M1A1savage Posted January 24, 2010 Report Share Posted January 24, 2010 I have an Erb MP40. Ever since I've had it, it will not run 100%...at best it would go 90%. A few months ago, I totally stripped it apart to clean it, and ever since then at best it will only run about 25%. I've also noticed that the firing pin is pierceing the primers on the rounds that it will feed. I've used 115 and 124 grain ammo from Winchester and Remington. I'm positive I've put it together correctly, but it seems to me that the barrel is setting back further in the reciever. I have not had any pierced primers before totally breaking it down...at least I hadn't noticed any. Anybody have any ideas on what to try? Help!! Link to comment Share on other sites More sharing options...
RoscoeTurner Posted January 24, 2010 Report Share Posted January 24, 2010 I have an Erb MP40. Ever since I've had it, it will not run 100%...at best it would go 90%. A few months ago, I totally stripped it apart to clean it, and ever since then at best it will only run about 25%. I've also noticed that the firing pin is pierceing the primers on the rounds that it will feed. I've used 115 and 124 grain ammo from Winchester and Remington. I'm positive I've put it together correctly, but it seems to me that the barrel is setting back further in the reciever. I have not had any pierced primers before totally breaking it down...at least I hadn't noticed any. Anybody have any ideas on what to try? Help!! In all seriousness, did you make sure you didn't leave any parts out such as the washer that goes between the sling swivel ring and the barrel nut? When you reassembled the gun did you use the original parts? There is not much that can go wrong with a MP40. Link to comment Share on other sites More sharing options...
TheGunny Posted January 24, 2010 Report Share Posted January 24, 2010 Without seeing or firing the weapon...here is what I would check: Functioning: 1. Crappy mags. Does it function equally bad with all mags? 2. Weak or worn springs. Wolff makes replacements for all 3. If that doesn't work, have the gun checked for headspace and proper assembly by whomever made it. Pierced Primers: 1. Firing pin protrusion out of spec. 2. Chamber out of spec 3. Shooting reloads or crappy ammo! These guns are pretty reliable and I have fired thousands of rounds through them, so it's hard to believe it works as bad as you say. Hope this helps! TG Link to comment Share on other sites More sharing options...
M1A1savage Posted January 24, 2010 Author Report Share Posted January 24, 2010 In all seriousness, did you make sure you didn't leave any parts out such as the washer that goes between the sling swivel ring and the barrel nut? When you reassembled the gun did you use the original parts? All original parts, and no parts were left out...I re-checked myself multiple times. Link to comment Share on other sites More sharing options...
M1A1savage Posted January 24, 2010 Author Report Share Posted January 24, 2010 Functioning: 1. Crappy mags. Does it function equally bad with all mags? 2. Weak or worn springs. Wolff makes replacements for all 3. If that doesn't work, have the gun checked for headspace and proper assembly by whomever made it. Pierced Primers: 1. Firing pin protrusion out of spec. 2. Chamber out of spec 3. Shooting reloads or crappy ammo! I have 20+ mags for it and it feeds equally crappy from them all. The recoil spring is a new Wolff, but the mag springs are, as far as I know, original. Is Erb still in business? Would a complete dis-assembly throw the firing pin and chamber out of spec? No re-loads...only factory ammo. Would it be possible for the barrel to be pushed forward from the years of gunk I cleaned out of it, and now that the gunk is not there, the barrel sets farther back into the reciever causing the primers to be pierced by the now overly long firing pin? Thanks for the quick replies, guys...I really appreciate it. Link to comment Share on other sites More sharing options...
RoscoeTurner Posted January 24, 2010 Report Share Posted January 24, 2010 Did you put the Wolf spring in before you had this trouble or after? Link to comment Share on other sites More sharing options...
M1A1savage Posted January 25, 2010 Author Report Share Posted January 25, 2010 (edited) Did you put the Wolf spring in before you had this trouble or after? I put the Wolff spring in the same time I detail-stripped it...I haven't tried the original recoil spring back in it. I'll check it out...thanks!! Is it possible the new recoil spring is too stiff and is moving the bolt forward too fast causing the pin to puncture the primers? Edited January 25, 2010 by M1A1savage Link to comment Share on other sites More sharing options...
TheGunny Posted January 25, 2010 Report Share Posted January 25, 2010 20+ mags.......wow! and they all work poorly? hmmm I have seen reenactors bend feed lips to get certain blanks to work, but 20 mags worth! You know anyone one else with a MP-40? You could swap parts and mags with theirs to see if yours would start functioning, then replace the offending part if one was found. As far as piercing primers. Take the gun's recoil / firing pin assembly apart again and see if you put it together right. Measure your firing pin and see how long it is and maybe get a good photo of the firing pin protruding through the bolt face and post it here. TG P.S..what kind of jams are you experiencing? FTF (feed), FTE (extract), FTF (fire), stovepipe, etc. Link to comment Share on other sites More sharing options...
snipershot1944 Posted January 25, 2010 Report Share Posted January 25, 2010 20+ mags.......wow! and they all work poorly? hmmm I have seen reenactors bend feed lips to get certain blanks to work, but 20 mags worth! You know anyone one else with a MP-40? You could swap parts and mags with theirs to see if yours would start functioning, then replace the offending part if one was found. As far as piercing primers. Take the gun's recoil / firing pin assembly apart again and see if you put it together right. Measure your firing pin and see how long it is and maybe get a good photo of the firing pin protruding through the bolt face and post it here. TG P.S..what kind of jams are you experiencing? FTF (feed), FTE (extract), FTF (fire), stovepipe, etc. Sounds like the spring is too strong. Link to comment Share on other sites More sharing options...
RoscoeTurner Posted January 25, 2010 Report Share Posted January 25, 2010 Is it possible the new recoil spring is too stiff and is moving the bolt forward too fast causing the pin to puncture the primers? Yes, if all possible stick with the original springs. I have a number of full autos most of which I have owned for over 20 years in none of them have I ever installed anything but an original spring for the type firearm concerned. Link to comment Share on other sites More sharing options...
TheGunny Posted January 25, 2010 Report Share Posted January 25, 2010 Sounds like the spring is too strong. Changing back to the original spring would be a good place to start. Link to comment Share on other sites More sharing options...
M1A1savage Posted January 25, 2010 Author Report Share Posted January 25, 2010 20+ mags.......wow! and they all work poorly? hmmm P.S..what kind of jams are you experiencing? FTF (feed), FTE (extract), FTF (fire), stovepipe, etc. Let me clarify about the mags...up until the complete teardown, all of the mags worked fine. I don't think the problem is in the mags. I know I have one or two whose feed lips are a little large and look like they will barely hold a round, but I have these marked and don't usually use them. The jams I'm getting goes like this: the first round will strip from the mag and chamber and fire, but it appears that it is firing before the extractor can get a grip on the rim. The bolt recoils, the fired case drops in the reciever. The bolt strips another round from the mag and hangs up on the fired case, causing a failure to feed. I'll clear it, and it starts all over...usually one shot, then clear jam. Occasionally, it will feed and fire five or six rounds before it jams. The extractor is in good shape with no missing chunks, and it will hold a live round on the bolt (without firing pin, of course!) Link to comment Share on other sites More sharing options...
M1A1savage Posted January 25, 2010 Author Report Share Posted January 25, 2010 Thanks for the replies, guys. Next chance I get to take it out I'll try changeing back to the old recoil spring. Link to comment Share on other sites More sharing options...
TheGunny Posted January 27, 2010 Report Share Posted January 27, 2010 Thanks for the replies, guys. Next chance I get to take it out I'll try changeing back to the old recoil spring. Make sure the previous owner didn't replace the original extractor with an aftermarket one from (I think) it was IMA. I've heard bad things about those. Link to comment Share on other sites More sharing options...
M1A1savage Posted January 27, 2010 Author Report Share Posted January 27, 2010 Thanks for the replies, guys. Next chance I get to take it out I'll try changeing back to the old recoil spring. Make sure the previous owner didn't replace the original extractor with an aftermarket one from (I think) it was IMA. I've heard bad things about those. Extractor is original. Link to comment Share on other sites More sharing options...
TheGunny Posted February 3, 2010 Report Share Posted February 3, 2010 Thanks for the replies, guys. Next chance I get to take it out I'll try changeing back to the old recoil spring. Make sure the previous owner didn't replace the original extractor with an aftermarket one from (I think) it was IMA. I've heard bad things about those. Extractor is original. So did we ever figure out what the problem was? Did the original spring solve the problem? Inquiring minds want to know! Link to comment Share on other sites More sharing options...
M1A1savage Posted February 4, 2010 Author Report Share Posted February 4, 2010 Thanks for the replies, guys. Next chance I get to take it out I'll try changeing back to the old recoil spring. Make sure the previous owner didn't replace the original extractor with an aftermarket one from (I think) it was IMA. I've heard bad things about those. Extractor is original. So did we ever figure out what the problem was? Did the original spring solve the problem? Inquiring minds want to know! Sorry...not yet. With all of the snow that was/will be dumped on us I haven't had a chance to take her out yet...the wait is KILLIN' me!!! Link to comment Share on other sites More sharing options...
robbo Posted February 12, 2010 Report Share Posted February 12, 2010 It sounds like you have a failure to eject problem. I doubt the mags or the barrel positioning is bad. Take the extractor out of the bolt and make sure all surfaces are clean. Double check the depth of the ejector against the bolt. I dont see the pierced primers as a problem either as I have the same thing happen with my guns occasionally. If possible, swap bolts with another and see if that changes anything. Link to comment Share on other sites More sharing options...
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