Pressure problems, worst in what cartridge

[John Y Cannuck]

I just picked up a box of once fired brass from a gunsmith. These were once fired factory loads he had fired in customers guns, during testing. I was surprized at the number of cases showing various pressure signs, from mild to OUCH! :eek:
The cases in this discussion were 308Win. So, as this is a high pressure cartridge, I was wondering if this is the norm for it, or and if there are other cartridges that tend to push the limits on some firearms.

[gunnut69]

The 308 while a high intensity cartridge is not especially so..  The signs you are seeing in those cases may be more indicative of headspace problems than high pressure problems.  Remember that even in normal loads a centerfire cartridge generates around 60,000 PSI...  In a sick chamber or an autoloader causing problems, there may be signs that could be misinterpreted as high pressure warnings.  Good luck from the gunnut69

[John Y Cannuck]

Having pulled them from the trash for another look, I agree. Surprising the number that show stretch marks (ring) on one side only. Is this due to the lugs not being true to the chamber, or the chamber not being true to the bore?
I got some 303Br brass at the same time, just went through those. Same thing, only worse (expected in the 303) out of 200 rounds, I discarded about 20. I know that I could have easily fired any of them, but as I use loads that are above the SMLE saftey limits, (Use Ross 1910) I tend to be picky about my brass.

[John Traveler]

Hi, J. Cannuck!

I completely agree with Gun Nut that apparent pressure signs may not be due to actual overpressure, but may indicate excessive headspace problems.

Case head swelling, primer extrusion, and partial incipient head separations can be signs of excess headspace.

That .303 caliber (like many other smokeless powder bottleneck rimmed cartridges) is infamous for short case life.  In the rush of wartime production, some gun chambers can and were cut eccentric, oversize, and misaligned with the bore centreline.  Military armourers used several sizes of boltheads to adjust for correct heaspace in the Lee-Enfield series.  A gunsmith can quickly check your rifle and determine if excessive headspace is the culprit.

[gunnut69]

JEC  
Actually poor locking lug contact and an out of square bolt face can produce stretch marks on one side of a case.  If the chamber out of square condition you refer to is the chamber not in line with the bore and the bolt head is square to the bore, yes that too can produce those dreaded stretch marks on the brass.  Combinations of the above can get very exciting..from the gunnut69

pss-forgot to note locking lugs not in contact with the locking shoulders causes what amounts to a bolt face out of square condition..

[stv]

I witnessed the saga of a fellow trying to work up a 7mm STW.  The fellow was an experienced reloader and was taking his time and doing it cautiously and correctly.  At that time there was very little data published for that round.  At on point he touched off the first of a series that according to the fellow who invented the round a Shooting Times should have been very conservative.  It locked the action up tight.  When the gunsmith who reamed the chamber and he got it out it was incredible.  The primer was loose and the headspace on the gun was shot.  The smith accused him of hot rodding and overloading it.  When they pulled down the rest of the rounds and weighed the charges they were in fact well within the range of what should have been safe in that gun.  Short of exploding the signs of high pressure are primer pocket expansion,  bolt face/extractor extrusion,  and gas leakage.  These occur just short of the action exploding in your face.  I think the gun was ruined and it was a perfectly good 7mm Rem Mag That really shot well before rechambering.  My candidate for a touchy high pressure round is the 7MM STW.

[John Y Cannuck]

Several of the comments made above make me think I should re-itterate, THESE ARE NOT MY CASES or at least they are not from my guns, I did buy them real cheap (they'd better be).

[John Y Cannuck]

The comment is often made that the rear locking action on the SMLE is the culprit. I don't agree, I believe that loose military tolerances, and wartime conditions are responsible for much of the brass stretching that occurs. As proof, I have a nice tight Aussie made #3 Never saw battle, that does not stretch brass, shoots nice too.

[John Traveler]

"Cannuck",

I made a new friend last summer, a seven-time Queen's Cup Canadian National Rifle champion who is also an armourer at Connaught Ranges during the annual shooting competitions.  You've probably heard of him: Ron Surrette.  He is also a professional gunsmith and reloader.

When I told him of my problems with short case life in shooting and reloading for my Lee-Enfields, his immediate response was, "Don't full-length resize your cases, and be sure to clock the brass."  

He explained that asymmetric case stretch was fairly common in surplus .303 Lee-Enfields, and that wartime rushed production often made for eccentric and over-long chambers, as well as normal wear and tear on the action.

The avoidance of full-lenth resizing I knew about, but the advice to "clock the cases" was new.  He explained that a chamber or bolt that is even slighted cocked off the centreline of the bore will stress one side of the cartridge case more than the other.  By always indexing a cartridge into the chamber the same way each time it is fired, the stress is minimized.  He reported that this will easily double or triple the number of times a case can be reloaded!  

I haven't tried it yet, but I will!

[John Y Cannuck]

Yup, heard that one before. Correct, but a PIA.
Another big problem is people that switch parts at random from one to another. Interchangeable bolt heads of different thicknesses are the method used to adjust headspace on this rifle it's quick, and effective, but if you pull a bolt from a different gun, and slip it in, headspace is wrong bigtime. My cousin asked me why his 303 was separating cases One quick look at the bolt stamp, and I knew this was not the bolt for the gun. e says, oh yea, I keep a mess of them bolts in a drawer, just grabbed one before we went out.  :eek:

[John Y Cannuck]

Connaught Range is about six hours from me. Never managed to get there. I have to some day, stuff of legend that place.

[gunnut69]

The problem with most 303's is not always the headspace.  A rimmed round headspaces on the rim, not the shoulder!!  But the cases expansion is halted by the shoulder.  A 303 may be perfectly headspaced and have an overlength chamber allowing excessive case stretch.  This leads to case seperations in short order.  The best solution is to set up a rifle to headspace on the shoulder not the rim.  Since these are surplus rifles and cost IS a factor, simply run the case into a sizer until the bolt will JUST close on the resized case and lock the sizer in place..  This will minimise case stretch and they'l last a bunch longer..  Of course it still behooves you to have the headspace check before firing....  Properly set up and with careful reloading these old rifles shoot quite well  indeed..  from the gunnut69