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

Ever shoot with guys who killed a lot of people in Viet Nam?
Big stressed out guys?
I saw one in 1995 clear a jammed FAL by jumping on the cocking handle like he was kick starting a Harley.
Like a one leg pogo stick.

So there is more than one way to break off a bolt handle.
I think the Gold standard in wimpiness is the Rem700 soldered on bolt handle. When they break off you can see.. not very well soldered on.

I think I have enough 1903 Turk bolt handle weld area left that squeezes between the scope eyepiece and the receiver to support me in shear if I ever do the pogo stick move.

Jack Belk [pres of the gunsmith guild] posted some pictures 15 years ago on TIG welding Mauser bolt handles. I saved those pics. Back then a lot of guys were notching out the receiver, as does the Dumoulin. That avoids these questions about not enough metal left on the handle. I would rather leave the receiver alone.
 
Reminds me of a younger guy that was doing a rebarrel and sporterizing a 99 Arisaka for himself. The bolt handles are pretty thin where they contact the receiver. Anyway, he brought the gun to me and said in about 6-7 test rounds, the cases were getting longer (Losing headspace). What was happening was the welded area had contacted the little notch in the receiver when he cut the chamber. The bolt lugs were not touching at all and he headspaced off the bolt handle. The weld started to compress and he got a form of "Setback".
I think the bad bolt stories are mostly left over from gas welding days. I have seen some really nice sporters with a crappy weld on the bolt handle. Some even have porosity in the weld. Nothing wrong with gas welding, but it is a different skill level.
The lousy Remington bolt handles are just poor brazing (Or silver soldering). You can see the tape did not attain enough heat when they pop off. Take a hammer and try to beat a piece of carbide off a large stick tool. Ever try to pound a sight base off a Mauser barrel? That is only soft solder.
 
I have taken the rear sight off a Mauser. Joe at Realguns was trying to restore and re blue one. I had lots of take off barrels so I experimented for him. I heated it up and hit it. That looked like a really good solder job when it came apart.

I am trying to get ready for the range AND visit the grandkid tomorrow.
 
Yes, they come right off with heat. One would think the solder would break down over the years on those Mauser barrels, but apparently not.
 
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

----------------------------------------------------------
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.
 

Attachments

  • Mosin Nagant 300 win mag 50 yards 8-26-2015.jpg
    Mosin Nagant 300 win mag 50 yards 8-26-2015.jpg
    155.4 KB · Views: 44
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.
Click to expand...

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.
 
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.
Click to expand...

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.
 
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.
 
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.
 

Attachments

  • 6mmRem 85 gr sierra 100 yards 8-28-2015.jpg
    6mmRem 85 gr sierra 100 yards 8-28-2015.jpg
    86.1 KB · Views: 37
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.
 
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.
Click to expand...

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.
 
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.
 
Last edited:
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
 
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.
Click to expand...

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.
Click to expand...

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?
 
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.
 
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.
 
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.
 
You must log in or register to reply here.
Back
Top