gas block. The loads were brand new FL sized .223 Rem Winchester brass (that I heard good things about and then was disappointed when the standard deviation of case weight was about 3 grains.) with Win. small rifle primers and 77gr SMKs. Charges were 23.0, 23.4, 23.7 and so on up to 24.1 gr all Reloader 15. OAL were EXACTLY 2.260 on all of them. (24.1 was the max load listed by Sierra) so I shot the 23's, no problem. Nice group at 150 yds. I had my gas block closed as not to loose brass in the cornfield. No pressure signs at all, so I move to the 23.4's. First shot upon inspection has a mildly flattened primer. Hmm. Second shot sounds fine, but on the case I find a .75" crack right down the side and flattened primer. (***?) 0.7 grains under max and I have a case failure. The other three also showed flattened primers. No extractor marks. No cracks. I didn't dare move up. Maybe some brittle cases? I'm so dismayed. Any advice? (other than keep all loads at 23.0 gr now?)
 

Attachments

  • image.jpg
    image.jpg
    89.4 KB · Views: 151
Yeah, it sounds like you've found the safest maximum load for your brass, powder and bullets in your rifle.
The reloading data isn't always exactly correct.
Maybe the brass has slightly less internal volume, or the bullets are slightly longer, or loaded a little too deep, or the brass is brittle, or the chamber is little short, or........
 
Looks like it is a 99.99% chance it was a bad piece for brass. Splits happen. This is assuming all the charges were correct, with no trash in the case taking up space, and I am sure you were careful there.

Welcome to THR.
 
Since this is a custom build, I would also confirm that the bullet is not contacting the rifling. Bad brass does happen quite often these days. May want to get a hold of some Starline...
 
Only one of two things can cause that.

1. Funky brass.

2. A way over-size, defective chamber.


I would try different brass first.
If the problem persists with different brass, you have a defective chamber in your barrel.

A chamber cast would confirm it.

But if two different brands of brass split like that?
I wouldn't bother doing a chamber cast.

Your barrel is cut wrong.

PS: Over-pressure does not split brass.
It expands the case head, leading to ejector marks, flattened head stamp markings, and loose primer pockets.

rc
 
Last edited:
Looks like a bad piece of brass to me. I load 24.1 grains of Reloder 15 in RP, LC, or Win brass using RP 7 1/2 primers in a National Match AR with Wylde chamber. No pressure problems. Have no idea what an adjustable gas block would do to pressure. My overall length is 2.250-2.255". Another example where a chronograph might help to determine load levels. A split case is not a typical first sign of high pressure but an indication of a case that isn't right.
 
Thanks for all the replies guys. I was hoping this was bad brass but that still leaves the issue of the flattened primers. I know Winchester SR primers aren't the hardest but I don't think I should be getting flattening at only 23.4 gr. I individually measure each charge and I'm 99.999% positive I didn't load even one wrong, much less five. I'm going to keep it low for now and maybe try a work up with other brass later. Maybe LC. Thanks for the welcome to the community :) and to Jesse: sorry for the confusion, by .223 Rem Win I meant the caliber is designated .223 rem and the brand is Winchester.
 
The left three are from the 23.0 gr load. The right three were 23.4gr. The flattening isn't severe, but easily noticeable.
 

Attachments

  • image.jpg
    image.jpg
    76.4 KB · Views: 100
The ones on the left look flatter than the ones on the right.

A short throat (leade or bevel at the beginning of the rifling) can raise pressure quickly. I dont know what the standard is (or if theres a standard throat) for the wylde.

I had a "custom" barrel on a 260 that was making rather flat primers (much more than yours) at starting loads. Took it to a gunsmith, we chamber cast it to confrim what he could see, it basically had zero throat.
 
I am not seeing flat primers from excessively high pressure.

Those would be flat, flat, even with the edge of the primer pockets.
Flat level with the case head with no remaining round edges on the primer cup.

Those still have rounded edges on the primer cups.

They got flat in the middle from blowing out of the case when fired.
And then slammed back in when the case blew back and re-seated them.

Check for excess headspace.
Either mechanical in the gun.
Or artificial, due to pushing the shoulders back too far during resizing.

rc
 
The primers are fine. Listen to RC. Your problem does not appear to be overpressure ammo.
 
77gr SMKs Reloder 15

A starting load for that bullet would be 21.7 gr (Alliant Data). The crack is bad brass or oversize chamber. I cant see the primer photo well enough to tell if it flowed back into the firing pin hole, like this. 223_20090302_1.jpg 223_20090303_2.jpg
 
All my primers look like the left three. No cratering though. I've been told it is no big deal w/o other signs of overpressure.
 
You may want to check the size of the firing pin hole in the bolt face, and the fit of the firing pin to the bolt, thats a lot of cratering into the firing pin hole for the well rounded edges
 
Even tho the primers show flow into the firing pin hole nothing else shows any over pressure signs that I can see. Most bolts will extrude primers into the firing pin hole first firing of brass as the case stretches to fill the chamber the casehead is not on the bolt face flat/tight which manifest this. This is just new brass, and I have had it show primers just like this in loads that don't expand neck enough to seal the chamber this is also a good reason you can't go on primers alone. I would adjust the full length sizing die to size the casehead to shoulder datum .003" making sure they chamber easily after sizing with several cases. There have been many post on this issue if you search on this.

I have never had any problems with winchester brass, nor remington for handloading I do however prefer LC brass for loading ar15 just because once fired is so affordable (even now with cost rising). I think you had one bad piece of brass, but keep an eye on the remaining cases, and the rifle in general....if it were mine I would continue on just thoroughly check the cases after next couple of firings.
 
Second shot sounds fine, but on the case I find a .75" crack right down the side

I would disagree, it looks like the case was gas cut.

F. Guffey
 
I'm sorry about the confusion. For some reason the photo of the primers I took was flipped upside down when formatted. The way it was posted, the left was the 23.4 and the right 23.0. The higher load was definitely flatter, but it's good to hear all the word about the primers not being seriously flattened. I guess the cracked case just gave me a scare. I'm relatively new to loading .223 (About 800 rounds so far, but at least 10,000 between all calibers) I'm still going to back out some and begin load development again, but I really hope the crack was just a bad case. Thanks to everyone for all the concentrated experience. :)
 
I would disagree, it looks like the case was gas cut.

but I really hope the crack was just a bad case.

I can not create nor can I duplicate the anomaly", I have had hundreds of cases with 'what appeared to be gas cuts'. It had nothing to do with the case, it had everything to do with what happened to the case when fired.

F. Guffey
 
Status
Not open for further replies.
Back
Top