I cracked my NDS-3 receiver below the front trunnion lower rivet hole. Crack is about 1/4" long as you see:


I was using a homemade bolt cutter tool with a separate bucking bar and didn't have the "bucking bar" secured well enough. I think it slipped & the jaw of the bolt cutter contacted the receiver when setting the rivet.

From reading about other guy's mistakes, I understand the "best" fix for this is drill 1/8" holes at both ends of the crack, V-groove the crack itself, & fill the holes & groove using a TIG welder. Do you cut the V-groove on the outside of the receiver with a Dremel tool? To what depth in 1mm sheet metal?

Any other recommendations? I have one of those "Uni-Pro Welding Kits" that you use with a propane or MAPP torch. It says for use on cast iron & stainless steel, but I don't suppose it would work on hardened 4130.

Since my weld-fu is non existent, I'll have to take it to a weld shop I guess.

what state are you in maybe theres someone here that would help you out with a tig or mig

i would not drill any holes in it... i would file the crack open slightly with a jewlers file set, then just shoot a weld in it, or fill the whole length of it. and that should probably do it. and you could also do the same on the inside as well.btw - it's not rocket science using a mig welder. otoh - a tig weld would probably be smoother. be sure you use the right type of metal.

actually, just carve open a slight more in the crack with a file like i said.. then just a shoot a weld. might want to use anti spatter or use some foil to protect the reciever. then grind flush and polish with the blue stone off ur dremel. just do the outside with a weld-it should be strong enough.

The holes dont need to be 1/8" and they dont NEED to be used at all.

Drilling holes in the end of cracks is a LONG trusted way to keep em from spreading. But usually only used when repairing with inferior materials.

Example....... cast iron waste pipe cracks in your basement...... drill a hole on each end to keep from spreading..... use silicone sealant to fix the crack..

The weld if done properly is stronger than the base metal..... so no holes needed.

Personally, I would build it and forget about it. If you can affore enough ammo for that crack to become an issue then you would probably not be building a gun in the first place. With the other rivets on the front trunnion it shouldn't get that much pressure. If you are really worried call NDS and ask they their opinion.

tip w/bolt cutter riveter: leave the top portion flush on your rivet on top side, on op side - pull more on the bottom handle(crush jaw). from what i can tell is too much pressure may have been exerted on the upper area? set-up as i pointed out and pull or push on the lower handle more... do the rivet in steps, rather then one dramatic smoosh... at the get go shoot for the rivet staying strait up and down as much as possible. that way when ya smoosh it'll go down nice n even.

as for the crack(no need to bother nodak), just file it open very slightly so the weld can slop on in there... just do the outside and ya don't need to do the inside. shoot ur globs and keep them only in the crack/depression.... grind and smooth out and move on. fyi- your hairline crack is small and should fill with very little weld. this is really a no-brainer.

i think fixing it with a weld would be my #1 choice. that crack could probably spread(get worse). it may or may not. but i think as always(BETTER SAFE THEN SORRY). i WOULD OPT FOR THE WELD. that's my vote.

I would agree with-ETG if that crack was a bit smaller and inside the rivet heads diameter.... but it appears YOUR crack there is substantially larger.... to the point, i think, i would def weld it.

and quit knocking ur head-ur reciever is salvagable!

If you have it welded, that FCG hole will probably need to be heat treated again as I imagine the weld will be close enough to get the metal over 500 degrees. At that point, I dunno...

Guys, given where the hole is and appears to not be in a critical spot, what about him hitting the inside of the receiver with some coarse sandpaper and hitting it with a daub of a strong epoxy? Maybe even, gulp, JB Weld?

Reasoning - it is not an impact bearing surface and just want to give it some degree of support to stabilize. The OP isn't a welder and the receiver would need the weld plus at least a spot heat treat on the one hole. The welding is the right way and a permanent fix, but I think the epoxy might fix it indefinitely and be something he can do himself.



Thoughts?

That is not an axis pin hole location. It is a lower front trunnion rivet location. I would not include JB Weld or epoxy as a solution. My opinion. Either leave it alone or a light weld.

Oh .... if it is a trunnion rivet hole then I would opt to leave it alone too.

If I had that problem, I would clean around it really good and hit it a couple of times with my spot welder, adding a little filler material if it cratered to bad for esthetics, sand smooth and build,,,,,,,,,but that's just me.


+1 on contacting NDS though

Take 5 minutes and weld it. mig or tig it really doesn't matter. I wouldn't
leave a crack in my nice new build.

Thanks for the advice, guys. Especially to jwc0506.

I'm glad to hear I don't need to drill any more holes in the receiver at the ends of the crack. I'll probably V-groove the crack, as suggested, and find someone to fill with a bead of weld.

Thx,
Dave

Mig or TIG. Welding with small holes at ends make sence or just weld away. I would leave the weld bead scarr - as a bueaty mark - extra strength.

This is a piont that does get some force and wave of structurual movement and torque, so {MY OPINION} this should be welded and not left alone or JB WWElded or shoe gou.

__________________
PLEASE WEAR EYE PROTECT & PROTECTIVE GEAR IN SHOP!!!!!! You can order another part from from manufacturer, but you can't order another finger or eye from your mother & father.

***This DOES NOT constitute GOOD or SANE legal - professional gunsmithing - psychiatric - CPA - MD - gardening advice. Please contactact qualified professional in their respective specialties.*** Go ahead mix and match professionals with what ever problem you have??? That would be funney!!!!!

Quote:

---

Originally Posted by TraFALgar
Thanks for the advice, guys. Especially to jwc0506.

I'm glad to hear I don't need to drill any more holes in the receiver at the ends of the crack. I'll probably V-groove the crack, as suggested, and find someone to fill with a bead of weld.

Thx,
Dave

---

Dont groove it out for a tig weld. You can for a mig but it isn't necessary. It's
thin and the welder can get plenty of penetration.

TraFALgar - bigwheel is probably right... Like i said, i have limited experience with welding.... also, my exp is with a MIG welder. so a weld over the crack will be fine.

anyhow, i just thought roughing it up with a little filing might help the weld stick(MIG WELD)... don't know anything about tig welding. but yeah, if he can have a guy shoot a weld over his crack -he's good to go!

and when you get to the grinding-just use a dremel grinding stone cause you have ample control if you use a light touch on the weld globs.. i recommend a double handed hold on ur dremel for optimum results.also, keep it tight and grind it down smooth to the surface... then take a blus polishing stone and smoooth it out completely. later when ya blast for painting etc., it should look a-ok.

V out that itty bitty crack!?

Just run a quick hot bead over it with some 7018 tig wire with the tig welder set on about 55 to 60 amps.

Done.

Lets not make this out to be more than what it is.

I just though of the easiest and best solution IMHO. Do not do anything except use some 400 grit sandpaper and a little cold blue and make the rifle a BFPU.., Battefielld pickup. The crack will blend right in. No structural integrity loss anyhow. Good to go. .

I have O/A, TIG and MIG and in MHO any one of them is suitable for that minor crack repair.
No holes or grinding needed.
If you want to start welding on the cheap go buy a portable O/A rig. practice a bit and then weld it yourself.
You can buy portable O/A sets for under $200.
It's not hard to do and would add another skill to your bag of tricks.
By the way, O/A is by far the most versatile of all the welders.

Quote:

---

Originally Posted by Seastar
I have O/A, TIG and MIG and in MHO any one of them is suitable for that minor crack repair.
No holes or grinding needed.
If you want to start welding on the cheap go buy a portable O/A rig. practice a bit and then weld it yourself.
You can buy portable O/A sets for under $200.
It's not hard to do and would add another skill to your bag of tricks.
By the way, O/A is by far the most versatile of all the welders.

---