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Grendel vie six8 recivers
#1
Ok so I'm going to go ahead and drop the ball now even though I haven't finished testing yet.

Not to long back I seen a post on anouther site where someone had put a Larue upper on a six8 lower and had it running grendel from the 20 round mags he had.

So I ordered up a set of recivers and some 10 round and 30 round mags and got too testing.

So here goes.

First I tested the 10 round mags.

They will hold and feed 9 rounds of grendel straight out the pack. There is a limiter built into the spring retaining plate they I cut down to allow the mag too hold 10 rounds.

The mag will hold 10 rounds of grendel but is a lil harder too seat. But with that it isn't reliable. One mag will feed fine but my other has trouble feeding the first round every time.

So if loaded with 9 rounds of grendel it seats easly and loads perfectly every time. It will also seat just fine with 9 rounds in the mag on a closed bolt.

I also windowed one mag just to see what kind of coal length it would give me and it comes out too 2.350 coal length that I can load too with the mag windowed. If someone try's this don't damage the over insertion tab. If the tab is damaged are removed it makes the mag completely useless.

So on too the 30 round mag. The 30 round mag will hold 29 rounds of grendel. But I could not get it too feed more then 26 rpunds. The issue at 26 rounds is you can't leave the mag inserted in the rifle for long periods of time. If you do it causes follower binding and the top 5 to 7 rounds get real lose in the mag and stop feeding.

So I dropped down to 24 rounds. The mag seated nicely and feed properly but again if leavt inserted in the rifle for long periods of time, it would have the same issue's it had when loaded with 26 rounds.

So I moved on and dropped down too 20 rounds and ding, ding,ding winner, winner chicken dinner. It loads fine and seats easly and feeds perfectly and doesn't have the follower binding issue I had before when loaded with more rounds and leavt the mag inserted in the rifle.

I have some 20 round mags inbound soon to test but I'm confident that they will work just fine loaded full with grendel.

The 30 rounds work great loaded with 20 rounds of grendel but if though the 20 round mags cost more I would rather have the shorter 20 round mag holding 20 rounds then the 30 round mag holding 20 rounds.

On too the recivers.

The fit is super tight and the recivers are well made. I don't know what Lwrci coats their recivers with but God dang it is a pain in the butt too break them in. Most ar15 sets I have broke in only took maybe 100 too 200 cycles. These six8 recivers took close too 400 cycles to get them nice and broke in and smoothed out.

A side point I forgot above about the mags. The springs in these mags are without a doubt the stiffest dang mag springs I have ever dealt with in my life. Like 2x stiffer then the elander grendel mag springs.

Ok back to the recivers. They came with ambi controls. In short I hate them, they just cause drag and slow down the action and make it harder to seat mags. I guess I could see the use of such things in a combat situation or for the mall ninja crowd. But for me they are just junk, regular single controls are just perfect.

I will post some pics soon.

So there it is fellas. Lil data point for guys to think about. Not saying everybody should do this. Just wanted too do it and see what I could shake out.

I'm going to go out and say this now. If you read this post and your first thought is too bump your gums and post stupid options based on your feelings or whatever. Just keep your words too yourself. I don't want this turning into a stupid argument or third leg measuring contest. Take it for what it is a data point that the grendel community didn't have before today.

Enjoy fellas, pics coming soon, hopefully someone can help me post them since my pics always come out small and hard too tell what it is. Sneakyone where you at bro?


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#2
Interesting post Blaster, thanks.
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#3
Best I could do for pics fellas.


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#4
Hey A5 thanks for the testing and the info. Very cool. Can't wait to see how the 20 rounders work.
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#5
m796rider Wrote:Hey A5 thanks for the testing and the info. Very cool. Can't wait to see how the 20 rounders work.

Should have them by end of next week. Shipping from LWRC is well let's just say SLOWWWWW.

I have no doubts they will work fine.
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#6
Did you use the LWRC upper and lower 6.8 receivers or a 6.8 lower and standard upper? My barrel will not accept cartridges seated 2.30", I think I'm only .020 off the lands with 107TMK seated 2.260". This is pretty interesting though, this would allow a throated barrel to run 130gr or 140gr bullets without burying the bullet in the case.
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#7
This seems like a way to get some extra overall length to run some heavy bullets at pretty decent speeds?
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#8
centerfire Wrote:Did you use the LWRC upper and lower 6.8 receivers or a 6.8 lower and standard upper? My barrel will not accept cartridges seated 2.30", I think I'm only .020 off the lands with 107TMK seated 2.260". This is pretty interesting though, this would allow a throated barrel to run 130gr or 140gr bullets without burying the bullet in the case.

Yes LWRC SIX8 sized reciver and SIX8 pmags.
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#9
RobUrban Wrote:This seems like a way to get some extra overall length to run some heavy bullets at pretty decent speeds?

Cpd metal grendel mags allow 2.295 coal length. The SIX8 pmags only allow 2.300 coal.

Unless you window it then it would allow longer. I windowed a six8 pmag and I can run loads from the mag at a length of 2.360 comfortably. My chamber doesn't allow that length, just the windowed mag will allow that. Would need a custom throated chamber to use that kind of length.
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#10
Very interesting, thank you for taking the time to post this.
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#11
pacificpt Wrote:Very interesting, thank you for taking the time to post this.

No problem sir.

On a side note I won't be testing the 20 round pmags. The mags I ordered should have been here today. Well LWRC decided to wait till today to let me know the 20 rounders were out of stock. So I told them too change my order too 30 rounds and ship them out.
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#12
Well a surprising update.

I had downloaded the 30 round mags too 20 rounds due too the rounds in the mag getting a lose fit when loaded to a higher round count and leavt locked into the rifle.

Well I been playing with it more since I did that and what I found is the mags just needed a lil breaking in. I loaded them too 24 rounds and inserted and removed each mag probably a good 50 times.

Now the mags lock in and drop out easily loaded with 24 rounds and the rounds don't get lose in the mag when leavt locked into the rifle.

So now I have 3 30 round six8 pmags that hold 24 rounds of grendel (same round count as the elanders) and feeds properly.

So all in all I'm a happy camper and soon as New Frontier Armory gets their budget priced six8 sized recivers on the market. I will be useing more of these sized recivers and six8 pmags to build all my future ar grendel rifles.
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#13
The other guy that did this sanded down the outside of the mag bodies where the body is inside the magazine well.
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#14
LRRPF52 Wrote:The other guy that did this sanded down the outside of the mag bodies where the body is inside the magazine well.

Yea I haven't had to do that. I belive he said he did that so the mags would fit with his Larue grendel upper installed on the LWRC six8 lower.

I'm useing a full set of six8 recivers.

I belive it was just a matter of it finally breaking in good. Cause now the mags will hold and feed 24 rounds perfectly and the mags don't seem to take much of any more force to seat then any other grendel mag I have used in a standard ar15 lower.

Trying to find someone that has one of those 3d printer machines. And have them make me a SIX8 follower but the top section match a cpd follower and see if that will improve the round stack.

Once I get past 24 rounds. The rounds point downward to far and them jam against the mag.

I think a purpose built follower could improve the round stack enough to allow the mag to run 26 or 28 rounds of grendel.
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#15
Ok lil more testing and anouther update.

Seems the mags are still breaking in. I was at 24 rounds but today. My most used 24 round mag let me load 28 rounds and feed perfectly under fire 3 times from full to empty and locked bolt.

Ohh and I had mis spoken in my first post the 30 round mags hold 28 rounds of grendel not 29. But with a lil trimming of the legs on the follower I'm sure I could get it to hold 30 rounds of grendel.

So I'm going to back seat my most used mag and start working more with the other 2 and see if they will do the same after more use and allow 28 rounds to feed.
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#16
Ok update time again.

Got anouther 300 rounds throw the mags today. Had 3 failures all due to gas issues. Each mag is running 28 rounds of grendel from the 30 round six8 pmag.

The first few rounds to be chambered are angled down just a hair more then I would like. And what has happened is the bullet tip has carved some false feed ramps through the very top of the mags front edge.

After seeing that I figured the mags were toast but strangely enough they started feeding even smoother and seemed to have finally finished breaking in. Because the mags loaded to full are easy to insert and lock into the rifle now.

Will be working on a modifiyed follower soon. First I will trim the followers legs and see if I can reach the 30 round mark. If that works and has reliable feeding. Then I will work on changing the shelf angle and see if that will improve the round stack and help bring the bullet tips back up enough so they won't hit the front mag lip like they have done.

I will post a pic soon of what I'm talking about with the false feed ramps.
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#17
Update for the day.

Sat down at the work bench and went to trimming on parts. Got the mag to hold and hand feed 29 rounds of grendel. But it's not going to be possible too get 30 rounds of grendel into these six8 pmags. There just isn't enough room in the mag body for that many rounds.

So they will hold 29 rounds max of grendel but I'm going to stay at 28 rounds. I have 4 30 round mags now and the extra 4 rounds ain't going too make any diffrence.

So there you have it gents. Once broken in the 30 round six8 pmags will hold and feed 28 rounds of grendel.

Working on a better follower to hopefully help the round stack so the bullets don't lightly strike the front top lip of the mag. Lil more angle is needed like maybe 3 or 5 degrees in angle change is all.
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#18
Comparing the taper and diameter of the 6.5 Grendel case compared to the 6.8 SPC case I’m not surprised the nose of the 6.5 G set nose down at the top of the stack. It would be interesting to compare the curvature of the 6.8 PMag magazine to an ASC or E-Lander 6.5 Grendel mags. If the curve is similar then a Pmag with the follower shaped like the top of the 6.5 Grendel follower with the body of the 6.8 follower might just work.
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#19
VASCAR2 Wrote:Comparing the taper and diameter of the 6.5 Grendel case compared to the 6.8 SPC case I’m not surprised the nose of the 6.5 G set nose down at the top of the stack. It would be interesting to compare the curvature of the 6.8 PMag magazine to an ASC or E-Lander 6.5 Grendel mags. If the curve is similar then a Pmag with the follower shaped like the top of the 6.5 Grendel follower with the body of the 6.8 follower might just work.

That was my thinking as well. That just changing the shelf area of the follower may give that very small needed change in the angle too keep them from hitting the lip edge.

I'm waiting on word from someone right now that's working on that very thing. I don't have the tooling in my shop too hold and machine the follower like I think it needs.

I have some CPD grendel mags, I will see if I can get a good side by side pic of it next too the six8 pmag for comparing.
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#20
The sure fire way would be too add material to the mag lips at the area of the case just forward of the case lip. That would give the need angle increase.

But that would have to be done during the forming of the mag. I can't pull that off.

So I'm thinking with some well thought out tweaks and testing the follower may be the answer.

As it sits right now. The mags feed fine and the fact that the bullet tips struck the front lip and carved a lil feed ramp in the polymer of the mag doesn't bother me in the least.

But I know others may be bothered by this so trying to see if I can fix that issue.

Test, tweak, break, rebuild, repeat till it works.
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