Multi-purpose rifle
 

Gents,
Recently a SOTIC instructor mentioned the desire for a rifle similar to an SR-25 (precision semi-auto .308), but with a collapsible buttstock and a shorter barrel (perhaps under 20") that could be used for assault if needed. Is this something you would find useful? If so, how would you spec it out?

1. Barrel Length (and/or desired effective engagement range)?

2. Weight (would you sacrifice a thick meaty barrel for more portability)?

3. Caliber cababitly (is .308 and its variants good enough or does it need to take the short mags as well)?

4. If it came with two barrels, say an 11" for DA and a 22-24" for long range precision, would you switch them out for different missions or just keep a medium length (16-20")barrel on all the time.?

5. Optic, what would you prefer for this type of setup.?

Ok thanks for the help gents. If all goes well, you may see something at SHOT show.
Justin

I'd just offer some thoughts after having played with (and spent money on) this idea for awhile. I invested in just such a project about 18 months ago, and had John Noveske build me one of his Leonidas rifles. The thread with pics and full specs is here:

http://www.professionalsoldiers.com/...=10252&page=28

With 168 gr. Federal GMM, the muzzle velocity is about 2650 fps and the maximum PBR is roughly 325-330 yards. I use a Nightforce 1-4x optic in a Larue mount, which sits about 2.75 inches above the bore axis.

If I were to limit the engagement range to "assault" distances, I would need to hold low 2.5-3 inches with a 100 yard zero. That seems a little strange for someone used to shooting 5.56 all the time, but I'm sure training could make up for it. At 200 yards, bullet drop is 3 inches and at 300 yards it is roughly 13 inches. My ballistics software tells me that at 300 yards the muzzle velocity has dropped to approx. 2075 fps and energy to 1620 ft. lbs. I'll let you judge for yourself whether or not that is acceptable for your purposes, but IMVHO 11" is too short and will greatly impact the above ballistics, which are already a compromise.

Despite the loss of velocity and energy, I have experienced no loss in accuracy with the short barrel. However, if I were building another rifle geared towards smacking two-legged predators and thin skinned game at ranges from contact to 350 yards, I would go with a 16" upper in 6.8 SPC. My rifle and its ammo are pretty porky, and I would dislike humping them long distances. The 6.8 would avoid both problems and allow me to use a single lower with one stock, grip, sling, etc.

Also, despite people's tendency to complain about muzzle blast, I would not get a Krink-style FH again. It adds too much weight to the front of the weapon and does nothing for recoil reduction. Using a low power variable optic like the Nightforce, which is wonderful but has a 1.5 MOA center dot and a limited field of view on 4x at 300 yards, I would go with the PWS FSC in either .308 or 6.8. IMHO, it is much more important to get follow-up shots on target quickly than it is to mitigate blast in the rare instances where you might shoot this thing inside.

Good points, but try getting quick follow-up shots with a shorty 7.62 at night without a flash suppressor.

I think you will see the utility of it.

A can is even better.

TR

TR, ;)

Very nice, Tuukka, how does she shoot? :munchin

Thanks for the info so far fellas. The weight and portability won't be a problem like on an AR-10. The size will be only slightly larger than a 5.56 platform (longer by a bit). Also it will be largely polymer and Al so should be fairly light.
I have designed a muzzle brake that I'm going to try, to keep recoil down, that has a provision to reduce muzzle blast to the sides and rear (for shooting in a room next to your buddy). I'm not sure how it will work, but it could solve that problem. Right now we're looking at both a shorty barrel and a long barrel at 18-20. The barrels are quick detach so switching is pretty easy. I'll have to run some ballistics and see if there is much range difference between 18 and 20". The new Iron Brigade Armory bolt action sniper rifle has an 18" barrel and they claim 800yd capability, if I remember correctly. I'd love to hear more thoughts on this. Thanks,
Justin

Justinmd,

Have you seen the GI issued muzzel brake for the M14? It is was detachable and fitted over the flash suppressor. It has a catch that slid back and locked on the bayonet lug. I think I picked mine up from Numrich. It might be worth looking at in designing a adjustable brake.

Thanks for the heads up. I'll have to check that out. It could save me some trouble,
Justin

At the risk of moving to far out of my lane....If you get a chance check out this thread:

http://professionalsoldiers.com/foru...ad.php?t=15765

Thread originator is another QP Longrange1947 that has hands on experience with a system that may fit your needs.

The system is the LWRC Sniper Assaulter Battle Rifle (SABR). It is a .308 piston driven rifle in an AR configuration that takes the SR25 mags with available barrel lengths of 16" or 20". It will supposedly be available after Shot Show 2008.

For more detailed info check these:
http://www.lwrifles.com/forum/viewtopic.php?t=1278
http://www.lwrifles.com/forum/viewtopic.php?t=6

It will also be in one of this season's episodes of Future Weapons along with other LW products:

http://www.lwrifles.com/forum/viewtopic.php?t=527

Full Disclosure:
I am in no way affiliated with or have any financial interest in LWRC.

Justin:

You have no choice with what you are describing but to go with a AR-10 or SR-25 with all of its bulk and weight. Do you want a 7.62 based cartridge rim or not is the question. If you do, accept the weight and bulk of an AR-10 or accept shearing bolt lugs.

I was firing a JP 18" .308 upper on an AR-10 lower for the last couple of days and even though it had an exceptional compensator, the recoil was quite significant when firing issued M-118 Long Range ammunition. John Paul's compensator did reduce recoil but it would blow out a fellow's ear drums he he was standing next to the muzzle when fired.

You haven't yet given any really good physical criteria to detail your requirements. Such as penetration through a specific medium, engagement ranges for such penetration, terminal effects on the human body, etc.

IMHO -- you are asking for somthing bigger than the 5.56 but smaller than the 7.62. A issued service load in 7.62 NATO is pretty stiff -- M-118 or M - 80 Ball.

OK --- there are two relatively available cartridges that give you perhaps what you want and from an AR-15. The 6.8 and the 6.5 Grendel. There are also .30 caliber cartridges that are used with the AR-15 aside from the 7.62X39 but these cartridges are still pretty much wildcats.

Of the 6.8 and the 6.5 Grendel, one uses a bullet that is better in terms of teminal effects and one is better in terms of exterior ballistics to 350 yards which is what you said was your engagement range. Both have less than half the felt recoil of a full size SR-25 or AR-10 without compensators or muzzle breaks and both can be shot from the issued AR platform which is smaller than the AR-10 / SR-25 platform.

I prefer the Grendel believe it or not because I believe it offers a higher hit probability at ranges from 300 - 600 and IMHO if you put a 120 grain bullet into someone at 500 yards for example, it will put more kinetic energy into that person than a 63 grain, tungsten tip, 5.56 bullet at a lesser velocity (at that range) .

Both the 6.8 and 6.5 Grendel are high pressure cartridges for the AR platform and both will blast someone at ten yards as well as the other with half the recoil and at least 70% less blast than a carbine firing an issued 7.62 round.

It is my opinion that both the 6.8 and 6.5 Grendel will kill someone as readily as each other at ranges to 300 yards. However, my bets are on the Grendel in terms of hit probabilities at any range from 300 - 600 yards over either the issued 7.62 LR or M-80 or any loading of the 6.8 when fired from any platform while under stress.

I know why I say these things and won't get into someones pissing contest so you Grendel or 6.8 'Bots' out there -- if you think I care about your prejudices then think again.

That ought to stir the pot for you some. Maybe others have solid views too and that is how you will learn what is needed.

Gene

Gene:

Good advice, but don't count on finding a lot of 6.8 or 6.5 Grendel in the AO if you did not bring it with you.

TR

Gene - Funny you should open the 6.5/6.8 "can of worms" again. Solid argument from the ballistics perspective but not much else to recommend either one as a practical military solution. My gunsmith and I have been playing with rebuilding AKs ($750 worth of parts, etc. to have a $350 rifle - not counting what the "smithing" services are really worth :D ) for entertainment/education. (They make a fun "truck gun".) He's actually decided to put one together in 6 or 6.5 PPC just to prove the point. We discussed the 6.8 but I haven't checked for magazine compatibility. Too much fun tinkering on winter afternoons.

Short AR-10
 

Armalite makes a select-fire 7.62 carbine that for all intents and purposes is a 7.62mm M4. The barrel is a lighter profile (very close to the original M14 taper).

DPMS also makes a comparable carbine they call an AP4 I think.

The SR-25K is a piece of shit in my very limited experience and my singular personal opinion.

HK used to make a shortened G3-style carbine (HK 51?).

There are actually quite a number of weapons out there now.

As far as the SR-25K, I rank it with the rest of Knight's junk.

As far as the 6.5/6.8 controversy, unless it is developed to the point where I go to Joe blow and get ammo from him them you will eventually have a club instead of a rifle. Give it only to the Spec Ops, as has been mentioned before, and you have a signature round. All bad.

Heck Gene, there are a bunch of ballisticlly superior rounds out there, but they are not compatible with other systems and that severely limits ammo distribution or becomes a signature round. Or there are other sever draw backs such as barrel life.

My 2 cents. :D

RB:

Not pushing either cartridge and not trying to start debates over them. The individual mentioned an intermediate cartridge and of them all, it seems those two have gotten the most attention.

I personally have no stake in this game as it ain't my life that will depend on it but I do commend guys who finally realize that the fastest way to lower recoil and a smaller overall weapon is probably a smaller cartridge.

So lets see who pops up for TR to blast! He, he, he.

Gene

Sorry Gene, had not meant that to be phrased as a debate, my written abilities are somewhat lacking at times. :)

You coming my way anytime soon?

Gents, thanks again for the input. I should have been more specific. I am building a rifle to fit the needs of the operator. Which is why I seek your opinions. The caliber is, perhaps unfortunately, fixed at .308. I do like the 6.5mm and 6mm projectiles (I have a lovely 243AI). My preferece would be a .243 actually.
The rifle is about half done or so, making progress every day. I hope to have it done by SHOT, so you guys can come and see it at the Magpul booth and we can BS. I haven't gotten to the muzzle brake/flash hider yet though. With luck we will have a long and short barrel. I haven't decided if the long barrel will be 20 or 18", the short will be right around 12".
Anyhow, the project is not widely known and for now that is what I prefer, though I have no problem discussing it with the team guys, (other QP input is important I feel). If you have any specific needs or things you feel should be addressed in a rifle that you may (theoretically) use in the future, please let me know.
Justin

I find this thread interesting but can't shake my old beliefs that there is no such thing as a good multi purpose anything. A rifle is basically a tool for launching a projectile. A rifle needed for urban combat is going to be different than the one needed for long open spaces. We are not a army of marksmen anymore, haven't been since the VietNam war. We expend a lot of rounds into an area to make one kill. It used to be that there were a variety of weapons within an infantry platoon to cover a wide band of circumstances. Now everyone has the same basic tool.......

Jim

I have to agree.

This may be an interesting academic exercise, and may result in a nice toy, but IMHO, the practicality of a sub 16" 7.62x51 rifle is nonexistent.

If you have not had the pleasure of using one before, I suggest that you and your fellow employees take any shorty 7.62 of the length you are contemplating and make a few CQB runs with it through an indoor facility, preferably jocked up and without ear pro. If you care to really get a critical analysis, make baseline runs with an M-4, and another with a full-length 7.62 rifle. I think the scores versus times will show you the truth.

You might also consider the terminal ballistics of the 7.62x51 when launched from such an abbreviated tube.

TR

Justinmd - While you're working the MP rifle how about putting a bug in somebody's ear to make a quality replacement floorplate for AK magazines. I've got 20 surplus (some are well used) I'm getting ready to rework this spring for my project guns. Unfortunately the stock floorplates are uninspiring. You guys have done a bang-up job for M16 magazines (love the followers, not so thrilled about the Ranger floorplates, will probably have to try the "L" plate). You guys seem like the ideal source for something "a bit" stronger than the originals but NOT one of your Ranger types, just "a better quality similar to original" one (decent AK mag pouches are hard enough to find without adding another inch/extra bulk to the magazine). This should be right up your company's alley.

Jim:

I think the guys today are better marksmen than during other wars. I have seen significant and positive changes in how leaders view marksmanship these days which is essential in the long run. The NCO's are also much more knowledgable and are able to create a very good military marksman to a much higer degree than before. Surprisingly, I see this ability increase each year which is pretty remarkable in terms of the Army. Please understand I am speaking in terms of the Army which to most civilians would seem to be incredibly slow.

I hear guys talking about urban combat verses longer ranges. I think the average soldier today will take a shot at something farther away than an Infantryman in WWI, II, Korea, or Vietnam would attempt, but I doubt those distances are past 300 meters about 95% of the time for a multitude of reasons -- the primary one probably is that the guy just can't see that far due to terrain.

I have differing views of barrel lengths than most. I never viewed a 18 - 22 inch barrel to be a hinderance in terms of fast movement of the rifle. I do view the stock length and its ergonomics to be the critical factor in both speed and precision for a service carbine or rifle. The M-4 isn't bad to 300 meters but a M-16A2 with a collapsable stock is better and a guy won't notice the extra six inches of barrel what so ever when doing CQB. Not as loud as an M-4 either but who is listening anyway? He, he, he.

Gene

RB:

No sweat at all. Couldn't sweat today as I was blasting in rain and snow mix. I believe March is a good time to head your way. Doesn't violate my personal rules about not going east of the Cascades after 1 April due to the excessive heat and humidity of the subtropical area where you live.

I also can't wait to see one of 'Mr. P's' $1K AK-47's. Does he also have match rifle sights glued to that sheet metal upper and Soviet pot metal barrel I wonder? He, he, he.

Gene

Gene - Don't go laughing at my "truck gun" til you've fondled it! :p If you get here in March to visit RB we'll have to do the McKellars lunch and a range session to prove the point. TR made an offline comment about Galil kits that already have rear sight blocks, etc. I'm almost afraid to broach the idea to my 'smith. God alone knows what he might come up with if he feels "challenged". Blasted redneck arti'ste is what he is.

Incommin and TR, I definitely see your point. But one of the brother SOF units is looking for a CQB 308, which is partly where this whole thing came from. It will have a supressor mounted so maybe that will help out a bit, though make it longer of course.
The other barrel will be longer so it can be used to its full potential as a medium range sniper or DMR type rifle. The SOTIC guy I talked to had mentioned the long (18-20") barrel version but with a collapsible buttstock.
Peregrino, I will bring up the AK floorplate. Rich seems to like doing stuff like that because it is easy fit into an existing mold.
Justin

IMHO, bull pups are more a novelty than anything else. Now having said that, a action similar to a AR 180, bull pup in .308 would keep the overall length down.

Cut down the barrel and add a can?

Are these the same geniuses behind the Mk 23 Offensive Hand Cannon?

Well, they will look cool as hell, till they are shot down, deaf and blind, or figure out that it just doesn't work. Waste of good MFP-11 money.

Not SF, no skin off my nose.

Drive on with your bad selves.

TR

OK, you keep mentioning a or the "SOTIC guy", could you be a bit more specific, by IM if you find it more comfortable. The way you are stating this makes it seem as if SOTIC is endorsing this weapon. I can most assuredly, without reservation state that we are not.

The sister unit is having all sorts of problems because the barrel is too short to burn all the powder. Which means you have one heck of a blast and flame coming out of the muzzle. Not good. To help in clarifying this, only the sister unit is seriously looking at this weapon due to the problems stated.

I was wondering, would a different design in a can be better or possible? Something where the barrel would go farther into the can, the can having a chamber that goes back over the barrel. It would be a fatter can.

Many newer designs do that already, but as noted, the real problem here is that the barrel is too short for a decent amount of the powder to burn. A 12" barrel with a 10" can is not going to have the ballistics of an 18" or 20" barrel, it will be heavier, shoot dirtier, require more care, and will get hot faster, but it may have better sound and noise suppression.

I have used 7.62x51s from 16" to 26", and I sold the 16" shortly after I fired it. The 18" versions are not too bad.

At 12", you might get better ballistics from a 7.62x39. I doubt if it will be much worse.

The 7.62x51 was developed in the early 1950s. In the past 50 years, how many countries adopted a version with a barrel less than 18", for any purpose?

TR

I've got a FAL Para, the 'smith has a SOCOM 16, another buddy has a DPMS carbine; none of them get points for anything more than "cool factor" and portability. They're all uncomfortable to be beside when firing. None of them realize the ballistic potential of the 7.62x51 cartridge. But they do make great "blasters". :D I've pretty much decided I'm going to keep full size cartridges in full size rifles. (That's why I'm playing with the AKs - intermediate cartridge [relatively cheap too!] in an intermediate carbine.) FWIW - Peregrino

I don't mean to imply that anyone is endorsing this thing. We had sent some stuff over that way to sample and it ended up in one of the committee member's hands (I'll pm you his name), and he happened to mention that having a collapsible stock for the SR25 would be nice. So I figured I'd get some more input on the situation from other QP's and see if we couldn't sove that problem (with our already in design 308). I'm thinking the problem with a regular M4 style collapsible stock on the SR25 is that there is really no good place to put a sock/bag under there and there's not a good hook for your non-firing hand either.
So now that we have established that a shorty is worthless except looks and for submission to a certain other SOF unit, is there any opinions on the length of a sniper/DMR version. Is an increase in portability with an 18" barrel worth the loss in velocity compared to a 20- 22", how about even a 24". Or is that added portability a non-issue since a few inches isn't that much?
Justin