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The 6.5mm Grendel Concept Rifle

18K views 342 replies 15 participants last post by  hcpookie 
#1 ·
Lets see if we can have some real fun with this one. Who's willing to help out? We're just looking for ideas here. Anyone good with photoshop?

At this point all we know is we're looking for a 6.5mm AK.
Given the caliber I think a DMR type rifle is the best config to go with, but what do you all think?

Now what about mags? Maybe I can cut and paste what has already been discussed in another thread.
 
#178 ·
#179 ·
Great pic find. Anyone have the magwell dimensions of a Galil?

BTW are any of those Galil Kits still around? The AR ones?
 
#180 ·
Got the Galil 12rd mags.No blocks or tabs .Seem normal but for a white stripe painted into the deep front groove.So it seems they possibly had some special purpose use.Nice mags too bad they must be mangled for scientific experimentation.Exploratory surgery scheduled for tomorrow morning.
 
#182 ·
pupwag said:
Got the Galil 12rd mags.No blocks or tabs .Seem normal but for a white stripe painted into the deep front groove.So it seems they possibly had some special purpose use.Nice mags too bad they must be mangled for scientific experimentation.Exploratory surgery scheduled for tomorrow morning.
Hope it's a baby boy! :headspin: As for the inside width, I believe the theory is that it is better to err a little narrow rather than too wide. Why? If too wide, I think cartridge cases then are too loose for an optimum upward push initiated by the follower and mag spring. After you widen the mag tube, you will need a new follower. The old spring should still work. A 7.62x39 un-modified follower might work. Will have to experiment. I may later be able to send you a modded follower, if needed.

The white stripe was the sign that the mag held rifle grenade-launching blanks. It is pictured on some Galil websites.

Can I shift our focus? I've been wondering what would make up a medium weight, medium stiff barrel for this project? Since the barrel is 6.5mm and not coming from another AK, let's optimize the barrel. If the concept is a mini-DMR (that's my desire) should the length be 18" or 20". Should the contour be custom diameter (I want a medium weight) or stick with the slender diameter and existing gas and sight blocks? Where will we be getting our barrels made? :confused:

FWIW, some may want a milled receiver, but I will, if I get to the build stage, be using a 0.050" thick stamped receiver, just for economy purposes.

What is the best detachable scope side mount and Weaver/Picatinny centered rail combination? What is the cost?
 
#185 ·
Butchered the Galil mag.Bit of a PIA.Mag body is soft mild steel.The latching tabs are held on by two built in peen type rivets on the back side thru the outer layer of sheet then a spot weld thru all layers.
It is cobbled back together with a ground on 47 follower.Cartridges stack nicely.Holds 9 maybe 10.Tabs are not back on yet and it is still to wide for a 47 magwell.The feed lip plates have to be ground wafer thin to get it down to the 47 width.The rolling ridges on the sides of the mag need to be shallower so the exterior is a little bit narrower to leave some beef in the feed lips.More work to do.Been working on other projects..some that I can shoot actually.
 
#187 ·
Here are pics of the unfinished galil mag adapter I have. When I bought them I found it was cheaper to just buy Galil mags than it was to buy AR mags so I put it on the 'way back" burner.
 

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#188 ·
Taipan,
Pupwag,

Do you both have 7.62x39 steel mags in 20, or 10, or maybe even 5 round capacity? I have been looking at the follower and am about ready to modify it. It would be best to try it in a 20 rd. It is a bit of a compromise on the shape, due to the overall banana curve of the mag doing the major dictating.

Are either of you skilled welders? I am not. Once upon a time, I could braze for auto bodywork.

OrdnanceGuy
 
#189 ·
LOL I have none of the above. That includes welding skills.
 
#191 ·
pupwag said:
Skilled no,hack yes.Got mags,got extra followers.Got access to Mig,Tig,Ox/Ac and a spotwelder.What are you hinting at,oh vague one.
Pupwag,

I am going to send you a modified follower to test. You have all the test components. We will see how it goes from there. I did not want to mislead anyone, so we need to test this first. The banana curve of the 7.62x39 mag, combined with the lesser taper of the 6.5 case, creates an ever-changing angle for the follower to "follow". I chose a compromise angle for the follower, so I am hoping that it will support the rear of the cartridge case for up to 20 rounds (thus the 5, 10 and 20 rd mag question), but probably not for a 30 rd mag. My test cases are approximations, not the actual 6.5 cases.

Sent you a PM. BTW, when the Galil mag was apart, you might peen or press the high ridges down.

*Taipan, if it works, I'll send you one.
 
#192 ·
Now that some of these other projects are finished.I can tinker with this some more.Had 30 cases lined up on the bench looking at the curve and the 223 curve is the closest by far.Even the 74 is too curved.Also got to thinking what the hell am I doing trying to fit the mag to the 47 magwell dimensions.Who said the 6.5 AK has the same magwell.No dimples ala RPK.Split the difference.Kinda forgot that there isn't anything to clone or copy.Use cheap available parts where convenient and do what ever you want with the rest.Aahh,nothing like a good belch of the mind to free room for more thought(especially when you have limited volume to start with) :confused:
 
#193 ·
Here's a really stupid but overlooked question that you sparked in my mind. Can we make the reciever in a way that will allow for unmoddified Grendel mags?
 
#194 ·
Probably,with a magwell "chimney" like an AR for that mag latch thingy.Don't know about feed angle.Looking at the pics of the Grendel 17rd mag it seems to be straight and folded from a single sheet-only one reinforcing rib.That maybe why there is only 17rds.More would need some curve and then making it gets much harder.10 rds is enough for the long barrel version but I would like 30 for the 21s clone.I'll measure an AR magwell and look at it more closely.Maybe I can borrow a mag to eyeball as well.
 
#195 ·
pugwag,

Follower was mailed yesterday, Saturday. I don't want to give my results because I am using approximations of the 6.5 Grendel cartridge case. It looks like it will work and then we won't have to worry about which mag to use. It can also be cheaper this way, since there are lots of 7.62x39 mags. If it also tests okay for 30 rd mags, so much the better.

When I test the original 7.62x39 mag with the 6.5 cases, I can get the first 3 and still have the rear of the case pushed up against the feed lips by the original follower. The 4th case does not get pushed up, so it sits low. With the modified follower, I get all 20 ...(oops, I don't want to give the results with my approximations of the case). We will wait for your test results.

I can think of one near-AR type magwell made from sheetmetal. That is the AR-180 lower receiver. The AR-180b uses AR-15/M-16 mags and magcatch. I don't know about the feed angle and heights, when mixed with the AK receiver and trunnion.

OrdnanceGuy :headspin:
 
#196 ·
PT, FWIW the dark bore Yugos are < $100 right now at CFS. Another thought, the $75 "80% kits" would be a real good thing to get right now. You could put whatever stock on it you like...

I'm probably going to order mine tomorrow - at that price, just too good to pass up, considering the application for this project. I gotta have one too! :D
 
#197 ·
OrdnanceGuy said:
I can think of one near-AR type magwell made from sheetmetal. That is the AR-180 lower receiver. The AR-180b uses AR-15/M-16 mags and magcatch. I don't know about the feed angle and heights, when mixed with the AK receiver and trunnion.
The AR-180 uses AR mags that have an additional slit in them for the mag catch (or is it the BHO, I forget now). In fact, the site I have saved in my favorites somewhere indicates you can use a dremel cut-off wheel to file the notch into the mag body. Its about a 10 minute job to make a plain AR mag fit the AR-180.

Are we in agreement that the closer the mag is to an AR curve, the better the fit? I'm wondering if there are some strange rifle mags out there somewhere that may be applied to our needs. I wonder if even a .308 mag could be hacked up. That would give us an absolutely straight mag. If that is the case, I bet that $20 sheet metal bending brake I have out in the garage could hack one together. I'd rather adapt an existing mag to the purpose, but hey...

What about Weiger mags? They are fairly abundant... right??? They are already built for 5.56x45 in an AK - right??? Here's the only place I can think of that has them in stock - seen them at gunshows lately...

http://www.interordnance.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=INTERORDNANCE.com&Product_Code=SARPSET


Speaking of 5.56 AK mags, rusmilitary.com is offering the AK-101 metal mags for around 40 GBP. That's about $80 per mag, but looking at the mags they would *perfectly* suit this project!

http://www.rusmilitary.com/html/c-deact_magazines.htm

 
#198 · (Edited)
hcpookie said:
The AR-180 uses AR mags that have an additional slit in them for the mag catch (or is it the BHO, I forget now). ...

Are we in agreement that the closer the mag is to an AR curve, the better the fit? ...

Speaking of 5.56 AK mags, rusmilitary.com is offering the AK-101 metal mags for around 40 GBP. That's about $80 per mag, but looking at the mags they would *perfectly* suit this project!
There are 2 versions of the AR-180. The original used the AR type with a slit for the mag catch and has no AR-15/M-16 mag catch (rectangular) hole with the stopper bump below it. To modify one takes slitting the new catch and pressing down the stopper bump. The newer "b" version uses straight AR-15 mags.

We are in agreement about the 6.5 Grendel working well with a curve closely matching and AR curve.

The problem of an original (edit: did not mean "straight") 5.56 mag for the 6.5 Grendel use, is that the mag is simply not internally wide enough. Simply cannot get a good double stack of 6.5 cases in it. Pupwag has split open a Galil 5.56 mag and re-welded it to make it wider.

I know the 7.62x39 mag is not perfect either, but it has the correct internal width. The banana curve is the problem. I modified a follower to support the 6.5 cases, without having to modify the mag tube in any way. I sent one to pupwag for further testing.
 
#199 ·
Roger that!


You know opening a mag & rewelding is a really good idea. I wonder - does it taper to the top to be a normal mag width? Or is it slitted & wider all the way to the top? I'm thinking that there's enough clearance that a normal follower could account for the "slop" that a wider mag would create, so long as the bullets can't ride under the follower - IOW, as long as the bullets are correctly forced upward by the follower, the follower doesn't have to fit all the way to the sides of the mag.

I would think that both Galil and Weiger mags would be perfectly suited for the job. Since IO is selling Weiger mags in a 4 pack + cleaning kit + mag pouch + sling for $50, that would be a better option. In fact, I'm going to order a few of those myself tomorrow... got other 5.56 projects to feed :D

Reason I say that Weiger mags may be better suited, is that since FAC is belly-up, I don't know of a good source for the (cheaper) used Galil mags.
 
#200 ·
hcpookie said:
... I wonder - does it taper to the top to be a normal mag width? Or is it slitted & wider all the way to the top?

(edit: new paragraph) I'm thinking that there's enough clearance that a normal follower could account for the "slop" that a wider mag would create, so long as the bullets can't ride under the follower - IOW, as long as the bullets are correctly forced upward by the follower, the follower doesn't have to fit all the way to the sides of the mag.

I would think that both Galil and Weiger mags would be perfectly suited for the job. Since IO is selling Weiger mags in a 4 pack + cleaning kit + mag pouch + sling for $50, that would be a better option. In fact, I'm going to order a few of those myself tomorrow... got other 5.56 projects to feed :biggrin: ...
The mag tube (big) sides need to be parallel, no taper. The relative positions of the cartridge cases need to be consistent all the way up.

The narrow 5.56 follower must be swapped out for a wider one. And of course the 7.62x39 follower is the correct width, but may have to tweak the angle of the supports. A narrow follower under all that spring pressure is not a good situation. Zig-zags sideways inside the tube.

Galil mags overlap at the front and back of the tube, so the spotwelds can be broken and the halves positioned wider, then re-welded. I don't know how the Weigers are. Do they have the back rib? Back ribs leave no extra steel to re-weld. Extra sheetmetal would have to be added, ribs probably removed, etc. Chinese/Norinco 5.56 mags have no rib. But they are difficult to find and a bit pricey.

*hcpookie, if the follower I modified tests okay, I'll send you one. It is for the 7.62x39 mag, 20 rd or less, will have to see if it works in a 30 rd.
 
#201 ·
Exciting progress guys. I'll be able to order on of the Yugo kits with my next paycheck. Maybe go with the original idea of the 24" M76/77 version.
 
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