Mosin ammo problem

[ckirby]

I've got three M91/30s: one is a 1931 hex receiver, one a 1936 round receiver, one a 1942 war production round receiver, all Izhevsk armory. I'm firing reloaded Partizan and S&B brass, as well as some Tula surplus. At the range today I discovered that many of my rounds won't let me close the bolt completely. On inspecting them later I found that there is a lot of variation in the shoulder length within the same brand ammo and between brands. The steel Tula ammo is always short case and feeds in all my rifles. The reloadable cases have variations of about 5-10 hundredths in distance from the rim to shoulder. The 31 hex will feed them all, the 36 round receiver feeds some of the long shoulder rounds but not others, and the wartime MN won't feed anything but the short shoulder rounds. All of the reloads are once-fired. All rounds are well within the max OAL and max case length.

So, I'm looking for advice on how to deal with this. Am I forced to sort ammo for which rifle will swallow it or is there some way to resize to "push" the shoulder down.

Thanks in advance for any advice.

[Junk Yard Dog]

I have not used Privi brass in this application yet, if the brass is not in spec before you have loaded it and fired it then return it to the seller and explain the problem. The surplus rounds work in all your rifles because they are properly constructed. Are you full length resizing the once fired cases? Neck sizing them works only if you are shooting them all in the exact same rifle they were first fired in, rifles have variations in chamber measurement, once a round is fired in that rifle the fired case then will conform to that rifle only. If the cases are out of spec before loading, then try full length resizing them before doing anything else with them, then measure them again. If you are going to shoot the same reloads in all three rifles than you must full length resize the fired cases first. Welcome to the forum.

[desdem12]

I have heard of this problem when reoloading with the S&B brass. I don't buy S&B for this and a couple of other reasons. The prvi partisan should work good, if it doesn't on the first go around then return it so they may be able to see if they have a batch problem to correct. I have some PrPa ammo but have not used it yet but have used winchester white box in a finn and it worked great. If you have trouble woith those brands then you may want to switch ammo. I generaly shoot surplus ammo in quite a few and have had no problem at all with it yet.

[entropy]

I use Graf's brass, exclusively. Never had a problem.

[Dragunov sniper 777]

what kind of dies do you have ? , i have a set of lee dies that way under sizes the casing and causes the same thing in a couple of reloads and it rings the case , you can't bump the shoulder back with my lee dies , i am replacing them with a set of RCBS w a neck sizer only die , all the chambers are on those rifles are not made to close dimensions , and seem quite large , and some may have mix matched bolts and head-space issues , i just have a couple of rifles i load for and try to keep the brass separate , the rest i just use brown bear in them .

[desdem12]

Is that with the .308 neck sizer DS? Would it make a difference if you went to the 303 british one?
I think the lee dies only come with the .308 one

[ckirby]

Thanks for the replies. Yep, I'm using the Lee full-length resizing dies. The cases that come out of the resizing step do have considerable variation. I assume this means that the chambers in the rifles vary so much that after firing the cases don't resize back to the same shape. Sorting ammo for three rifles is doable; if I keep collecting Mosins it could get complicated.

[tjtM38]

The cases tend to stretch; it varies from firearm to firearm and depends also on whether you have excessive headspace. I reload Privi-Partisan brass and find that I have to trim cases to the specified trim length about every other loading, depending on which gun I am shooting them in. They don't stretch much and I only have to trim them a little, but I make sure they are to spec by measuring all of them each time. I use a 7.62x54r RCBS trim die to do the trim work.

[ckirby]

For anyone who might have the same problem, I found a jury-rigged solution. Looking at the shell holder on the Lee die set I noticed there is a small amount of play in the vertical spacing of the holder. I cut a small piece of 28-gauge aluminum flashing I happened to have handy and slid it into the shell holder, in position to slide the bottom of the case over it when I put the case in the shell holder. The .015 thickness of the metal was just enough to take up all the slack in the shell holder but still allow the case to fit into the holder. By luck, this was all that was necessary, as the metal shim raised the cases just enough to allow the dies to move the shoulder down an RCH. Four or five firm passes of the cases through the re-sizing die, with a quarter turn of the case between strokes, and the cases now fit all three Mosins perfectly.

When running the already-resized cases through the dies again I could feel the die forcing the shoulder down into proper position. It's nice when things actually work out. For a more permanent solution I've ordered an extra 7.62x54 shell holder and I'll grind down the top of the holder a bit to produce the same result without having to fool with the little thumbnail shaped piece of sheet metal.