I don’t shoot my AR as much as I’d like, maybe once of twice a month (~200 rounds each time). My AR started life as M&P15MOE, with a carbine gas system & 1/9 twist. I read about advantages of the mid-length system, but would I benefit from it? I can probably sell current barrel to offset the cost and go with a BCM mid length barrel with 1/7 twist.
My rifle is all apart as I install TRX Extreme rail, so it would be no big deal to put in a different barrel at this time.
I would rather have a midlength than a carbine, but selling what you already have for one? That’s up to you.
Middy systems are a fad.
The stripped barrel from BCM would run you $229, plus $13 more for a mid-length gas tube. Is your rail long enough for a mid-system? Or would you also need handguards? I figured you would be keeping your front sight, but if not that is also an extra cost. You could reach north of $300 real easy. What is your budget?
If you are building a whole new rifle I would say go middy. I think sometimes you have to ask yourself if you have skills that are limited by your rifle. I have three carbines and cannot outshoot them at this stage in my game.
I have an 11" TRX Extreme rail, so it will cover mid-length gas system. I already have a front MBUS amd Troy low-profile gas block, so my investment would just be in a new barrel and new gas tube, then I’d sell existing barrel, so my total upgrade costs would be around $150.
I’m just wondering if I would notice any benefits for how much I shoot, or is it really just a fad, as another poster said?
Why do you say this?
the biggest thing would be the added handguard length so you can get your hand further up and therefore be able to retract the buttstock some and have better balance. Of course there’s the reduced recoil, longer sight radius, and other benefits as well. Carbine just have no advantage I can see over a midlength.
Since you dont shoot a whole lot then it might not be worth it. Maybe if you build a new rifle it would be good to select a midlength.
I’ve shot a S&W M&P15 and it had noticeably more recoil than my BCM midlength + H buffer.
I will have an 11" long handguard, so the benefits of placing the support hand further out as well as placing the front sight further forward will be there regardless of the gas system.
dennisuello,
My experience is that my middy upper gives me less felt recoil, than a similar carbine upper. Going to a 1 in 7 twist gives you the option of shooting heavier bullets. But if you mostly shoot 55 grain fmj, maybe you do not need that.
They’re popular right now. I don’t really mean to use the term ‘fad’ as a derogatory one in this instance; there are clear advantages, however minute, to the mid-length gas system. A decent rifle with a carbine-length gas system is reliable enough for the majority of users… who aren’t shooting 20k rounds or more per year. If you’re buying fresh, there’s no reason not to go middy; I would. If you’re wondering whether or not it’s worth upgrading to a middy barrel when you already own a carbine then I’d say no.
yea since you already have a setup its not really worth getting then. I would definitely recommend it if you ever get an black rifle disease outbreak and get the itch to make another 
I used to have a BCM carbine upper with 9" DD Omega Rail, I sold it and bought a BCM middy + 12" DD Lite Rail upper.
Agreed.
Unless the OP is going to shoot 77 grain ammo almost exclusively for the most part, your 1x9 carbine length weapon is fine for the majority of the shooting and common bullet weights used for formal training, personal range sessions and plinking beer cans most folks perform. You should wear out your current barrel first before considering replacement.
I have 2 of each type in 1/7 and do occasionally train with 77 grain ammo. The middies does have quite a few advantages over the carbine, but I wouldn’t worry about it. I enjoy shooting both.
The correct answer is, buy a complete BCM or DD light weight Middy and have one of each weapon system.
I recommend that you not turn it into a Frankengun. Now that your tastes have changed / improved, just sell the S&W and buy a higher end rifle with a mid gas system and the Troy rail that you want.
I’m also of the opinion that it’s more trendy than practical. Having just sold my M&P15 MOE for a grand, I was all set to pick up that nice Spikes midlength LE upper. Got all excited thinking of the benefits mentioned above: longer sight radius, lighter recoil and wear to the receiver/receiver extension, greater reach with support hand, more rail space, etc, etc.
But In the end, I went with a carbine again because I use a RDS and there’s no benefit to that extra whopping 2" sight radius even should I need to use open sights. I really don’t need to reach further out to support my precision movement between targets so the extra few inches i can put my forward grip is needless. I don’t think the extra violence of the carbine will translate to more wear and tear in my rifle’s lifetime of monthly shooting with an occasional training…at least in anything I’d notice (“Oh hey, with this middy, I can get another 3k rounds out of it than I could with that carbine!”). Also, with my 14.5" barreled carbine (pinned phantom), and it’s shorter handguard, I will possibly shave off yet a nother few precious ounces of weight. As for recoil and quicker controlled pairs, meh…I do fine with a carbine and can’t imagine a need to have it be easier in my estimation and use.
The only thing I could think of that would be a benefit is having something that looks a little different from everyone elses…or in short, vanity. Frankly, for “ME” there is no utility in the middy over the carbine…call me crazy.
I would just keep shooting what you currently have and purchase a middy in the future if you want one. Although the middy does have some relatively minor advantages, the carbine length gas system will still get the job done.
To me the 1/9 vs. 1/7 would be a bigger consideration than the Mid vs. Carbine.
If you really think that you might want to shoot some heavier ammo in the future, then it might be worth it. So if you want to change out the barrel anyway, I would go with the middie.
I would probably just keep what you have, and if your needs change down the road you could just buy a complete 1/7 middie upper and sell your M&P. Or just buy a complete 1/7 carbine and have both.
I’m not too concerned about the fact that my gun is a lowly carbine and not a middy.
Well, I just ordered BCM BFH™ 16" Mid Length Barrel. Since I have it all apart I figure I’ll just swap the barrel now, and not have to do this all over again if I decide to do this later.
dont forget the middy gas tube as well