Chamber wear

[Dave 101]

Any one heard of a situation like this , I have a Enfield No 4 MkII which was converted to a 7.62 x 51 TR . The last few times I have used it after a few rounds the cases start to stick in the chamber leading to very difficult extraction and in a couple of instances case separation . A friend of mine came up with this theory today , the area around the shoulder of the case becomes worn and the expansion of the case is causing the case to expand into this worn area , which causes the hard extraction .
Whatever the theory is , I had decided it may be time to retire this rifle or just use it with downloads and cast bullets for short range work or just chop it up with the angle grinder .
Any ideas welcome .
Dave

[The Gun Pimp]

How does it become worn? More likely to be a problem with the surface of the chamber combined with 'orrible old brass! A borescope will provide the answer.

[Dave 101]

Nothing wrong with the brass new Lapua .

Dave

[R.G.C]

Nothing wrong with the brass new Lapua .

Dave

I wpuld ssuggest to measure precisely the fiired cases ahead of the extraction groove.

If over 12,03mm or ovalised, the chember could well have inflated after an overpressure?


The fired cases coild also show inflation at this level,where usually start the separation.
R.G.G

[dromia]

If it is goosed then a rebarrel to 303 would be in order.

[bnz41]

Nothing wrong with the brass new Lapua .

Dave

Morning Dave,
Is this the first firing of the Lapua brass factory ammo or reloads?

I had a similar problem with one of my No4 7.62 conversions with new .308 brass (Remington) damaged shoulder (dimples) but no case separation, so I started using GGG 7.62x51 factory Nato spec ammo which I can reload, not seen any shoulder issues. May be worth trying 10 before you take a grinder to it. Many threads on the inter web about the differences or not between .308 and 7.62x51 chambers and brass spec. Just a thought.

[tackb]

If it is goosed then a rebarrel to 303 would be in order.

quite right , it's a tragedy for an enfield action to be sullied with a 7.62 chamber.

bad form you know and just not cricket !

[meles meles]

Many threads on the inter web about the differences or not between .308 and 7.62x51 chambers and brass spec. Just a thought.

http://89.145.88.102/~buttere/hbsanorth ... age_id=140

[Rearlugs]

Sticking cases are usually a sign of either untrimmed reloads, or an obstruction on the chamber wall - can be a pit, or even a small flake of brass.


Hard extraction and/or case separations together are sign of serious over-pressure - always due to bad reloads.


7.62mm Enfield barrels will normally handle any type of 7.62mm or .308W ammunition without issue.

[Dave 101]

Nothing wrong with the brass new Lapua .

Dave

I wpuld ssuggest to measure precisely the fiired cases ahead of the extraction groove.

If over 12,03mm or ovalised, the chember could well have inflated after an overpressure?


The fired cases coild also show inflation at this level,where usually start the separation.
R.G.G

I have already resized the Lapua cases but measured some Winchester cases and there is an expanded ring about 6mm up from the base measuring 11.99 - 12.01 .
I also measured some mil spec cases and they are the same . Probably this rifle has only been out 4 times in the last year , my normal load charge is 39 gns of N140 so not a massive charge .
Will try it on some down loads and then consider its future .
Thanks for all your comments .

Dave