Piston 5.56 Rifles

I have a great problem: I can't decide which of my 5.56 piston carbines should be "go to" in an emergency. Each design has positive and negative attributes.

Bushmaster ACR

Positive Attributes

+ Hammer forged free floating barrel with 20k service life;
+ Side folding stock;
+ Durable stock design with maximum adjustment capabilities;
+ Monolithic upper rail (not really a benefit, but some like it);
+ (Ambi) Reciprocating charging handle with "real" forward assist capability;
+ Effective flash suppressor;
+ Ease of bolt group disassembly;
+ Multiple QD sling ports.

Negative Attributes

- Factory BUIS are PLASTIC;
- Two position adjustable gas is only for "regular" and "suppressor" use. An "adverse setting" does not exist;
- Rifle is HEAVY and unbalanced feeling;
- Rifle lacks extensive military testing;
- Safety feels "mushy" and is not positive.

FN Scar-16S

Positive Attributes

+ Extensively tested by US Military;
+ Hammer forged free floating barrel with 20k service life;
+ Side folding stock;
+ Monolithic upper rail (not really a benefit, but some like it);
+ (Ambi) Reciprocating charging handle with "real" forward assist capability;
+ Light weight;
+ Effective muzzle brake;
+ Ease of bolt group disassembly;
+ Multiple sling ports.

Negative Attributes

- Chrome lined bore (I've grown to prefer nitrided bores);
- Rear BUIS does not lock into up position;
- Removing gas piston (after extensive firing) is difficult;
- Plastic stock latch is prone to break;
- Non standard (read: AR15) trigger components (not an issue as I have a spare set + a Geissele Super Scar);
- Non standard sling ports are prone to wear with HK style hooks and therefore require unconventional attachment solutions;
- Buttstock has nice adjustable cheek weld, but polymer feels very flimsy;
- Two position adjustable gas is only for "regular" and "suppressor" use. An "adverse setting" does not exist.

LWRC M6 Individual Carbine - Enhanced

Positive Attributes

+ Hammer forged free floating spiral fluted barrel with 20k service life;
+ Barrel weight is 20% lighter than unfluted of same diameter;
+ All gas components are NiCorr treated.
+ Unlimited pistol grip options (AR15);
+ Unlimited stock options (AR15);
+ Monoforge upper provides enough "receiver" rail for RDS and magnifier;
+ Ambi charging handle is enhanced with superior construction and oversized pivot pins;
+ HIGLY effective tuned flash suppressor;
+ Ease of bolt group disassembly;
+ Fail Zero coated BCG adds lubricity and is easy to clean;
+ 100% ambi lower (bolt release; mag release; safety);
+ 9" free float handguard system that allows user to install rail sections were needed;
+ Factory BUIS are best on market;
+ Multiple QD sling ports;
+ Lightweight for rifle with mid-heavy barrel.

Negative Attributes

- Two position adjustable gas is only for "regular" and "suppressor" use. An "adverse setting" does not exist;
- Factory trigger is awful;
- Rifle did not pass the military's Individual Carbine tests (neither did the HK 416...).

POF P-15 Minuteman

Positive Attributes

+ Hammer forged barrel with 20k service life;
+ All gas components are nitride treated or stainless;
+ Unlimited pistol grip options (AR15);
+ Unlimited stock options (AR15);
+ Charging handle is reinforced and easy to manipulate;
+ Ease of bolt group disassembly;
+ Fail Zero coated BC and chrome add lubricity and are easy to clean;
+ Roller cam pin reduces wear on the receiver, and makes operation very smooth;
+ E2 extraction technology (simple description: modified and IMPROVED HK fluting) works amazingly well for such a simple concept - all 5.56 rifles should use this tech;
+ Amazingly crisp 4.5# factory trigger group;
+ Gas piston system is essential FAL and easiest of all four designs to disassemble.

Negative Attributes

- Three position adjustable gas is only for "regular" and "suppressor" and "off" use. An "adverse setting" does not exist;
- Rifle does not include BUIS (however the front BUIS mounts on the gas block which is a positive attribute);
- Rifle is limited to MagPul "MOE" midlength handguard owing to the gas piston design;
- Rifle lacks extensive military testing.

Here's a summary analysis...

Bushmaster ACR

This rifle had unlimited potential, but Bushmaster's "engineers" (I use this term exceedingly loosely) were unable to capitalize on Magpul's vision. From everything I've read, the Remington Defense version addresses the issues I have with this gun:

1) Its way to front heavy. The QD barrel and stupid M4 profile added to this problem.

2) The rifle is too heavy overall. Remington's revised rails system and "ultra light" allow lower should help.

3) The safety is plastic and not positive. Remington uses an allow lower, and hopefully metal safety components.

All of this is academic, because I have the Bushmaster version and the RD version is not available to civilians.

FN Scar-16S

This is clearly a rifle designed for special operations troops. It has great pedigree (its FN) and is manufactured by a company I trust (again, FN). However, owing to the need for lightweight construction I worry about the durability of the buttstock assembly. Additionally, why not add 0.01 ounce of weight and have a locking rear sight? The front sight has a complex locking mechanism.

LWRC M6 Individual Carbine - Enhanced

This is likely the finest evolution of the AR15 design to date. It addresses virtually every concern I've had with AR15s. The factory trigger group is AWFUL, but this is easily remedied. I have a Geissele SSA-E in mine.

POF P-15 Minuteman

I feel like this AR15 is someone's attempt at combining DI AR15 accuracy with FAL or even AK simplicity and reliability. The net result is a simple to operate, highly accurate, and 100% reliable rifle. It lacks customization capability, but for someone wanting a KISS Piston AR this is definitely a "best buy".

I'd probably go scar or LWRC but I've got limited experience with booth. There are some kits that allow for a different stock on the scar.

The ACR is definitely out of the running. The POF is just second to the LWRC in the piston AR realm.

It's really a debate between the Scar and LWRC.

I change my mind daily, but think extended testing will prove one over the other.

Yeah. I wish I had those guns to test lol

Adams arms? I have loved mine and minor non-government spec parts is a big plus to me.

Gary, what is your take on a box stock Colt AR15A3 with the carbine length barrel (can't remember the model number but I've had it for 15+years).

Randy,
I'm moving away from DI altogether. One niece and one nephew just returned from Army Basic. We asked them to document the number of failures their issue M16A2s experienced. One had 9 difficult to clear and the other stop counting.

Granted these are worn out basic training rifles that get disassembled by newbs, but the rifles loosening up should actually INCREASE reliability. The AK is sloppy and Works as a result. It is designed to be loose, but the point stands.

If I were going to chose a DI rifle it would be a Colt 16" lightweight (like the 6520 with fixed sights or 6720 ...preferred...with "flattop" so I could mount an Aimpoint T-1...4oz RDS) or a BCM MidLength with Aimpiont CompM4S.

The BCM would be my preferred choice.

IIRC you have a 16" heavy barrel without flash suppressor. The weight of the HBAR is a waste, and sans FH is a no go for me.

It would be easy to have your department armour to swap out the barrel for a Colt LW or BCM ML. You'd be go-to-go (for a DI) then.

BTW - your Colt has non mil standard FCG parts (pin diameter is larger as is the corresponding hammer, Disconnector and trigger). If a replacement is needed you'll have to find old Colt parts. Colt started using standard around serial number LE63000 on their LE marked guns and now uses them in all.

Randy, you could be much worse off. If you asked about an Armalite, Bushmaster, DPMS, Rock River, Smirh & Wesson, etc....

I'll have to check on the model number etc. later on today when We get back home. It IS a flat top model.

Department Armorer? What's that. Seriously, we don't have ANYONE that does anything like that "IN HOUSE".

Each Deputy is allowed to purchase their own handgun. Right now the Boys are running 9mm, 40S&W and 45acp.

The DEPARTMENT has issued 12ga pumps (mossburg?) and milsurp M16's. IF (Ok WHEN) a department weapon needs working on it goes to one of the local self taught "Smith" locally.

Dang you must live in the sticks Randy lol

You could say that Mike. We have 32 employees. That is Deputies, jailers, dispatch AND office workers, everyone! We only have SEVEN deputies!

Randy,
You could put one of CDNN's $799 LWRC M6A2 with Flip Sight uppers on your Colt lower.

$699 without sights
$799 with sights

$100 for a SET of LWRC's remarkable Skirmish Sights makes the $799 deal even better. I've paid $200 a set for them.

The M6A2 is a self regulated piston system with free floating quad rail and 20,000 round service life hammer forged barrel.

Sell your Colt upper for $350-$400 and have a M A S S I V E upgrade for $400-$450 net.

In 31.5 years of AR15 ownership, assembling, shooting, and trading (I've had a remarkably high number of ARs pass thru my hands) I've have yet to see or experience a single lower receiver failure. I did have an EXTREMELY low quality cast lower in the early 1990's that was grossly out of spec....but it still worked.

This is why I've sold my extra complete rifles. I bought two spare LWRC uppers as replacements for the couple of complete rifles I kept. I have no worries about wearing out the complete rifle lowers, but the uppers I could eventually wear out.

OK. MY Colt AR15A3 Tactical carbine is as follows:

Marked Colt AR15A3 on the lower receiver. Below that is
SN BD002915 (only thing I can find is this/ BD000134 and Below - Pre-Ban (AR-15A3 Tactical Carbine - very rare model).

On the barrel is marked CMP (I THINK) and 5.56 Nato 1/9 Hbar.

It also has the flat top forward assist W/case deflector.

I THINK it is model 6721, but there isn't any other markings on it that I can find.

Oh and it does have the detachable carry handle as well.

I read your post again Gary and Mine DOES have a flash hider. It is VERY similar to this one, but the bottom side is solid with the slots only along the sides and top.

http://www.midwayusa.com/product/343064/dpms-flash-hider-a2-1-2-28-thread-ar-15-matte
AND mine also has the bayonet lug. JJ sent me a bayonet for it and the "Lock up" rattles a little due to the "Ring" being to large but other than that it fits nicely.

YUP, this looks like what I got. AND I bought it somewhere late 1994-early 1996.

The AR6721 HBAR model.

http://www.colt.com/Catalog/Law-Enforcement/Products/Colt-Tactical-Carbine
Click on the Tech Specs section under the picture.

I've had a 6721.

Your rifle is fine for someone wanting a HBAR DI. You have a very good Colt that would address most peoples' AR needs.

I'm not a fan of: Carbine length gas systems, HBARs, fixed front sights and DI guns. However, that's just my opinion.

ETA: if it works for you don't worry about it.

Regarding the fixed front sight....

I PREFER them if I don't plan on using an optic. I always coupled them with a LMT fixed A2 rear sight. However, I equip all of my social rifles with an optic and UBER PREFER the uncluttered FOV of a flip down front sight.

Today's high end optics are of such quality and durability to actually render flip sights as true "back up" status.

Wouldn't own a rifle without METAL BUIS.

If I planned on running an AR with iron sights only I strongly feel the best option is the fixed front with A1 Rear. I hate that Colt "upgraded" the 6420 from an A1 rear to a A2 rear and renamed it the 6520.

The super lightweight 6420 was the perfect DI KISS Carbine at 5.6#. The 6520 is the same but with unnecessarily complicated and more fragile A2 sights. I have no illusions of shooting 500 meters with the 6520's super LW barrel profile. Let's face it, the 5.56 has ballistic limitations anyway.

Thanks for the info Gary. Yeah I figure that this will serve me well for MANY more years to come.

After training with them I will take static 45deg offset sights all day long over pop ups. As you said Arch less complicated (read failure points) and always ready if needed.

I've only had one set of 45d offsets, and didn't keep them long enough to form an opinion. I like the idea and should explore it further. I'd also like to try a 45d T-1 sistered with an ACOG.

greaser, are your sights fixed or flip?

They are fixed.
Kind of hard to see here but.

Any problems when firing against a barrier (weak side)?

ETA: I love the fixed stock. Have the same on my POF. Very solid and comfortable.

Piston rifles interest me quite a bit. Anyone have any experience with Adcor Defense? The forward charging handle intrigues me.

No experience here. My AR piston experience is limited to:

LWRC M6A2
LWRC M6A2 Stretch
LWRC M6A3
LWRC M6 SL
LWRC M6 IC Enhanced Basis
LWRC M6 IC Enhanced Spiral
POF Minuteman
POF Puritan

Seems like you've found a couple brands you like Gary.

I'll say.

I tilt the rifle so it shouldn't be too much of a hindrance although I must admit I haven't tried that with this set up yet. (I will now though)

Thanks Yeah I love the fixed stock it is one of the best updates I have done to this rifle.

I only kept:

LWRC IC Enhanced Spiral
POF Minuteman

I bought a spare LWRC upper to go with my two compete LWRC rifles.

The upper can work on the POF lower too. Lower receivers almost never fail, but you can wear out an upper.

Maybe SOME of you can, but I don't think that I ever will.

It takes a lot of rounds or abuse to wear out a quality upper.

Doubt I'm going to be that guy lol

you keep up the 3 gun and I wouldn't be so sure about that.

Same thing I was thinking Greaser.

great minds think alike.

Haha. Hey did you see my post in the Gun talk thread. I though what I found out was interesting.