Hello guys, I am thinking about buying a MK-760 and need some info. I don't know much about these but want to learn. Does anyone have one of these. What should I be looking for and looking out for, reliability, parts replacements and prices on parts. Basically just a quick rundown of the do's and don'ts. I have looked online but it doesn't compare to info one gets directly from someone that owns one. I have a full auto now that I'm selling that is the reason for looking at this one.  Thanks for the help, Andy...

Take a look at the bolt face (specifically the lower lips).....they can crack/chip.

Make sure your ejector is nice and "sharp"

If the mags in the gun have had lots of "fitting", thats not a really good sign.

Test the trigger for function in semi and full......make sure it disconnects on semi, and doesn't on full.......

I've had 2 and they both ran 100%.......some folks can't get more than 2-3 rounds out of theirs without something going wrong. I've heard a lot of issues can be traced to the trunion not exactly "square" in the front of the receiver

Spares are expensive........stock up on extractors.....and make sure you are using the right strength recoil spring for the ammo you're shooting otherwise you'll pound your endcap/takedown pin

Scott Andrey machine has about all the "shooters" spares you'll need to keep one running

The S&W 76 forum at Uzitalk is your friend as well......

Having had one that I put many thousands of rounds through, here are my thoughts in addition to what was said above.

1)  Do NOT use hot ammo.  It will break takedown pins and cause the holes in the receiver to elongate.
2)  Swedish K/Suomi mags work fine.  Buy a bunch.  Only use the ones that lock up tightly.  These guns are very sensitive to magazine movement and feed lip height.  
3)  Do NOT hold it by the magazine when firing.  They are sensitive to magazine movement and will jam if you hold the mag.
4)  Scott Andrey makes buffers.  Use them.
5)  The barrel will rotate during firing unless it has been modified with an index pin.  Barrel rotation makes your groups look like a shotgun.
6)  The stocks are relatively easy to bend.  This is a bad things as once bent, they WILL bend again more easily.  Replacement stocks are expensive.

Shoot it before buying it. Make purchase contingent on three separate magazines fired without a jam.  Fire one mag as a single burst.  Another as short bursts, and the last alternating between semi and short bursts.

Most of these have been properly sorted out.  But when new, there were a lot that had issues as they were very hastily produced right before the May 19, 1986 cut-off date.

The MK-760 was originally designed for hot ammo, just like the S&W 76. It should have a 20lb recoil spring as standard. Try to find a 15lb spring and you can shoot standard ammo all day long.
Check the rear of the receiver where the end cap pin goes through the receiver and see if the hole has ovaled. If it has, the receiver may need to be repaired.

If possible, test fire.  If not, do the checks mentioned above.  Make sure there is a buffer in it when you check it out.  If not, chances are it was fired without one and that could have stressed the parts.  Check the extractor and expect to replace them.  I've gone through two in mine already, but I have spares and I can make more if need be.  Don't sweat the mags, they are available and fairly inexpensive.  You can get some spares from Scott Andrey Machine, but it could take some time as mine did.  Good guy to deal with though.  Keep an eye out and you might find a complete spare parts set like I did.  Don't worry about the barrel indexing thing.  Scott Andrey makes some good adapted barrels for using cans...I have one adapted for Uzi threads so I can run my Uzi can on it.

If you do get it, you might feel tempted to go shoot up a pool full of mafia guys...don't do it.  Just watch Magnum Force instead.

WWW.samachine.com   Scott has a wealth of information about what to look for and check on the 760.  And he is a good guy to deal with.