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SIG-Sauer M400 Enhanced AR-15


Pat's Product Review: SIG-Sauer M400 Enhanced Permalink | Print

Without a doubt, the hottest selling long-gun these days is some sort of AR-15/M4 type of gun. Thanks to the efforts of anti-gunners like Dianne Feinstein and Barack Obama, with their proposed bans on certain classes or types of firearms, there has been a run on these types of guns that has never been seen before. With looming threats of banning certain types of firearms, as well as magazines over 10 rounds, the American People are waking up, and are spending their hard-earned money on what they presume will be banned or regulated. Without a doubt, this has led to a buying frenzy, like no other in firearms in history to the best of recollection. This has also led to a shortage of ammunition, the likes we have never seen before, and I suspect it will take the ammo companies a couple years to catch-up with supply and demand. The hottest-selling ammo right now is .22 LR followed by .223 Rem/5.56mm and then 9mm - however, most calibers are in short supply these days. Prices on ammo has about doubled or even tripled in may instance. Some mail-order companies have completely ripped-off their customers - what used to cost $150 now cost almost a $1,000 for certain types of ammo. I hope that SurvivalBlog readers are taking note of which companies are doing this, and won't throw their business to these companies. I know I won't! For the past three months, I've been testing the SIGSauer M400 Enhanced version of their M4-type carbine. This is, for some reason, one of the most in-demand M4-type rifles on the market these days. At my local Wal-Mart, they usually carry a SIG-Sauer M400 in-stock. However with the recent buying frenzy, these firearms go out the door as fast as they come in. For several months now, there have been customers camped out in the sporting goods department of my local Wal-Mart store. They arrive early in the morning, and borrow some folding chairs from the camping section, and sit at the gun counter, waiting for UPS or FedEx to arrive with a few M400 guns. Some days none arrive, and some days only a few arrive. I requested the M400 Enhanced version, because I wanted something a little bit different. The Enhanced version comes with a flat-top receiver, that has a fold-down rear sight. It is also equipped with MagPul Original Equipment (MOE) furniture - butt stock, pistol grip and forend. I like the look and feel of the MagPul furniture, especially their butt stocks. The M400 also comes with a MagPul 30 round magazine. (An aside: You had better get plenty while you still can. MagPul is located in Colorado, and they have promised to move from that state, if they enact a ban on magazines over 15 rounds. If MagPul does indeed move, it will take quite a while for them to set-up shop again, so get some of these mags while they are still available - or before they get banned by the FedGov with some of their looney legislation that has been proposed.) The M400 is a 5.56mm caliber rifle, that can also handle .223 Remington, and FYI they are not the same caliber. If you happen to have a rifle that is a .223 Remington caliber, do not shoot 5.56mm ammo through it without consulting the manufacturer's web site! The M400 is also direct impingement via a gas tube, just like the original AR-15s are. Overall length is 35.6-inches long with the stock fully open, and 32.5-inches with the stock fully closed. The barrel is 16-inches long with a 1 in 7 inch twist, so you can fire some heavier bullets. The gun weighs in at 6.7-pounds and the trigger pull is stated at 7.8-pounds, but my sample felt much lighter than that, with no over-travel or grittiness at all. There is also a flash suppressor on the end of the barrel and the barrel has a unique shape to it - not quite M4-ish, nor is is plain, either - check it out on the web site. The barrel is forged with a phosphate coating on the outside, and chrome-lined inside, that helps it stand-up to harsh weather conditions. The lower receiver is forged aluminum - 7075-T6! Okay, so we have a very well made M4-type of carbine, but what sets it apart from any other similar carbine, by any number of makers? Well, that's a good question, and first of all, it is manufactured by SIG-Sauer, so you know the quality and workmanship is there - just like it is in all SIG products. You can also get a plain-Jane version without the MagPul MOE furniture on it, for a little less money. And, the Enhanced version comes with black furniture, OD green or tan - my sample was black. For the slight difference in price between the plain-Jane M400 and the Enhanced version - go with the enhanced version. We have a couple unique features on the M400 that set it apart from other M4-type of firearms. First of all, we have a tensioning device in the lower receiver - this is a spring-loaded pin, that takes any slack out of the upper and lower receiver - no rattling between the upper and lower, and the upper and lower are perfectly matched, too. A lot of AR-type guns require a little rubber tensioning device that you insert into the lower, to take-up the slack between the upper and lower receivers to the two parts don't rattle. Secondly, there is a spring loaded pin in the upper receiver, that goes into the chamber, and this applies pressure to the extractor that is in the bolt. What purpose could this serve? Well, one of the parts that wears out or breaks is the extractor. With this spring-loaded pin, keeping pressure on the extractor, it allows a good bite on the rim of a round, and this aids in extraction. It also helps keep the extractor from blowing out, should you have a hot round that might let loose - bringing your gun to a deadly stop - when you don't need it to. So, two really great ideas were incorporated into the M400 by SIG. They also incorporated a ambidextrous magazine release. And, they also have ambidextrous mounting points on the lower receiver for installing a single-point sling. Here's where I have a complaint. SIG didn't include any type of sling, not even a mil-spec two-point sling. And, if you want to mount a single-point sling on your M400, you have to purchase the little sling adaptor that snaps into one of these two mounting holes. Come on, SIG, you could at least have included a cheap $5 mil-spec sling or gone the extra mile and included some type of single-point sling with the mounting hardware. With the ammo shortages we are seeing these days, it's even a bit hard for gun writers, to lay their hands on sample ammo, and I'm no different than any other writer - it's hard to get ammo these days, but my usual suppliers came through for me. From Winchester Ammunition, I had their USA brand 55-grain FMJ ammo - which I like to use when testing an AR-type gun for function - and I run through several magazines as fast as I can pull the trigger - no malfunctions at all with the M400. From Buffalo Bore Ammunition I had their superb 69-grain JHP Sniper load - which is always an outstanding performer. From the good folks at Black Hills Ammunition, I had quite an assortment of ammo. I had their 55-grain FMJ reloads as well as brand-new ammo. Their 52-grain Hornady V-Max, 55-grain Soft Point, 60-grain Soft Point, in reloaded and brand-new ammo, their 68-grain Match HP and lastly, their 75-grain Heavy Match Hollow Point (HP) load. In all, over a three month period, I burned-up close to 1,000-rounds of ammo - again, something I regret doing, as replacing all that ammo is hard to do right now, but I'm still begging! My M400 sample didn't much like the Black Hills 52-grain V-Max load, and I suspect its because of the 1 in 7 inch barrel twist, which is more suited for heavier loads - but this load still came in at around 3.5 inches at 100-yards if I did my part.The Black Hills 55-grain FMJ, 55-grain Soft Point and 60-grain soft point loads all came in slightly under 3-inches - not bad, but not as good as I expected. The Black Hills 68-grain Heavy Match HP starting shrinking my groups under 2-inches, again if I did my part - and my accuracy testing took place over 3-months, in all types of weather conditions. Things started to get very interesting when I fired the Buffalo Bore 69-grain JHP Sniper load - I was getting groups about 1.5-inches, and I was starting to get impressed with the M400 sample. However, when I tested the Black Hills 75-grain Heavy Match HP load, I consistently got groups under an inch and a half. Again, I shot in all types of weather, and some days were better than others in the accuracy department. I did manage some groups under an inch and a half with the Buffalo Bore 69-grain JHP Sniper load, but the Black Hills 75-grain Heavy Match HP load was ever so slightly more accurate in my M400 sample. I'd like to see SIG-Sauer offer the M400 with either a 1 in 7 inch barrel twist, as well as a 1 in 9 inch barrel twist. I believe the 1 in 9 barrel twist would give better performance with lighter bullets, like the Black Hills 52-grain Hornady V-Max load and even lighter loads. And, the 1 in 9 barrel can still handle bullets up to about 69-grains a little bit better than the 1 in 7 barrel could - in my humble opinion. However, when going over 69-grain bullet weight, you'd want the 1 in 7 barrel twist. Now, I will say that, during all my testing, I never once cleaned my M400 sample and I had no malfunctions. I was also testing Italian Gun Grease lube in the M400, and found it to hold up quite well over several months of testing. Now, seeing as how I never cleaned the M400 during all my testing, I know the barrel was getting dirty and fouled - so this could have contributed to accuracy not up to par with some of the ammo tested. I think, with proper maintenance, and a good break-in period, and proper barrel “seasoning” the M400 will be a pretty consistent shooter in the accuracy department with most bullet weights getting you 2.5 inch groups on a regular basis. Of course, the different bullet weights also shoot to a different point of aim - I zeroed the M400 for a 55-grain bullet at 100-yards. Needless to say, some rounds hit dead-on, some slightly lower and some slightly higher. But the groupings were there - the gun can shoot and it shoots quite well - and I was only using the open sights - not a scope mounted on the gun - and you can easily mount a scope or red dot sight on the flat-top receiver. Now for the bad news, the M400 is hard to come by right now - even at your local Wal-Mart. And, I've been checking some of the gun selling web sites, like, and people have been going crazy bidding or buying the M400 - over the past couple of months. The M400 has been selling for $1,800 to as much as $2,400 while the suggested full bolt retail is only $1,234.00 on the SIG web site, That can be attributed to supply and demand. Again, some gun sellers are taking advantage of the short supply and jacking-up their prices on anything AR or AK these days. I have no problem with a gun dealer making a decent profit, but when they go way above and beyond, and rip people off because of shortages, I simply won't do business with them. And, the M400 is probably one of the most in-demand M4-type carbines out there right now, and they are still a bit hard to come by, but prices have started to come down a little bit. And, if you want to camp out in your local Wal-Mart sporting goods department, you might possibly get your own M400 for under the suggested retail price. Much as I don't like Wal-Mart, I will applaud them for not taking advantage of the current supply and demand, and they have kept their prices where they were before all this market turmoil started last December. Overall, I was very favorably impressed with my SIG-Sauer M400 Enhanced sample, and I'm keeping it. Now all I have to do is find the funds to pay for my sample, but one thing is certain, it will not be going back to SIG. The gun is well-made, has some features other M4-type carbines don't have, is quick handling, and the accuracy is there, with a variety of ammo. So, if you're in the market for a well-made and popular M4-type of gun, give the SIG-Sauer M400 a close look - if you can even find one. And, if you do find one, don't hesitate, buy it 'because if you put it down, the gun next to you will buy it right out from under you. - SurvivalBlog Field Gear Editor Pat Cascio


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sig-sauer_m400_enhanced_ar-15.txt · Last modified: 2020/03/12 18:38 (external edit)