Do I have a problem here please?

[sutts]

I've been looking at the empties from my first 91/30 sniper shoot. A few features give me a little cause for concern. Is my rifle sick or is this just standard for used military rifles? I was hoping to get into reloading but I'm thinking this kind of brass deforming could make that a little dangerous. Any feedback much appreciated.

Thanks

[Longcolt44]

Did you check the head space before firing this rifle? This has all the signs of not being checked.

[Junk Yard Dog]

Looks like sloppy headspace to me. Once upon a time I would have suggested you get some Okie coin type gauges and check it, but Okie is gone. Now you will have to call Brownells or Midway and order some Forrester gauges, more expensive, you can get away with just the No/Go for a basic test.

[sutts]

Thanks guys, I was hoping for better news. Dealer reckoned it had been checked and it was all greased up in the export box so thought it would be OK.

I do actually have some original head space gauges (bullet style) but haven't figured out how to use them yet. Some say you need to take the spring out of the bolt first which sounds like a major pain. Has anyone used this type before please?

Even if I confirm that I have a head space issue, there don't seem to be any replacement parts available in the UK. Plenty in the US but nobody will export :(

Cheers

[Junk Yard Dog]

Yes, to use these you will have to remove the extractor. Be careful as these are thin and break easily. With a lack of parts your other option is to have brass custom made with slightly thicker heads to make up the extra headspace. This would be expensive here unless one was a skilled machinist with access to a lathe, drill press, and so on. If it is not illegal to import gun parts of this type into the UK maybe somebody here on the board has a spare bolt head. Try advertising the need in the wanted/for sale forum.

[sutts]

Thanks for the advice JYD. I've ordered a device to allow me to easily strip the bolt down without it flying apart so I'll hold off on the headspacing until I get that.

Unfortunately it does require an expensive export licence to bring bolt components into the UK as they are classed as pressure bearing components (or something like that). Hopefully I'll be able to find a new bolt head over here with time.

Is increasing head space usually caused by wear to the bolt head or the chamber opening? The above casings don't look dangerous do they? I'm wanting to shoot again this weekend really but I won't if they look close to rupturing. From what I've read, when head space is extreme, the primers start popping out or becoming domed.

Thanks for the help.

Dave

[Junk Yard Dog]

They look typical Dave, the Mosin is not known for tight tolerances except by chance. Close was always good enough for the Soviets, and rimmed cartridges are much more forgiving of poor headspace than rimless ones.

[sutts]

Good to know JYD, thanks. Any idea what is causing the highlighted indentation line towards the top of the case (neck?). Badly machined chamber perhaps? If the chamber was worn at that point then we'd be seeing a ridge there I guess but this definitely sinks inwards.

Dave

[Junk Yard Dog]

That's possible, a borescope would allow for closer inspection.

[sutts]

Thanks, nice piece of kit and cheaper than I thought they would be. Will definitely be putting that on the shopping list.

Cheers

[AMCHornet]

That ridge up by the case shoulder is likely a roughly machined are of the chamber that the cases are embossing themselves into.

A slight line and bulge near the bottom rim of the cartridge is somewhat normal because the base of the cartridge where the primer presses in is very thick. That thick base prevents it from fire-forming to the chamber when the powder burns. The thinner part of the case above the thick base will expand, so there is a transition point there. However, yours looks more extreme than normal.

Definitely need a head space check. If it passes on headspace, then you might just have a generous chamber and will have to live with it.

[Lavitias]

That ridge up by the case shoulder is likely a roughly machined are of the chamber that the cases are embossing themselves into.

A slight line and bulge near the bottom rim of the cartridge is somewhat normal because the base of the cartridge where the primer presses in is very thick. That thick base prevents it from fire-forming to the chamber when the powder burns. The thinner part of the case above the thick base will expand, so there is a transition point there. However, yours looks more extreme than normal.

Definitely need a head space check. If it passes on headspace, then you might just have a generous chamber and will have to live with it.

Probably doesn't help I saw he was shooting S&B and that stuff is always loaded a little hot I get signs of overpressure from it out of my mosin and it's passed it's checks. But ya as long as you pass headspace you'll just have to live with it.

[AMCHornet]

Every single surplus or commercial load I've ever fired through any Mosin-Nagant showed flattened and cratered primers and stretching of the casing up around the neck and shoulder area, yet every gun passed headspace checks with flying colors.

It just seems to be normal for them.

Still, you don't hear about many people blowing their face off with a Mosin due to primer or casing failures. Iraqveteran8888 fed some insanely overloaded cartridges through a 91/30 and ultimately destroyed it in the end, but he had to reach insane pressure levels before primer and casing failures became a problem.

[awalker1829]

Eric stopped once he started having problems with the cases, but was nowhere close to a failure of the bolt or receiver. Hatcher’s book reported pressures in excess of 100,000 psi without the receiver failing. Nominal pressure generated by a service round is 54,000 psi. Realistically, nothing a reloader accidentally does is likely to be a fatal mistake with a Mosin in safe working order.

[sutts]

Thanks Guys. I've ordered a coin-style head space gauge so I can check without mucking about with the extractor. There does appear to be a bit of roughness inside the chamber which I'll try to address. I don't mind a slight case bulge as long as it's safe. I definitely won't be reloading these cases though.