Case Separation -- Straightwall/PC'd

[mehavey]

Anyone else experience this?

https://i.postimg.cc/prVm9FtC/38-55-Case-Sep.jpghttps://i.postimg.cc/Qx1cRpd9/ACC38-320-E-Pure-Lead.jpg
Bullets are actually high-gloss/beautiful finish)

38-55 Uberti HiWall
Three cases separated.

First one left the separated piece in the barrel/near muzzle (fully rifled BTW)
Bullet printed normally in 1.5" group at 100.

Second and third had the case piece exit the muzzle along w/bullet/not found
Both bullets printed normally in 1.5" group at 100.

- Bullet is Accurate 38-320E pure lead (330gr actual) Sized 0.380.
- PC is Eastwood 5:1 Appliance White/Mirror Blue (450 Flow+30min at 400)
-- (Never any issue with any Eastwood/Coating -- perfect bullets.)

Starline case -- (deliberate High[er] Pressure for Pure lead/Plain Base trials)
AA2495/28.2gr (Full case under bullet)
102% fill/96% burn
Burn_Ba = 0.403 adjusted
QuickLoad32” = 21,451psi/1,623fps(1,624±03 actual)
Redding Profile/taper crimp case mouth to 0.392"/ OAL: 2.56"

Barrel spotless on dry patch.



Thoughts ?

[DHDeal]

Did the cases separate at the bullet base? Looks like it was close to that.

I have a habit of running the sized cases of my 45/70 and 40/65 BPCR's on a brush chucked up into my drill and polishing the inside. Whether it's necessary or not is another argument but I do have very smooth seating of my bullets and I suspect a very smooth release of those bullets. This is for GG bullets as the PP bullets aren't in the case far enough to matter.

My SWAG is those pretty PC'd bullets are holding onto the case walls and not wanting to let go. Having pulled PC bullets and regular lubed bullets before, the lubed bullets always come out without too many whacks. The PC'd rascals take some extra whacks before they decide to come loose. If my cases have been cleaned with SS pins or freshly annealed, they are even more grabby than usual.

[GARD72977]

Measure the rim thickness on the cases that seperated. I bet its a headspace issue. Its either the gun or the brass out of spec

[mehavey]

Has had no problem with thousands of rounds of BP and/or classically-lubed bullets.

That, and the fact the normal case stretch will cause separation near the base -- and not effectively create a
bonded jacket around the bullet itself, carried all the way through the barrel/out the muzzle/and far downrange.

(Note the rifling on the separated neck section in the OP.)

[Shanghai Jack]

TexasMac has some interesting reading on straight-wall case separations
http://www.texas-mac.com/Case_Stretching_and_Separating_in_BPC_Rifles.html

[Wilderness]

See also thread on bullets bonding to case walls, esp Larry Gibson's reply re a .45-70 separation with a commercial cast bullet with hard lube, then tumble lubed. One other respondent mentions PC bullets bonding. I am running some tests on lubed bullets and will add to the thread when I have the information. I have experienced bonding sufficient to increase velocity and change POI. So far no neck separations, but trying to head off the problem before it gets to that.

https://castboolits.gunloads.com/showthread.php?423755-Bullet-lube-gluing-bullets-in-case-necks

Test for bonding is to reseat bullets another .010" or so - 1/8 turn on 7/8x14 die. A bonded bullet will resist and then make an audible crack as it lets go. Prior to reseating, bonded bullet may be near impossible to pull. Bonding can go all the way from just a little resistance to something a lot more. For a really good illustration, load some bare unlubed cast bullets in a dummy case, then after a week (or even a day or two) try to pull one, and try to reseat some.

[Shanghai Jack]

This is one of the more intriguing threads that I have read.

[Sasquatch-1]

How old was the brass?

[mehavey]

Brand new brass...

[Shanghai Jack]

Okay - let me start by saying that I'm stupid when it comes to powder coating and only slightly less so when it comes to the 38-55 so I have a couple of questions/thoughts.

I am of the understanding from some other sites that starline brass in the 38.55 is relatively thin-walled.

Concerning the 38.55 I found this comment in another forum

"The 38-55 has about the worst variation in groove diameters across all the different rifles ever manufactured.
It was originally supposed to be a real .38 cal with a .379 to .380 groove diameter. But they have been manufactured at .375 up to about .383 groove diameters. The SAAMI drawing permits the chamber to be about .394 maximum which means that some companies have manufactured rifles with small chambers and large bores that are not really compatible with shooting groove diameter or larger grease groove bullets."

A quick view of a couple of old loading manuals - not by any chance the definitive sources - shows a bullet diameter of 3775.

When one sizes down to .380 and then powder coats what's the increase in bullet diameter? Is it significant with reference to the case mouth diameter/chamber size and groove diameter.

Could it be a combination of thin case wall, increased case neck tension and friction, and max chamber/min bore?

I really don't know but am interested in what the experts have to say.

[Kraschenbirn]

I'm also using Starline brass in a Taylor & Co 38-55 Highwall (mfg'd by Uberti) and, after several thousand rounds, have yet to see anything even resembling the OP's case separations. I load, essentially, to duplicate original BP ballistics and don't powder-coat - tried PC but found my 'as cast' (.381) boolits, pan-lubed with Emmert's, to be more accurate. Cases are neck-sized just enough to hold boolit in place with a very light taper-crimp to remove any flare of case mouth. Some of my cases have been reloaded 10-12 times and, other than an occasional split mouth, have yet to see any significant failures.

Off the cuff, which length Starline brass are you using...the 'short' (2.080") or the 'long' (2.125")? The chamber of mine is cut for the 'short' cases and it's possible that 'long' cases might cause a significant increase in chamber pressures. Just a thought.

Bill

[mehavey]

Long brass... and like you have had no issue with anything til that deep-seated/PC'd shank of the ACC38-320E.

I sized/ALOX'd eight of them last night/heat-dried overnite -- and will shoot them this PM and see that reduces the
PC deathgrip on the brass.

FWIW: with 102% fill, I have no need of a crimp either -- I'll back the Redding Profile die way off

[Win94ae]

Too tight of a fit in the chamber?

[243winxb]

Second and third had the case piece exit the muzzle along w/bullet/not found
Both bullets printed normally in 1.5" group at 100.


This is amazing. :shock:

[popper]

What I noticed is the base is where the case failed. Had trouble in 30/30 with radial neck cracks. I was using light bullets that has base in the neck with unique powder. My thought is a stress area that firing expanded the neck below the base. Other question for your brass, was it factory annealed after final forming? My experience with PC - I seat deeper to pull bullets - not much different than jacketed. I don't crimp, just remove the bell, even for jacketed.
edit: I was using sierra HJ in the 30/30 unannealed cases. IMHO it was the fast powder (unique) with a fast pressure rise that did it. Loaded in 300BO cases (or even 110 jacketed) with necks turned to 10 thous and SLOWER powder, no problems. Never used the powder you do, possibility it is really compressed and spikes? You indicate 102% fill (QL?) might really be a compressed load.
Been playing with 4227 and msrp in BO as that's what i got. Previously with srp I got crumbs left in the barrel. NOT with the msrp (CCI). Actually 98% fill and good accuracy. IMHO I got better burn as bore is clean. QL (GRT) says burnout after the muzzle. Didn't see it.
I have not seen a difference between PC,HiTek, BLL or jacketed as to real neck tension - aka, left loaded and pulled much later. HF red or Smoke's red. Stuck a lot of GC when pulling though, 308 & 30/30.

[rodsvet]

Post #12 interests me. The word "deathgrip " makes me wonder that if the PC makes the boolit stick to the brass to the point that causes pressure spikes. I have flattened primers on brass that fired PC coated Boolits. Anyone else noticing this on their brass?

[oley55]

Too tight of a fit in the chamber?

my thought as well. That's assuming my understanding of brass to bullet grip and release are true. I have been under the impression that the expanding powder/gases causes the brass case to swell/expand away from the bullet rather than the powder/gases merely overcoming the friction grip. Or are both of those things working together? If yes to both, which is the dominate factor, case swelling or breaking the friction grip? I am inclined to give the nod to case expansion. Especially when considering the old varnished military ammo.

[country gent]

On the separations I have seen you can see the burned ring where it failed on the inside edge.This isnt apparent on these case. What Im seeing is a "clean" fracture. Im thinking that the pc coating may ave increased loaded round dia to where the case couldnt release the bullet. 38-55 brass is on the thin side

[mehavey]

All were sized [after PC] to my standard 0.380" for that rifle.

What may be happening is that
- Extra-soft pure lead is obturating too well, too quickly.
- PC is holding it locked during that primer ignition/pressure build-up instant before static friction is overcome.
(Maybe vice-versa)

I've got some ALOX-over-PC coated loads of the same bullet to try, but my HighWall came down lame.
[It's at the vet's]

[ole_270]

Maybe leaving the burnt powder residue in the case neck or dipping in powdered graphite might cut down on the bonding.

[beshears]

Pure lead is swelling and not letting case release bullet?

[Wilderness]

If the bullet is clinging to the case and carrying the front end away, perhaps the first thing to establish is whether the bullet and case are bonded before the shot goes off. A simple test is to try seating the bullets another .010" or so. If they are bonded they will resist and then go with a distinct click. This might or might not be enough to cause the rupture.

If they are not bonded prior to firing, then the theories of bullets upsetting to lock up the case, or case not being able to expand etc will have legs.

[mehavey]

I've lightly ALOX'd/dried a double handful of the PC'd projo's to test the lock-up theory.
But the High Wall went lame last Sunday and I've got it at the Vet's right now. :-(

BTW: I've had exactly the same thing happen w/ long-case (45-3¼) Sharps using paper patch/pure-lead using BP.
`tis a puzzlement....

[TimD]

The pure lead compressed enough to allow the torn part of the case to travel down the bore to the muzzle or exit the muzzle. I would think this indicates a significant amount of adhesion between the case and powder coat. If a tight neck condition existed the neck could be torn off, but I would not expect it to travel the length of the barrel.

You could make up some dummy rounds with and without powder coating and check for adhesion.

Interesting issue. I hope things turn out well at the vet.

[Walks]

I recently broke down 70 odd .44Mags loaded with PC'd bullets. It took a LOT OF WACKS with a Impact Hammer to break the death grip that those bullets had on the cases. Once the bullet started out of the cases it took one wack.

Only straight case head separation I've ever experienced was with the very 1st box of .38Spl brass I ever bought. Nickel Winchester, a std load of #358495 over 3.0grs of Bullseye.
Just a fluke.

[mehavey]

You could make up some dummy rounds with and
without powder coating and check for adhesion....That ACC38-320E (DGL-lubed) is my standard/heavy BP loadout in that rifle.
https://thefiringline.com/forums/showpost.php?p=6818201&postcount=11

Nary a problem....



I think that there is a deep-seating/surface area limitation associated with the adhesive
characteristics of bare PC/brass under obturation/expansion pressure.
I may have just found it.

Wax-based materials under high pressure turn more liquid
Paint/PC materials under similar pressure turn more adhesive
The expansion hydraulics of extremely soft/pure lead plays here
The larger surface-grip area of big case/deep seating make it worse.
(That's my theory and I'm sticking to it) :popcorn:

Of note: The pure lead bullets tore every neck off
The 30-1 bullets (only slightly harder) tore off sporadic necks

[popper]

I use a 185gr slick sided in my 30/30, PCd and sized. Surface area is the same as yours, .5" vs .52". I use wire cutter to pull bullets and once in a while I totally destroy the nose pulling, alloy/PC is the same but didn't notice what brass (Win/Fed/Hornady). I've run pretty good loads (psi) with fast and slow powder, no separations. Conclusion (?): there are some 'glued' situations but not often. I've also run very hard and very soft alloy. Thinking factory annealing either is not right or not deep enough for your longer bullet. Looks torn, not the normal case separation. I blew the head off a 40sw case once (bad brass) and it had a ragged 'tear' similar to yours. I started using SS pin/wet tumble that cleans the inside neck and haven't noticed the 'glued' problem.