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Product Review:

Rock Solid’s Mosin Nagant Rifle Products


By R. Ted Jeo




Scope mounts for mil-surps.  They abound a plenty.  There are all types out there.  The type that replaces a rear sight or attach with a set screw; the one that I would like to discuss takes a little bit more work.  Not out of the realm of the average garage-joe though. 


The First Step


Rock-Solid Industries ( picked an appropriate name for their company.  They currently make two mil-surp rifle mounts:  one for the K-31 Swiss and the other for the Mosin Nagant family of rifles.  The one that I am going to talk about is the Mosin family mount.



The mount comes with all the hardware needed for installation.


First off all, this is not a slap it on type of mount.  Consequently, you can read between the lines and see the letters “D” and “T” standing for DRILL and TAP.  Yes, fellow shooters, this is a mount that will put holes into your Mosin rifle.  Is this an issue?  For the vast majority of us, no.  We have rifles that are “near worthless” in terms of collector value.  The Ruskies made these rifles like their lives depended on it (hmmm…their lives DID depend on them…), and millions are out there.  This is not to mean that there are NOT valuable collector’s editions out there.  That is up to YOU to decide what you have.   



Hand tap will be needed for this project. Nothing fancy, but go SLOW and used your cutting oil.  You will need a 16-32 drill and tap to get the project done.


In my case, I actually had a M38 MN carbine given to me, sans stock.  One cannot do all that much with a stockless action.  This M38 has a round receiver type, and was in a typical mil-surp condition of scratches and metal wear.  In any case, this was the donor action, so it would suffice.


Now, I do not hunt.  That being said, I do help many, many local hunters prior to them going out into the “wilderness” to rid the countryside of those pesky white tailed critters.  I help them during my two shooting club’s sight in days.  I see all types of hunters and their chosen tools for hunting.  Everybody from the first time “which-end-is-up” types to the “leave me alone I’ve been doing this for decades BEFORE you were ever born” types.  It’s in my nature to wander the firing line, looking at the gun and ammo combos (making sure they are the correct match) and making small talk in between issuing commands as the range officer. 


And I get to see them all.  Shotguns, rifles, scoped pistols.  Long, medium, and short.  All sorts of calibers.  So, it was only a matter of time that I started to wander the fringes of the dark-side and contemplate combining the types of guns that I have with the sport that they do.  I continued my wandering of the lines and figured that a short rifle, with the power to take a deer easily would be the project for me to look at.  So the goal was to do this as easily as possible, with the idea that the project must be simple enough that no MAJOR special tools would be needed and the average person could put it together with adequate deer killing success.  So anyway, back to our topic.


Rock-Solid claims in their literature that it is the “..only system that will deliver maximum accuracy and speed for the Mosin Nagant rifle”.   Some big shoes to fill.  If you go to their web site, you will see some pretty incredible results shown.  After having done the project, well, compared to what I’ve seen in other products that want to do the same thing, I’d have to say that theirs does certainly have the best potential of delivering exactly what they claim.  They use a big hunk of metal, and, what is different, are the three screws to hold it to the rifle’s receiver.  Other’s that I have seen only use 2 screws, or (and I’ve used these) use just the replacement of the rear sight.    Don’t get me wrong, there are those of you out there that say, “nope, no D&T for me”.  In that case, this mount is not for you.  But I seriously doubt you will get as solid as a set up with anything else.   The mount is also designed to keep as low a scope profile as possible to the rifle as well.



The big difference with Rock Solid’s mount is the third hole on the side.  That very effectively holds the mount in place.


Rock-Solid sells mounts designed for either the round or the hex receivers of the MN rifles.  Obviously, you will have to get the one that fits yours.  Mine is a round receiver.  Before we go further, I will have to say that you WILL have to also replace the bolt handle of the original bolt.  The original straight bolt will not work with these scope mounts, and, besides, once you use a bent bolt, you will be surprised how well the action works.  There are sources for bent bolts and even DIY kits to convert the bolt handles, but, of course, Rock-Solid offers a “rock solid” modified bolt.  More on this later.


So let’s take a look at the mount.  Weighing in at 5.3 ounces, it is, repeat, a solid chuck on aluminum.  Along its top are cross slots similar to those found the 1913 Picatinny or Weaver  rail system to mount your scope rings to. Their claim to fame is that it uses three screws.  Two on top and one on the side.  Being that the Mosin action has a split rear, well, the side mounted hole makes sense.  It makes the final lock so that there is no flex of the mount and no movement from recoil.



A solid piece of metal, the Rock Solid mount weighs in at just over 5 oz.


Installation is, well, as simple as it COULD be.  I will not lie to you.  It takes some time.  The one item that you will need that I think is a MUST is a small drill press.  Nothing fancy.  One of the $60 jobs from your local mega hardware store will do the job easy enough.  The reason is that you need holes to be square and the metal you are drilling into is both thick and hard.  You will want to use a slower speed with cutting oil to make the job easy.  And, as the adage goes, MEASURE OFTEN AND DRILL ONCE.


The instructions that came with the mount are pretty straightforward and even have some photos.  I found that the easiest way to drill and tap the action was to follow the guidance and methodology of the article written by Jamie on mounting a different D&T mount to a Mosin rifle.  Rather than rehash exactly the same method here please refer to his article at: .  In that article, he is able to square up the mount to the receiver by using his calipers and  “…opening the jaws so that I could place the lower jaw on the square part of the bottom of the receiver and the top jaw on the top of the scope mount.”.  I used the same method and it worked fine.  The idea is to make the mount square so that the scope rides atop the rifle square.  Whereas, if you are a bit off, well, I suppose it would work, you would adjust windage accordingly, but it won’t look as nice.


One item to keep an eye out for as you do your measuring is to make sure that you do not actually drill into the CHAMBER of the rifle.  That would be a serious mistake.  The good thing (and bad thing we’ll get to in a moment) with the Mosin rifles is that the chamber sits way forward in the action.  So, the good thing is that it leaves a big area of metal of mount such things as scopes to it.  The bad thing is that it makes it difficult to figure out exactly where the chamber actually starts.  Before I did anything, I used a wood dowel to get an idea where the chamber was.  I slid a fired case into the chamber and then slid the dowel in along the top edge of the action until it stopped and then marked it with a pencil.  Using that mark, I was able to get a good feel where I should NOT drill.



Before you start to drill, make sure that you know where the chamber actually starts.  (this photo, obviously, was taken post project completion)



Knowing where your chamber starts will make sure that you don’t mess up your project by drilling into the actual chamber.


One thing that I noticed was that I perhaps COULD have lined up the front of the mount with the front “lip” of the receiver, before the barrel starts.  I was not exactly comfortable with the minute tolerances where the chamber started, so I backed out just a bit and therefore the mount does not line up exactly.  However, that was more of a “be safe than sorry” attitude on my part. 



It MAY be possible to just line up the front of the mount with the lip of the front of the receiver, but I decided to err on the side of caution and back it off a bit so that I would stay a bit away from the actual chamber.


As you probably noted, I was using the round receiver mount.  They also, as mentioned before, make a hex mount.  I cannot tell you for sure, that I would SUSPECT that the hex mount may be easier to line up and install.  The round mount is harder to make sure it is lined up perfectly with the center line of the barrel/receiver.  That was probably the hardest thing to measure and figure out.  I ended up doing a lot of marking and measuring using the sight line between the rear and front sight.  To make life easier once I had figured the best location of the center line, I placed a witness mark on the barrel.  Then I found the center of the mount (easier as it has a flat front) and marked it as well.  At that point it was a matter of keeping the two marks on line to make sure the mount was as nearly in line as possible.


When you drill, as per Jamie’s method, you will be drilling such that the mount acts a guide.  Rock Solid instructions recommend that you do the front hole first and then do sight alignments so that you know your mount is still in line with the barrel.  This is a good idea.  WORK SLOWLY.  You should, at this point, use the drill press to make sure that the holes will be vertically straight.  You can use Jamie’s method of using a small drill to make a pilot hole; I went right to the point and used a center punch to mark the center.  You will need to do one of the two methods; otherwise you will risk having your drill bit wander around the smooth, hard, round surface of the receiver.  Remember, MEASURE OFTEN AND DRILL ONCE!  Set the drill to a slow speed and work carefully with cutting oil.  Do not drill so fast that you cause an excessive amount of burrs on the inside of the hole. 


The one thing that I learned on this project is that haste makes waste (or more appropriately, a MESS).  I had drilled the front hole first, that went really well.  I was CRUSIN’ you know the feeling.  I whipped out the tap and put on the cutting oil and proceeded to cut the threads.  Yeah, right.  Let me warn you right now, the metal is hard and thick.  I was going along pretty well and then I hit the tight spot, the spot where the maximum number of thread cutting surfaces were engaged.  Instead of slowing down and backing out, nope, old hair brain here had to CRANK down on the tap.  Now, a bit of knowledge of taps would be good.  In order for the tap to cut, it has to be made of a very hard metal.  A very hard metal, especially one so thin/small, is very BRITTLE.  Put those two factors together with too much elbow grease and CRACK, you have a broken tap in an uncompleted hole.  You can’t screw it out and you can’t screw it in.  After trying all sorts of hair brained ideas, I was informed the only way to get it out was to knock it out, effectively just pound it right through the hole, which I did.  And, after replacing the tap, I wisely completed that and the rest of the holes working SLOWLY and CAREFULLY (hint hint hint).



Notice the top of the receiver is “scarred”.  That would be because of the idiot that broke the tap off in the first hole and had to knock the broken piece out.  (NOTE:  this is a post project photo, that is why there is no cutting oil present)


There are three screws that hold the mount to the rifle and they come as one length.  In other words, you will have to measure and cut the screws to a finished size.  I found that I ended up with screws of three different sizes, the longest is the front hole, and the shortest is the rear third screw.  The screws will need to be cut to a length that does not hinder the operation of the bolt or chambering of the round.  I ended up using my caliber to determine the hole depth and then a cutting disk on a Dremel tool to finish the job.  You should be able to run your finger into the action and not feel any part of the screw sticking through.



The three screws that hold the mount to the rifle will need to be cut by a Dremel cutting disk.


When you assemble the mount onto the rifle, it is a good idea to use some screw locking material (i.e., Locktite) to hold everything together.  Once mounted, I found the device to be solid and stable.  I placed a ubiquitous 3-9 x 40 Simmons scope with Millett Angle-Loc medium height scope rings atop the mount to complete this phase.


The Next Step


You may use the original rifle stock, but you will, absolutely have to replace the original bolt.  The original bolt, of course, is a straight handled short affair.  Because of the scope being over the center line, this bolt will knock your scope.  There are alternatives out there, one of which requires you to cut and grind off the bolt handle and then use a screw and tap to attach an angled bolt handle. 



Like their scope mount, I found the replacement bent bolt body made by Rock Solid to be, well, rock solid!  The long body and angle of the handle actually makes for very fast cycling times.  And smooth as well.


Another alternative, and, in my opinion, a stronger more useful alternative is to go with the Rock Solid Bolt body with bent handle.  This is a “drop in” replacement for your original straight handle bolt body.  It is solidly TIG welded to a bolt body and angled toward the trigger for faster cycling.  It also is made so that it maintains a very low profile.  To replace your bolt with the replacement bolt body, follow the directions on the website on how to take apart your Mosin Nagant rifle bolt.  See:


By the way, if you happen to have access to welding equipment, you can also order just the bent bolt and do the job yourself.  If you use any stock, other than the ATI replacement which we will discuss shortly, you will need to inlet the stock to work with the Rock Solid bent bolt.



Wrapping it Up


Along with the mount, Rock Solid provided me with a two other (optional) items that they sell to help stabilize and accurize your Mosin Nagant.   First we’ll look at some replacement action screws.  Unlike the screws that are standard slot head type on the rifle, the Rock Solid screws are made of hard 4140 alloy steel with hex heads.  This allows for tightening up with less of a danger of stripping the screw head.  They send one of the short and one of the long types.



The 4140 steel alloy hex head screws will tighten up your action nicely with less of a fear of stripping the head.


The second item that Rock Solid sent was their aluminum bedding pillars.  Bedding pillars are used by many modern firearm makers to help strengthen and accurizing their rifles, especially those that are sold with composite type stocks.  In my case, I had to drill out the existing holes in the ATI replacement stock that I was going to install the action into.  The front pillar hole was little of an issue.  The rear one had to be drilled at an angle to match the existing hole in the stock.  These pillars could also be used in wood stocks. The pillars basically will allow the tightening of the action screws without compressing the stock, no matter what the stock is made of.  The strength of the aluminum will also take up the recoil of the rifle better as well compared to stock material. 



Photo of the front aluminum pillar installed into the ATI replacement stock.



The rear pillar is installed into a slightly angled hole. 





Some Final Thoughts


The final package, with all the options installed topped the scale at about 9 lbs 6 oz.  The overall length of the rifle turns out to be 39 ¾”.  The rifle makes for a very nice full powered little carbine, quite useful for trudging through the tullies.  And let me tell you it does pack a full powered wallop! 


Before heading to the final portion of the article, I would like to mention that there are still a handful of additional accurizing procedures that could be used on the rifle.  First off, as Rock Solid points out, if you find voids between the mount and the receiver, you could use something like Accra-Glass to make sure of 100% contact between the two.  Secondary, of course, one could action bed the rifle also using Accra-Glass.  I checked the mount to receiver layout and did not find any discernable voids between the two.  I did not want to bed the action because I wanted to see what the set up could do on its own.  As it was, the ATI stock did allow the barrel to be free floating, as I could slide a dollar bill along the length of the barrel.



Total weight for the entire package was 9 lbs. 5.6 oz.



Range Time!


It actually took me a LONG time to complete this project.  No, it was not all that hard, but I had issues of getting the space to do the project.  It was at first too cold in the garage to work in the winter, followed by the fact that the wooden replacement flooring project for the basement required a higher “honey do” rating then a gun thing.  I was elated to finally get to the range to test out the rifle.


Range shot

Not a bad looking combination, but it did not like mil-surp ammo at all!


I figured that I would test the rifle first using standard ball ammo (cheap and plentiful) and then follow up with ammo that would be more along the types that hunter types would be using.  Imagine my surprise and dismay that I could not get any sort of grouping with the ball ammo I wanted to zero with.  I was looking for any possible culprit, loose screws, bad scope, anything to make it not so.  I nearly gave up, but instead decided to risk a few shots with the hunting ammo.  Whew. What a relief that was.  Turns out that the 7.62x54R surplus ammo that I was using (Albanian) was not good for ANY of my Mosins.  It basically puts a shotgun pattern on a target.  In any case, with any of the ammo mentioned, the full powered heavy bulleted ammo packs a hefty recoil and muzzle blast.


I was relieved to see that the Rock Solid project gun did perfectly fine for minute-of-whitetail type hunting.  Using either of the quality (Bear or Wolf) ammo, I easily shot about 1 ½” three shot groups.  The Wolf shot a tad higher and to the left of where the Bear ammo shot, but both were quite easily in a kill zone at 100 yards. 



Silver Bear ammo is Berdan primed and comes in a nickel plated brass case.  It is topped with a 203 grain spire point type bullet running at about 2330 fps.


Silver Bear ammo is made in Russia by the JSC Barnaul Machine-Tool Plant who makes ammo for the Russian military.  The ammo features distinctive highly polished zinc plating on the cartridge case; hence the “Silver” Bear name.  This plating is supposed to make the case operate smoothly in rifle actions.  This ammo is Berdan primed and sealed.



The Wolf Gold ammo is a premium brass boxer primed cased ammo topped with a spire point (exposed lead) 280 grain bullet that is listed at a 2640 fps velocity.



The two commercial lines of ammo that I found in the local area that had rounds topped with hunting useful bullets differed slightly in results, but cost wise, the Wolf was nearly twice the cost of Silver Bear.



Final Thoughts?


My final thoughts show perhaps the one downfall of the Mosin as a sporter rifle.  It does not have to do with anything that we changed during this project but rather it has to do with the design of the Mosin rifle action.  This is a LONG action receiver.  The large replacement handle that Rock Solid makes that make cycling the long action a heck of a lot easier than the stubby original straight handle.



To do or not to do?  If you do, Rock Solid makes some solid products to help you do it right.



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