Mosin Nagant Help, what else can I try?

[cobullseye]

Mosin Nagant

barrel slugged, bore .299/.300, grooves .313. Really clean, smooth, shiny. Shoots jacked ammo very well.

Brass cases boxer primed. After firing the inside of the case mouth is .308. Only knock out the spent primer, do not full length or neck resize.

Lee 178 grain bullet, out of range scrap, fluxed, dropped on a towel, at a temperature near frosty to get to fill out, air cooled, left in mold long enough to get the scar on the back of the bullet to be round, not scraped. They drop .311 to .313, not sized, pan lubed with liquid Alox. I have tried as cast and Beagled the mold up a couple thousandths, does not seam to matter much. I did size in a 308 sizer a batch of these, tried them same results. Also added gas checks to the above, same results.

Also tried Lee TL314-90-SWC 90 grain bullet, 90 grains, with 6.9 grains of H110. Same results.


Loaded with a Lyman M dies, flares the mouth a little to get bullet started. Lee factory taper crimp die just a tiny bit to push bell back.

Powder 13 grains N110, no filler, WLR primer. Gone up and down in powder, seams the sweet spot.

Best I can do is 2.3” at 25 yards off a rest

I think it should shoot better, What else can I try? I was hoping for 2-3 MOA, is that reasonable?

[Maven]

First, I think you need a mould that drops a larger diameter bullet.* NOE offers a version of Lyman's #314299, for example, but you won't know what diameter you'll need or to size to until you slug the bore. Also, try to remove the copper jacket fouling. Last, I had great success with 12.5gr. of Unique in my MN's and #314299 (sized to .311" and .312"), so you may want to consider this.

*always with a gas check. Are you adding the GC?

[Scrounge]

Mosin Nagant

barrel slugged, bore .299/.300, grooves .313. Really clean, smooth, shiny. Shoots jacked ammo very well.

Brass cases boxer primed. After firing the inside of the case mouth is .308. Only knock out the spent primer, do not full length or neck resize.

Lee 178 grain bullet, out of range scrap, fluxed, dropped on a towel, at a temperature near frosty to get to fill out, air cooled, left in mold long enough to get the scar on the back of the bullet to be round, not scraped. They drop .311 to .313, not sized, pan lubed with liquid Alox. I have tried as cast and Beagled the mold up a couple thousandths, does not seam to matter much. I did size in a 308 sizer a batch of these, tried them same results. Also added gas checks to the above, same results.

Also tried Lee TL314-90-SWC 90 grain bullet, 90 grains, with 6.9 grains of H110. Same results.


Loaded with a Lyman M dies, flares the mouth a little to get bullet started. Lee factory taper crimp die just a tiny bit to push bell back.

Powder 13 grains N110, no filler, WLR primer. Gone up and down in powder, seams the sweet spot.

Best I can do is 2.3” at 25 yards off a rest

I think it should shoot better, What else can I try? I was hoping for 2-3 MOA, is that reasonable?

I thought the rule was 1-2 thousandths of an inch over groove diameter? If you've got a .313 groove diameter, that would require a boolit of .314-.315 diameter, would it not?

[nicholst55]

I thought the rule was 1-2 thousandths of an inch over groove diameter? If you've got a .313 groove diameter, that would require a boolit of .314-.315 diameter, would it not?

If his fired case mouths mike at .308", he may have great difficulty trying to chamber a cartridge loaded with a .314-315" bullet. I would suggest that the OP do a chamber cast, and measure the throat diameter. Size your bullets as large as will chamber, and try that.

[Larry Gibson]

"Lee TL314-90-SWC 90 grain bullet, 90 grains, with 6.9 grains of H110."

Is this load actually correct?

[cobullseye]

"Lee TL314-90-SWC 90 grain bullet, 90 grains, with 6.9 grains of H110."

Is this load actually correct?

Yes, I just tried it to see if the .314 bullet would make a big difference.

[Larry Gibson]

Okay, using that bullet in the MN is fine. Using that powder (H110) under that bullet in such a rifle cartridge is not fine. If you want to see if the .314 bullet will shoot then try 3.2 gr of Bullseye. Set the rear sight on 400 and test at 25 yards.

Also, that Lee 170 gr bullet is a .30 caliber bullet and you have a .31 caliber rifle. As already mentioned you should get a .31 caliber mould. You should also size them at .314 and GC them (the .31 caliber bullets).

Are the necks of the fired cases that measure .308 from your loads of from factory or milsurp fired cases?

Do you have any manuals with cast bullet data? Particularly Lyman Cast Bullet Handbooks #3 or #4?

[nvbirdman]

Load a round, then pull and mic the boolit. Is it still .315?

[dale2242]

What Larry said.
If they would chamber, I could send you some bullets that measure .314 and .315.
Larry sent me a number of sized cast bullets of different sizes to get me started with my .314 diameter bore.
Once I found the right diameter I bought molds of the right diameter.
The neck of my M-N is plenty large enough to chamber .314- .315 sized bullets.

[cobullseye]

Load a round, then pull and mic the boolit. Is it still .315?

Bullet measured 0.318", seated it, pulled it, measured 0.314" to 0.316".

does that help?

[Larry Gibson]

Sure does, you've definitely got a .31 caliber rifle. It needs a .31 caliber bullet. The NOE 314299 or the 316299 are suggested.

What is the neck inside diameter of factory or milsurp case (non steel)?

[pworley1]

Did the round you loaded with the .318 bullet chamber in you rifle?

[cobullseye]

question: What is the neck inside diameter of factory or milsurp case (non steel)?

Measured a couple, inside diameter is between 0.307" and 0.309".

[Larry Gibson]

With the .318 bullet seated in your cases do they chamber?

[cobullseye]

With the .318 bullet seated in your cases do they chamber?

yes, have them seated to the crimping groove.

[Larry Gibson]

Appears the NOE 316299 is the cast bullet for that rifle.