Rekraps Posted January 4 Report Share Posted January 4 So, as I'm sure Nick has covered in his book, the M3 and M3A1 are designed so that the bolt never touches the receiver. Instead it "floats" on two mainsprings with end plates that are fixed to the receiver. This means that the gun, as ugly as it is, will fire and fire and fire and fire. The only other SMG's that I am aware of that tried to distance the actual bolt surface from the receiver are the Sterlings (the bolt has lans) and the S&W M76 (receiver has lans). Of the three, I have to say that the at first bizarre design of the bolt and recoil group is the most robust for field and combat operations. IMO of course. Of course as great as the operating system is for the M3, the silly cocking handle and ejection port cover are glaring weaknesses! Link to comment Share on other sites More sharing options...
StrangeRanger Posted January 5 Report Share Posted January 5 (edited) Looked at an Uzi bolt lately? Clearly inspired by the sand-cut TSMG it rides on the corners with lots of space between the rest of the bolt and the inside of the receiver And FWIW M3A1s and to a lesser degree M3s beat the living hell out of the back end of receiver, especially if you don't change the springs often enough. They were a typical GM product, designed to be traded in for a new one every couple of years 🤣 Edited January 5 by StrangeRanger Link to comment Share on other sites More sharing options...
BillinBama Posted January 5 Report Share Posted January 5 My M3A1 doesn't bother with a cocking handle. And I put a piece of leather at the rear of the receiver tube to somewhat cushion the bolt when it slams against it. Worked so far. Link to comment Share on other sites More sharing options...
StrangeRanger Posted January 5 Report Share Posted January 5 Putting in the larger back plate from an M3 will help a lot more but it won't solve the planned obsolescence thing Link to comment Share on other sites More sharing options...
Rekraps Posted January 5 Author Report Share Posted January 5 36 minutes ago, StrangeRanger said: Looked at an Uzi bolt lately? Clearly inspired by the sand-cut TSMG it rides on the corners with lots of space between the rest of the bolt and the inside of the receiver And FWIW M3A1s and to a lesser degree M3s beat the living hell out of the back end of receiver, especially if you don't change the springs often enough. They were a typical GM product, designed to be traded in for a new one every couple of years 🤣 I just knew you'd chime in with an UZI fact.... just to pound my head in the sand because that is one of the few open bolt SMG's that I have yet to add to my collection. Fine... and no I have not seen an UZI bolt, however I can certainly believe that the IDF, in their middle east environment gave it careful thought! Link to comment Share on other sites More sharing options...
Rekraps Posted January 5 Author Report Share Posted January 5 24 minutes ago, StrangeRanger said: Putting in the larger back plate from an M3 will help a lot more but it won't solve the planned obsolescence thing I actually installed a M3A1 back plate, no room for a buffer. I guess I'll order a replacement set of springs. How do you know when they are aging? Link to comment Share on other sites More sharing options...
StrangeRanger Posted January 5 Report Share Posted January 5 Just before they start pounding the back of the receiver out of shape 🙄. I think Got Uzi said around 3000 rounds, assuming that you started with a fresh set Link to comment Share on other sites More sharing options...
Got Uzi Posted January 5 Report Share Posted January 5 It’s well worth putting an M3 plate in the back. If you want the ease of taking it apart without taking off the lower (on an M3A1) then cut a slot in the plate for clearance so the ejector will pass through it. Link to comment Share on other sites More sharing options...
Rekraps Posted January 5 Author Report Share Posted January 5 4 hours ago, Got Uzi said: It’s well worth putting an M3 plate in the back. If you want the ease of taking it apart without taking off the lower (on an M3A1) then cut a slot in the plate for clearance so the ejector will pass through it. I'm having trouble picturing what you guys are talking about... any pics? Link to comment Share on other sites More sharing options...
Rekraps Posted January 5 Author Report Share Posted January 5 And, any source for M3 recoil springs? Link to comment Share on other sites More sharing options...
damifino Posted January 5 Report Share Posted January 5 (edited) pic won't load Edited January 5 by damifino Link to comment Share on other sites More sharing options...
Got Uzi Posted January 5 Report Share Posted January 5 M3 guide rod set or back plate was a fully round disk that had a couple holes drilled in it and a couple flats to hold it for said drilling operation. It makes contact with nearly the entire back end of the receiver. M3A1 guide rod set or back plate is only 1/2" wide (going off memory here) and makes very little contact on the back of the receiver. Less contact means all the backwards force of the bolt is being put into one small area and over time WILL stretch/crack/blow out the back of the receiever as well as egg out the guide rod locating holes. You can "buffer" all you want on an M3A1 backer plate but it wont help much....and for the person who will say "it makes taking the gun apart easier" just remember this- WE ARENT IN COMBAT so it doesn't mean a darn thing to take the extra 60-90 seconds and drop the ejector housing out of the gun to remove the bolt assembly. If that is too much of a mechanical difficulty for you and you just have to do it you own way, then cut a slot in an M3 backing plate so it'll clear the ejector when you remove the bolt assembly. For a $32.5k to $35K if you are too darn cheap to put a $20 set of spring in or a $40-$50 M3 guide rod set in....you are just kidding yourself..... Link to comment Share on other sites More sharing options...
damifino Posted January 5 Report Share Posted January 5 (edited) trouble loading pic. Edited January 5 by damifino Link to comment Share on other sites More sharing options...
BillinBama Posted January 5 Report Share Posted January 5 I had not know there were different back plates until this discussion started, and FWIW my M3A1 has the M3 back plate so I'm set. AS for springs, maybe Wolf has them? They seem to carry all the major ones. I'm gong to look myself right now. Link to comment Share on other sites More sharing options...
BillinBama Posted January 5 Report Share Posted January 5 Well, Wolff doesn't list any, and they don't even have a search feature to check that way. I have bought S&W 76 springs and others from them, so maybe we should request they make some. I"ll check SARCO and others when I get a chance. Link to comment Share on other sites More sharing options...
BillinBama Posted January 5 Report Share Posted January 5 That didn't take long, SARCO has M3 "driving springs" which has to be what we're after. $13.00 each. Link to comment Share on other sites More sharing options...
BillinBama Posted January 5 Report Share Posted January 5 Just now, BillinBama said: That didn't take long, SARCO has M3 "driving springs" which has to be what we're after. $13.00 each. Oops, out of stock. Just now, BillinBama said: Link to comment Share on other sites More sharing options...
Rekraps Posted January 5 Author Report Share Posted January 5 32 minutes ago, BillinBama said: That didn't take long, SARCO has M3 "driving springs" which has to be what we're after. $13.00 each. Sold out. My M3 has the M3A1 backplate. And..... I found a set of M3/M3a1 recoil springs on GB and bought them right away. Link to comment Share on other sites More sharing options...
Blanksguy Posted January 6 Report Share Posted January 6 The guy on Gun-Broker has a lot of the recoil-springs for the Grease-Gun........more than we would use. He sells them in pairs.....and fast shipping. Link to comment Share on other sites More sharing options...
Rekraps Posted January 6 Author Report Share Posted January 6 48 minutes ago, Blanksguy said: The guy on Gun-Broker has a lot of the recoil-springs for the Grease-Gun........more than we would use. He sells them in pairs.....and fast shipping. Yep, I got a pair for $15! (plus shipping) Link to comment Share on other sites More sharing options...
StrangeRanger Posted January 6 Report Share Posted January 6 One whole pair? Sure you have enough? Link to comment Share on other sites More sharing options...
Got Uzi Posted January 6 Report Share Posted January 6 Every spring I changed the recoil springs, sear, and sometimes the extractor (if it was worn) that was what I did Jan 1 every year to get it ready for the shooting season. Link to comment Share on other sites More sharing options...
StrangeRanger Posted January 6 Report Share Posted January 6 One season with the M3 for Got Uzi was like 3 or maybe 5 seasons for most people. Maintain accordingly Link to comment Share on other sites More sharing options...
Rekraps Posted January 7 Author Report Share Posted January 7 On 1/5/2024 at 8:52 PM, StrangeRanger said: One whole pair? Sure you have enough? Plus... I already had an extra complete OEM bolt, guide rod/spring assembly, and just for kicks, one extra OEM bolt in box (with extractor and retaining pin). So, I do think I have enough. Link to comment Share on other sites More sharing options...
BillinBama Posted January 8 Report Share Posted January 8 On 1/5/2024 at 2:36 PM, BillinBama said: That didn't take long, SARCO has M3 "driving springs" which has to be what we're after. $13.00 each. Oops, out of stock. On 1/5/2024 at 2:36 PM, BillinBama said: I ordered two pair just in case.... Link to comment Share on other sites More sharing options...
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