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

[tobnpr]

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.

This type of inconsistency is often seen from receivers moving around in the stock. The wood inletting looks a bit rough in the picture. I'd glass bed the receiver behind the recoil block, the right side of the action (left side is tough due to the interrupter) and the tang if you continue have issues. Good luck.

[Clark]

It also might be me moving around on a wobbly old wood bench and seat that do not fit me.

I will leave for a month in the desert in 3 or 4 weeks. I can get good stability when prone.

[skizzums]

I would like to add, I think what you did with the 300 is pretty amazing. hope you get your expected accuracy out of it. congratulations on your build. I know it's not the first 300WM mosin, but it is one of very few. Apparently a few have been built and used in the (Finn Sniper challenge?) whatever that is.....

cool project, keep it up, love your posts and learn a lot from them

[Clark]

I went to the range a 4th time yesterday and wrote up a range report.

I had cleaned the Copper out of the 3 rifles and introduced a 4th rifle I built 10 years ago, a 300WinMag VZ24 Parker Hale midland barrel, vari x II 3x9x50 scope.
I put moly bore paste in all 4 barrels.

6.5-06 with a couple sighting and fouling shot first with 3.5" OAL ammo
2.4" 5 shot group at 100 yards with 3.34" ammo
2.1" 5 shot group at 100 yards with 3.34" ammo
2.25 moa

300Win Mag Mosin, no first fouling shot
2.1" 5 shot group at 50 yards with 3.34" ammo
1.9" 4 shot group at 50 yards after fouling shot
4 moa

300Win Mag VZ24, no first fouling shot
1.15" 5 shot group at 50 yards with 3.34" ammo
shooting 2.7" to the right of point of aim at 50 yards .. needs 5.4 moa adjustment
2 moa

6mmrem 1903 turk 85 gr Sierra bullet no first fouling shot
3.2" 5 shot group at 100 yards
1.85" 4 shot group at 100 yard after fouling shot
2 moa

Conclusion; cannot hunt with Mosin as is. Shorten the barrel or super glue the scope mount or something.

[tobnpr]

Conclusion; cannot hunt with Mosin as is. Shorten the barrel or super glue the scope mount or something.

You think this is due to barrel harmonics?

I know you're being sarcastic on the mount since you've never had issues with the ATI.

[Clark]

I dunno what is wrong.
Like a becalmed sailor, I am ready to whistle for a wind.

https://en.wikipedia.org/wiki/Hierarchy_of_beliefs

[Slamfire]

300Win Mag Mosin, no first fouling shot
2.1" 5 shot group at 50 yards with 3.34" ammo
1.9" 4 shot group at 50 yards after fouling shot
4 moa

Check mounts, glue them to the receiver if necessary, change scopes.

[Gunplummer]

I worked on a Savage that had a similar problem. The guy had mounted a Simmons (Been a long time, pretty sure it was) scope on a .300 Magnum. What was going on was the scope tube was too flexible (Thin) and moving around in the rings. At first I thought alignment problems and lapped the rings in. I simply could not tighten the rings enough to clamp that scope tight.
Put a mark on the tube or measure off something before cranking some rounds thru it. I am not saying that is the problem, but maybe.

[Clark]

Thanks for the encouragement.

Up until now I took a 0.3000+ pin gauge and poked in and felt for any change in amplitude of wiggle as I pushed the pin in deeper. I never felt any.
But last night I could see a real threshold in the bore where the thread relief cut is on the muzzle brake threads.
Then I tried pushing the 0.3000+ pin gauge in further. At 1.75" insertion, hardy any protrusion left for gripping the 2" long pin, the pin hits interference instead of wiggle
If I drop the pin into the breech and pound it through the bore with a cleaning rod, it is 20 pounds of force the whole way, until the trailing end of the pin gets 1.75" from the muzzle and it is free.
So the change in shininess of the bore under the muzzle break threads is not the problem, it is an overall bigger bore for the last 1.75" that is the accuracy problem.

So I need to pull the rifle apart, put the barrel in the lathe. Dial in the bore, cut off more than 1.75" and recrown. The barrel will change from 23.5" to ~ 21.5".

The next day the range is open is Wednesday at noon.
I would bet even money that Wednesday that rifle will improve from a 4 moa rifle to a 2 moa rifle, 5 shots at 100 yards.
That sounds bad but all most all the deer and antelope I have shot were with rifles that did 1.5" 3 shots at 100 yards =~~ 2" 5 shots at 100 yards.

Nothing about hunting goes as planned.
Not much about this gunsmithing is going as planned.

[skizzums]

What kind of scope mounts do you guys use on the ATI mounts? Tried a Nikon P-series the other day, and it just doesn't fit. I could machine it down if I had to, but hoping you guys had rings that work well and fit tight. Thanks

[tobnpr]

Any idea how it could have happened?

I think Krieger air-gauges their barrels, which means this difference in bore diameter would have (presumably) been caught if it were a defect from when the rifling was cut. I'd call them, even if the "easy" fix is to cut and re-crown.

[Slamfire]

The barrel will change from 23.5" to ~ 21.5".

A 300 Win Mag with a 21.5" barrel?! Better wear sunglasses, the fireball will be huge!

[Clark]

I am running 150 gr NBT moly with 62 gr bulk 4895 that matches H322 in the QL library. QL predicts 3174 fps
I measure:
3189 fps
3093 fps
3159 fps

QL thinks that 100% if the powder will be burned with a 12" barrel... but the velocity drops to 2618 fps, and the NFA laws would get involved.

3110 fps for 21.5" barrel
3057 fps for 20"
2975 fos for 18"
2879 fps for 16", the legal minimum, and burning 62 gr Powder to get 308 performance with 16,474 psi muzzle pressure [louder than any gun I ever shot]

[Clark]

The Mosin 300 Win mag project has had 3 disappointing trips to the range, and things must change. Adding weight makes it kick less and thus more accurate.

The Mosin 300 Win Mag 150 gr 62 gr H322 [bulk 4895] is accelerating the bullet from 750 fps to 2200 fps during the interval between 0.4 ms and 0.7 ms
That acceleration is delta V / delta t =[ 2200-750]/[.7ms -.4ms] = 4,833,300 ft per second squared
The bullet reaches a speed of 3160 fps
The bullet weighs 150 gr = 0.021 pounds
The bullet advances 20 inches
The rifle weighs 9.2 pounds with scope and bipod
The rifle reaches a speed of 7.2 feet per second = 4.9 mph
The rifle has a peak acceleration rate of 11,000 feet / second squared
The rifle recoils 0.046" before bullet escapement.
------------------------------
I have just added a 4 pound block of 4140 tool steel to the butt.
That sounds like the wrong kind of steel for ballast, but it was just the right size and I did not want to wait on Speedy Metals.
I drilled and tapped 5/16-18 holes to fasten the grind to fit limbsaver recoil pad to the steel block. I drilled a .25" hole with 0.8" deep .375" diameter countersink for the conventional wood screws to the stock butt. That is 4 holes in tool steel. I flooded it with Cool Mist /water mix to keep the steel from getting hot. When it gets hot, it can get harder than the drill. That wrecks the drill and leaver a hard spot that must be drilled out with a carbide drill. I don't have 115 sizes of carbide drills, so I have to be careful. I shortened some 5/16-18 cap screws with the grinder. To get the threads back in condition at the screw tip I ran the screws through a 5/16-18 tap. I did that with an electric drill. After enough power screwing, they are civilized again.
--------------------------------------
Now the rifle weighs 13.2 pounds.
The rifle reaches a speed of 5 fps = 3.4 mph
The rifle has a peak acceleration of 7,666 fps squared
The rifle recoils 0.032" before bullet escapement

I predict that this change alone, at best could improve the 4moa performance to 2.8 moa

That is still not good enough to hunt. We need at most 2 moa precision.

But we are doing everything we can, and tomorrow I will cut off the muzzle that offends me.
And the next day, Wednesday, I will be back at the range to do testing.

[tobnpr]

I predict that this change alone, at best could improve the 4moa performance to 2.8 moa

So you think it's due largely to flinching/recoil management?

[Clark]

*I went to the range both yesterday and today.
*The VZ24 has a long trigger. I ordered a Timney from Brownells
*The 1903 Turk bolt handle broke off. The late Randy Ketchum did not have enough penetration on the TIG weld. I am cannibalizing another rifle
*The Dumoulin 6.5-06 shot a 1" 5 shot group at 100 yards.
*The Mosin Nagant 300 Win mag shot a 0.7" 3 shot group at 100 yards today. It was finally shooting well enough to go to 100 yards.

[Clark]

I broke a bolt handle Thursday at the range. The TIG weld had no penetration.
Today I drilled and tapped both halves with 1/4-28 thread.
I screwed them together. Clocking did not work out. There was a half a thread gap when oriented.
I filled that gap with Silver solder.

[skizzums]

.7 with the mosin. quite the achievement friend

[Clark]

I made a turret tonight.

[Clark]

I tried to put a Stoney Point Aftermarket turret on a 1973 Leupold Vari X ii 3x9x40 riflescope [The 350 Chevy of all riflescopes]
Stoney point has been sold. These have been dropped from the product line. They were always made in China. They have not been on the Stoney point web site for years, but new supplies keep coming in.
My guess is that it is all bootleg.
The scope elevation adjustment slot was designed for a coin [Yeah,,, LEOPOLD!]
They get adjusted by screwdrivers and the Aluminum slot gets beat up.
The Stoney point turret driver would not fit.
I thought it was because the slot was beat up. So I started de burring the Stoney point driver and the Leupold slot.
But measuring with pin gauges, the slot was 0.069" and the driver is 0.071".
It is not going to fit.
So I milled the screwdriver like tip of the Stoney point turret down to 0.066".
Still no fit.
Wrong radius on the tip.
So I changed the radius and it went in.
Then on to the standard Stoney Point turret nightmare, the shims.
I could not select from Stoney point or my collection of washers to get it to stop rattling.
So i tried bending a washer like a Belleville washer [spring].
That was to much force for the wimpy turret and it would not turn.
So I scrounged up a coil spring that would pass a .25" shaft on the inside, shortened it down to 3 coils, and stretched it out.
That works.

But the scope is so old, it does not have the standard elevation rate of 15 moa [minutes of angle] per revolution.
It is more like 6 moa or 6.5 moa, that i can see in my Leupold zero point boresighter system.

[tobnpr]

There's a few companies making custom printed BDC "stick-ons" for popular turrets- based on the dope you provide them. Just dial the distance, and wind hold, and press. Press right on like tape.

[Clark]

I put white tape on turrets and mark the ranges based on targets.
That grosses some "gun beautiful" guys out.

[Clark]

I took the 300 Win Mag Mosin to the range; 8-22, 8-26, 8-28, 9-3, 9-9, 9-10, 9-16, 9-17, 9-23, and today [9-25].

1) I loaded some 300WinMag ammo after finding only 90% of the primed brass would fit into the Mosin Nagant 300WinMag.
The difference seems to be a bulge in front of the belt.
300WinMag 125 gr Nos Bal Tip Moly, 66 gr IMR 4166, 3.34" over all length [OAL]
Quickload predicts 3174 fps 47 kpsi

a) Mosin Nagant Krieger barrel 14 pounds as tested with 4 pound butt plate and bipod

I fired 7 rounds.

Fired one sighter at 50 yards
Fired one over the chono and into the dirt
1.2" 5 shot group at 100 yards [ or 0.6" 4 shot group if I could throw out one]


What does it all mean?
good enough to proceed to long range target practice for big game.


Why did things improve?
Copper fouling powder, IMR-4166, lighter bullets, lighter triggers, less wind, and me shooting better.