No.4 Enfield problem - over pressure?

[Gaz]

Started a new thread for this one as I think this might get lost in my original thread, Building a No.4 Enfield.

Background - the barrel on my rifle is a secondhand one with a lot of throat erosion present. The bolt is matched to the receiver and had a new head fitted when the barrel was fitted.

I took the rifle to the range on Sunday and fired it for the first time. Ammunition was factory S&B with 174gr heads. It pierced a few primers and suffered light strikes on others (which I refired so you can't see them below):



Below is a rather poor pic showing the web area of two fired cases.


In these two you can just about see the bulges in the necks of the two cases on the left. On the right is a fired case from another No.4 which is in good condition.




My question is, is my rifle running over pressure? Fultons, who fitted the barrel, assured me they'd correctly headspaced it so I wouldn't think it's that. Any ideas? :?

[dromia]

Firstly you should never re-fire a miss-fire it is dangerous range practice and contrary to the miss-fire procedure.

Secondly have you taken a cast of your chamber?

Thirdly have you checked you firing pin protrusion and have you stripped the bolt down to ensure that the inside is clean and there is no dirt or debris interfering with the spring and its functioning?

Fourthly what was the recoil like and how easy was it to open the bolt and extract the rounds?

[Dougan]

I can't see any untoward 'buldging' on the necks - If you're refering to the way they have 'rounded' after firing from the normal 'straight' shoulder angle - then I get this too when I fire factory (PPU) in my smle - I think it's just the necks taking on the shape of the worn chamber, and when neck-sized and reloaded, fit the chamber realy nicely....

...that said, the 'rounding' action on the necks may well stretch the cases, and being a rimmed cartridge could cause problems at the case head end - for this reason, I'm keeping an eye on mine but haven't seen anything to worry about...but maybe this effect is more significant for your chamber...?

I'm fairly new to reloading myself, so can't advise you (and don't have a clue about the primer/pin strike problem?), but will watch for other's comments with interest...

[John25]

Excess firing pin protrusion is number one suspect.

If it was excess pressure there would be other signs like the metal around the primer dent flowing back and the bolt face 'imprinting' on the primer.

stgeo

[bnz41]

Hi Gaz

I know someone who got Fultons to fit a No4 new barrel/bolt head, and head spaced it then got it proofed etc, only when the owner was on the firing range he was getting the same marks on the brass near the base as yours, some cases seperating on extraction. Took it back to them they checked head space (nothing wrong with it)faulty brass they said, but we will replace the barrel and bolt head, just to be on the safe side. They did.... Not a problem since, get them to re check there work on your rifle.

[Gaz]

Dromia - Good point on misfires - too many years of just turning .22 rounds and popping them back in. No hard extractions, recoil and muzzle blast was all the same throughout. Will get the striker protrusion gauged and strip the bolt as well. Chamber casting, how do you do that?

Dougan - if you look carefully at the shoulder of the cases, you can see one or two tiny bulges at intervals There's five in total, equally spaced around the shoulder.

bnhz41 - thanks, I might just do that...

[dromia]

Hi Gaz

I know someone who got Fultons to fit a No4 new barrel/bolt head, and head spaced it then got it proofed etc, only when the owner was on the firing range he was getting the same marks on the brass near the base as yours, some cases seperating on extraction. Took it back to them they checked head space (nothing wrong with it)faulty brass they said, but we will replace the barrel and bolt head, just to be on the safe side. They did.... Not a problem since, get them to re check there work on your rifle.

That is appalling.

[dromia]

Dromia - Good point on misfires - too many years of just turning .22 rounds and popping them back in.

You shouldn't do it with .22RF either for the same safety reasons.

[Gaz]

Dromia - Good point on misfires - too many years of just turning .22 rounds and popping them back in.

You shouldn't do it with .22RF either for the same safety reasons.

I have to ask, what reasons? Never had it explained clearly. I assumed it was something to do with pressure and weakened metal around the striker mark...

[dromia]

Exactly, the primer or rim is weakened by the first blow and if the round ignites it can give way and there is a gas escape with possibly brass fragments letting go close to your eye.

Also if there is a miss-fire then that indicates that all is not well with either the ammunition or the firearm and the cause of the miss-fire should be established rather than blithely "giving it another pop". Familiarity can breed contempt and that should never happen when you are to all intents and purposes discharging a pipe bomb next to your face. Firearms can be lethal but only with human intervention.