And which specific models would that be?

Your top covers look pretty cool and they seem to be well accepted.

You guys should think about putting together a mounting system that enables folks to mount just the top cover and use regular lower hand guards.

I don't like too many rails on my guns, so if I could mount just the top cover, I could use a regular poly or wood lower hand guard.

I'd definitely purchase the top covers for the AKs I own.

Sounds good.  I just started shooting my AKs regularly, so I can't wait to see what you bring out.

I attempted to make contact through your website (phone & mail) and have gotten no response.  My question is does this or other hand guards (rail) offered by MI fit my NHM-91?

Thanks for your response, I had called and got no answer so I used your contact form about 3 weeks ago, give or take, without any response.  Anyway the gun is a Norinco NHM-91 and my barrel is .668 diameter.  It is a long heavy barrell like an RPK style.  I like your railed hand guards and especially like that they are american made.  I just want to make sure Im not buying something that doesnt fit.  Thanks again.

Last weekend I had a problem with my MI universal handguard with an Aimpoint T1 micro red dot sight and upper handguard: it suddenly shook loose after about 100 to 120 rounds of rapid fire. The handguard and Aimpoint had been installed a couple of months prior and probably had 500 to 600 rounds through it prior to coming loose. I disassembled the handguard and found some greasy loctite residue on the inside of the handguard and some around the screws (this was the loctite supplied with the handguard kit).

Although the screws were held fast by the loctite, they had obviously backed out since they had been installed, which caused the whole handguard to shake loose (i.e. the 4 screws holding the barrel clamp. Also, the screws holding the Aimpoint on the top cover were a couple of turns loose from when they had been installed. The instructions made no mention of using locktite on these mounting screws, so I am wondering if I should use any (hopefully better) loctite to secure the Aimpoint to the top cover. I am assuming the loctite supplied with the kit was no good, as I followed the installation instructions to the T. It appears to me that the locktite simply melted under rapid fire and allowed the screws to back out, then after the rifle cooled, the loctite held fast again, but the handguard itself had shaken loose (throwing the Aimpoint sight way off).

Getting ready to reimstall the handguard & Aimpoint on the rifle: the original barrel mount screws are too crudded up with loctite to reuse, so got some new (longer) stainless steel ones at Home Depot. However, I am wondering if I should use lock washers for this, and/or stronger or different grade loctite. However, I don't want such strong loctite that I can never get the handguard off again.

Also, it would be helpful to have torque specs (i.e. for the four barrel clamp screws).

Any help would be appreciated.

Use Rocksett on the handguard screws and never worry about it again.




 
 

What should the barrel mount screws be torqued to?

Also, should Locktite be used on the screws securing the sight to the upper handguard?

This Rocksett has some really impressive temperature specs (-350 to +2,150 F) but I'd be afraid I'd never get it off again without a lot of hassle or ruining the threads on the barrel mount. Is that medium or high strength?

I think what I'm going to do is use some industrial grade Loctite 2422 blue, which is medium strength, but good to up to 650*F. Regular Loctite 242 blue (which I assume is similar to what MI supplies with their kits) is only good to 300*F, which seems kind of low to use on a rifle barrel. Only problem is you normally have to order 2422 from an industrial supply house –– you can't just walk into Auto Zone for it, like the run of the mill 242.

Thanks!

I guess oil contamination is possible, although I didn't notice any and surely would have done something about it if I had noticed any oil –– it was a brand new kit that I just took out of the plastic package and installed per the instructions, with the supplied tube of blue thread locker. I suspect the threadlocker was bad, as loctite has a shelf life of 2 years, but for whatever reason it failed under rapid semi auto fire, I assume because it couldn't handle the heat.

I'm going to try it again with new stainless steel screws and Loctite blue high temp 2422 PLUS lockwashers for good measure, torqued to 40 in. lbs.  

It's only slightly stronger than the blue Loctite and nowhere near the strength of the red.  Ignorance of the product is what often causes people to be afraid of it.





 

I assume the blue liquid threadlocker supplied with the MI kit is Loctite 242 or something similar, is that right?

According to the Loctite website, the 242 has a breakloose torque of 70 to 150 lb.in. when fully cured and is good to 300*F, which seems kind of low to me, only about half again as hot as boiling water. Loctite 2422 (which I understand is a paste) has a breakloose  torque rating of 102 lb.in. but is good up to 650*F. So both 242 and 2422 have comparable breakloose strength (both are designed to be removed with hand tools). However, the 2422 has a much higher temp rating. Seems I read somewhere that cookoff temperature for cartridges @ 600*F so hopefully the 2422 should have more than enough heat resistance to stand up to semi auto rapid fire.

Of course, all my guns are first and foremost SHTF shooters, so the last thing I want is to have a sight mount work loose in the middle of dealing with a pack of looters, etc. So, for me the primary concern is making sure the handguard/sight holds when shooting rapid fire, when it counts, removing it later is secondary. If the 2422 gets stubborn, apparently it can be heated to remove with hand tools.

Interesting stuff, this Rocksett. Unfortunately, there's not a whole lot of info on it (i.e.: the breakloose torque, etc.). Apparently, Flexbar is the manufacturer, but they don't give all the info useful for the MI barrel mount application, which I assume is going to need a happy balance of vibration and temperature resistence:

"Cured Properties of Rocksett
Tensile Strength  1.5 N/mm2 or MPa (230 psi)
Shear strength 3.0 N/mm2 or MPa (460 psi)
Temperature Range -180 + 1100°c
Gap filling  >.15mm
Electrical insulation  up to 20 radio MHz"


Unfortunately, tensile and shear strength don't really compute with breakloose torque, so it's difficult to compare with Loctite or Permatex threadlockers in that respect.

Searching the web, I see bits of anectdotal info. According to some, it has a breakloose torque something less than Loctite blue, others say it's impossible to get off unless you soak or boil the parts in water (supposedly is water soluble). Apparently, people use it to threadlock muzzle devices...

It would be good to know what temperature to expect for an AK barrel fired sustained rapid (or full auto) fire, but there's not much info on that. The only thing I could find was a wikipedia temperature of 400*C (@ 750*F) for a 1914 Hotchkiss machine gun fired for a thousand rounds at 120 rounds per minute ("The barrel could attain a temperature of about 400 °C, at which temperature it would be dark red in color. At this point the barrel dissipated heat as fast as it was generated. This only occurred after long continuous firing in a combat emergency situation.") Well, I doubt I could get my semi auto AK THAT hot before I went bankrupt!

Troy -  As a manufacturer with a certain amount of liability when it comes to recommending thread lockers, I completely understand your position on the matter.  But....I have been using Rocksett at both a personal (at home) and professional (at work) level for quite some time.  In my experience, Rocksett's holding strength is quite modest, I have had the opportunity to disassemble numerous assemblies that had been previously assembled with Rocksett and have never had to doing anything other than use the proper tool that the fastener requires.  Rocksett's claim to fame is not it's strength (as mentioned I find it to be quite modest in that regard), but it's ability to continue holding at temps that far exceed what other thread lockers are capable of enduring.  I do not claim to be an expert on this subject, but my experience is considerable.  I do not have a dog in this fight, as the manufacturer it's your prerogative to recommend whatever you desire and as a consumer it's Meataxe556's prerogative to use whatever he wishes.  I do not wish to labor this issue and will not comment further on this, but I did feel the need to clear the air on this from my perspective.
 

???

http://www.youtube.com/watch?v=PXZn3iC7JtE

http://www.ar15.com/forums/t_4_64/141672_MI_rail_coming_loose_.html

http://www.ar15.com/forums/t_4_64/141496_Anybody_else_s_MI_universal_handguard_shake_loose_.html

Anyway, the absolute worst outcome would be for this thing to shake loose again when the SHTF. Even a small amount of play has enormous effect on POI if you're using a sight on top of this handguard.

I'm assuming the loctite I got with the kit was bad (it has a shelf life) or it otherwise won't stand up to rapid fire for whatever reason. If the handguard was contaminated with oil, it wasn't obvious when I put it together, but if it was contaminated it must have gotten that way before I opened the plastic packaging because I sure as heck didn't put oil on it myself.

So I'm going to try it again, this time with fresh Loctite 2422 which has comparable breakloose strength to run of the mill Loctite 242 and blue Permatex –– but has more than twice the heat resistance. I'm going to tighten the screws to your specified torque specs of 40 lb.in. (that would actually be a useful bit of information to add to your instructions). Then I'm going to run it through the ringer on rapid fire and see if it holds up.

And don't worry, if this thing shakes loose again, or in the unlikely event that I have to destroy it in order to disassemble it at some point in the future, I absolutely will not be calling you for parts.
.

I think the big problem here is that people are not cleaning the oil off of their screws before applying the locktite.

Oh yeah, you don't want to overthink tightening a screw until AFTER you've stripped the aluminum threads on the barrel mount or when the handguard & red dot sight shakes loose while you're shooting at a bad guy.

Well, hopefully your sight will stay in place when the SHTF.

Now that we've established what the torque specs are (40 lb.in.) and that the MI parts should be degreased out of the box by the purchaser –– and probably that the threadlocker should be verified to be fresh, hopefully this thread will spare somebody the aggravation I went through, or worse.

Also I would offer MI some constructive criticism that they include this info in their instructions, and in general, make their instructions clearer. For example, reading MI's instructions, if you didn't know any better, you'd think the threadlocker goes on after assembly –– which can be done with certain types of (green) threadlocker, but not what is supplied with the kit.

Hopefully, MI has taken this as constructive criticism, which they seem to have by and large –– unlike the DSA rep who recently committed brand suicide by getting into a pissing match over (legitimate) quality control issues on the FAL Files. That was an object lesson on how NOT to respond.

Does this work with the bushnell trs25? Co witness?

Troy, do you have any plans to create a top cover that extends even with the extended lower rail?

Awesome, thanks. I'm going to order the extended rail for my WASR during the Black Friday deals all over.