M1A1savage Posted August 26, 2003 Report Share Posted August 26, 2003 Has anyone had any problems with the FBP bolts from IMA? The one I have will not work on my sear...in other words it will stay cocked the first time, but when you pull the trigger, it dumps the whole mag. The original bolt works fine. Link to comment Share on other sites More sharing options...
mp40 Posted August 26, 2003 Report Share Posted August 26, 2003 M1A1savage, how well does the sear hold the bolt? try forcing the bolt forwards with finger pressure and move the bolt handle up and down, does the sear hold the bolt firmly? try to slightly pull the trigger while pushing the bolt handle, does the bolt slip? Possibly then, the bent is too shallow. (ok for the fbp but not for the mp40) Also, how "loose" is the bolt in the receiver? it has the possibility of being loose enough to "skip" over the sear while trying to stop firing. Also, assemble the mp minus the bolt/recoil spring assy, and check the sear protrusion-shallow,deep? and how much spring pressure does the take-down knob have? it should be fairly hard to pull. Also, how much does the take-down "pin" protrude into the receiver? because the receiver might be slightly "twisting" enough to affect the sear protrusion. This might not affect the original bolt but, as you know, that the mp40's where all hand-fitted so tolerances seem to be a factor with the mp40. Also what does the fbp bolt weigh? does it weigh more than the original bolt? and is the tension of the original recoil spring comparable to the fbp spring? And finaly, what type of ammunition are you shooting? Link to comment Share on other sites More sharing options...
RichUrich Posted August 26, 2003 Report Share Posted August 26, 2003 Also, Check to make sure the ejector is not rubbing the bottom channel of the bolt. Link to comment Share on other sites More sharing options...
M1A1savage Posted August 27, 2003 Author Report Share Posted August 27, 2003 Thanks for the replies, guys. mp40, the sear does not hold the fbp bolt well at all. You can tell a big difference in the trigger pull...with the original bolt, the pull is approx. 6-8lbs...the fbp bolt is about half of that. The bolt will not move forward with finger pressure, even when the handle is moved up and down. With the fbp bolt in, there is no way to slightly pull the trigger...there is 0 slack. The bolt is not loose in the reciever at all. When assembled without the bolt/recoil spring assy, the sear portrusion looks shallow to me. When disassembled, the sear protrudes approximately .225" above the band in the grip frame behind the sear. The take-down knob is fairly hard to pull. The fbp bolt is heavier...not by much, I don't have a proper scale to weigh them. The recoil springs seem to be extremely close in weight. The ammo being used is 115gr FMJ from Federal, Winchester, Remington, and Wolf. Rich, I also checked the ejector and it is not rubbing on the bolt. In checking all of these suggestions, I think I may have found out why it dosen't like the fbp bolt. I got out the trusty calipers and the fbp bolt is .020" shorter at the cocking notch...so that would make up for the difference in trigger pull weight and why the sear didn't grab it when firing. I appreciate the help...you guys saved me an awful lot of head scratching!! Link to comment Share on other sites More sharing options...
mp40 Posted August 27, 2003 Report Share Posted August 27, 2003 M1A1savage, Hey, no problem! i am glad that we might have helped! http://www.machinegunbooks.com/forums/invboard1_1_2/upload/html/emoticons/biggrin.gif is your mp40 a tube gun or an original? and what manufacturer and variant do you have? (2 flat barrel nut etc.) Link to comment Share on other sites More sharing options...
TSMGguy Posted August 27, 2003 Report Share Posted August 27, 2003 It's not very helpful, but weren't these bolts for a post war Spanish SMG that had very little parts commonality with the MP40? As I recall, the firing pin is fixed, and you've already noted the differences in weight and length. I think it a little misleading of IMA to give the impression that these are interchangable with German MP40 bolts.I understand the need to have a spare bolt, and have found one, early war, with WaA 37 markings but no serial number. I acquired this after a really embarrassing moment at the range. A good friend who is very active in Second Amendment issues was making a video of class III weapons and shooting, and I was invited to participate. Each owner gave a short descriptioon of the gun(s) that he had brought, followed by a firing demo. My MP40 fired about ten rounds before the cocking handle flew off. I'm left-handed, and didn't see it depart, so the gun fired a few more founds before the bolt rotated in the receiver and jammed solid! So much for German wunder weapons. After repairs involving a simple tack weld inside the bolt, I've laid in the spares I consider most useful for the MP40: a bolt, extractor, and firing pin. Of course, there have been no further problems, but man, I'm ready! Link to comment Share on other sites More sharing options...
M1A1savage Posted August 28, 2003 Author Report Share Posted August 28, 2003 mp40, mine is an Erb tube gun built on a '42 bnz parts kit. TSMGguy, I do have a spare original bolt/recoil assy, but I like the idea of a fixed firing pin, since I've heard that original firing pins are prone to breakage. I've also heard of other people using the fbp bolts in their '40's with success, which is why I decided to give it a try. Link to comment Share on other sites More sharing options...
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