Tula TOZ-99 bolt handle (Russian 22lr)

[ThePenguinKnight]

I have a Russian Tula TOZ-99 semi-auto 22lr. It was not very expensive, and some of the machine work is quite rough, but it shoots very well and is a lot of fun.

The only problem I've ever had with it is with the bolt handle. The original broke after a few thousand rounds. The importer sent me a replacement, which broke after a few hundred rounds. I then consulted my local gunsmith, who machined a pair of replacements bolt handles. Being a little apprehensive about it, I rarely shot the rifle after that, but even so both the replacements broke with extremely low round counts-- the only reason I didn't take it back to him is that it took over a year before I shot the gun enough to break the second of his bolt handles (despite only shooting a couple hundred rounds).

Before I continue, please take a look at the pictures below to understand how the breaks are occurring. All four bolt handles broke in exactly the same way.

The bolt is cut with a T shaped slot, into which the end of the bolt handle sits. The walls of the receiver hold the bolt in place during normal operation. The front leg of the bolt handle is the one which always breaks. See the following pics for an abbreviated sequence of field stripping:









The bolt handle in the bottom pic is facing the wrong way. The broken leg of the T is actually from the front.

I want a more permanent solution. The importer is long out of stock of replacement parts, and I don't want to pay for another bolt handle to be made that will likely just break again.

My first thought is to drill and tap for a bolt, but I'm afraid we don't have enough material forward or aft of the T cut in the bolt.

My second thought is to fill in the T cut, then drill and tap directly into the filled-in area. However, I do not have the experience or equipment to weld the bolt, or to weld a nut into the bolt.

Is there a third option? Is there an alternative material or process to welding to fill the T cut, which would be strong enough to drill and tap?

Oh, one last question is whether the bolt is thick enough there to drill and tap anyway. The T cut is only .157 inches deep, and just past that depth is the thin wall of the firing pin channel. That is not much material to work with. The following picture shows my caliper measurement:



Maybe I'm out of luck, but I figured I'd ask. Any ideas? Thanks.

 

[WardenWolf]

I believe you're first asking the wrong question. What you should be asking is, "Why is it breaking in the first place?" The most obvious answer, to me at least, is that it is impacting the rear of the receiver slot. There are a number of potential solutions for this problem, including recoil buffers, shims, and stronger springs. If done properly, they will likely ensure any replacement bolt handle does not break.

The material the handle is made from is also important. Hardened tool steel will suffer much less wear and metal fatigue than normal materials. Using that for the replacement may not be practical, but it WOULD help.

However, simply performing the first fix should be enough to keep your rifle running indefinitely.

 

[rcmodel]

From what I can see, it is just a very poor design.

That much mass hanging off the little lips that hold it on is more inertia then most materials could stand.

The trick, if there is one, is to make a new one with less mass hanging out in the air slamming and banging each shot.

Tool steel, with no sharp corners (stress risers where cracks always start), then annealed & tempered to medium hardness.

Then drill it out hollow as thin as practical to reduce reciprocating mass / inertia trying to break it off every time you pull the trigger.

Bottom line?
Make it lighter, out of good steel, with no sharp angles.
And it shouldn't fatigue & break nearly as easily.

PS: WardenWolf noticed something that I failed to notice.
If the handle is impacting the rear of the receiver slot each shot, there is no stopping it from breaking.

Check for a shiny wear spot at the rear of the slot to see if it is hitting it.

rc

 

[WardenWolf]

A recoil buffer would also help reduce stress even if the bolt handle itself does not strike the receiver, as it would soften any impact. As long as you enjoy the rifle, and the cost of fixing it is not exorbitant, you may as well get it done properly. I believe it CAN be fixed so it will never happen again, and shouldn't be too hard.

 

[ThePenguinKnight]

I should have spoken a bit more to the why in my original post. I felt I was already being wordy. Sorry for that.

It is not possible for the bolt handle to hit the receiver during normal operation. I can include the pics to prove it if someone wants to see them, but when assembled the bolt is stopped by the bolt retention plug when the handle is a good 3/8" in front of the end of the receiver cut.

I agree, it's not the greatest design in the world. But I'd rather not throw away the rifle until it at least becomes truly unusable. I know this one can be salvaged, so I will explore some options.

The bolt handle you see in the picture is the one that the smith made me. It is quite a bit larger and somewhat heavier than the original design. My though was also that the inertia of the handle is too much for that little tab of steel, especially if it is not tool steel. As much as I'd like to learn, I am not a machinist and don't have access to the tools, so I'm looking for alternatives. Unless someone knows of a machinist they could recommend close to the St. Louis area.

I've considered using a buffer, but I don't think it would solve this inertia-induced problem. RCModel's suggestion of a lightened bolt handle is the solution I would really prefer to go with, but I'm at a loss where to even begin asking for that. I guess I could go back to that gunsmith I used last time and ask him to use harder steel and make it smaller and lighter....

The only other problem is that the lips of the T cut in the bolt are already peened over a little from the bolt handles that have been bouncing around in it. I'm wondering if it would eventually become unusable, even if I did find a bolt handle that wouldn't break under its own inertia. A threaded bolt handle wouldn't have that problem, which is why I asked.

Thanks for the input. Any other comments?

 

[WardenWolf]

The buffer would still help a lot because you'd be reducing the hard stop at the back end. There'd be less of a forceful whip when it impacts.

I'm not sure how this bolt works, exactly. Does the handle play any mechanical role, or does it simply move the bolt? If it doesn't play a mechanical role, then you want the fit to be as tight as possible to eliminate movement. If there's enough meat on the bolt, you could also increase the width of the attachment point or pin it. Pinning it should allow you to still remove it at a later point, although it would require removing the receiver from the stock.

If you manage to get a buffer, better steel, and pin it in place so it won't move, it should last more or less forever. If removing the bolt isn't a concern, I'd have the replacement soldered or welded in place, rendering the bolt one solid piece.

 

[SDC]

Right angles of all sorts are "shock traps", which make things more likely to break at that bend; to reduce the amount of stress on this part, I would probably drill and tap a hole all the way through the centre of the bolt handle, with a little divot in the middle of the raceway it sits in, so you can anchor it in position with a long set-screw and allen wrench.

 

[natman]

Lightening the handle might help the breakage problem, but reciprocating mass is an important design element in a blow back semiauto, so any mass you take away from the handle should be added somewhere else on the bolt.

 

[rcmodel]

The OP said:

The bolt handle you see in the picture is the one that the smith made me. It is quite a bit larger and somewhat heavier than the original design

On top of that the Russian gun designer didn't take all that into account in the first place or the original bolt handle wouldn't have snapped off.

Myself?
It needs to be lighter, and made of suitable steel.

I also like SDC's post #7.

Drill through it and screw it to the bolt with a socket head machine screw so there is no slopping around in the bolt slot.

rc

 

[ThePenguinKnight]

The buffer would still help a lot because you'd be reducing the hard stop at the back end. There'd be less of a forceful whip when it impacts.

I'm not sure how this bolt works, exactly. Does the handle play any mechanical role, or does it simply move the bolt? If it doesn't play a mechanical role, then you want the fit to be as tight as possible to eliminate movement. If there's enough meat on the bolt, you could also increase the width of the attachment point or pin it. Pinning it should allow you to still remove it at a later point, although it would require removing the receiver from the stock.

If you manage to get a buffer, better steel, and pin it in place so it won't move, it should last more or less forever. If removing the bolt isn't a concern, I'd have the replacement soldered or welded in place, rendering the bolt one solid piece.

I may add a buffer at some point, but I seriously doubt having one will significantly affect the leverage + inertia problem of the mass hanging off that little T of metal. Pinning it in place is very impractical, as the base of the handle (and the bolt for that matter) is internal to the receiver when the handle is installed, and there is no way to install a pin. Removing the bolt is not critical, I suppose, but it is very difficult to clean the gun thoroughly with the bolt in place, so permanently attaching the charging handle in place is not an attractive option.

The design is fairly simple. The bolt is a machined metal mass that reciprocates inside the receiver, driven back under the force of the fired cartridge and returned via a couple springs. The firing pin/striker rides in a channel inside the bolt and is powered by its own spring. The bolt handle is along for the ride and only serves to make it easy to retract the bolt.

I have detailed pictures of the entire rifle and its internals, including the operation and field strip processes, if anyone wants to see them.

On top of that the Russian gun designer didn't take all that into account in the first place or the original bolt handle wouldn't have snapped off.

Myself?
It needs to be lighter, and made of suitable steel.

I also like SDC's post #7.

Drill through it and screw it to the bolt with a socket head machine screw so there is no slopping around in the bolt slot.

rc

I like this plan. The set screw would have to be VERY small to fit, and drilling a tiny hole in a tiny part for a tiny screw without screwing it up sounds like a challenge. But if it could be done, this might be the way to do it.

I will have to find and make friends with a machinist. But in the mean time, I'll go talk to that gunsmith again-- maybe I can convince him to have another go at it. It's a bit of a drive, but he's a friendly guy.

 

[BoltLover]

If you just replace the firing pin spring with a stiffer one it will solve this problem... Your striking the rear of the receiver on every shot.. Do this and have another bolt handle made... You'll be a happy camper.. Do not drill or tap into your bolt unless your an excellent machinist.