Designing a Grendel IAR

[usar_ds]

16.5 inches, because that's the barrel length of the M27 IAR, Mk46 LMG, and LSAT LMG.

Perhaps also plan for a 12.5-inch barrel version, due to that length being used on a CQB variant of the LSAT prototype made for SOCOM.

nice!

[stanc]

Sorry, Stan is "stanc" who started this thread. He wrote some really great articles you may have read and his name (since it's already public-- I wouldn't "out" him otherwise...) is Stan Crist.

ARRGH! I was trying to keep it a secret! Sheesh!

He's a pretty swell feller.

Ha! Got you fooled, too, eh?

We get irked at some of the positions he takes sometimes, but he certainly helps keep everybody honest.

I keep trying to reform, but you know what they say about old dogs and new tricks.

[Variable]

ohh, my bad, i guess it was me that was confused. lol

i have been reading up on the general dynamics .338 norma mag beltfed MMG lately, and been thinking alot about how it needs a 6.5 gren SAW lil brother.

it will be interesting if anyone with a sear actually makes a dedicated one, and what direction they end up going with it.

I'd love to have a Grendel conversion for my Shrike, but since it took almost a decade to get it in 5.56.....


There is a guy in this thread over on Arfcom who is getting ready to run Grendel in his SAW.

http://www.ar15.com/forums/t_6_24/362809_M249_SAR_Project.html&page=9

To run 6.5 Grendel in a beltfed there are currently two hurtles, both of which are link related.

1.) You need to use Russki non-disintegrating links ala RPD style, and use an appropriate belt feed mechanism to handle them.

or

2.) Someone would have to actually manufacture disintegrating links for the 6.5 Grendel cartridge.

The number 2 option has never been actually explored to my knowledge. The standard M27 link won't play well with the Grendel cartridge in it's current geometry. Remember I said above that Stan sometimes takes positions we get irritated with? I just poked that monkey with this post.LOL

Stan is somewhat pessimistic about the chance of a functional disintegrating link being possible, while the rest of us are more optimistic. Regardless, Stan takes the Missouri ("show me") position, and without someone being actually motivated to incurr the considerable expense of designing, manufacturing, and debugging a link stamping assembly line--- we are at an impasse.

Stan doesn't see it in his mind's eye, but I think I do. If I had photoshop on my iPad I'd try to jerry-rig a photo of what I'm seeing, but I don't and I'm way too lazy to schedule an entire evening with an actual computer to figure it out (my computer-fu sucks).LOL

[bwaites]

I think an aluminum heat sink is an interesting approach. Could possibly be a very good idea.

JP makes heat sinked barrels, LRRPF52 has an MGI quick change upper if I remember correctly, Variable has a registered sear. As a group we could pull this puppy off without any cost but the barrels. I'd trust either Variable or LRRPF52 to put it together right, but since the sear is the legal piece that makes it work, that leaves it in Variables lap. A bunch of us will be in Utah in 10 days or so and we could discuss it round the campfire!

[Variable]

Ya'll are about 1600 miles too far over yonder bud.LOL

We still wouldn't have enough ammo either. Even if I burnt up what steel cased I have left now, it wouldn't really make a dent in any decent chrome barrel. I have a fair bit of Hornady and Wolf Gold MPT laid back for the zombiepocalyose, but it would take major coin to replace it, and the MPT isn't even to be had lately...

What would you be looking for data-wise?

Temps? I've been looking for an excuse to buy an IR thermometer. I want to measure suppressor temperatures anyway.

Burst group sizes at a certain distance? Doable. I can get plenty of PQC targets at work if I needed to.

Barrel life? That'd be the biggest bear. My pockets ain't near deep enough. This 12.5" LW build is stretching me already.LOL

I've still never learned how to do videos right. I'd have to email you the raw vid and then you could edit and post it I guess.


I don't think LRRPF52 would need to fess up his MGI upper though. I have extra upper receivers just laying here. It wouldn't be a biggie to simply slap one on a barrel if you needed two compared to each other or something.

To even compare two barrels you'd need a wealthy benefactor with an inside ammo connection though.LOL The cost would be up there!


I used to blast cases of M193 and M855 a lot when I was single and they were only about $150 a thousand. Things have certainly crept up a might in the interim.


If anyone could get a barrel and a large pile of ammo reasonably near me, I'd be more than happy to use one to see how hard it is to kill the other though.

[Variable]

On switchable barrels? I personally wouldn't go that route myself. Too much crap to wag already IMO. Colt didn't, and the M27 isn't either.

With a base load of 22 mags (M27 IAR loadout) between the gunner and whoever helps him hump the load, you are only looking at about 550 rounds. Any remotely reasonable firing schedule through a well made LMG/IAR barrel isn't going to be harmed by that IMO.

Skip the barrels and hump more mags. Put the meatwads in the burst pattern/cone of fire/beaten zone, shorten the bursts somewhat (since you'd likely be more accurate than a beltfed anyway) and I think it'd be okay.


LRRPF52 likes 5.56 for some things--- I agree with him about how you could hump and lay out more with 5.56. A 6.5 would be pretty interesting in an IAR though. Not a belt-fed, but a more specifically targeted group mailer. With a very well designed (non politically correct) projectile, I personally believe it'd be a "hit".


ETA: It looks like they spec the M27 for a sustained rate of fire of 36 rounds per minute.

http://www.manta.us/resources/pdfs/m27_productsheet.pdf

That's one 3 round burst every 5 seconds (without even factoring mag changes in). That'd burn through the 5.56mm 22 mag base load in:

3 round burts---
22 mags = 660 rounds
660 rounds / 3 = 220 bursts
220 bursts x 5 seconds = 18.33 minutes (1100 seconds)

5 round bursts---
22 mags = 660 rounds
660 rounds / 5 = 132 bursts
132 bursts x 8.33 seconds = 18.33 minutes (1100 seconds)

Basically it appears it can eat it's entire base load in roughly 20 minutes without harm if I understand their specs correctly.


If a well made 6.5 Grendel barrel presented the same sustained rate of fire it'd eat it's base load of 550 rounds in roughly 17 minutes (15.277 minutes plus mag changes).

So you'd give up about 15% of your firing time (3 minutes) in exchange for more penetration and down range energy. If the gunners were good and spent it wisely, I'd take that trade personally, but I'd likely defer to LRRPF52's opinion. My beltfed time was mostly spent on square ranges killing paper, steel, scrap equipment, and teaching the same later after crosstraining. As AF, I also had the luxury of our version of death before dismount as well.LOL Bandoleers and cans are pretty light when they're lashed down in the back of the PK or Duck or Hummer. Nowadays they even have fancy MRAPS.

[Michael]

On switchable barrels? I personally wouldn't go that route myself. Too much crap to wag already IMO. Colt didn't, and the M27 isn't either.

Agreed. If you are looking at an IAR as opposed to a LMG, no barrel change/spare barrel is needed. Being mag fed, heat will managed by the pauses to change mags.

[stanc]

To run 6.5 Grendel in a beltfed there are currently two hurtles, both of which are link related.

1.) You need to use Russki non-disintegrating links ala RPD style, and use an appropriate belt feed mechanism to handle them.

or

2.) Someone would have to actually manufacture disintegrating links for the 6.5 Grendel cartridge.

The number 2 option has never been actually explored to my knowledge. The standard M27 link won't play well with the Grendel cartridge in it's current geometry. Remember I said above that Stan sometimes takes positions we get irritated with? I just poked that monkey with this post.LOL

Stan is somewhat pessimistic about the chance of a functional disintegrating link being possible, while the rest of us are more optimistic. Regardless, Stan takes the Missouri ("show me") position...

A position that I still consider prudent. But -- thinking back on those (and other) discussions -- I see now that I was often more than a little obnoxious.*

You folks deserved better. So, rather belatedly, I offer my sincere apologies to all of you whom I needlessly irritated.




*Clearly, there was good reason why I was one of only two people ever to attain the rank of "Board Curmudgeon" on the old forum.

[bwaites]

Nothing wrong with the "show me" position, so long as it is tempered by the "somoeone has to have a good reason to do that" position as well!

I just don't think anyone has a good reason to invest the money, unless a .gov organization gets serious about offering the best possible option for the troops. (I'm not implying that the Grendel is that option, only that it would at least need to be evaluated if someone was looking for it.)

As an example, how many pistol trials have been announced, only to have companies spend gobs of money, and then have the government decide, "Lets just order a bunch more Berettas!"

[Variable]

A position that I still consider prudent. But -- thinking back on those (and other) discussions -- I see now that I was often more than a little obnoxious.*

You folks deserved better. So, rather belatedly, I offer my sincere apologies to all of you whom I needlessly irritated.




*Clearly, there was good reason why I was one of only two people ever to attain the rank of "Board Curmudgeon" on the old forum.

Nah. If I didn't understand the nature and style of your writing, I could incorrectly interpret it as being "obnoxious" once in a while, but I don't believe that is really the case. We've conversed enough that I believe I understand your approach, and you don't just follow the herd in anything, but just stick to your guns and are a stickler for proof. Just because I'm willing to run on a semi-educated hunch once in a while doesn't mean that someone doesn't need to hold my feet to the fire to help keep me honest.

Steel sharpens steel my friend, and you help keep the edge pretty keen around here IMHO.

[LRRPF52]

I think the whole concept of an IAR (mag fed) is flawed due to capacity limitations, even with reliable drum mags. Linked is really the way to go with the duty position.

What I see with the Russians is that they love 45rd RPK mags, but you don't see the RPK used much at all, while you do see the PKM as one of the most important weapons at the dismount level.

[stanc]

I think the whole concept of an IAR (mag fed) is flawed due to capacity limitations, even with reliable drum mags. Linked it really the way to go with the duty position.

I definitely agree. The only reason I even broach the subject of a Grendel IAR is because -- unlike a Grendel belt-fed LMG -- it appears feasible to create with existing technology, at a cost that should be affordable by an individual Grendel enthusiast.

P.S. I see that you're now a "Super Moderator," Paul. What super powers do you have?

[usar_ds]

Maybe this has been covered elsewere but would it be possible to get something like the mga mk46 (hk sear eligible) in 6.5 with rpd link compatibility

So 6.5 bolt, 6.5 barrel, widened fed trey slot, and modified feed paws.

Or would that not work

[stanc]

IIRC, arfcom member "sharky47" said some time back that he planned to Grendelize a Mk46, using RPD belts.

[Variable]

Maybe this has been covered elsewere but would it be possible to get something like the mga mk46 (hk sear eligible) in 6.5 with rpd link compatibility

So 6.5 bolt, 6.5 barrel, widened fed trey slot, and modified feed paws.

Or would that not work

I don't want to be a party pooper, but are you positively sure that a transferable HK sear is legal to run in a MGA MK46???

http://www.hkpro.com/forum/hk-nfa-talk/167821-transferable-sear-mga-mk46.html

I don't think it is, but I'd love to be wrong!

Reading the thread in the above link, and also reading MGA's FAQ page leads to me to believe they are playing a dangerously deceptive game with their wording. If their product was legal to run with a pre-86 registered pack or sear, I'm quite positive they'd be screaming it from the rooftops!