What is this bulge at the neck?

[Ultraman550]

So I shot my very first rounds today. Heres the specs below. I don't have a chrony yet but will very shortly. I looked for any type (that I know of) of pressure signs but could not find any. My concern is the bulge at the neck of the brass. Did this occur because of the crimp?

LC brass 5.56 - cleaned
deprimed
reprimed
FL sized with Redding FL die and bushing, went .002 smaller than original loaded case measured
trimmed to 2.260
used 62 grain green tip
23.1 gr of H335
CCI BR primer
LEE .223 crimper

 

[deadnbrkn84]

Not really seeing the "bulge" you're describing but the redding bushings will leave a slight on in the neck where it meets the shoulder. It's because the bushings have a chamfer on them. Totally normal.

 

[beercow]

Did this bulge occur on all cases? It could just be from hitting the brass deflector assuming you are running these through an AR. I'm no expert though. That ring around the case head looks kind of suspicious to me as well.

 

[1SMALLJOHNSON]

Likely, the top portion of your brass, at the neck, is obdurating out against the chamber wall, while the bottom portion of the neck is not. You are shooting a mild load (by indication of your numbers). As you increase pressure, I'll bet my paycheck that you'll see this bulge go away. Just for S&G, get a caliper or micrometer, and measure that expanded section, then measure the "non-expanded" section. Write those numbers down in this thread. Then, watch us all argue over them. It'll be fun, trust me.

 

[1SMALLJOHNSON]

Next question: Where'd you get the rifle? Do you know who chambered it? Factory gun, or custom? Next, do you know what cerrosafe is?

 

[Ultraman550]

deadn - I was reading about the dreaded doughnut that occurs right where the neck meets the shoulder but this bulge is right at the top of the mouth exactly below where the crimp occurred. Maybe I'm mistaking the ridge for the uneven surface of crimp over case neck that is non crimped?


beercow - Yes sir. I only loaded 5 cases to test things out and its on all of them. When I run my fingernail up from the shoulder over the neck its smooth but then right at the tippy top it drops lower but thats where the crimp was. Here's my thoughts/questions - I was wondering if because of the crimp there was too much pressure or it really is just the crimp? All cases were measured to SAAMI specs with digital calipers, Wilson case gauges and even a Sinclair bump gage. Yeah I'm running them through an AR. It's a Frankengun.


1SMALL- I measured the middle of the case neck and it comes to .255. At the point Im talking about it measures .249 - .251
The rifle is a mixture of parts, Stag 5.56 1:9 barrel 16inches, HD billet upper and lower, Bravo Company BCG etc... One of the gunsmiths at my local gun shop put it together. Every other ammo I've shot through it didn't have these signs on the upper case necks. I'll load up another 5 and not crimp them and see if this happens again. I guess it's ok to maybe do 23.2, 23.3, 23.4, 23.5, 23.6 grains or how much more would you recommend? I read that others were loading 24.1 grains and that 25 gr was max load so theres probably room to wiggle right?

 

[1SMALLJOHNSON]

ANSI drawings for the .223 REM chamber show the front of the neck CHAMBER dimension at .254" minimum. So, your .255 number on your fired case is very reasonable. However, I do ask you to share your CASE dimension at the BASE of the neck, on a fired round. By my calibrated eyeball, it seems to me that this specific area (base of the neck, fired case) is a different dimension than the top of the neck. Can you get that number? Might take a caliper instead of a mike.....

 

[Ultraman550]

1SMALL, Base of the case neck is .257 and .257.5 between the 5 rounds. As you can see in the Wilson gage even though the round has not been FL sized so the base is not sitting below proper depth line, the case mouth is not sitting snug against the wall. On my other rounds that were factory 62 grain LC when I put them into the gage having not been FL sized yet either, the case mouth was flush. Thank you by the way for helping me, I truly appreciate it.

 

[1SMALLJOHNSON]

Judging by both your first and second set of pictures, I'm not sure I understand your problem now. Where exactly is this bulge you speak of? Your measurements are good. No problem with them. Are you talking about the crimp marks at the peak of the neck?

 

[Ultraman550]

Yes. Am I overreacting? That's exactly what I'm talking about. I just didn't know if it was truly the crimp mark or if the case mouth was jammed up against the chamber and caused this upper indentation. If the numbers check out and there's no other signs of over pressurization then I am good to go. It was the first 5 rounds I have ever loaded so I was being a bit cautious, maybe too cautious I guess. Anyway thank you and everybody else for the help.

 

[gmz71]

Maybe Im missing something, but it says you trimmed to 2.260. Is this correct? My book says 1.760 is max case length and 2.250 is mag length?? Im sure Im missing something though.

 

[KYpatriot]

I think he is talking about the crimp mark right at the edge of the case mouth. It means your crimper works lol.

 

[1SMALLJOHNSON]

Ultra,

Ok, chill. You're doing fine. A collet crimper will leave those marks, and they are permanent, unless you physically trim them off.

Small

 

[Ultraman550]

gmz - yeah my bad, OAL was 2.260, not trim length. I trimmed to the L.E Wilson case gauge length which is 1.760

Small - LOL, I'm chill now. If you guys would have seen what I wore the first shot I took you would think I was a retard. I put on on ski goggles, my ear protection, a helmet, a face mask, my extra thick carhart jacket with a neck protetor, ski gloves, I tied a string around the trigger and laid behind a 12"x24" AR500 plate. The car was about 50 yards behind me.......I'm serious. The thought of a round exploding was freaking me out. I weighed the charge on the RCBS Chargemaster then checked it on an Ohaus 10-10 and then recalibrated the RCBS Chargemaster and weighted it on that again.