Methods to attach HK MP5 front sight??

[tjschul 0]

I'm getting to the point in this convertion where I'm going to have to figure out how to attach the HK front sight to the saiga gas block.

My original though was to silver braze it after getting the fit "tight" enough. Then I noticed that this unit is sold as a "weld on" front sight.

I really don't want any weld showing around the base of the sight, and am considereding drilling four holes in the sight base and plug welding it to the gas block with my mig.

 

What is the preferred technique?

 

thanks

[nycGUNguy 61]

Welding is the cleanest install that you will get, preferably TIG but you can also use MIG and just clean up the weld with a grinding machine.

 

nyclu3

[mscottrogers 56]

Welding is the cleanest install that you will get, preferably TIG but you can also use MIG and just clean up the weld with a grinding machine.

 

nyclu3

 

Don't crank up the heat to high or you will burn through or warp it with a mig, just be careful and start low them turn it up

[Gunfixr 76]

I just weld around the base of the sight, and dress the welds with a dremel to give it a smooth, blended look. I did just weld across the very ends of the base one time and dressed those, but it came off and I had to redo it. I have considered drilling holes and plug welding it on, it should stay if you get good penetration on the gas block before back filling. I do that now on the rear sight, drilling a couple holes in the dust cover and plug welding the base on, looks a lot neater.

 

FWIW, every one I have welded on has warped the gas block sufficiently so that the gas plug no longer freely screws in. I don't know if Tony has this same problem, maybe he'll chime in when he gets back. I'm thinking that plug welding might reduce or eliminate this problem.

[tjschul 0]

I just weld around the base of the sight, and dress the welds with a dremel to give it a smooth, blended look. I did just weld across the very ends of the base one time and dressed those, but it came off and I had to redo it. I have considered drilling holes and plug welding it on, it should stay if you get good penetration on the gas block before back filling. I do that now on the rear sight, drilling a couple holes in the dust cover and plug welding the base on, looks a lot neater.

 

FWIW, every one I have welded on has warped the gas block sufficiently so that the gas plug no longer freely screws in. I don't know if Tony has this same problem, maybe he'll chime in when he gets back. I'm thinking that plug welding might reduce or eliminate this problem.

 

 

And warpage might be the big drawback to silverbrazing it on. I'm sure that with #8 silver and a good fit, I'd get a solid joint, but it takes a bit of heat over a wider area.

By the way, the sight I got came with a good amount of rust all over it, and one "leg" a good 1/8" shorter than the other, not real good quality control somewhere along the line, so I've got a bit of work to do before I attach it.

[BobAsh 582]

Tony TIG welds them, but he's the best TIG welder I've ever seen. He has amazing heat control.

[Gunfixr 76]

I TIG weld them also, but I don't get to weld that much anymore, so am a little out of practice. I used to build custom magazines, which involved welding very thin metal, and my heat control was much better then.

 

It's kind of like riding a bicycle, you may not forget, but you can get "rusty".

[maroast 1]

Is JB weld a viable option? Or would that be too much of a hack-job?

[6500rpm 670]

Can some of you elaborate on a few things that might be of interest...warping the gas block really suprises me as it's pretty stout, I would understand the cover a lot more.

 

1) are you welding with the block still on the barrel?

2) is the plug and piston installed?

3) are you removing the plug retainer spring as I could see where heat could effect it?

 

Additionally, what method are you using to align the front and rear sight before affixing. I find this pretty interesting because on "SOME" of the installs I've seen it looks like you loose the ability to adjust the windage when using the HK rear sight, but I could be mistaken.

[tjschul 0]

Can some of you elaborate on a few things that might be of interest...warping the gas block really suprises me as it's pretty stout, I would understand the cover a lot more.

 

1) are you welding with the block still on the barrel?

2) is the plug and piston installed?

3) are you removing the plug retainer spring as I could see where heat could effect it?

 

Additionally, what method are you using to align the front and rear sight before affixing. I find this pretty interesting because on "SOME" of the installs I've seen it looks like you loose the ability to adjust the windage when using the HK rear sight, but I could be mistaken.

 

Lots of good info here, that's for sure.

 

Not sure how you would lose the ability to adjust the rear, but I can see running out of adjustment is its not properly aligned. I was planning to use a laser bore sighting tool to avoid that.

Not having access to a TIG (or the skill to use it), looks like I'm going to plug or slot weld it on using my MIG.

[Gunfixr 76]

Can some of you elaborate on a few things that might be of interest...warping the gas block really suprises me as it's pretty stout, I would understand the cover a lot more.

 

1) are you welding with the block still on the barrel?

2) is the plug and piston installed?

3) are you removing the plug retainer spring as I could see where heat could effect it?

 

Additionally, what method are you using to align the front and rear sight before affixing. I find this pretty interesting because on "SOME" of the installs I've seen it looks like you loose the ability to adjust the windage when using the HK rear sight, but I could be mistaken.

 

It is pretty stout, but it's basically a short tube, and any time you weld on the sides of a tube, it's roundness will be changed. For the precision fit of the gas plug threads and piston, this can mean they don't fit anymore.

I have welded them with the block on the barrel, and off. Alignment is more assured on the barrel.

The plug and piston are removed.

Not always, if you're quick enough, and don't crank up the heat, that area won't get hot enough to hurt the spring.

 

Alignment is the hardest part, at least for me, Tony might have a fixture by now. I set the gun up in a small vise and set it vertical with a level. Then I set the front up on the gas block and get it vertical by measurement and eyeing it. I then just barely tack it in place, and recheck. Since everything up front is rounded, it's hard to clamp and tack without something moving. If nothing has moved, I finish welding it down, and dress the welds as necessary.

 

You don't lose the windage adjustment on the rear unless you've just welded everything into one big blob of steel. I take the drum off of the base first. I was welding along the sides, putting the cover on the gun with the gun vertical as before, using a level to square up the rear on the cover. Then tack and check, if good, finish along the sides. Lately, I've been playing with drilling a couple holes through the cover and plug welding from underneath. This produces a much neater appearance, but is much harder to set up. Often, the cover doesn't sit square on the receiver, so it can't be just squared to the cover. It has to be leveled on the gun, marked, cover removed and sight clamped, tacked, then checked before final welding. It's also harder to clamp as the clamp ends up blocking where you want to weld. But in the end, it looks much better, like the sight was made there.