First 5 shots very tight...after that not so much

[jderimig]

Hello,

New Mosin Nagant owner here. 1938 Tula 91/30. Put about 120 rounds (surplus Russian) over the last 2 weeks. Noticed a pattern in that the first 5 rounds give me a great group (<3" inches at 50 yrds offa rest), after that about basketball sized groups. Then I get up an shoot off-hand and the group is a little tighter, go figure.

Bore is not shiny but the rifling looks very strong. The barrel is counterbored but otherwise looks decent for a 74 yr old $100 gun. Hasn't anyone else seen something like this before?

Regards,
John

[Sgt. Rob]

Most likely as she heats up, the barrel is pressing against part or parts of the stock and changing its natural point. When rested it is being accented with extra pressure from the rest. When you shoot off hand, you have removed one of the additional pressure factors. However you need to back out to at least 100yds to make more conclusive observations.

Semper Fi, Rob

[desdem12]

Welcome to the forum John I am sure someone here has experienced that. I don't pay too much attention to my groupings most of the time but maybe Sarge Rob can help you here.

[Sgt. Rob]

BTW, Welcome Aboard! Glad to have another shooter join!

Semper Fi, Rob

[desdem12]

And there he is just before i can get the words out

[Junk Yard Dog]

Welcome to the forum, and as for the problem, what Rob said

[jderimig]

Thanks, and its not really a problem, I did not get the rifle to compete in matches. Just part of my process of learning about these remarkable rifles.

[jderimig]

Most likely as she heats up, the barrel is pressing against part or parts of the stock and changing its natural point. When rested it is being accented with extra pressure from the rest. When you shoot off hand, you have removed one of the additional pressure factors. However you need to back out to at least 100yds to make more conclusive observations.

Semper Fi, Rob

Thanks Rob,

Just to be clear, the first 5 shots (from a cold barrel) are tight. The rest of the session, each 5 round group is twice as large. The offhand experiment was just done once for the fun of it. So the POA was not the only thing that changed when the barrel heated up, the group did too. If that is what you understood then I just used up some bandwidth for no additional information

[Sgt. Rob]

Yep, as the barrel heats up, and expands as it gets hotter, she will shift and /or open up to larger groups. You can try adding some buisiness card shims under the barrel to exert more upward pressure and possibly reduce the amount of change to POA. If your groups do not open up more than say 6 to 8 inches at 100yds, I would not sweat it. If they do go over 8 inches, I would not really use it in competition. However if the first 5 are good and consistant from day to day on a cold barrel she is more then adequate for hunting. And it is always good for plinking!

I recently bought a '38 Tula myself with a worn looking barrel and do not expect great things from her accuracy wise. Still need to take it to the range soon and see, but I bought it for its personality, charecter and because I did not have a '38 Tula yet! For collector purposes, the shooting part does not matter as much, at least to me. I'll end up with more then enough for milsurp shoots, as probably so will you!

One option also is to try diffrent ammo types and weights, such as both light and heavy ball, and say commercial vs. surplus. May be the rifle might tighten up some with one type over another. Very common in comercial sporters.

I will not discuss other options for tuning up a milsurp rifle like the Mosin, as it would entail making unchangeable alterations. And as a collector I can not stomach that. Too many are competitive enough as is to monkey one up.

Keep us posted on your shooting experiments!

Semper Fi, Rob

[jderimig]

Yep, as the barrel heats up, and expands as it gets hotter, she will shift and /or open up to larger groups. You can try adding some buisiness card shims under the barrel to exert more upward pressure and possibly reduce the amount of change to POA. If your groups do not open up more than say 6 to 8 inches at 100yds, I would not sweat it. If they do go over 8 inches, I would not really use it in competition. However if the first 5 are good and consistant from day to day on a cold barrel she is more then adequate for hunting. And it is always good for plinking!

No I am not interested in modifying the rifle, just trying to understand what it is doing. Is it possible the the bore id is expanding and the rifling is losing bite or is that not likely? If so is that why the reloaders use slightly oversize bullets?

[MN Fan]

Hello and welcome to the forum!

It looks like you're in good hands with Sgt. Rob. Your questions and Rob's replies have been interesting. I simply wanted to say welcome

[desdem12]

The bullet should expand to fit the rifling of your gun unless it is way too loose and shot out. I have not seen any in that condition myself but i guess there are T53s that shoot sideways.

[Sgt. Rob]

The barrel I.D. won't expand. When the rifling wears too much and or the muzzle end becomes to worn or gets a nick or ding, you will start to see tumbling. Readily noticeable on the target by weird jagged holes. As the barrel heats it will expand against parts of the wood stock which will push it in one direction or another depending on how much it already touches the spot. The expansion is not enough to see with the naked eye, but it does not take much deviance to send the bullet on a diffrent path. Harmonics can also play a part in how well a rifle shoots, this whole harmonics thing is very prevalent with M1 Garand competitors. Basically every thing needs to vibrate or move in a consistant fashion, the same time every time. I think to a lesser degree it can effect Mosins via cleaning rods, barrel bands, and screw tension, etc.

Sometimes worn rifling can be delt with by increasing bullet diameter, which is best done with cast lead bullets. The cast bullets can be sized (and usually lubed at the same time) with a sizing die after they are poured and cooled, to specific diameters. Casting and sizing bullets represents a small (large?) financial investment however in tools, molds and dies etc. so it is not for everyone. I myself have not cast anything for 7.62x54R cartridges....yet. I hopefully will branch out into this this summer if time and money allows, as it intriges the heck out of me. I have done this for 45-70, 45-90 and .375 Winchester black powder loads, this will be my first work with a bottle neck cartridge.

Well I gotta go help with Super bowl dinner. Its the only football game we watch every year, and the Wife is calling. Will get back to this later Gents!

Semper Fi, Rob

[jderimig]

Well I did some playing. I put a business card shim at the recoil lug and another small piece at the end of the stock. With this I was just able to slide a sheet of paper under the barrel along the stock. Took her to the range today and the initial group was just a little larger but seemed to stay constant as the barrel heated. Ran about 3.5-4" at 50 yrds with the cheap Russian surplus ammo.

Still learning how to shoot the thing and some of the group size was most likely me. I will probably try removing the shim at the end of the stock (just leaving the shim at the recoil lug) to see what happens.

--john

[Junk Yard Dog]

These rifles also heat up fast, POI will shift as the barrel heats after 20 rounds shot quickly. This is why I bring more than one rifle with me to a shoot, I let the rifle cool while I go bang away with something else. Get ot hot enough and the cosmoline will start to boil out of the stock.

[jderimig]

These rifles also heat up fast, POI will shift as the barrel heats after 20 rounds shot quickly. This is why I bring more than one rifle with me to a shoot, I let the rifle cool while I go bang away with something else. Get ot hot enough and the cosmoline will start to boil out of the stock.

Brilliant! That's why I need to go out and get another rifle!

[desdem12]

I can't think ....Have i ever heard a bad reason to go buy a gun..hmmmm.

[Junk Yard Dog]

Last shoot I brought six rifles, a shotgun, and a pistol

[desdem12]

Last one i went on i took 7 rifles 2 shotguns and 4 pistols. We shoot all but one rifle between 2 of us.

[Junk Yard Dog]

The pistol shooters I went with hated the US M1903, some whining about "recoil" but fought over the Mosin 91/59, I mostly shot my M39 and left them to it. They are way to cheap to buy their own Mosins, they will wait until I kick and take mine, or so they think. One of them dropped over 2 grand on a new Mac computer he don't even know how to use, but is to tight to spend a hundred bucks on a rifle, claims why do it when he can use mine.