[charliemike6]

Get one, run it, make sure it works as it should.
It's called a "locking piece". Not a locking shoulder and definitely not a locking device.
Should be either 100 or 110 from the factory in both the 5 and the 5P/K.
Start spending money on parts before you know the gun works perfectly at your own peril. Especially the two pieces you mentioned, the MAD bolt head, which have proven to make perfectly working guns jam-o-matics.
The 80 degree LP is for a very specific group of combined parts and if you don't have all of them, you don't need the 80. Most likely it'll turn your gun into a extractor spring eating jam monster.

If you decide to buy the gun, right out of the box change a bunch of parts and add a can, and the gun doesn't work, don't come here screaming about how the gun is junk and clones suck and you should have never wasted your money on the junk MAC or AP5, or whatever you buy. As I said, get one, run it, run it some more, make sure it works as it should. Once you see that happen, then you can start screwing it up with parts changes.

Your money, good luck.

My MAC-5 locking piece is not labeled so I assume its a 100 but I've not shot anything from mine but 147gr sub-sonic and suppressed with a TiRant 45M and its dangerously quiet and functions flawlessly. I wouldn't change a thing.

 

[charliemike6]

Very well put thanks for that information. I think im just going to spring for an SP5 and call it a day.

To each his own but a SP5 is certainly $2k more at the very least than a MAC-5, if you get it at the standard price of $999 like I did. I wouldn't even consider an HK. There's no magic or voodoo in the MP5 design. Having had experience with HK, POF and now MAC-5, I fail to notice any difference at all. Get a MAC-5 and then spend your savings on upgrades to it, like double stamping it, get a suppressor, a nice HK A3 Stock, HK magazines, and other geedunk and then get some ammo.