Designing a Grendel IAR

[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 :p

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. :eek:

[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. :eek:

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/1...-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!

[cory]

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?

While I agree it'll be cheaper to build, from an engineering stand point, I think it'd be easier to design a reliable belt fed Grendel than a reliable 45+ round mag for the Grendel.

[usar_ds]

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/1...-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!

well holy crap, i just read that thread and re-read MGA's faq and yeah, there wording is deceptive (at least to me). wtf

[Variable]

well holy crap, i just read that thread and re-read MGA's faq and yeah, there wording is deceptive (at least to me). wtf

Yeah, same reaction here. Double WTF. It's like they are trying to play a $250,000 and 10 year federal felony joke on somebody. They appear to be playing with the definition of "transferable". The common definition of a "transferable" sear or pack amongst the NFA community is that it is a pre-86 civvy legal transferable. They are technically correct that a post-86 sear or pack could be transferred to another SOT, but that's not what their deceptive wording comes across as, unless you read it very carefully. Definitely not cool.

If sears were mobile outside their weapon "family" they'd be the Holy Grail of the NFA world. I wish it were so! Instead they are just revered artifacts of lesser power.LOL Now if I could get a Shrike style AR upper that takes 6.5 Grendel in RPD belts.... Booyah!

[Variable]

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.

Agreed as usual. I'd rather rock a belt. I guess we always come back to IARs because it's easier to acquire something like that in the civvy world.

I sort of envision a narrow engagement window where an IAR would be simpler and handier, but since the real world doesn't feel constrained to that narrow window, I'd default to a belt-fed where and when I could.

[Variable]

I frequently wonder if there couldn't be some kind of ingenious way (that I haven't seen yet, and can't personally envision) that'd stack 50 rounds of grendel in a P90 style mag that was somehow dead-nuts reliable, quiet, sturdy, and somehow unobtrusive while allowing rapid swaps and wasn't awkward on the weapon? That would really peak my interest, but I don't guess I'm asking for much am I?

[stanc]

...I think it'd be easier to design a reliable belt fed Grendel than a reliable 45+ round mag for the Grendel.

a. Is a 45-rd mag necessary? Doesn't the USMC use 30-rd mags on the M27 IAR?

b. Considering that 30-rd mags have long been made for 6.8 SPC, it seems like it should be no great feat to design and manufacture 30-rd 6.5 Grendel mags.

c. You force me to bring this point up, once again: It has not yet been demonstrated that viable disintegrating links can actually be designed/developed for the 6.5 Grendel cartridge.

[stanc]

Agreed as usual. I'd rather rock a belt. I guess we always come back to IARs because it's easier to acquire something like that in the civvy world.

Yes, that's the main reason I keep coming back to it. I view a Grendel IAR as an affordable approach to quickly create a concept demonstrator, which might inspire some entity to develop a belt-fed LMG in the caliber.

And let us not forget, the Marines currently use an IAR. So, there could possibly be military interest in a Grendel IAR as well.

[cory]

a. Is a 45-rd mag necessary? Doesn't the USMC use 30-rd mags on the M27 IAR?

b. Considering that 30-rd mags have long been made for 6.8 SPC, it seems like it should be no great feat to design and manufacture 30-rd 6.5 Grendel mags.

c. You force me to bring this point up, once again: It has not yet been demonstrated that viable disintegrating links can actually be designed/developed for the 6.5 Grendel cartridge.

Nor has it been demonstrated that a 30+ rd magazine can be made to mil spec requirements.

Do I think it can? Yes, with a wider magwell.

[stanc]

Nor has it been demonstrated that a 30+ rd magazine can be made to mil spec requirements.

Do I think it can? Yes, with a wider magwell.

IMO, a wider mag well, a la that of the LWRC Six8, would certainly be desirable. But, since standard-width, 25-rd 6.5 and 6.8 mags are available, and Barrett has made a 30-rd 6.8 mag for use in standard-width mag wells, I see no reason to think that such a 30-rd mag couldn't also be created for 6.5 Grendel.

In contrast, there is good reason to doubt that viable disintegrating links for 6.5 Grendel are actually doable.

[dobrodan]

Agreed as usual. I'd rather rock a belt. I guess we always come back to IARs because it's easier to acquire something like that in the civvy world.

I sort of envision a narrow engagement window where an IAR would be simpler and handier, but since the real world doesn't feel constrained to that narrow window, I'd default to a belt-fed where and when I could.

Well, I suspect you have walked down the normal route of one beltfed vs one magfed. The beltfed would win just about every time.

However, if you stack one beltfed against TWO magfed, I think the odds would be stacked the other way, even if the beltfed had a QCB. (at least if the barrels of the beltfeds and the magfeds were of similar profile.

Two magfeds would give:

-Better precision
-higher firepower for a short window of time
-be able to take out a higher number of targets inside a given window of time
-no firebreaks if properly used
-better mobility

Or, you could have two beltfed lightweight lmgs, without QCB, like the KAC LMG. Which would give you many of the pros, and even lose some of the cons with small magazines.

I am not a big fan of QCBs in the classic offensive infantry-role. IMO, it should only be brought along when you have large amounts of ammunition readily available, like in a defensive position.