Engineers and experts: Y-Man needs you advice

Our Nigerian friend needs some advice (If you have not read his latest guest blog post, it is here) …

I need your advice; and maybe you could ask a few friends. Remember that Mossberg 500A 12-gauge I got? Well, it came PGO (Again! Do they have something against regular stocks in Nigeria?!) Well, you know me: I have a restless mind, and restless hands (And some money to burn occasionally!) so I did some fabrication/ modification.

I kept it simple this time: I welded an “L-shaped” wire-type stock (Made out of a strong, springy steel rod derived from a screwdriver.) to the steel bolt that fastens the grip to the receiver. Once I tightened the bolt as normal to the shotgun grip: it was good to go. (See picture attached.)

My worry is this: I’m no engineer, but wouldn’t this put some stress on the bolt-hole of the receiver? Might repeated firing cause the Shotgun receiver to possibly fracture and even crack? Normally: the stress of recoil/ impact of firing taken by the stock (Or PG) is spread on the flat end of the receiver (Where the stock or PG contacts the receiver.) but my modification puts all the impact at the point where the bolt screws in.

  • I haven’t tested my modification yet, but am I setting myself up for a cracked receiver? (Or worse?)

  • Is my angle of the stock okay? It is straight along the “line of recoil”, it should be okay… What do you think?

  • LOP is about 11 inches: and this is comfortable. But is it okay?

  • No cheek-weld at all. I guess I’ll have to live with that.

Anyone know if the stress on the receiver during recoil could cause problems?

I am sure the length of pull will be fine as long as it is comfortable.



Steve Johnson

Founder and Dictator-In-Chief of TFB. A passionate gun owner, a shooting enthusiast and totally tacti-uncool. Favorite first date location: any gun range. Steve can be contacted here.


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  • Mad World

    Just thinking out loud here, but why not make a standard wooden stock? Cheers!

  • Mu

    It’s not the impact you have to worry about but the torque you’re putting on it. You have that long stick without any angular support, that’s a lot of momentum transfer. At minimum I’d use a L or U bracket to lay flat at the back of the pistol grip, and mount my stick to that.
    But I’d say you’d be better off having a foldable stock shipped as “replacement part for foldable crutch”.

  • Sam

    I agree, it’s going to have a pretty big moment at the base of that stock. Using a stock that sticks straight back, in line with the recoil vector, should help minimize the moment. A stronger mounting system would also help.

  • urban smith

    Hi Y-Man, way to go on the mossberg 500 thats a great gun! I do think the stock in its current design is going to damage the receiver threads though. I am a welder here in the states and I often see stripped out or damaged threads on nuts and bolts that are subject to vibration and shock. many mossberg receivers are made of hi-grade alluminum that is much softer than steel and cannot be easily welded on,so you really dont want to damage the threads in the gun body. You could make a “U” shaped mounting bracket that would go around the back of the grip and run screws into the sides of the plastic near the mounting nut. Then weld the stock to that. Also cheek weld is really helpful in getting the most out of rifle type sights. Hope this was helpfull Y-man, keep shooting and keep us posted!

  • Y-man, I’m worried about your stripping the screw threads. You’re really not supposed to put an axial load on bolt fasteners. Bolts are best for sideway loads (imagine trying to snap a bolt in half.)

    If you drill a hole on your pistol grip, from left to right. Put a bolt or rod through the hole. Then attach the wire stock to both ends of the bolt. That would be the ideal way to transfer recoil through a bolt.

  • CMathews

    I have a Mossberg 500 myself, and shooting it in the pistol grip configuration can be fun. However, I do understand your need for a stock for I keep my Mossy as my castle gun and it has the standard stock equipped. Due to the location of the safety I prefer not to have a pistol grip rifle stock, it gets in the way of manipulating the safety switch. My suggestion is to try to make a wire or tubular stock. Or maybe a rifle style wood stock. The pistol grip only will be far too much of a hassle to hunt or shoot with practically. The design you have would stress that mounting point, and direct the recoil in an un-natural direction.

  • bullzebub

    my vote is make a wooden stock too. its not that hard actually. you could always make it out of a softer wood as a first try.
    or do you require that its easy to remove?
    a SVD styled stock might be easiest.
    or why not make it into a bullpup? 😀

  • Kyle Huff

    It depends on the materials at the bolt interface. If it’s strong enough and thick enough on the female side, then you’ve got to worry about the bolt itself cracking from the bending moment being applied. If the bolt is strong enough, this probably won’t be an issue. I’d guess the failure point is either going to be near the weld, where the metal is probably now quite brittle, or the female side of the bolt interface if the material isn’t thick enough.

    Fire some slugs and look for cracks, I guess.

  • CMathews

    http://world.guns.ru/shotgun/sh03-e.htm

    hmmmm… a wooden Mossy 500 bull pup would be simply amazing. bullzebub, you have inspired me. I think i will partake in this project after my current AR is finished, or else my better half will wring me out for having too many projects at once.

    Or….. you could do as previously mentioned, ship a real stock under a false title.

  • Wolf

    I don’t know the bolt diameter or how deep it’s set in the receiver, so I can’t really estimate how it would hold up, but I can say the angle the mounting bolt is at is going to put alot of torque on the receiver-stock connection. Urban Smith’s seen the receiver up close and doesn’t think it’s a good idea, so that’s probably the best advice.

  • bullzebub

    CMathews >> 😀
    ive thought about this, and i think it might be a idea to construct it “upside down” so the tube is above the barrel.
    like the neostead: http://world.guns.ru/shotgun/sh08-e.htm
    That would make it much easier to load. although the trigger linkage would be harder.
    since the barrel would sit lower (closer to the center of the shoulder) barrel climb would be minimized too..
    Anyway. shouldnt be extremely hard anyway. maybe use a wire (like a bicycle wire?) instead of a hard link.
    a p90 type trigger might also work.

    remeber to take loads of pictures and share them with us!

  • Mad Saint Jack

    If making a stock doesn’t work an alternative is to set up a single-point sling. Pushing the gun forward against the sling would help keep it stable, all though not as much as a stock.

    Here is an example of a single-point set up on an AK pistol.

    http://www.youtube.com/watch?v=Jt8LIuX4NDY

    Also adding a front vertical grip would make it easier to push forward with both hands.

    example:

    http://www.cheaperthandirt.com/SHT080-1.html

  • Y-man

    Thanks guys! Muy muchas gracias!
    I appreciate the advice. I have a stop-gap to avoid the stress to the receiver screws as mentioned: I am putting in a spring in between the stock and the bolt to the receiver. This would take the initial impact. It is a strong spring: gotten from the valves in a car engine.

    Check out a photo of the idea copy link and paste in browser. (I hope it works! I just joined Flickr…)

    http://www.flickr.com/photos/44877118@N04/4121137837/

    Let me know what y’all think?

  • Y-man

    I had already finished up the stock with the right kind of padding. See photos here:

    http://www.flickr.com/photos/44877118@N04/4121159379/

    http://www.flickr.com/photos/44877118@N04/4121156731/

    Let me know what you think?

    Thanks!

    • Y-man, looks great 🙂 I will update the blog. Did you get the email I sent you?

  • Lewis

    OK, for the Nigerians, but my bet is that you will mess with this for a while before scrapping it and buying a real pistol-grip full stock.
    I got mine at a second-hand gun store last week for fifteen bucks. Hope you don’t spend much $ on this or break something real expensive.
    Try this: grab it by the barrel and wack it against a tree or something a few times. If it doesn’t break , well, shooting it, it will, sooner or later.