Nagant 91/30 troubles

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awelton85 posted this 29 May 2018

I have a rifle that I can't seem to sort out. My Mosin is not liking cast bullets at all. I have always shot cheap jacketed surplus ammo through it with about 2 MOA results with issue sights.

I decided to make up some 312-185-1R Lee bullets because my mold drops a little over .314. I slugged the bore at .3125, and opened a .311 push through sizer to .3135.

I have tried these bullets with IMR 4198 at 1700 fps, which produced barn door sized groups, and a reduced 1300 fps load of red dot, which tightened it up to about a 4 foot group at 75 yards. I have tried ruining the oal everywhere from a mile long to way too short. There is no tumbling or keyholing, it is just slinging them everywhere.

I would like to get some direction here. I have been lucky enough with everything else I cast to come up with a working combination fairly easily. I can think of a million "could be's", but I'd like some help from all the years of experience on this board on the best places to start. I'd hate to spend a paycheck on a bunch of different powders and molds only to find out I could've sized them up .0005 or something and fixed it.

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GP Idaho posted this 29 May 2018

awelton85: I too have a problem child  M/N .  Mine is an Polish carbine.  First off make sure you do a pound cast and get a good throat measurement. ( If it even has one left) disregard slugging the bore measurements and size your bullets to the throat   measurement. Now, here comes the fun part on my old carbine.  Bullets sized to fit in my guns throat won't chamber, The neck area of the chamber will only accept bullets up to .314 and that's with very little room left for bullet release.  My bore/throat needs .316+ so in this case neck turning is needed to get the rounds to chamber. Check and make sure this isn't the problem you're having.  I don't shoot mine much any more. The bore is a sewer pipe anyway so it's hardly worth the effort.  I do like the sturdy if less than pretty old mosins and will be looking to add a better one sometime as I've got moulds and components in excess. Hope you get it sorted out. Gp

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Ken Campbell Iowa posted this 29 May 2018

when trouble shooting my lawnmower or a poor shooting gun ... i start with the most probable source of the bad behavior ..

so ...  usually there are two places to start :: one is getting a tight fit in your chamber  THROAT ...  i like to think that " everything happens in the first inch " after ignition ....  seems if the bullet is guided real well that first inch or so, that it does better than a perfect fit in the barrel ( of course match chambers are created so that the throat and barrel are in agreement. ) .

the 2nd is barrel condition .... but it is very rare that we find a barrel so bad that it doesn't shoot at least under a foot ... some really rough looking barrels shoot under 2 inches ... i won't mention brand names ( g ) ..

the best thing to do is to make a casting or soft lead upset of your chamber especially the neck, throat and a little bit of the rifling ... ...then you can inspect that and determine what you can do to get best guidance for your bullet.  ideally your bullet should look just about like the casting you make !!

also, and what many of us do when frustrated and out of patience with great big groups ::: you can just use as big a bullet diameter as you can get to chamber in the throat .... trial and error, they call it ....  you might find in your case that even the bullet as cast isn't fat enough ....   then we get into either finding a fatter mold, or polishing your mold out a little to get that snug fit.  a 3rd choice is to squish the bullet a little, still another is a crutch method that actually seems to work ... we call it " beagling " ... where you put a thin shim in your mold and cast a fatter but oblong bullet .... but it seems that the throat fit is more important than a perfectly round bullet that doesn't fit.   interesting mystery about our cast shooting.  likely when you shoot the square bullet it is sized into a better shape by the round throat.

just some starting thoughts, and please keep asking here as you go along ... we actually like to solve problems such as yours.... it gives us a chance to see if any of our ideas actually work ... ( g ) .

ken

 

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Ed Harris posted this 29 May 2018

Making a pound cast of the throat is the best approach. 

Russian and Chicom M-Ns I've measured have HUGE throats, some as large as .318"!

My Finn M28/30 and M39 rifles have .314 throats and shoot well with bullets of that diameter, though the barrel groove diameter of the 28/30 is .3095 and the M39 .3125, throat size is what matters and both rifles shot well with NOE clone of #314299 cast of wheelweights+2% tin, sized .314" and loaded with either 16 grs. of #2400, 22 grs. of 4198, 24 grs. of RL7 or 30 grs. of 4895, 4064, RL15 or Varget.  A 1 grain loosely tucked in Dacron filler into the case neck also helps.

 

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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awelton85 posted this 30 May 2018

Thank you all, I believe I have found the culprit. The throat is .315. The chamber is .3380, and my case thickness is .011, so it looks to me like I could beagle a little and size to .316 in a perfect world. I don't think that will work in practice though.

How much do you think I would have to turn the necks to get it to chamber? I'm not sure how much clearance it takes to chamber.

I'm glad I decided to try this rifle. It seems like a good 'worst case scenario' to learn with. Every other gun I've tried has just worked, so there wasn't much learning to be had.

The only thing I like more than shooting is learning. Looks like I'm in the right place for both.

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45 2.1 posted this 30 May 2018

The throat is .315. The chamber is .3380, and my case thickness is .011, so it looks to me like I could beagle a little and size to .316 in a perfect world. I don't think that will work in practice though. How much do you think I would have to turn the necks to get it to chamber?  You will lose cases fast if you turn down under 0.010" wall thickness, try turning enough to lightly clean up the neck (not all the surface will show cut marks and that is OK). Try the larger bullet as you need 0.001" or slightly more total clearance to be safe. Clean that chamber neck and your cartridge necks well and keep them that way if you have that minimum clearance.

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GP Idaho posted this 30 May 2018

It's all in the measurements, each rifle will be different. Cases turned down to .0115 give me .002 clearance when seating bullets that were .316+   Another option to beagling and will still give you a round bullet is to powder coat your bullets. this will give you an approximate .002 gain in diameter. Gp

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onondaga posted this 30 May 2018

Awelton85

I believe you missed the most important basic of bullet fit. Without a stable start in the chamber your bullets are wobbling down the bore and shooting all over the place. Ignore bore dimensions completely. Try your bullet unsized in a dummy load and ink the bullet. One bullet is good for one test chambering/unchambering. Can you chamber a dummy round with an unsized bullet? does the ink show sliding contact on chambering on at least the first exposed driving band. That is the ideal fit when your bullet needs 1-2 pounds more force to close the action with a cast bullet than with a jacketed bullet. This is different  because cast bullets have an ideal fit much different than jacketed bullets.

Shoot the largest size bullet you can chamber and it will have a stable start and not wobble down the bore and shoot all over the place.

You should ignore all measurements and get your bullet to verify a slide fit on chambering. Your bore will size the cast bullet with no difficulty as it is shot. The stable start from that fit is the primary factor in cast bullet accuracy. Use no sizing or the minimal sizing for a verified slide fit.

Less fit than a verified slide fit on chambering a cast load subtracts accuracy potential in a linear fashion and constitutes nearly all accuracy grief with cast bullets. You only have to learn this once and it applies to all cast bullet fit in any caliber and any action. I don't think you have got it yet. You are not alone and your problem is completely fixable.

Gary

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awelton85 posted this 30 May 2018

After much fiddling around I found that the biggest bullet that would chamber without having to get violent with the bolt handle is .314. I powder coated a few to see if I could go a little bigger, but .314 is all it will suffer.

I marked it up and the front driving band doesn't look like it is touching anything, which makes sense due to the throat measuring .315.

I'm going to try .314 with a long COL to see if I can get it on paper. If all else fails I have 4 more still packed in cosmoline. Maybe there is at least one that still has a throat.

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onondaga posted this 30 May 2018

Awelton85

Your throat measuring 315 is insignificant. The exact area where the throat should be contacting the bullet is what gives stability when there is good contact. You may need a .316-.317" or even larger.. Don't let the size spook you. It is the verified fit that matters. cast bullets that fit the chamber are easily sized by the barrel without the pressure spike that jacketed bullets would have.  That is still just the basics.

COL has nothing to do with it either, unless you seat the bullets to a COL that engages the chamber ball seat. I recommend up to .010" cast bullet engagement if that will function and the additional contact of the ogive to the ball seat will enhance a stable start and increase accuracy potential.

You may even need a mold that casts larger for your rifle. I have posted on honing Lee molds and it is easy. I posted on honing the Lee 30-30 170 and 150 gr FNGCs to fit my Remington Spartan 7.62X39.I also had to hone a Lee bullet sizing die for that project of fitting a cast bullet to that rifle. This is normal life with cast bullets...It takes work to get a good fit.

Expect consistent groups under 1" @ fifty yards with H4895 at ~1950-2050 fps when you get your bullets to fit.

Gary

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Larry Gibson posted this 30 May 2018

Alloy?

GC?

Lube?

 

LMG

Concealment is not cover.........

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awelton85 posted this 30 May 2018

Water cooled wheel weights, Hornady copper gas checks, and Lee liquid Alox.

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Ed Harris posted this 30 May 2018

Water cooled wheel weights, Hornady copper gas checks, and Lee liquid Alox.

 

Stop water dropping your wheelweights.  Unnecessary unless you are attempting velocities over 2000 fps.

Air cooled wheelweights + 2% tin should be about 13 BHN and will work fine to 1700-1800 fps.  

73 de KE4SKY In Home Mix We Trust From the Home of Ed's Red in "Almost Heaven" West Virginia

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Larry Gibson posted this 30 May 2018

That combo should work fine. With rifle bullets like the 312-185 I like to dab the tip of my finger in the LLA and apply it to the groove area then stand the bullet on wax paper to let thoroughly dry. That gets sufficient lube where it needs to be.  

Your bullet sizing should do well. I suggest loading them over 28.5 or 29 gr 4895 and use a dacron filler. I have been using that bullet in numerous MNs for almost 40 years and that load has shot well in every MN.

LMG

Concealment is not cover.........

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awelton85 posted this 02 June 2018

OK gentlemen, I have a bit of an update. Progress has been made.

I polished my mold out a little and made some .316 bullets and made a dummy round that wouldn't chamber. I opened my sizing die a little more and sized them down to .3155. I then had good contact with the throat (verified with an ink test) , but couldn't get the bolt to close without a healthy couple slaps. I then turned the necks ever so slightly to take out a few high spots, and everything seems just right.

Tomorrow I will fire up the lathe and make a bigger expander for my sizing die, with a range test to follow.

Thank you for all the help. I feel like I'm 100 miles ahead of where I was three days ago.

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GP Idaho posted this 02 June 2018

Glad to see that it's working out for you. I went through the same steps with my M/N and it was kind of fun making it work. I've got to find a decent example as my 7.62X54R is trashed. I like the beastly old rifles and have a lot of components so if any of you have a decent one for sale PM me.  Gp

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awelton85 posted this 12 June 2018

Success! Now that I have a properly fitting bullet things have tightened up considerably. I didn't have time to set up a target, but everything I loaded was consistently hitting a 2" foam ball at about 70 yds.

Now I need a day off work to go put it on paper.

Thanks to everyone who helped me out. I know a lot more now than I did a few weeks ago.

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Ken Campbell Iowa posted this 12 June 2018

... and thanks to you for keeping at it and reporting your results as you went along ....

somebody said " i love it when a plan comes together " .... it is rewarding to all of we here onlookers when somebody improves their cast bullet performance with suggestions that we think work most of the time ...cool

ken

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awelton85 posted this 18 June 2018

Just wanted to post a group picture as a conclusion for anyone that stumbles upon this thread in the future. This rifle is actually fun to shoot now. https://ibb.co/cYk7hy

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