Here you go first one I found on ebay

Snap On Torqueometer

I have a few of this type for gun stuff and automotive stuff

I've taken some apart.  Recalibrating old ones.   One just like the photo on page 1.

Torque is a crude estimate in fastener tension. More accurate methods are snug plus some degree of turning.  This is the basis for the torque to yield as it results in more uniform tension on a properly designed joint.  Other methods are a bit more difficult to do, like heating the bolts, then snugging the fasteners down.  Or hydraulic stretching of the bolts, then snugging them down.  There is an entire industry for this application and I work with these service providers.

I just got off the phone with Gene Swanson at LMT.  I told him of the situation, and he initially wanted me to send the entire upper in for repair ... I told him this was probably unnecessary, as the bolt broke cleanly in half and both pieces had been removed, and the threads were undamaged.

He then said he would send me 2 extra bolts in case I somehow managed to snap the next one, and that if they didn't work I should send it in for repair.

He asked about what my washer setup was ... apparently they switched from using 2 washers, to one washer, or perhaps the other way around, but when I look at my MRP I don't see ANY washers ... so I dunno what the heck.  Either way, he's sending a washer or two along with the bolts, he said it's a stainless washer, while some of them are black.

Either way, the ball is now rolling and we will see if the replacement bolts/washers do the trick ... now I just need to find a quality torque small torque wrench.

The washers are very small and thin.
I have almost lost mine several times.
Both of mine came with one washer per screw.

If possible, I would still like to know if this is happening with any of the gas operated MRP's. There are quite a few out in the field now and I have not seen this situation before. There has to be some people on this board that have been changing barrels routinely?

Hmmm, mine has no washers either.  Guess I'll email LMT.

Big deal... you have a buffer, right?

huh +2

huh +3?

I snapped one last night the same way. I emailed them today so hopefully they can get me bolts soon. Also the crap torque wrench is still in one piece, my knuckles aren't though. Glad to hear they took care of it for you.

Hmmmm... So you just didn't feel the 140 in/lb breaking point and kept torquing, or the breaking point never came, or the screw just broke or what?

Can you also check to see if your torque wrench is still set at 140 in/lb?

The supplied torque wrench "breaks" sometimes at 140 inlbs, and other times it does not... it has turned out to be extremely unreliable.  I'm sure LMT is reading this... so... Craftsman torque wrench... $79 at Sears... look into it.  I realize it is twice as expensive as the one you supply, but I didn't buy LMT to save money.
Matt

I think you guys are overestimating how much 140 in/lbs is and are missing the "click" it is very faint at 140 in/lbs and easy to miss. !40 in/lbs is easily genereated with your wrist alone. If ypou lost control of the wrench when the bolt snapped I get the feeling you were putting waaaaaaaaaaaay yoo much torque into it. If you aren't experienced with various torques and such, it's an easy mistake to make. I think LMT would have been better served by just including a plain, short, L-shaped Torx wrench and tell people not to use any extensions. It's too easy to generate 30 foot/lbs w/ a torque wrench of that size.

Nope, didn't feel anything. You are probably right though about the over estimating the 140 in/lbs. But either way I should have felt some kinda of give besides the bolt snapping. I've used the wrench once before and definatley felt it.

I haven't checked the AR forums for a couple of days and so just came across this thread this morning.  The same thing happened to me the day I brought home my rifle around last Easter.  I have to head out to work now but will post my experience tonight if I have time.  Have a good day!

Are the bolts 8-12 backlog?

I purchased a complete LMT MRP CQB rifle around last Easter.  I took it home for the standard dissasembly and cleaning before the initial trip to the range.  While reinstalling the barrel with the supplied torque wrench correctly set to 140 in. lb. I snapped the front bolt off in the same manner as the original poster.  The next day the dealer whom I purchased the rifle from took a bolt from another new-on-the-rack rifle and installed it in mine using his (Snap-On?) torque wrnech from the shop.  That is good customer service as now he couldn't sell the store's rifle until he received a replacement bolt.  I called and spoke to Gene Swanson to get some pointers so it wouldn't happen again.  I too was asked to send the rifle in but I declined saying everything seemed to be fine now but was just looking for instructions to prevent this from happening in the future.  He, like some of the posters in this thread, speculated that the wrench operator (me) may have missed the "click"  and continued to tighten after correct tension had already been reached.  I, like everyone else, make mistakes but having used lots of torque wrneches in the past at the machine shop I used to work at somehow doubt it.  I asked if he knew the breaking strength of the bolts and he indicated he wasn't sure but maybe around 180 to 200 in. lbs. so that the bolt would break before the upper was damaged by over tightening.  Makes sense to me.  I asked how much tension would it take to damage the receiver and he said a lot more that I could ever produce using the supplied bolts.  In the end he sent me free of charge a couple spare bolts just to ease my mind.

I have since had the barrel on and off many times without incident.  I have done it, however, using a one of two other torque wrenches I own.  I think the fault is in the supplied wrench.  Most torque wrenches have a range, 120 to 960 in. lbs. in the case of the supplied wrench.  Most wrench manufacturers, however, only certify the accuracy of their wrenches within a range of that range, usually between 20% to near 100% of capacity.  If that were true of this wrench 268 in. lbs. would be the 20%.  To use a wrench at 140 when the minimum range setting is 120 doesn't seem right.

Disclaimer: the proper way to check the accuracy of a torque wrench is to have it calibrated by someone with equipment I do not own.  What follows is my experimenting for whatever it is worth.  I attempted to compare my three wrenches by mounting a bolt to a metal plate, thighten to a set torque tension with one wrench and see if the other wrenches would "click" when they were set to the same setting.  At 140 in. lbs. the two torque wrenches I previously owned seemed to be within 2 to 5 in. lbs. difference of each other.  When the bolt was initially tightened on the plate to 140 in. lbs. using the LMT supplied wrench my other wrenches would need to be set around 200 in. lbs. to further tighten the bolt without a "click."  Likewise, using one of my other wrenches I would have to tighten the bolt in excess of 180 to 200 in. lbs. before the LMT supplied wrnech would "click" when set to "140" without further tightening the bolt.  My conclusion:  Is the LMT wrench accurate when set in its midrange settings?  I don't know.  When set at 140, however, it is atleast 40 to 60 in. lbs. off.  

I am not bitching about LMT products.  I have an MRP and a standard LMT Defender which I like as much as my Colt and more than my Armalite and DPMS.  I think LMT set themselves up for problems by supplying an insufficient wrench.  If they supplied no wrench than some owner would try to guess at the correct torque using a standard socket set wrench and either undertighten or break off a lot of bolts.  If LMT included a Snap-On quality wrench they would have to pass on an additional $200 cost to the end user.  I don't know what the answer should have been.

Finally, to you who may consider a Craftsman torque wrench in the $79 range:  read the reviews and know that it is not covered by the Lifetime Warranty.

Thank you for bearing with me on this long post!  

Shoulder bolts are typically very hard because the should has been precisely ground round and to a standard size.  This is so it can be used as a bearing surface, for alignment, etc.



 

Thank you.  Your experiences with the MRP and with customer service mirror my own.

I think it's clear that the supplied torque wrench is to be treated with extreme caution, especially if Gene said the breaking point of the bolts is 180-200 in/lbs, a mere 40 in/lbs above the required torque level.

Whether I missed the breaking point in the wrench, or the wrench failed to break is a moot point I suppose ... either way the wrench messed up or it is an easy wrench to mess up with.  I'm looking into getting a quality replacement torque wrench.





Let's hope not



No, it was pretty easy.  It would have been much harder if the MRP bolts had not been "drilled" on the leading face.  By drilled, I mean the first few millimeters are "hollow", as in the inner half of the bolt has been bored out (or they were just cast that way, I dunno).

I used a standard screw extractor to get it out, as seen here:



It was brothers set, so I'm not sure what brand or type exactly ... but it's basically a hexagon or octagon shaped wedge that you drive into the bolt and then twist out.  You normally have to drill into the bolt before using a screw extractor, in order that the wedge can penetrate and grab onto the bolt ... but the LMT bolts have hollow leading faces, as previously mentioned.  They probably did this for precisely this reason ... they expect people to snap their bolts.

I like the idea that they intentionally let the bolts break way before the receiver could get damaged ... as that was one of my fears in buying the MRP, if any part of the upper got damaged the whole thing was damaged as it was a one piece billet.  I realize the inserts are probably replaceable, but I've stripped enough threads in my day to be paranoid of damaging a $1500 upper with brute force torquing.

The replacement screws have not arrived yet, but hopefully they will soon.

Thanks for the info and help.

Wow, Leafy really went into detail. Good post. I got a chewed up envelope from LMT in the mail today which was supposed to have my replacement bolt in it. Looks like it got caught in a machine at the PO. Obviously no bolt. I'm thinking of going to the hardware store and matching one up. Bad idea? Gene at LMT told me to turn the wrench 1/4 turn at a time. He said that should help. I'm thinking new wrench, and maybe a little less elbow grease

Here is what I just got from Gene at LMT:





I guess that's what he meant before when he said they went to using "one washer instead of 2" ... I thought it was kinda funny they'd use a washer on one bolt and not use one on the other, turns out he meant they had switched to a one piece design.

I'll get these installed into my MRP asap, I just need to find a good torque wrench

Does anyone else have this style of one piece, 2 hole "soda can top" washer?

Thanks for posting the pic.. I'll have to see if I get one of these in my order.

Definatley don't have that. Seems like that would spread out the clamping force more. I called again today and he is sending a box this time, hopefully with one of those washers.

That's what mine has.  At first I didn't think it had any washers, I was looking for them to come out with the bolts as individual washers.  I removed the bolts again and noticed that the double washer fell out when I turned the upper over.

How old is your MRP?

Ya those bolts are in Inch lbs, not Foot lbs.  Also 100 inch pounds is still way too high.  A lot of bolts like that usually never get tightened beyond 60 inch pounds.  For example I think torque specs on bolt carrier keys is 60-65 inch pounds.

About a month.

I'm almost ashamed to say I've had an MRP since 2005 with god knows how many rounds through it and I've never taken the barrel out.... However if I take it out I by god will be sure and use a quality torque wrench.

I've got over 50,000 rounds or more on the same mrp receiver and three different barrels (one being 6.8) and have used the same bolts that came with the receiver.  I've fired both suppressed and unsupressed without any issues.  Probably a third of these rounds have been in the full auto mode.

How is the upper holding up?  Any pics?

Common theme of broken bolts?  I also broke one bolt only to find out I snapped the other one as well.  Wish they packaged in a better torque wrench and that is fine with passing on the cost since right now I am looking at buying a quality in-lb torque wrench.  Any suggestions people?

I just got one of these today. How many inch pounds am I suppose to use and can anyone suggest a good torque wrench. I am a Chemist not a Enginner. I also have never use a torque wrench before.

I'm looking in the MSC catalog on the torque wrenches.  They are not cheap, but it will probablyl save your gun from down time.  
I can't imagine breaking bolts making this a good weapon for the field.  Duty probably okay since you wouldn't change configuration a lot, but if your overseas, like in Iraq, a broken bolt = broken rifle.  

Surprise to really see something like this from LMT.  I'll probably contact LMT for some spares just in case.

Well I can't wait.. going to get mine this week.

The wrench supplied by LMT is rated at 120 to 960 inch pound range. It's cost $20 on the internet. Some were for sale for $11. A torque wrench for $11??? I am definately getting a better quality one.

Guys,

There is no point in you buying a snap-on or other expensive "clicker" type torque wrench.  These are precision instruments and by the time you use them years from now they will be out of calibration anyway.  

I STRONGLY suggest you save yourself some money and maybe a couple of bolts (heh heh heh) and run down to Sears and buy one of their beam type torque wrenches.  Not sexy looking, definitely slower to use than a clicker.  This can be a pain if you are torquing 20 lugnuts on your car.  But considering the 2 bolts on an MRP, it will only add 15 seconds to the job.  

If you cant find the in-lb version at Sears, I suggest you google the Park Tool TW-2.  You can buy it on line.  It will work great, and no calibration necessary.

Don
p.s.  I learned all about torque wrenches when I rebuilt my airplane.  I've got 2 beam type torque wrenches and 1 calibrated (but expired) clicker.

this is quite a misleading thread title.

How you figure ... I have MRP Piston ... and I snapped one of the bolts in half?

ETA - Ohhh I get it, a "bolt" bolt.  I didn't even think of that.

Hey Duncan,
I was wondering if you had any issues with burrs on your MRP?  I just got mine and it has burrs, scratches & dents!  



edit:
Gene is taking care of me.  Sent in my MRP CQB.. and now just waiting for the replacement.
Fast response on taking care of the issue.  Sent packaging slip via email (so no paying for return shipping).  Now I'm just waiting for them to send me another one.. They received the MRP already so just waiting game now..

How long did it take you from when Gene told you shipped to receiving?  I been going on 3 weeks from first contact to 2 weeks now from when he said it shipped.  Pretty slow non-responsive in my opinion.  I have emailed and called him a few times now to no avail.  Starting to really frown down on their gear.  Not as durable as I would like.   LWRC is looking better now.

I don't beleive that I have any type of burrs or rough edges like that.

I don't think anybody does.   Just looks like I had the unfortunate luck with LMT on this one.  

I got my LMT Piston upper and use the supplied torque wrench to tighten. That was a big mistake. I didn't snap the bolts but ended up stripping the head of the bolt.



It's a good thing LMT has these bolts in stock and I order 6 of them just in case.

I then got this torque wrench from precision instruments. They can be found on the web for $125. The range is 0-150 inch-pounds. So there is no way to snap the bolts unless I pull it off the scale. It's got a 2% accuracy which makes it the most accurate wrench you can buy. Here is a picture of mine.

Could you supply a link or part number for that wrench?  I can't seem to find that model on the website.  It looks like it's perfect for the job.

Also, does anyone have a part number for the bolts and double washer package that LMT is sending you guys? I want to get a couple sets just for peace of mind.

Thanks