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...
komodoj Posted July 29 Report Share Posted July 29 Just got my M3 grease gun springs from Jeff Turk, superb quality, awesome customer service and fast shipping. The first set he sent me went MIA, but he quickly sent me a replacement. Awesome guy to deal with and very knowledgeable!! Thank Jeff for suppling this great product! Link to comment Share on other sites More sharing options...
Rekraps Posted July 30 Report Share Posted July 30 On 1/24/2019 at 2:52 PM, Blanksguy said: …...and it looks like the manual that may have this information is: TM 9-1005-229-35 DS, GS, and Depot Maintenance Manual Dated: September 1969 So I have that TM (original, dated Nov 1969) and it notes the "Spring, Helical Compression", FSN: 1005-200-5864 as an Organizational Level Maintenance item. No mention of specs at all. I also have the FM 23-41 (original) and likewise, no mention of specs. Now, I happen to have two complete new/OS bolt/recoil assemblies that are OEM so I pulled one and took the measurements: Spring one: OAL: 12.75 inches Wire diameter: 1mm (too small for me to read the micrometer in inches) Coils: 67 Spring two: OAL: 13.0 inches Wire diameter: 1mm Coils: 67 I suspect that these guns will run on anything that is even close to OEM. 1 Link to comment Share on other sites More sharing options...
Rekraps Posted July 30 Report Share Posted July 30 BTW, I also ordered a replacement set of springs from Turk and they work just fine, and fit just fine. 1 Link to comment Share on other sites More sharing options...
komodoj Posted July 30 Report Share Posted July 30 (edited) Yes but .032 to (1mm). 039 is a big WD difference. I’d suspect increase in ROF or decrease in ROF? YMMV. Edited July 30 by komodoj Link to comment Share on other sites More sharing options...
Rekraps Posted July 31 Report Share Posted July 31 2 hours ago, komodoj said: Yes but .032 to (1mm). 039 is a big WD difference. I’d suspect increase in ROF or decrease in ROF? YMMV. I can't comment on the rate of fire as I.... 1) have no way to measure it and, 2) see no point in doing so. I suppose that the rate of fire was always measured as a range... so to allow natural manufacturing outcome differences not to impede the production of the gun. Link to comment Share on other sites More sharing options...
StrangeRanger Posted July 31 Report Share Posted July 31 FWIW Spring rate is proportional to wire diameter to the 4th power. With all other dimensions held constant increasing the diameter from 21 ga (.0317") to 20 ga (.0348") increases the rate by a factor of 1.45 If the measurement actually is 1mm (doubtful with US made parts) the increase is 2.39 1 Link to comment Share on other sites More sharing options...
komodoj Posted July 31 Report Share Posted July 31 19 hours ago, Rekraps said: I can't comment on the rate of fire as I.... 1) have no way to measure it and, 2) see no point in doing so. I suppose that the rate of fire was always measured as a range... so to allow natural manufacturing outcome differences not to impede the production of the gun. Was only giving you a reference because of the huge wire diameter difference between “your” m3 springs and Turks! You measured .039(1mm) to Turks .032 if that’s so. The bolt will operate differently to a larger degree. Ex. Increase or decrease in rof. Possibility of short stroking. Or lightened primer strikes. Yada. Yada. Yada. I’m sure you get my point. Link to comment Share on other sites More sharing options...
Rekraps Posted August 1 Report Share Posted August 1 16 hours ago, komodoj said: Was only giving you a reference because of the huge wire diameter difference between “your” m3 springs and Turks! You measured .039(1mm) to Turks .032 if that’s so. The bolt will operate differently to a larger degree. Ex. Increase or decrease in rof. Possibility of short stroking. Or lightened primer strikes. Yada. Yada. Yada. I’m sure you get my point. Absolutely do and did not mean to come across as anything but providing info. Link to comment Share on other sites More sharing options...
Rekraps Posted August 1 Report Share Posted August 1 As we delve into the never ending pit of analysis of M3 recoil springs, I think it is safe to say that most of us have units that run quite well, rather it be OEM (as far as we know) or Turk replacement springs. The guns work and seem to run just great. Link to comment Share on other sites More sharing options...
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