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Discussion Starter · #1 ·
I've noticed a lot of people talking about counter bored Mosins. How do I tell if the 3 I own are counter bores, and what exactly does this mean??
All the Mosins I have are shooters and have nice minty bores, I have an M38, an M44, and a M91/30.
 

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If you have a counterbored rifle the muzzle will look huge and you can see the "lip" depending on how far down it goes, from the tool. It was done to fix a muzzle damaged or worn by careless use of steel cleaning rods. I have Mosins with CB's as shallow as 1/8" and one as deep as 3".
 

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Insert a X54 cartridge in front and if it goes in up to case neck it counterbored!
Shine a borelight in front and if the front of barrel is round then its C-bored.
Take a cigarette and insert in muzzle and if it gets hung aftre 1- 3 inches it is C-bored!

This was done on many guns since they crown was damaged from rough cleaning rod use,so it improves accuracy.
In general a C-bore is 1 1/4 -3 in long!
A few peolple dont like C-bored guns, but many were done and i rather have 1 C-bored than not and have a bad muzzle!
Might drop price of gun by $10. at best!
 

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Counterboring is no big deal and I've done it with my cheap little chinese tabletop drill press. If the bore at the muzzle is so worn the rifling is ineffective a counterbore can bring accuracy back within the milspec, approx. 3 inches at 100 yards. Unlike cutting and recrowning the barrel it has no affect on the bayonet attachment. The most accurate MN I've ever owned was a Finn marked 91, a 1916 Tula, that had a half inch counterbore.
 

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3 INCHES for accuracy is not MILSPEC. No offense jjk308 but I flat out disagree, respectfully so.

Too many guys here get 1 inch and less at 100 yds so this 3 inch accuracy is a rifle that shoots poorly or the shooter is shooting poorly (often as not).

If a rifle shoots 3 inches, it may or may not be the counter bore. It may be a non counter bored rifle.

If you wish the files on how to bed Mosins and tweek triggers to chase their accuracy potential, email me.

The files are pulled from the boards here over the last 3 yrs and they WORK if your rifle has a decent bore and you can shoot.
IF and that is IF the counter bore is done correctly, the rifle will retain its accuracy. I know of
no gauge to help you determine that and because of that, I choose to pass on counter bores but I had no
choice on my M38. I waivered and bought the only nice M38 found in 3 yrs and it had a counter bore. I consider
myself lucky that it shoots 1.5 inches at 100 yds as it has a repaired muzzle. As soon as I find a nicer M38 without
a counter bore, I will trade out this CB M38. But that does n ot mean the non CB M38 will shoot better until its tested.

I take huge exception to the common "Thought" that lingers on this board regarding 3 inches as "Milspec" for the Mosins
because thats not a established fact of manufacture, its only the results of some people on this board and assumed to
be representative of what the standard accuracy is for this model rifle.

Let me know if you wish these files and I will send them to you.

I will start a new myth on Milspec: Poor condition rifles will shoot 3 or more MOA at 100 yds. Poor shooters with accurate Mosins will shoot 3 MOA or greater at 100 yds.
 

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Too many guys here get 1 inch and less at 100 yds
Or claim to. Now, if you do, then you do. Most such claims, however, I take with a very large grain of salt. I mean no disrespect, here, but this is my honest opinion.

Were the various military users issuing individually bedded, carefully tweeked, lovingly worked over rifles to the troops?

I'm sorry, but I just have a hard time buying MOA or less as the standard of accuracy expected from an off the rack, standard issue Moisin, with garden variety service ammo. Or, for that matter, from pretty much any other contemporary military bolt action.

What somebody can tease out of a piece in their home workshop isn't MILSPEC.
 

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Or claim to. Now, if you do, then you do. Most such claims, however, I take with a very large grain of salt. I mean no disrespect, here, but this is my honest opinion.

Were the various military users issuing individually bedded, carefully tweeked, lovingly worked over rifles to the troops?

I'm sorry, but I just have a hard time buying MOA or less as the standard of accuracy expected from an off the rack, standard issue Moisin, with garden variety service ammo. Or, for that matter, from pretty much any other contemporary military bolt action.

What somebody can tease out of a piece in their home workshop isn't MILSPEC.
Nor is a tweaked rifle likely to be collectable after the fact....
 

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just my .02. 10 shot 3" (actually that is sub 3 m.o.a.) with a milsurp gun with common milsurp ammo is excellent. not counting swedes or 28/30s,28/76s,maybe swiss k-31s. mn refurbs,turks,rode hard swedes,yugo mausers,sks,ak,and the empire/american stuff. we are talking surpus ammo too. had a PU repro to do sub m.o.a. easy with S&B match struggled to do <4.0 with surplus. all guns are different. all ammo is different. but,3 m.o.a.,esp 10r groups (bands and handguards are not accuracy enhancers) in a common milsurp with common surpus ammo is a very good "shooter".
 

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The only counterbored Mosin I have is a scrubbed 1898 M91 with at least a 1 1/2" counterbore. It has the easiest cycling bolt of all of them and since I am not out trying to shoot Germans with it, I don't care that much if it is that accurate. I got it just because I did not have an M91.
 

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Discussion Starter · #13 ·
Thanks for all the answers guys, I didn't mean to get an argument started. None of the three Mosins I own are counter bored and I am quite happy with the 2 inch groups they print at 100 yards with Silver Bear 203 grain soft points which is what I used in my M44 to kill 2 deer with at about 60 yards. One was shot out my kitchen window, and it dropped in it's tracks. I've started reloading for the M38, have taken it out of the original stock and put it in a synthetic to try and see what it will really do (still have the original stock so I can put it back to original after I retire it). Using PRVI 150 grain bullets and some IMR 4350 to start with. If ya wanna know what I mean by retire it, after I kill a couple of deer with it I figure it will have paid for itself and then I can retire it and use on of my other milsurps that hasn't gotten broken in yet.
 

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If one beds a Mosin and polishes a Mosin trigger / sear spring just like the Russian sniper rifles were done, and it performs 1 MOA or better,
its not a ton of salt needed to see that the rifles accuracy has been obtained.

If one carefully finds Mosins with tight bores that are mirror bright, there is a good chance the rifle will perform extremely well for accuracy.

If one does not believe this is true, he is destined to be a 3 MOA or worse shooter

The one IF that is not a IF is this: if you do not try to obtain the max accuracy your rifle is capable of, then you will be a 3 MOA shooter or worse.

A paper shim and polishing the sear spring is hardly going to damage the collectability or MILSPEC status of a Mosin Nagant.
 

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For a discussion on real, honest accuracy see http://www.chuckhawks.com/practical_accuracy.htm I was VERY happy that, shot at 100 yards from sandbags, my Weatherby Vanguard in 300 Wby Magnum did an honest repeatable 1.75 inches with little load workup of hunting rounds.

The best military (type) rifle accuracy I've been able to find is an American Rifleman machine rest test of the new SIG 516 in 5.56x45. Its best performance was with 69 grain match ammo that resulted in 5 shot groups of from .89 to 1.42 inches at 100 yards, an average of 1.12 inches. Top of the line bolt action sporting rifles get from about 3/4 to 1.5 inches, depending on the ammunition, in these NRA tests and its not reasonable to expect an old, mass produced milsurp to do anywhere near as good.

As for the ammunition, according to Hatcher's Notebook the 30 cal match ammunition produced for the US Army usually had calculated dispersions of .3 inches, and about .5 inches when shot from test barrels. But the specifications for normal military ammunition production were:

Cal. .30 M2 Ball
500 yards test - Mean group 13 inches (2.6 MOA) Maximum group 38 inches (7.6 MOA)

With the vagaries of normal military production and a real military rifle barrel a high degree of accuracy seems impossible and a requirement of 3 MOA - and I assume spec match type ammo had to be used so any inaccuracy wouldn't be blamed on the ammunition - seems reasonable.

I didn't feel like buying an M14 Milspec, but below is some sourced information from a Wikipedia article on sniper rifles - 1 minute of angle (MOA) is roughly 1 inch at 100 yards. These are dedicated sniper rifles. Milspec accuracy requirements range from 3 MOA for most main battle rifles in western nations to 6 MOA for the combloc Ak types. Note that these are maximums and any rifle that doesn't test within them supposedly would not be accepted.

Wikipedia:
In 1982 a U.S. Army draft requirement for a Sniper Weapon System was: "The System will: (6) Have an accuracy of no more than 0.75 MOA (0.2 mrad) for a 5-shot group at 1,500 meters when fired from a supported, non-benchrest position".[6] Actual Sniper Weapon System (M24) adopted in 1988 has stated maximum effective range of 800 meters and a maximum allowed average mean radius (AMR) of 1.9 inches at 300 yards from a machine rest, what corresponds to a 1.6 MOA (0.5 mrad) extreme spread for a 5-shot group when using 7.62 x 51 mm M118 Special Ball cartridges.[7][8][9]

A 2008 United States military market survey for a Precision Sniper Rifle (PSR) calls for 1 MOA (0.3 mrad) extreme vertical spread for all shots in a 5-round group fired at targets at 300, 600, 900, 1,200 and 1,500 meters.[10][11] In 2009 a United States Special Operations Command market survey calls for 1 MOA (0.3 mrad) extreme vertical spread for all shots in a 10-round group fired at targets at 300, 600, 900, 1,200 and 1,500 meters.[12][13]

In 2008 the US military adopted the M110 Semi-Automatic Sniper System which has corresponding maximum allowed extreme spread of 1.8 MOA (0.5 mrad) for a 5-shot group on 300 feet, using M118LR ammunition or equivalent.[7][8][14] In 2010 maximum bullet dispersion requirement for M24 .300 Winchester Magnum corresponds[7][8] 1.4 MOA extreme spread for 5 shot group on 100 meters [15].
 

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If one beds a Mosin and polishes a Mosin trigger / sear spring just like the Russian sniper rifles were done, and it performs 1 MOA or better, its not a ton of salt needed to see that the rifles accuracy has been obtained.
MILSPEC = military specifications. Not Russian term, but I'm sure they had something similar.

When Tula, Izhevsk, or whatever armory finsihed building a new 91/30, your basic service rifle, and sent it to be test fired, what standard of accuracy did it need to demonstrate before it earned its targeting and accuracy proofs, and would be accepted by the military? 1 MOA or better? If so, a whole lot of perfectly good rifles wouldn't be making it out the factory door. Or was it something more in the 3" group range? Whatever it was, that was the MILSPEC for that particular criteria. And I don't know what the exact standard was, but I doubt it was 1 MOA. I don't think the ammo was MILSPEC'd to 1 MOA performance standards. But the rifle shoots to whatever the standard is, gets its proof marks, the army takes it away, and hands it to Ivan. Everybody's happy. And nobody is expecting Ivan to shoot 1 MOA groups when he goes to the range to qualify.

Now, if you take this same rifle home, and shim, polish, and tweak it to the point you can tease 1 MOA performance out of it, hats off to you, but that isn't MILSPEC. Not unless you can show that this is what the Russian standards called for. It's YOURSPEC.

Most of the 1 MOA or better results people report also appear to involve handloads, which removes things even further from the realm of MILSPEC.
 
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