H&K clone build...

[Heath_h49008]

I'm new to the accuracy game, but I have an FA91/Dan Coonan receiver G3 build, and possibly a crazy idea.

These have VERY rigid cast aluminum receivers that would seem to offer a great base for a tack driver. The downside is the cocking tube is G3steel and tacked to the front sight post.

The solution would be to make an aluminum cocking tube, or sleeve for the steel one, that can be TIG welded to the receiver, and still support itself well enough to allow the barrel to be free floated.

Anyone else ever do this or anything like it?

Edit: This is a side project, I'm an engineering student, and this weapon is second to my Saiga 12, AR pistol, and my new Savage 10FP... I'm thinking an all aluminum DMR rifle on the H&K platform would be fun, and it won't leave me short a gun for any of my needs while I build it.

 

[DV]

Re: H&K clone build...

The Springfield Armory HK91 clone that was made on the aluminum receiver with the integral scope rail proved to be so problematic that Springfield began to give customers having issues with them M-1A rifles in exchange.

I wouldn`t be comfortable using an aluminum receiver on either a HK 91 or FAL style rifle.

The HK91 series isn`t very easy to turn into a `tack driver` in any case.

I don`t think your project will turn out to meet your expections.

 

[Guest]

Re: H&K clone build...

Heath,

Welcome to the hide. I think you are making things a little too hard on yourself here. If the HK G3/91 platform has room for improvement in the accuracy department, the cocking tube would not be first on my list. Consider the accuracy of a free float tube on an AR...still not technically "free float" if you consider the fact that the gas block and gas tube are still points of contact. Although minute, it is still a point of contact. In the true HK design, the cocking tube never makes contact with the barrel. And I'm pretty sure its attachment to the sight base is minimal. The only true "free float" for HK is if you tried to be consistent with the PSG-1 and MSG-90 where the fore end is attached to the trunion and the front sight and cocking tube tie into the fore end.

As for the question of maximizing accuracy, I would look into obtaining a high-quality barrel. The PTR-91 has had success merely by installing a thicker, more modern barrel. I would say the other area to look for improvement would be the trigger. The "set" trigger for the 33/G3 SG-1s a definate improvement. If you're looking to re-invent the wheel, that might be a good place to start is with the sometimes horrific trigger pull.

I also think you're heading down the wrong road with the cast receiver. I have never seen an HK clone with cast receiver that I would consider to be "quality"....which is sort of key in a precision build. Granted, the thin sheet metal receiver is a weakness, but it's the nature of the beast...as is the blow-back action.

In short, i'm not saying it can't be done, or shouldn't. I'm just offering what i've learned. Do as you wish. But to me, what you are suggesting is like saying I want a car to drag race, but i'm gonna build it on the frame of a panel van, and i'm going to get extra speed by customizing the tail lights.

 

[BigBoss0311]

Re: H&K clone build...

Hi, this question should be posted here for more answers:
http://hkpro.com/forum/

 

[W54/XM-388]

Re: H&K clone build...

The roller lock system in the HK91 style rifles is rather picky and you run into all kinds of issues trying to play around with the receiver.

It's a very good main battle rifle but does not lend itself to improvements all that much, with exception of a trigger job.

I had a PTR clone one that I spent way too much money trying to make into a target rifle and in the end I just had to break down and sell it at a pretty good loss, before I sunk even more money into it.

They are great rifles for what they were designed to do but are a nightmare trying to make into a target rifle, not to mention they tend to destroy your brass.

The M1A rifle would be much easier to make into a target rifle and could be built up piece by piece if you wanted to. (Or you can buy some very accurate ones already done up)

If you want a tack driver however, you will probably need to go with the AR10 style platform and accept the trade off of needing more careful cleaning regularly and a bit more care in ammo choices.

 

[warrenator]

Re: H&K clone build...

The aluminum cast receivers biggest problem is when it comes to barrel attachment. On HK rifles the barrel is pressed into the trunnion which is then welded and pinned to the receiver. With the aluminum receivers the only way to attach the trunnion is by pinning which makes that particular receiver the worst of all HK clone receivers especially if you want an accurate rifle.

These rifles are expensive to make accurate but it can be done. A correctly made MSG90 or PSG1 clone will shoot 1/4 to 1/2 MOA consistantly. There are many guys on HKpro that have rifles that preform that well. The original PSG1 rifles were required to make 50 consecutive shots in a three inch group at 300 meters. Thats a 50 shot group not a three or five shoot group. So people that say this platform is not accurate are not well informed or are only familiar with the HK91 battle rifle. There is a world of differance between an MSG90 or PSG1 and an HK91. There is also a big difference in cost.

The best receivers are made by PTR. To increase rigidity you can have rails welded into the receiver. The most rigid clone receiver without adding receiver rails is the Century cast Stainless steel receiver however some of the exterior dimensions are incorrect which makes mounting furniture and scopes somewhat problematic.

Accurate HK90 series rifle:

1) Original HK or PTR receiver with PSG/MSG90 receiver rails
2) US made MSG90/PSG Trunnion
3) High quality PSG or MSG90 profile barrel: Try HKparts.net
4) Trigger job or PSG trigger: I suggest Williams Trigger
Specialties they make an SG1 set trigger and a PSG trigger

As already suggested go to HKPro.com there is lots of info there and guys that can help.

Also go to Militaryfirearm.com and weaponsguild.com

Here are some links to my builds.

http://www.snipershide.com/forum/ubbthre...191#Post1564191

http://www.militaryfirearm.com/Forum/showthread.php?t=2618

 

[Heath_h49008]

Re: H&K clone build...

My idea is one of finding a new life for the "old girl". Right now she is a perfectly serviceable 7.62x51 battle rifle, club, and paperweight.

I was going to re-barrel her anyway, but the only way I can free-float the new barrel, is by finding a way to connect the cocking tube to the receiver instead of the front sight post. The other way would be to build a rigid fore-end and secure the cocking tube to that, after that was secured to the receiver and the base of the barrel, kinda like the PSG-1 and MS-90 do via the trunnion extension. A combination of the two methods might be the solution.

I have the resources to fabricate in steel or aluminum... at least simple tubes and brackets anyway.

My goal is simply to maximize the rifle with as little effort as possible. These receivers have a built in/on rail topside. One crazy idea may be to attach to that and extend a bar forward to hold the cocking tube, and simply put a scope mount option on top of that. It could even be steel and detachable with 6" or so of contact rail.

In any case, it looks like I'm a special kind of crazy to try it.

Thanks for the tips

 

[ORD]

Re: H&K clone build...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: HeathH</div><div class="ubbcode-body">
In any case, it looks like I'm a special kind of crazy to try it.

Thanks for the tips
</div></div>

Yes...that's probably true!!

BUT, if you have the resources at your disposal and want to see what you can make happen...go for it! Innovation is a good thing (especially if you have unlimited funds and/or resources). Even though I think that you'll ultimately end up disappointed with the aluminum receiver route, anything is possible (again...with enough time and resources dedicated to the project).

Hit up the folks over on the HKPro Forums re: your ideas, questions and concerns for maximum effect/input. WHile there are a few certified HKophiles here (me included), I think that you'll likely get more mileage out of posts in a dedicated HK environment than here.

Good luck!!

 

[jnfphd]

My idea is one of finding a new life for the "old girl". Right now she is a perfectly serviceable 7.62x51 battle rifle, club, and paperweight.

I was going to re-barrel her anyway, but the only way I can free-float the new barrel, is by finding a way to connect the cocking tube to the receiver instead of the front sight post. The other way would be to build a rigid fore-end and secure the cocking tube to that, after that was secured to the receiver and the base of the barrel, kinda like the PSG-1 and MS-90 do via the trunnion extension. A combination of the two methods might be the solution.


One crazy idea may be to attach to that and extend a bar forward to hold the cocking tube, and simply put a scope mount option on top of that. It could even be steel and detachable with 6" or so of contact rail.

I don't own a G3/HK91 clone, but used to own a HK 770 (receiver mounted non reciprocating charge handle with the roller lock). The think was a tank, but hard to take apart to clean. The roller locking mechanism really appeals to me, as much for gadget factor as anything else.

I'm looking to build something along the lines of a SG-1, so I've been looking into improving accuracy. Seems like Warrenator covered everything that I've found (though I would mention the Century Arms receivers are essentially the Special Weapons, LLC receivers , from what I know).

In terms of accuracy fundamentals, free floating the barrel sounds like a good idea (I think PTR's MSG SS, has a set up similar to what you're describing). I like the idea of reinforcing the charge tube AND attaching the tube to a forend that has rail on top. Some type of receiver bracket would also be good. I think the key is decoupling the barrel from the tri frame.

Have you had any success with your design?

 

[KULT]

If you want to do a PSG style rifle expect to break the bank on the correct parts to get it sub MOA.. Much cheaper to build another platform. Check out HKparts.net and see what the cost is for some of the parts.

 

[ORD]

HOLY NECRO-POSTS, BATMAN!!!

This thread was dead and gone for ~3.5 years before today's posts...the OP hasn't posted since 1/2011!!

Best of luck with your SG-1 project, jnfphd. You should head over to the HKPro forums for addt'l details, info, etc. Lots of quality information over there on recreating something along the SG-1's lines. If money/time/frustration are no object, there is a LOT that can be done to the HK platform to make it more accurate without sacrificing reliability for which the rifles are so acclaimed. The welded on T-rails, PSG/MSG cocking tube/handguard mod, etc. are but a few things. You can get into the PSG/MSG trunnions which will help support a longer/heavier barrel, upgrades of multiple kinds to the trigger pack to improve all aspects of the fire control system...the list goes on and on.

 

[jnfphd]

hey man, if you're the moderator, sorry, didn't mean to violate any forum rules. sure its an old thread, but sometimes it takes time to build a project rifle, as was the case with my Rem700. I thought Warrenator's write up was spot on (consistent with much of information at HKPro) and liked Heath's ideas about free floating the forearm. both timeless topics.

 

[JelloStorm]

hey man, if you're the moderator, sorry, didn't mean to violate any forum rules. sure its an old thread, but sometimes it takes time to build a project rifle, as was the case with my Rem700. I thought Warrenator's write up was spot on (consistent with much of information at HKPro) and liked Heath's ideas about free floating the forearm. both timeless topics.

Usually users bitch and moan people don't use the search features LOL.