Condition of M/N rifling

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Ed Novak	Condition of M/N rifling	Lead	[-]
Posts: 1652 (08/22/08 09:55 PM) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	Tags : None In a different string (Buyer's Remorse), I voiced concerns about the quality of the rifling remaining in a 'B' barreled M39 I just received, as c/w the rifling in a "rearsenaled" (SOG) 91/30 and another well-used M39 I purchased from a private seller - they all have very similar rifling quality and pattern. NotPC commented that I might be surprised at the usefulness of these rifles "with the right loads". I have no shooting experience at this time with any of the MN/M39s that I hold. The rifling seems very "shallow" as c/w other milsurps I've owned. Cannot find any useful information about the designed bore/land/groove patterns on any of the MN sites I visit. In the LE data, examples of bore/groove/land dimensions are easily found for barrel evaluation by slugging - anyone have similar information for the MN?
Pahtu		#1	[-]
Posts: 2059 (08/23/08 01:45 AM) Veteran member Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	I do not recall reading the spec's on rifling differences between Russian/Soviet/Finn/ any other maker of MN's. Casual observations indicate the rifling appears deeper on my Russian & Soviet made MN's and somewhat more shallow on my M39's & other Finn made MN's. The barrels on my Finn made MN's appear to be polished better with better quality machining/rifling. The Soviet made MN's appear to be completely functional, but machining & tool marks are visible, esp on the WWII years. No gauges to measure, just my opinion based on the limited number of rifles in my humble collection pahtu.
Pahtu		#2	[-]
Posts: 2060 (08/23/08 01:58 AM) Veteran member Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	"Ed: Some Mosins will truly surprise you (with the right load) if judged them by a cursory visual exam of the bore. Some, of course will perform as you doubted they would. Odds are that yours still have some life in them. " NotPC is right, proof in an accurate rifle is shooting it. B barreled MN's almost always have fantastic bores as some were not used much(if at all) after they were assembled. I have 91-30's with pitted bores that shoot just as well as 91-30's with shiny sharp bores - Makes no sense really, but that is just the way it is. Shoot the B barrel M39 with a variety of loads & I suspect it will shoot between 2 & 4 inch groups or better, at one hundred yards.... That said, I have fired many MN's & my best MN does not shoot as well for me as my Swedish Mauser M96 & M38 - Perhaps my K-31 also. My Finn M39 MN's outshoot any other MN I own, but with military ammo, they are not as accurate as the rifles listed above. Pahtu.
zeebill		#3	[-]
Posts: 3272 (08/23/08 08:11 AM) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	Boy Ed you have breached a mystery to me when you talk about bore conditions on Mosins. I have some that look so bad I would be embarrased to show them to anyone yet they shoot just great? I have one B barrel M91 that I am sure was never shot till I took it too the range and she was clanking the gong like it was five feet away at 200 yards. The catch and mystery is why do the ugly bores shoot as good at times? I don't have the answer I know that! Bill
NotPC		#4	[-]
Posts: 5423 (08/23/08 12:51 PM) Host Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	The Mosin rifle was designed as a "Three Line Rifle", where a line (liniya) equals 1/10". One inch equals 25.4mm.; 0.10" equals 2.54mm, and three times this number is 7.62mm. This describes the main drilled hole (0.300"). The grooves on a Mosin may run to 0.005" or 0.006" deep, adding 0.10" to 0.12" to the 0.300" number. Part of the success of the Mosin can be attributed to its deeper grooves than our American "standard" of 0.004" (or 0.308"). With worn bores I find that heavier projectiles - because they are longer and can provide more engagement in worn lands - often shoot better. Here are some recent postings that I made on a gunboards thread (#13 and #16 with target pics). http://forums.gunboards.c...d.php?p=451281#post451281 The Finnish developed the 200 grain D-166 projectile for its accuracy and stability. It is longer than the 150-grain "light ball" projectile and its ogive is "fatter", which required lengthening the rifling's throat to accomodate it. Finnish firearms and Finnish-owned firearms so modified have a "D" stamped on the barrel shank. By 1939 the loading was "standard" and M39's were usually not stamped with a "D" (except for VKT's). These projectiles are still available from Lapua. Here is a post including the Finnish 170gr. D-46 and 200 gr. D-166 projectiles: http://forums.gunboards.c...p?t=48683&highlight=Lapua Also referenced there is this page from Ted's site, which gives a sketch of lands and grooves as typically found in a Mosin: http://forums.gunboards.c...p?t=48683&highlight=Lapua From Lapin's book - Finnish rifle bores: 0.3095" - M91/24, M27, M91 ("P" series), M91 (1925-1927), M91 (WW II series) 0.3082" - M28 0.308" to 0.314" - M39 and M91/30 (aka M30) Note: the term "bore" is technically the "main hole" or nominal diameter that is bored (drilled) in the barrel tube. It is often used/misused to refer to major, larger dimension of the groove O.D., which requires a machine operation to expand that nominal bore dimension - except in the case of a hammer-forged barrel. Simplified, you just cannot tell how well a Mosin will perform until it is fired. Give it a chance with different loadings and different projectile weights. A variety of surplus 7.62x54R is available: http://7.62x54r.net/MosinID/MosinAmmo.htm HTH, Regards.
CR Hound	Condition of M/N rifling	#5	[-]
Posts: 698 (08/23/08 02:07 PM) Veteran member Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	The M39 B barrels where made in Belgium on different machinery. It has been a long time since I have shot my B barrel, but I seem to recall it has shallower grooves than all my Finland barreled M39s. IIRC Russian M91/30s have narrower lands than Sako & VKT M39 barrels? IIRC the M28 or M24 article on mosinnagant dot com had barrel specs and a description of why the Fins changed them. Does your B barrel M39 have a "plum" color barrel knoxform? While visually desirable to some collectors, it may be an indication of an overhaul re-blue. Plum rear sight leaf is also a possible sign of an overhaul. Similar to what NotPC noted, most all of my really worn bore Mosins shoot flat-base heave ammo much better than light ball. 200 or 203 grain Wolfe and other Russian commercial ball or soft point is great in my worn bores. The Finland arsenals also used an amazing variety of different crown cuts when they first built and later overhauled these barrels....
NotPC		#6	[-]
Posts: 5424 (08/23/08 02:46 PM) Host Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	And of course matching projectile diameter to groove diameter - or about 0.001" undersized (w/ jacketed projos) and handloading can yield excellent results. Regards.
Ed Novak		#7	[-]
Posts: 1653 (08/23/08 02:53 PM) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	CR Hound wrote: The M39 B barrels where made in Belgium on different machinery. It has been a long time since I have shot my B barrel, but I seem to recall it has shallower grooves than all my Finland barreled M39s. IIRC Russian M91/30s have narrower lands than Sako & VKT M39 barrels? IIRC the M28 or M24 article on mosinnagant dot com had barrel specs and a description of why the Fins changed them. Does your B barrel M39 have a "plum" color barrel knoxform? While visually desirable to some collectors, it may be an indication of an overhaul re-blue. Plum rear sight leaf is also a possible sign of an overhaul. Similar to what NotPC noted, most all of my really worn bore Mosins shoot flat-base heave ammo much better than light ball. 200 or 203 grain Wolfe and other Russian commercial ball or soft point is great in my worn bores. The Finland arsenals also used an amazing variety of different crown cuts when they first built and later overhauled these barrels.... CR Hound: Yes, plum colored nock's form but unfortunately, this rifle is going back to the seller for reason of a fine split from the trigger guard to the splice and another from the splice to the rear retaining band. Hate stuff like this; just makes life more complicated than it ought to be for a buyer. I have only FB HB milsurp to shoot. Wish I had a view of a new bore for comparison to what my rifles have...
NotPC		#8	[-]
Posts: 5425 (08/23/08 03:51 PM) Host Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	I have several M39's with like-new bores having various dates. If you want a brandy-new bore, look into some of the 1967 to 1970 dated ones. I have a couple of them that I think are truly unissued. One is a 1970 with a hang tag dated 3-26-1970. It was likely built and then went directly to storage. Regards.
george1108		#9	[-]
Posts: 12 (08/25/08 10:14 PM) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	If you think the bore is worn, grease the bore and slug it with a lead fishing sinker and then measure it. My B barrell measures 0.300"/0.311" within 0.001" of all of my other M39's. My 91/30's measure 0.302"/0.313" Looks can be deceiving, but a measured dimension is a fact. My best shooters are the SKY models. I have 2 which will regularly shoot 3/4" groups at 100yds with czech light ball. The Czech ammo sticks in ALL of my M39's and 91/30's but I get the best results with it. I compensate for the sticky bolt by using the cocking piece to cock the bolt before opening the bolt. This takes the spring pressure off the bolt and makes it easier to open.
NotPC		#10	[-]
Posts: 5430 (08/26/08 02:04 AM) Host Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	Bore Slugging Tutorial: http://www.7.62x54r.net/MosinID/MosinSlug.htm DDR
Ed Novak		#11	[-]
Posts: 1665 (08/26/08 08:25 PM) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	Thanks for that; I just bookmarked the site. I have everything on hand but the sinkers.
8point3		#12	[-]
Posts: 13 (08/26/08 09:54 PM) Reply Quote More My Recent Posts Message Me Connection Blocking Invite Ignore User's Posts Report Post	I would clean and shoot it first before I got too concerned about the rifling. Most of my M39's have wide grooves and lands. I had one 1967 M39 that had thin cut/fine line rifling more like some of the newer rifles. The bore was in mirror condition and the rifle shot ok. As far as I could tell the barrel was original. I'm thinking a different style of bore cutting lathe was used. I wanted a SKY to help complete the collection so I bought a lower priced 43 that had seen some use. The stock is rough,the bluing almost gone, and the bore is about bright and shiny. I didn't expect much when I took it out but it has one of the smoothest triggers I've had on a mosin. I usually work on them some but I left that one as is. I always fire 3 shots for function and sight location at 25 yards from a bench rest. My better shooters will put 3 shots in a clover leaf at 25 yards and as good as my eyes will permit at 100 yards with open sights. I was shocked when this rough old SKY shot a clover leaf dead on in a one inch red dot. It was getting late so I didn't move on out to 100 yards with the rifle, but I've learned not to pass judgement till I've shot the rifle some. I keep a record on every rifle I shoot, to include ammo type,distance fired,group size, and wind conditions. It makes it nice later for reference and info on each rifle. When I get time someday,I'll take the old SKY out and see what it does at 100 yards but from the info on all the others at 25 yards, I think it will shoot great. Let us know how it shoots.