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Discussion Starter #1 (Edited)
Have been thinking of having a HK G3K made out of one of the HK91s, however, wondering is just cutting down the barrel an option or does one need to change barrels?
Looks like the front sight needs to be changed if you wish the grenade ring, plus change locking piece and hand guard ... anything else?

As always could use some real life experience for guide lines and smith options, either on line or off line.

Regards
John

Updated the thread as had started out asking: Does the HK G3K use the same forearm as on the G33, or at least one of nominally the same length?
And found the answer is yes, with additional searching: http://www.hkpro.com/forum/hk-long-gun-talk/113706-g3k-conversion-question.html
 

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Have been thinking of having a HK G3K made out of one of the HK91s, however, wondering is just cutting down the barrel an option or does one need to change barrels?
You could cut it down, but the profile on the barrel I suspect would be wrong for where the front sight would attach. Also the splines/indents at end of the barrel would be lost. I suppose you could do just a basic thread job. But when you can get a nice G3k barrel from HKparts for a bit over $225 dollars, last I looked, I figured why take the time to pay a smith to rebuild/refinish the gun the way I want, and then not seal the deal with a proper barrel?
 

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Discussion Starter #3 (Edited)
You could cut it down, but the profile on the barrel I suspect would be wrong for where the front sight would attach. Also the splines/indents at end of the barrel would be lost. I suppose you could do just a basic thread job. But when you can get a nice G3k barrel from HKparts for a bit over $225 dollars, last I looked, I figured why take the time to pay a smith to rebuild/refinish the gun the way I want, and then not seal the deal with a proper barrel?
The splines/indents can be "moved" (cut off, thread the inside and then attach on the threaded barrel). The G3K barrel was looked at (assume is RCM who makes nice barrels) but by the time I take a nearly new German HK91 barrel out of a German HK91 and replace with a US barrel one could also sell the HK91 and do a clone build or post ban receiver (the SAR8's were looking interesting for that ;-). Thus one has to decide how far past 100% German to go before it is easier / better / lower cost (selling the HK91 intact) starting over with a a clone receiver and doing a 922r compliant build. For the 33K went with one of the Vector guns that was built on an actual 33K parts kit and made a good shooter until it got "lost" (i.e. friend made me a deal I could not refuse as I was not shooting it between the MM53 and MM23eK ;-).


Also if one goes a clone build from a new receiver, can make a G3K pistol if a sear host mostly (but a SBR would still be interesting w/o the sear installed). Guess will wait and see if any of the current generation of HK smiths comes out with a run of G3K's ...


Thanks
 

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Thus one has to decide how far past 100% German to go before it is easier / better / lower cost (selling the HK91 intact) starting over with a a clone receiver and doing a 922r compliant build.
I've got a PTR-91 receiver sitting in the safe, a form-1 out for approval, and a RCM barrel sitting in the parts box... so you know which way I'm going.

When I looked at the cost for a G3k conversion of my 91 TSC wanted about $1100 to do the job. + the cost of the HK91. Parts, a ptr receiver, and Ghillies labor... about 1/2 the price. Yes, its never going to be quite as good as the 'real thing' but for a sear host/range toy it will suit my purposes just fine.

If at some point in the future I want to do an all German G3K, I've still got the 91 in the safe, and TSC is only 90 min away.
 

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have build a few give me a call sometime Brother..
918-696-8715
918-781-3939
Jeff

Have been thinking of having a HK G3K made out of one of the HK91s, however, wondering is just cutting down the barrel an option or does one need to change barrels?
Looks like the front sight needs to be changed if you wish the grenade ring, plus change locking piece and hand guard ... anything else?

As always could use some real life experience for guide lines and smith options, either on line or off line.

Regards
John

Updated the thread as had started out asking: Does the HK G3K use the same forearm as on the G33, or at least one of nominally the same length?
And found the answer is yes, with additional searching: http://www.hkpro.com/forum/hk-long-gun-talk/113706-g3k-conversion-question.html
 

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I had mine built by Mike at TSC. He cut the 91 barrel to length and added the grenade ring etc.. I also went with a 4 inch flash for now to avoid dealing with SBR. I love how it came out and it will NEVER leave my collection. I wanted it all German and I figured a 51 would make a better 308 sear host anyway. I bought a PTR PDW for that and it fills the need very nicely at a bargain price.




 

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Discussion Starter #8 (Edited)
I had mine built by Mike at TSC. He cut the 91 barrel to length and added the grenade ring etc.. I also went with a 4 inch flash for now to avoid dealing with SBR. I love how it came out and it will NEVER leave my collection. I wanted it all German and I figured a 51 would make a better 308 sear host anyway. I bought a PTR PDW for that and it fills the need very nicely at a bargain price.
.......
Thanks for the photos and ideas and looks good. Is there a 1x15 threaded muzzle under the pinned on flash hider?

Anyone have velocity data from a 12" 308 barrel using M80 (aka 308 ball) ammo?
- Looking at: http://www.m4carbine.net/archive/index.php/t-48392.html it appears that that " ... advertised muzzle velocity for the 12.5" HK417 with 175gr M118LR is 709 m/s (2,326 fps)..." A quick search finds in longer barrels (22" & 24") the M118LR being listed at 2600 fps plus or minus and thus in a HK91 one would expect it to be on the minus side of 2600 fps, for a loss of under two hundred fps (which agrees with a 30 fps per inch loss estimate).


Thus unless someone comes up with a reason to replace the barrel on the HK91, I am thinking down to two options plus an alternate:
- Option 1 being a German HK91 with the German barrel, along the lines of yours
- Option 2 being a clone built on a non pre-band receiver, if a virgin receiver then could be pistol/sear host while waiting on SBR paper work

The alternate depending on pricing and weight of the "HK"G3K is going with some type of a "HK"11ek (or the MM23eK with a 11eK kit), however, at this time appears the weight and price would be higher for the 11eK and while the 11eK would make a great sear host, it would not be as handy for off hand shooting as the "HK"G3K, besides have the MM23eK to do the heavy lifting for a sear host.

Appreciate a discussion on the details, merits and pricing of various options to create a "HK"G3K.
 

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Thanks for the photos and ideas and looks good. Is there a 1x15 threaded muzzle under the pinned on flash hider?

Anyone have velocity data from a 12" 308 barrel using M80 (aka 308 ball) ammo?
advertised muzzle velocity for the 12.5" HK417 with 175gr M118LR is 709 m/s (2,326 fps)..." A quick search finds in longer barrels (22" & 24") the M118LR being listed at 2600 fps plus or minus and thus in a HK91 one would expect it to be on the minus side of 2600 fps, for a loss of under two hundred fps (which agrees with a 30 fps per inch loss estimate).
.308 Velocity Comparison ( RRA 16, 20 and 26 inch) - Sniper's Hide Forums

175 HPBT Black Hills Factory (Red Box)
16 ave vel 2437 ES 141
20 ave vel 2465 ES 123
26 ave vel 2615 ES 103

Looks like the testing this guy did supports a 12" in the 2300 range, and the other long barrels are in line with the numbers you found.


The alternate depending on pricing and weight of the "HK"G3K is going with some type of a "HK"11ek (or the MM23eK with a 11eK kit), however, at this time appears the weight and price would be higher for the 11eK and while the 11eK would make a great sear host, it would not be as handy for off hand shooting as the "HK"G3K, besides have the MM23eK to do the heavy lifting for a sear host.
If you already have a MM23, the utility of a 11/13 is limited, unless you wanted the option for a SLIGHTLY lighter, mag fed option. Perhaps someday Mike will offer a mag adapter / bolt for the 23 and you can get 11/13 like functionality.
 

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G3k is a really fun weapon to shoot. Very controlable, doesn't loosen my fillings, add a 50 rd drum and it's a blast (20 rd mags just seem to empty too fast). Took mine to the range yesterday with a 22 kit (shortened barrel insert), and the lighter front end is also more comfortable to shoot.

PS. That 33 forearm may need to be opened up just a bit to fit the slightly wider 308 magwell.
 

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Discussion Starter #12
I had mine built by Mike at TSC. He cut the 91 barrel to length and added the grenade ring etc.. I also went with a 4 inch flash for now to avoid dealing with SBR. I love how it came out and it will NEVER leave my collection. I wanted it all German and I figured a 51 would make a better 308 sear host anyway. I bought a PTR PDW for that and it fills the need very nicely at a bargain price.
All - Would be interested in a detailed discussion on the "HK"51 vs G3K for a sear host. Obiefox I am assuming went with the "HK"51 as a sear host due to lower recoil and/or more impressive flames and muzzle blast?
 

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All - Would be interested in a detailed discussion on the "HK"51 vs G3K for a sear host.
If you want a 51k, I'd just pick up a PTR-91 PDW in .308. Readily available for $900. There is no way you're going to convert anything and be any where near that price point.
 

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Discussion Starter #14 (Edited)
I was trying to under stand the advantages of a "HK"51 as a sear host, they always appear not to be totally house broken ;-) ... at the moment trying to decide clone vs HK91 host for the G3K is hard enough (i.e. of course like a German G3K but would be one less HK91 in the herd).
 

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Go ahead and call mike and order a .308 kit with a short barrel for your MM23E-K. You know you "need" it. It will be somewhat heavier than the G3K but think how much cheaper 50 round belts are than 50 round drum mags.
 

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The PTR PDW is a no brainer for a cheap, fairly reliable, 51. I had one problem with the recoil spring binding and PTR was great to work with and took care of it. They make a great sear host with just a quick reweld of the carrier.

I think the G3k and the 51 are about the same as far a sear host goes. The 51 puts on a better show, but the G3k is no slouch in the shock and awe department...
 

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Discussion Starter #17
The PTR PDW is a no brainer for a cheap, fairly reliable, 51. I had one problem with the recoil spring binding and PTR was great to work with and took care of it. They make a great sear host with just a quick reweld of the carrier.

I think the G3k and the 51 are about the same as far a sear host goes. The 51 puts on a better show, but the G3k is no slouch in the shock and awe department...
Thanks, that is what I was getting at, however, from my point of view I am looking for a nice shooting moderate size host gun that can still fill in as semi accurate rifle (until the barrel goes ;-) vs a good show. How does the G3K compare to a full size HK91 to you?


Go ahead and call mike and order a .308 kit with a short barrel for your MM23E-K. You know you "need" it. It will be somewhat heavier than the G3K but think how much cheaper 50 round belts are than 50 round drum mags.
Too late a fellow addict (oops guess that is "shooter") already sent me a 50 round drum to try and of course will need a couple of my own. In your case after my "support" of your addiction (or is that "belt fed shooting hobby" ;-), the lease I can expect is similar support. But the "30 call" kit is someday soon, unless I break down and just get a MM21e to go with the MM23eK ;-), however, also shopping for lab equipment for the "other LLC" (i.e. the start up company that pays the bills ;-) so each in it's own time.
 

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Discussion Starter #19 (Edited)
Thanks everyone for the discussions on line and off line, ideas, photos and examples, it's appreciated. Now my decisions have to be sighting options (in particular if go with a PTR receiver might go with a rail) and between a nice clone G3K and making one of the HK91s into a G3K ... of course the easiest answer is do both, but not this year ;-).

I have had 3 G3Ks built the last one was the one I wrote up in http://www.hkpro.com/forum/hkpro-members-gallery/142358-moaxps-g3k-cqb-dmr.html
The others were just straight G3Ks without the 21E sight tabs - and one was sold and the other relegated to the back of vault since the last one shoots so well.
Thanks for the links and photos. The 21E sight tabs are interesting and do work nice with a low power scope, which the 21E sight tabs does get the scope down nearly on top of the rear iron sights, and thus the scope is as low as one can go for a scope w/o loosing the iron sights. In my case went with the rail on top of my MM23eK as an Aimpoint fit a little nicer / lower than on friend's MM23e with the 21E sight tabs. Figure the G3K would get a low to moderate power scope vs the Aimpoint on the MM23eK.

Any changes you would make to the last G3K if one was doing another?
 

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I have a HK91 coming in, and I'm going to have TSC Machine perform the G3K conversion. I have a spare A2 stock with a heavy buffer. So should I get a vented or non-vented HK93 forearm? Also, do I need a #18 G3K locking piece? Thanks!
 
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