I am having a Mosin Nagant day ... 300 Win Mag

[Clark]

I fixed the 6mm, it shoots now:
6mmRem 90 gr Nos Bal Tip moly 257 Roberts RP brass necked down, 39.1 gr bulk 4895 = H322 in QL library 2.955" OAL, 67 kpsi, 3316 fps QL, stablity = .892
1.5", 5 shots 100 yards

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There is something wrong with the Mosin Nagant 300 Win mag, but it made a tiny 3 shot group today. So the tiny one Saturday was real. Something is loose.

300WM, 150 gr Nosler Bal Tip moly, 62 gr Bulk 4895 = H322 in QL library, 3.34" OAL, 64 kpsi 3189 fps QL,

0.3" 3 shot group 50 yards.

[CowTowner]

Clark,

Something is making unexpected noise? Are you feeling an abnormal vibration?
How do you know something is loose?

[Slamfire]

There is something wrong with the Mosin Nagant 300 Win mag, but it made a tiny 3 shot group today. So the tiny one Saturday was real. Something is loose.

The Mosin Nagant was never designed to carry the structural loads that a belted magnum creates. The amount of thrust on the lugs, receiver seats, barrel threads that a 300 Win Mag produces is undoubtedly above the proof pressures of the 7.62 Russian round.

If you find cracked lugs, receiver seat set back, how about posting the pictures. At some round count, you will experience issues due to metal fatigue.

[Clark]

The steel does not know what it was designed for.
See post #7.

[Slamfire]

And when I measure the bolt lugs and calculate the lug cross section area in shear:
Mosin Nagant 0.414 square inches
Savage 110 0.396""
Remington 700 0.387""
Win M70 0.376""
96 Mauser 0.325""
98 Mauser 0.313""

When I run 7mmREM in an old 98 Mauser with 110 kpsi QL, the lugs and abutments start to show plastic deformation.

It is good you measured shear. Now, look at your load in shear. How much load will a standard Russian cartridge provide on the bolt face.

I did the calculation for an Mauser action.

From Cartridges of the World

8 mm case head diameter 0.470” Area 0.1735 square inches
338 Win Mag case head diameter 0.515” Area 0.2083 square inches

Bolt face loads

8mm (Mauser design loads) 0.1735 in ² X 43, 371 lbs/ in ² = 7, 525 lbs
338 Win Mag = 0.2083 in ² X 65,000 lbs/ in ² = 13, 539 lbs

The 338 Win Mag provides an 80% increase in bolt thrust over standard military loads.

The service pressure of the 8 X 57 cartridge, at the time Paul Mauser was alive and designing actions, was 43,371 psia. So that is what I used.

Then, you have to account for the design safety factor, a common one for rifle actions is two. Which means the designer doubled the amount of material. Not that the action is twice as strong, rather given the uncertainty of materials and fit, the designer hoped the action would complete a normal service life with a load of one.

So, you with your hot loads have eaten into the safety margin of the action, and, you have not looked at the fatigue life given the shear and the load.

So, you get plastic deformation at 110 Kpsia. What's your fatigue life at 110 Kpsia? How many cycles to failure do you expect? Carrying the load once, and carrying the load a hundred times or a thousand times are different things. I have looked at fatigue curves and metal that has been over stressed, stressed at or beyond yield, fails rather rapidly compared to metals that were not over stressed.

And how many firing cycles have your actions been through, before you rebarreled them? Each round counts for fatigue life.

[tobnpr]

Bolt thrust of 30-.06/.308 is 10,279 lbf (54R is in the same class- so should be very similar...)

Couldn't find the spec on the .300 WM, but the .300 WSM purportedly has more bolt thrust than the LA and comes in at 15,362.

Roughly 50% more.

[Clark]

Put new scope rings on 300WM and went to the range for the third time this week.

a) 6mmRem 85 Sierra shooting 1.6 moa, 95 gr Nosler shooting 1.4 moa
b) 6.5 got a round jammed in front extractor and no one had a cleaning rod
c) 300WM shot 0.9" 3shot at 50y and 5" 3 shot at 100y
d) 6mm Sierra group looks like something is loose, two holes over here, and then two holes over there
e) With the wind at 5 mph, the most I could blame on that is 0.35 moa, so none of these (3) rifles I built in 2015 are good enough to hunt with beyond 450 yards, and I had results out to 550 yards in 2014.

Disgusted.

[Gunplummer]

Long before the lugs on that gun "Shear off" there will be plenty of signs of set back in your brass. I have seen this in older Mausers barreled up to something hot, but generally the rounds were small caliber, high pressure rounds. The Mauser is a good example to use, as the material and heat treating process is similar. I am not a fan of the Russian rifles, but the only bad things I ever remember hearing about them were attributed to the improperly re-cut 30-06 models that some importer did years back. As with the Mauser, I would stay away from the early models when stepping up on a re-barrel.

[Slamfire]

I am not a fan of the Russian rifles, but the only bad things I ever remember hearing about them were attributed to the improperly re-cut 30-06 models that some importer did years back.

Russian rifles are difficult, if not impossible to convert to standard rimless rounds. Then there is the clunky bolt, trigger and safety. People generally don't sporterize these things and very seldom convert them to different calibers. If a number of these things were floating around in WSSM or belted magnums, we would be reading reports of conversion problems.

The stories of improper conversions to 30-06 and 8mm are true. I saw pictures of both conversions. The chamber section was cut off until the inside diameter was the size of a 30-06 or 8mm cartridge . Then a reamer was used to cut a chamber. The chamber went way up into the thin wall section. The conversions show the incredible ignorance of the converter, that is the chamber carries most of the load, as the surface area of the cartridge in the chamber is greater than the surface area touching the bolt face. So these converters cut out a massive amount of material in the area where it was needed the most, and what was left was the thin wall section of the barrel.

[Gunplummer]

There has been more stuff done to the Russian rifles than you know. Anytime there are cheap (Or free) guns around with no ammunition available, they pretty soon end up on workbenches as experiments. I have seen some bizarre stuff at gun shows and auctions years ago. Rarely do you see that kind of work pop up anymore.
Why is it difficult to convert to a rimless case in a Russian rifle? It is usually a lot harder to go the other way.

As is usually the case using figures, pressures applied to the bolt face and chamber walls can be deceiving. This was tested by P.O. Ackley, and finish (Texture) of the chamber walls can really change where the most pressure of a fired round is directed. Apparently, a highly polished chamber will shift the pressure load to the bolt face.

[Jimro]

This isn't the first Mosin Nagant conversion I've seen.

Most popular are the 45-70s, but there was a guy in Finland who did a 300 WSM conversion. He also shaved off the back of the right rear bridge on the action to weld a bolt handle back there for a more modern bolt handle placement.

Never heard of any of them failing, there's a lot of steel in that action and bolt head. Clark's blown up more rifles than anyone else I know, and the Army pushes 300 Win Mag with a 68k psi load (Mk248 Mod1) through Rem700s, so it seems to be a similar amount of steel for a similar load.

Jimro

[Slamfire]

As is usually the case using figures, pressures applied to the bolt face and chamber walls can be deceiving. This was tested by P.O. Ackley, and finish (Texture) of the chamber walls can really change where the most pressure of a fired round is directed. Apparently, a highly polished chamber will shift the pressure load to the bolt face.

P.O Ackley was selling snake oil; his tests while interesting, are hardly conclusive, they are in fact, closer to being meaningless. P.O Ackley was selling his cartridge designs on the chamber wall tests, and if you notice, he does not provide pressure data. I don't even think he has velocity data.

Never heard of any of them failing, there's a lot of steel in that action and bolt head. Clark's blown up more rifles than anyone else I know, and the Army pushes 300 Win Mag with a 68k psi load (Mk248 Mod1) through Rem700s, so it seems to be a similar amount of steel for a similar load.

So, are the steels in the Russian rifles the same steels in the Rem 700's? All steel is not the same, the differences are significant. Can you provide the chemical composition and the heat treatment used in the Russian rifles?

[Gunplummer]

Again, get out of the book and get some solid facts. Many years ago I made brazed carbide boring bars for a job. I started with .187 carbide blanks and brazed them in a holder. The bar was sticking out of the holder about 3.875, which is pretty darn far with the clearance on the bar. A new job came in almost identical, only longer and with a bigger bore. The boys in the office figured out the length and thickness of the bar from the old job (.187) and ordered the the 3/8 carbide for the new job with out telling me. The part they did not figure on was how much should be brazed in the holder (About 1/3 or more of the extended length). I was allowed about .250. It was a total failure, but they insisted I try because "Mathematically it was correct". The first bar chattered so bad it snapped off. I am all for using facts and figures to work something out that is already proven. Other than that, I go forward with caution. P.O. Ackley was not full of stuf. He did real world experiments, and I think a lot of the others were full of it. I never read anything that Hatcher (Seems to be quoted a lot here) wrote and really do not plan to. At least Ackley had the sense to do a chemical analysis of the steel he was working with. It is a good thing to gather knowledge, but without the experience thrown in, knowledge can be worthless.

[tobnpr]

Clark,
Did you do any work on the receiver before installing the barrel?
Lap the lugs? True the receiver face? Clean up the threads in any way?

I had an inquiry about trueing the boltface as well, but see that as being of dubious value due to the floating bolthead. I think it's similar to a Savage design- and while some do it, most think it would not accomplish anything.

It really should be shooting better even without any blueprinting with that barrel- there's got to be something wrong, somewhere. Whose chambering/throating reamer did you use? The military barrel with a good bore will shoot inside of two minutes with the correct handloads- I've got a couple that shoot one.

[Slamfire]

My objections to converting military actions to calibers they were never designed rests on the idea that in 1889 Captain Sergei Ivanovich Mosin never intended his action to be used with a 300 Win Magnum cartridge, nor for cartridges of 300 Win Magnum pressures and loads. Therefore, a first pass analysis is that these cartridges are not appropriate for this action.

Secondly, I don’t trust the steels made by the Socialist Paradise. I have a short story about this but I am not going to write out right now, but the quality of Soviet steels reflected their society: shoddy.

I am going to offer a paradigm shift. Instead of me attempting to prove this is dangerous, let those who advocate such conversions, prove they are safe.

Since none of the advocates are going to do anything but hand waving and pointing at clueless authority figures, then I am willing to wait for Clark to tell us how the conversion goes.

To make a convincing case, Clark needs to keep a round count. If he really wants to wring this concept out, he needs to continue shooting. A great way to prove the soundness and get the round count up would be to shoot in mid range and long range matches. A 300 Win Mag is an outstanding long range cartridge, mid range (600 yards) and long range (1000 yards) are fun, a real test of the shooter and his rifle. Serious prone/F Class shooters are at a match every weekend, the round count is typically 66 rounds for the day. Shoot two or three matches a month, for nine months, and the round count adds up. (about 1700 rounds) I would be curious if Clark can put enough rounds down the barrel to shoot the barrel out. That should be around 2000 rounds. At some point the barrel will not cluster, and when he takes the barrel off, he can tell us how the receiver threads, receiver sets, are doing. Then, rebarrel and continue shooting. If Clark can take that receiver 5,000 or 10,000 rounds, without any set back, and tell us, he will have added to human knowledge.

[Gunplummer]

Paul Mauser never intended his '98 for the .308 and .358 Norma magnums, but they seem to hold up fine. Norma used to supply chamber drawings for both to use them specifically in the '98. I seriously doubt they (Norma) did any in depth study of German Military receivers.
So what if the rifle gets set back after a couple thousand rounds. I have welded on Russian receivers and the material used is low carbon steel. It certainly will not "work harden" and shatter. I doubt half the commercial rifles chambered for the .300 Magnum in the 60's through the 80's could pass that kind of test. Even light machine guns have a receiver life specified per so many rounds.

[tobnpr]

Far as the Mosin-Nagant action...

47 grains (full case) of 2400 did not cause receiver failure, skip to about minute 12:
https://www.youtube.com/watch?v=gfiXFyIbOZw

In Part II, they used a full case (again, 47 grains) of what they call "range trash", which is mix of every type of powder swept up off the reloading room floor...again, receiver did not fail.

For anyone with Quickload, it would be interesting to know the pressure developed with 47 grains of 2400 under a 147 grain pill...

[Slamfire]

Paul Mauser never intended his '98 for the .308 and .358 Norma magnums, but they seem to hold up fine.

Specifically which M98 actions and for how many rounds do they hold up fine?

Norma used to supply chamber drawings for both to use them specifically in the '98. I seriously doubt they (Norma) did any in depth study of German Military receivers.

Looks like Norma is now German owned, at one time it was Norwegian. I thought it was Swedish. If Americans are going to blow themselves up, with their guns, seems to me that a Swedish Company has very little legal liability in this Country. They are free to provide Americans all sorts of dangerous advice, as long as they make a profit off American’s buying their cartridges. Sounds like a win-win.

However, things are different in Germany, I read about German proof laws. Up to the mid 60’s, if your thunderstick failed proof in any sort of way, the whole thing was crushed, cut by welding tools, and sent back to the owner in pieces. Since then, only the offending parts is smashed and welded. We can all understand how German shooters reacted to having perfectly good stocks, scopes, scope mounts, bolts, barrels, destroyed because of a non functional safety. Proof house workers probably had a great time smashing customer’s rifles to pieces. All thundersticks go through the proof house from private sales to newly manufactured, from the gun company. I am of the opinion that all EU countries follow similar proof laws. The law’s desired effect was to weed out old actions.

So, just how many old Mauser actions go through Norwegian/German proof houses, and how many pass? You have an idea?

So what if the rifle gets set back after a couple thousand rounds. I have welded on Russian receivers and the material used is low carbon steel. It certainly will not "work harden" and shatter. I doubt half the commercial rifles chambered for the .300 Magnum in the 60's through the 80's could pass that kind of test. Even light machine guns have a receiver life specified per so many rounds.

I am glad to see that you understand that every firearm has a design life and a fatigue life. Designing firearms for an infinite fatigue life would create heavy, unusable firearms. I do have long range friends who have gone through a number of barrels on their long range rifles. It used to be that the most popular actions were the pre 64 M70, push feed M70, and the M700. Actions like the Panda Stoll and Bernard are popping up in great frequency. For the last couple of decades the 300 Win Mag level cartridges have dropped out, they used to be popular in the early 60’s and probably up to the 80’s. I saw them, occasionally in the nineties. The development of good 6.5 mm bullets and rule changes have been good, because the 6.5 mm rounds are ballistic ally better, and kick less. About the only 30 caliber being shot is the 308 Win because of Palma and F Class Tactical rules.

As for the half of the commercial actions you are referring to, I have no idea which ones, nor whether you have actual test data.

I am not going to spend $400 on a good match barrel, $800 on a match stock, $500 on sight bases, drilling and tapping, mount a $1,000 scope, and then screw on some old Russian action, to finish up a $2,700 rifle. And, I am not going to advise anyone to do so, in fact, I will advise against it.

Gunsmiths, desiring to draw in business, will of course, ballyhoo such foolishness.

[Clark]

Tobnpr,
No, I have not trued a receiver face nor lapped a lug for 10 years.
My brother is lapping a Mauser lug today, due to folklore in Kuhnhausen book.

Slamfire,
I have fired 36 rounds @64kpsi. The primer pierced once.

[Gunplummer]

Slamfire, Have you ever actually re-barreled a rifle? Sure does not sound like it. You started out good. I have seen and heard some of the dumbest things about guns, and it usually involved either heat treating or headspace. Now I am going to have to throw your last couple posts out on the pile with the rest of the silliness. I was always partial to Arisakas. I guess Ackley was full of stuff about them too, or didn't you get that far in your research?

[tobnpr]

Still bugging the hell out of me as to why it won't shoot close to bugholes with a Krieger barrel. Something's wrong, clearly...

Did you epoxy bed the receiver after that pic showing the recoil cross-block/pillar?

[Clark]

3 times to the range, and 3 times I saw a tiny 3 shot group at 50y teasing me.
I do not glass between the Aluminum and the receiver. That is a pre compressed connection. I think the winds will die down and I will try again Thursday.

[Slamfire]

Slamfire, Have you ever actually re-barreled a rifle? Sure does not sound like it

Yes I have. Short chambered barrels that I installed and cut to depth. I don't have a machine lathe and gunsmiths that I know who are competitive shooters, a couple of whom I shoot with, turn and install my barrel blanks. Gunsmithing takes a lot of time, time of which I am either reloading, or shooting reloads in competition. I am willing to pay for trusted individuals to do the machine work on things that I don't feel confident doing, and don't want to take the time and effort to master.

I was always partial to Arisakas. I guess Ackley was full of stuff about them too, or didn't you get that far in your research?

I like the Arisaka design, it is a very well thought out and clever design, one of the few actions that could be considered equal to or better than a M98. It was interesting to read in Ackley's book, about the heat treatment of the receiver.

Since you can't understand headspace, heat treatment, or cartridge support discussions, you probably are clueless why the Arisaka action is so strong, for a plain carbon steel action.

So Gunplummer, what is the extent of your education? You have a College Degree in Engineering, preferably Mechanical or Aerospace?

[Clark]

I live in a world of engineers....socially.. relatives and friends. My neighbors are mostly attorneys.
My father was showing me math when i was a little boy and I was showing my son math when he was a little boy. I have long challenged Piaget's concept of volume conservation in children. One of my one year old granddaughter's other grandparents is a physiology professor who has challenged me to disprove conservation by testing our granddaughter. The kid is about to get strange shaped glasses of water, not math from me. She can wait until she is 6 to get calculus, like her father did.

[Gunplummer]

Slamfire, I think you should stop now. "A plain carbon steel action"? As opposed to what other kind of action? The Arisaka actions are as close to 4140 as you can get. This is a high carbon steel and is designated in many books as a tool steel. I have cut, welded, heat treated, and made bolts for quite a few. Arisaka receivers have qualities that are not even close to low carbon steel receivers. I no longer have a surface grinder, but have probably made more headspace gauges and reamers than you have held in your hand. I don't even need a headspace gauge to check a rimless chamber if the barrel is off and I have the bolt and receiver. I can get out the Machinery Handbook and figure out how to check it with the appropriate sized ball and a depth mic. There have been tapered bore jobs checked like that for years in machine shops. Yes, we are all wrong and you are right.
I stood next to a blanchard grinder once and knew the guy that operated it. I guess I am qualified to surface a flywheel on one.