Ok, so as most of you guys know, I picked up a good condition Type 53 Mosin-Nagant Carbine.

I have checked it out really good, and everything seems to work just fine, but I have a few questions and concerns about it.

#1 The barrel looks clean, but when I run a brush through it, this "Soot" appears on the patches and it can take 10 or more before they come out clean again. Running a brush makes the process repeat again, and again. It's endless!

#2 Since the bolt does not match the Receiver, there's a natural concern about head-space. The rifle locks up tight, and the bolt moves very smoothly, but there may be a small gap present that could still be an issue.

#3 Is there any way to check for an over-sized/out of spec chamber? Could that explain the split casings during rapid-fire?

Now Before any of you jump to conclusions, These are just common concerns I have for most of my milsurp guns, I'm just a bit more alarmed with this one being that something bad happened up at the pit.

And another thing, I bought this gun as a Collectible, not a Plinker/Shooter. I don't really care if it's perfect, it just completes the collection, but I would like to solve some of the problems and perhaps make sure it's "Safe" to shoot since it is fun to bring out and knock over some tin cans with!

There may be some pits in the barrel that are filled with gunk, and the more you work it the more of it you get out. Just keep at it.

That said . . . I don't subscribe to the "run patches through until they come out clean" philosophy. "Endless" is a good word for that process, even with a newer gun. I run them through until they're "clean enough" in my book, which is typically 2-3 patches using a jag. (By the way, use a jag, not one of the worthless slotted tips. It will do a MUCH better job.)

Excessive head space can happen during slow fire as well.

Do you have a fired case or two? Just measure them and that will give you a rough idea of the "head space".

Headspace for the 7.62X54R is measured from the head of the cartridge to a point on the shoulder where the tapered part measures .417".
That measurement is "spec'd" as 1.622' Hornady sells a "headspace measuring gauge which attaches to a set of ordinary calipers. With different inserts this same gauge is used to measure bullets and finished cartridges when one is adjusting the "jump" of the bullet before it hits the lands.

There are also "Go-No Go" gauges that one can buy but they don't tell you what the existing measurements are, just "good/bad". A fired case is real close to the exact measurements give or take a thousandth or two for "spring-back".

You might also try measuring several fired cases from case head to the sharp edge of the shoulder. This is spec'd at 1.553". If your bolt is allowing for excessive headspace then it should show up on this measurement as well although findign the exact "edge" is going to be the issue.

Lastly, escessive headspace usually manifests itself in case head separations, split shoulders first. Split necks can come from just plain metal fatigue of the neck itself, especially if it's "vintage" ammo.

The 7.62x54R really "headspaces" off the rim, much like a revolver cartridge, although the "technical headspace" is that 1.622" measurement to that "magic line" on the shoulder. Because of this one can take a fired case, knock the primer out so it's held in the primer pocket by about 1/3rd of it's length. Then chamber that spent round with the extended primer. Force the bolt closed, even if you have to "coax it" with a soft faced mallet. Remove the case and measure the protrusion of the primer after the bolt forced it back into the pocket. It should be very minimal especially since you say your bolt closes tight.

#1 It usually takes dozens - and I mean many dozens, not 2 or 3 - to clean most Mosin barrels out. I just cleaned one and I should have taken a picture of the patch heap that formed at the end of the barrel - it was roughly 5"x3"x2" :-).

These two IMHO are the best cleaning agents. Start with C4 remover to get rid of the gunk, then follow up with Eliminator to remove the copper fouling.
http://www.midwayusa.com/product/155799 ... andPopProd
http://www.midwayusa.com/product/984488 ... andPopProd
Note that eliminator makes copper fouling - and brass on your jag - stain the patch. Unless you use either plastic jag or this:
http://www.midwayusa.com/product/136525 ... read-brass
you will not know if the stain is from the remaining copper or just your jag.

#2 For the headspace, I have gauges. If you want you can drop by and headspace the rifle. Early on I checked headspace on Mosins religiously, but after the first 50 or so with none being bad I stopped doing this.

#3 You could make the chamber cast with this:
http://www.midwayusa.com/product/462291 ... loy-1-2-lb
...and then measure it. I have never heard of a Mosin having a chamber out of spec, but these are T53s, they are rare, there is probably not enough statistic. Is it steel or brass cases that split? How often do you get the splits?

Great info above, thank you.

Do you know if measuring the fired case works for steel cases as well? Does the steel stretch just like brass does?

Thanks for the Links! I will "Update" my cleaning supply! That solvent should do the trick, and I have 500 patches ready!

I would like to check the head-spacing on that Rifle. Not that I don't trust it, but with a 7.62x54R going off several inches from my head, you just can't be too safe.

A chamber cast may be in order. It may be the answer I need, and a good way to get a true measurement.

The Splits I got were with Bulgarian 1953 Manufactured "Heavy-Ball". I believe the bullets were 180 grain, and the cases were made from brass. The splits were not on the case neck, but on the case body. And they seem to occur when the rifle warms up, usually after 10 rounds within a 2 minute period. I did get a split neck on a 7n1 Sniper Round, but it was very small.

Steel tends to "work harden" quicker than brass and thus split. It still stretches but depending on the alloy, may have more "spring-back" The fact that cases are made from a thin piece of metal minimizes the negative effects.

An easy way to see the difference is to measure a fired Steel case neck diameter and likewise measure a brass case neck diameter. Both had the same starting dimensions when they gripped the bullet and both were "stretched" the same amount in the chamber. The difference in "springback" will manifest itself in the fired neck diameters.

You have a situation involving Age Hardened Brass. That stuff is almost 60 years old. Believe me, brass is one thing that gets harder with age. I wish I could make that happen with something else

When your rifle heats up the chamber might expand a few thousandth's and that's all it takes for the case to split. Try some New ammo (or maybe something only 20 years or so in age) and I'll bet your problem will go away.

Pay attention to Solyanik's note on checking these rifles for headspace. Remember, they are MILITARY rifles that are way overbuilt for the cartridge. I'd worry more if you had one of the current "Magnums" built on a lightweight hunting rifle chassis.

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