Blanksguy Posted December 17, 2018 Report Share Posted December 17, 2018 What is the difference between M3/M3A1 Grease Gun recoil springs and Thompson SMG recoil springs if they are not in a marked government package (?). Number of coils (?).......or spring-pressure (?).Clear photos of the difference may help out here..... TIA, RichardSUS Army, RET Link to comment Share on other sites More sharing options...
Got Uzi Posted December 17, 2018 Report Share Posted December 17, 2018 There is a big difference. Wire diameter is the first thing that comes to mind. I havent put them side by side to check OAL or coil count but the M3 has a much smaller diameter wire than a 28 Thompson Link to comment Share on other sites More sharing options...
Blanksguy Posted December 17, 2018 Author Report Share Posted December 17, 2018 Maybe someone with both recoil springs could measure the wire-diameter and possibly post clear photos of these (?). TIA, RichardSUS Army, RET Link to comment Share on other sites More sharing options...
mbatvburg Posted December 18, 2018 Report Share Posted December 18, 2018 Interesting. I purchased 2 sets of grease gun springs from Apex. The Type 1 set is identical in length and wire diameter to my recoil spring out of 1928a1. 11.25 - 11.5 long. Very stiff springs.The Type 2 springs are smaller diameter wire and longer. About 14.5 long. Much lighter spring rate.Either Apex sent me the wrong springs or there is a notable difference in springs between the M3 and M3a1 Link to comment Share on other sites More sharing options...
Got Uzi Posted December 18, 2018 Report Share Posted December 18, 2018 The springs between the M3 and M3A1 are the same. There is no documentation to speak otherwise in any of the field or armorer manuals I have from 1943-1969 Link to comment Share on other sites More sharing options...
Blanksguy Posted December 21, 2018 Author Report Share Posted December 21, 2018 mbatvburg,This might be a good time for someone with both recoil-springs (M3/M3A1 Grease-Gun....and Thompson M1/M1A1 and/or 1928/1928A1 Thompson) to post some information and clear photos so we can sort this out (?). Regards, RichardSUS Army, RET Link to comment Share on other sites More sharing options...
JeffTurk Posted January 7, 2019 Report Share Posted January 7, 2019 I have M3/M3A1 drive springs available. I believe GotUzi has gotten some of mine and Blanksguy will be receiving a couple sets in the next few days. You can email us at STPAUTOMATICS@gmail.com and/or get them thru Gunbroker.com as well. Link to comment Share on other sites More sharing options...
Got Uzi Posted January 8, 2019 Report Share Posted January 8, 2019 I have them and they are running well so far. I have 500 or so rounds on them with no issues in felt recoil, cyclic rate, or weapon function. Looking like a viable reproduction option compared to USGI springs Link to comment Share on other sites More sharing options...
JeffTurk Posted January 8, 2019 Report Share Posted January 8, 2019 Awesome GotUzi. I appreciate your feedback on them. Link to comment Share on other sites More sharing options...
bartomark Posted January 19, 2019 Report Share Posted January 19, 2019 (edited) OK I measured the recoil springs in my guns. Grease Gun, OAL 14.5, wire dia. .032, 78 coils. Thompson M1A1 RIA rebuild, OAL 11 1/8, wire dia. .042, 69 coils. Thompson Savage 28A1 OAL 10 3/8 wire dia. .042, 69 coils. When I first got my grease gun, very early serial number #0014252 someone had cut the springs down to 12 5/8 OAL possibly trying to change the cycle rate. I had a squib load from not enough pressure, I didnt know any better because I didnt have anything to compare it to Until I got another set of original GI springs. As a sidenote, many years ago I talk to a gentleman who was very knowledgeable about military firearms and he told me that the original design for the grease gun called for the springs to be wound in opposite directions but it was soon dropped. Hope this helps Edited January 20, 2019 by bartomark Link to comment Share on other sites More sharing options...
Blanksguy Posted January 24, 2019 Author Report Share Posted January 24, 2019 (edited) I received my newly-made Grease-Gun Recoil-Springs yesterday........and did some counting of coils and measuring wire thichness......and what I come up with is listed below:1: Over all free length (not compresses) came out to 13 1/8 inches (+ - 1/16" between the six springs that I received).2: Wire diameter came to about .031"-.032"3: The were 67 coils on each recoil-spring. Please note:1: I do not have a US GI "TM" (for a rebuild-shop-level to check/overhaul Grease-Guns) that would list the measured lengths and possibly the number of coils for a new Grease Gun recoil-spring. This may be listed in a TM at the -3 or -4 level (?)…...and maybe someone has a manual that they could "scan" that page and post for us here (?)……...I will keep looking.2: The Company (STP-Automatics/Jeff-Turk) was quick to answer questions and ordering time was a minimum. Shipped in sturdy tube.....well packed...….and yes, once I get this original information I will be ordering again. Regards,RichardSUS Army, RET Edited January 24, 2019 by Blanksguy Link to comment Share on other sites More sharing options...
Blanksguy Posted January 24, 2019 Author Report Share Posted January 24, 2019 …...and it looks like the manual that may have this information is: TM 9-1005-229-35DS, GS, and Depot Maintenance ManualDated: September 1969 Link to comment Share on other sites More sharing options...
JeffTurk Posted February 16, 2019 Report Share Posted February 16, 2019 (edited) Thanks for the shout out Rich. I hope the springs are serving you well. Plenty of the newly manufactured drive springs available on Gunbroker https://www.gunbroker.com/item/796199396 and you can order them at STPAutomatics@gmail.com still for only $15.00 a pair plus shipping. Edited February 16, 2019 by JeffTurk Link to comment Share on other sites More sharing options...
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