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My neighbor tells me after shooting his piston AR it's far easier to clean than the non-piston type. (don't recall the terminology for the non-piston AR) He tells me his BIL owns the non-piston type AR and it's a headache to clean, burnt powder all over action, hither and yon...

Does anyone else think this is so...?

Also, once the craziness settle and prices aren't totally out of reason, I'm interested in buying a Colt LE6920, however, I don't know if this model is available to non-LEO's or frankly if the the LE model is superior to the civilian model and if it's a piston/non-piston type rifle.

Can 5.56 and .223 rounds be shot in both LE and Non-LE models.

Anyone know the answers?

Thanks.

I've done some research and my google-fu is minimal...though I did find the twist rate to be 7:1 on the Colt LE 6920 - though I'm not at all certain that that's particularly better than 9:1...

I would have to agree with him that Piston Guns are much easier to clean than DI (Direct Impingement) guns as far as the bolt and chambers are concerned but thats about it. The DI guns blow hot, nasty gas back into the action to blow the Bolt back and chamber another round. Piston guns blow the gas into a Op-Rod that then hits the Bolt and knocks it back and any excess gas is ported out the gas block. LE and Non-LE shouldn't matter as far if the will fire .223 and/or 5.56mm. If the barrel is marked 5.56 then it will function safely with both rounds. If it says .223 then that's all you should shoot in the rifle. The rounds are pretty much identical but the 5.56 are usually loaded to a higher pressure. Colt 6920's are Mil-Spec, DI guns and they are fine weapons. They are NOT piston driven. Besides the fact they have a 16inch barrel instead of a 14.5 is pretty much the only difference between them and the M4s our troops carry. Oh and the select fire capability but i am sure you already knew that. I own a DI rifle and unless you fire thousands of round without cleaning or fire it suppressed then its not bad to clean. Even piston guns get filthy if you fire them suppressed though since gas comes back down the barrel and into the chamber.

Oh and Piston guns are generally about a pound ,give or take a few ounces, heavier than DI guns. You also asked about twist rate. There is nothing wrong with a 1:9 twist if you are shooting 69 grain or lighter bullets. 55 grains is the most common .223 bullet weight. A 1:7 twist rate allows you to shoot the heavier .223/5.56 rounds like the 75 and 77 grain ones. The heavier bullets are the same diameter so of course the have to be longer to get the added weight. The tighter 1:7 twist rate is required to stabilize the longer bullets. I have heard that some 1:9 guns stabilize bullets heavier than 69grains but you will need to try your gun and see. For the most part though 69 grain is the max bullet weight/length that will stabilize reliably in 1:9 twist barrels. You can shoot at paper at 100 yards and look for keyholing to find out. Also, if your groups open up a ton then your barrel probably isn't stabilizing them correctly.

Abraham wrote:
Also, once the craziness settle and prices aren't totally out of reason, I'm interested in buying a Colt LE6920, however, I don't know if this model is available to non-LEO's or frankly if the the LE model is superior to the civilian model and if it's a piston/non-piston type rifle.

Can 5.56 and .223 rounds be shot in both LE and Non-LE models.

..

The answers to your questions are yes in above.

I've owned several AR with the standard GI systems, and I've never owned a GP AR, and they may run cleaner, but I think that the whole thing is way overstated. Clean your gun thoroughly, then treat the internals with a good surface treatment like FrogLube, then don't worry about it. Shoot your gun, clean it once in a while. Not a big deal. Also, depending on which gun it is, the way some GP systems vent the gas out, it covers the forend in in a fine layer of soot and carbon. So maybe your bolt is clean, but your off hand is dirty. Six, meet half dozen.

Thanks everyone for your excellent help.

The only questions left is the difference between the LE and civilian models of the Colt 6920 and the particulars (other than higher pressure) between the 5.56 and .223? Greater reach? Or...?

Thanks again.

Abraham wrote:Thanks everyone for your excellent help.

The only questions left is the difference between the LE and civilian models of the Colt 6920 and the particulars (other than higher pressure) between the 5.56 and .223? Greater reach? Or...?

Thanks again.

Colt makes about 30 AR type rifles. The 6920 is their basic AR, it shares many of the refinements that make the M4 a CQB workhorse for our troops. The 6940 is similar but comes with a pop up irons instead of a carry handle, monolithic top rail and improved buttstock. 6921/6941 are 14.5 inch barrels.
To compare the various Colt models use these two links.
http://www.coltsmfg.com/Catalog/ColtRifles.aspx
http://www.colt.com/ColtLawEnforcement/ ... rbine.aspx

For your questions in regards the NATO 5.56 and the SAMMI .223 Remington, http://www.gundigest.com/ammunition-rev ... 23-vs-5-56

Wow, the 6920 no longer has a carry handle, has pop up irons and the improved buttstock.

My LMT MRP Piston was a solid gun. Stayed clean and never had an issue, even when pushed hard. However, so does my Colt, and it is considerably lighter. Though it was a "working gun" that I used for patrol, I'm not doing water insertions or operating in many austere wet or dirty environments for extended periods of time utilizing regular full auto firing, it wasn't worth the added weight.

Abraham wrote:Thanks everyone for your excellent help.

The only questions left is the difference between the LE and civilian models of the Colt 6920 and the particulars (other than higher pressure) between the 5.56 and .223? Greater reach? Or...?

Thanks again.

There is no ballistic advantage at all to the higher pressures of 5.56 over .223, but there is however a more than theoretical difference in personal safety if you put the wrong ammo in a .223 rifle.

In my experience, and the current shortages and panic buying aside, 5.56 is more plentiful and cheaper for general use. Since you can still safely and accurately shoot .223 in a 5.56 chamber, it doesn't really limit your ammo choices if you buy a 5.56 gun. However, if you buy a .223 gun, your ammo choices are limited to .223 only.

The advantage is in favor of 5.56 chambers from a purely practical perspective, and if we were spending my money here, that is what I would want. In my personal experience, the practical accuracy difference is negligible and is more a matter of speculation than any practical application. If I were buying a highly accurized bolt action varmint rifle, I would buy a .223—but mostly because they don't really make as many highly accurized bolt rifles in 5.56, so the available selection of models is larger. But for a semiautomatic general purpose carbine/rifle—and the vast majority of civilian owned AR15s fall into this category—5.56 NATO chambered guns are a fine choice. By "general purpose," I mean a gun that is going to be used for everything from hunting, to home defense, to plinking, to target shooting, to CQB.

Also, and I am not intimately familiar with the Colt products, but it is worth investigating whether their .223 rifles are truly .223. I have heard it said and even seen it here on these pages that, with the exception of their match rifles, those rifles marked .223 are actually 5.56 chambered and that only their match rifles are true .223 chambered. I would love to own a Colt, but when I was on the market for AR15s, building my own was what I could afford. (As it is, I have an "unofficial" Colt part in my carbine—the upper receiver being an early Cerro Forge item, which is what Colt uses, or used to use anyway, in their own rifles. I say mine is an "early" example because it lacks the M4 receiver cuts.) Anyway, the particulars of my mongrel dog AR aside, if I could afford to buy a Colt today, I would buy one, and I wouldn't buy a .223 only version because in practical use it would be a limiting factor. I would buy the 5.56 version and be very happy to own it. Certainly, whatever quality Colt brings to the table would be found in either chambering, but the 5.56 version would be more versatile, without really making any sacrifices.

Reading material about cartridge and chamber differences between .223 and 5.56 NATO:

• http://www.cheaperthandirt.com/mediapag ... ediaid=316, an overview of the differences.
• http://www.m4carbine.net/showthread.php?t=55149 - this one shows cross-sectional photos of of the differences between the .223 chamber leade and the 5.56 NATO chamber leade. Look at the pictures, and you'll immediately understand why 5.56 ammo is unsafe in a .223 gun.
• http://www.combatsimulations.com/ar15/223vs556.html, a short dissertation on the practical dangers of mixing ammo, and the proper responsibility of the gun's owner.

Lastly, buy the 5.56 gun, and then pick up a 6.8 upper for it with upgraded barrel, optics, etc., and you will greatly expand the gun's usefulness.

gigag04 wrote:My LMT MRP Piston was a solid gun. Stayed clean and never had an issue, even when pushed hard. However, so does my Colt, and it is considerably lighter. Though it was a "working gun" that I used for patrol, I'm not doing water insertions or operating in many austere wet or dirty environments for extended periods of time utilizing regular full auto firing, it wasn't worth the added weight.

What gigag04 said about GP.........

All the same, I'd like to buy an Adams Arms GP upper for my carbine some day, just to see what all the fuss is about.

The Annoyed Man wrote: All the same, I'd like to buy an Adams Arms GP upper for my carbine some day, just to see what all the fuss is about.

<Unsolicited advice>
Snag an LMT MRP piston upper - the monolithic platform is super stable, and they are widely used enough for extra parts to be out there. Plus their .308 MWS in the same design got slotted by the Brits for super secret squirrel sniper ops - so that says something. I also find them to be more prevalent on the 2nd hand market. To offset the added weight, I suggest go full deal lucile and stamp it and get an SBR flavor.

http://www.lmtstore.com/monolithic-rail ... -auto.html" onclick="window.open(this.href);return false;

Don't worry - prices will get normal soon I hope, and the 2nd hand ones are out there.

The Annoyed Man wrote:Also, depending on which gun it is, the way some GP systems vent the gas out, it covers the forend in in a fine layer of soot and carbon. So maybe your bolt is clean, but your off hand is dirty. Six, meet half dozen.

Like TAM stated and like I stated earlier, the bolt and chamber stays cleaner but that's really the only advantage to cleaning a piston gun. Also, TAM pointed out the gas has to go somewhere and it goes all over your forend in a piston gun. Plus it gets even hotter up there and trust me DI guns get plenty hot up there as it is. Reliability of a piston over a DI gun is what is usually argued and I think that is overstated as well. Most of the horrible reliability stories about standard DI AR15's are from people who "Heard if from their uncle in Vietnam" or from people that for some reason still believe that ARs don't need much or any lubrication to run. I hear people all the time say "Oh in sandy, dirty environments AR should be run dry" Well IMO that's totally wrong. AR's and especially Direct Impingement AR's need lube and plenty of it. I like grease cuz it doesn't burn off and it stays on the BCG even during lots of shooting. Oil either burns off or get slung off as the bolt cycles. We could argue all day bout AR lube but I think most people will agree that whatever you use....use it and plenty of it.

Wow!

Thanks everyone for your kind help.

I've got to continually look far more carefully into buying my first AR.

It's kinda funny. My first gun: A Remington single shot .22. I was 12. I spent hours and hours oiling and rubbing the stock and forearm so it would gleam.

I worked like crazy doing odd jobs to buy it. I was so proud of it. With my Dad's safety instructions and my own doggedness, I became an excellent shot. Yeah, yeah, it aint bragging if you can do it. I could, quite literally light kitchen matches with my shooting. Of course, I was young...

Now, I want to buy an AR with all the top quality I can.

Decisions, Decisions...

And thanks again for everyone's input.

It really helps.