i'm going to be building a carbine for myself and putting a couple together for my dept. (to be issued to the guys that don't already own one).

for MINE i had decided on a 16", but have started to considered the 14.5 w/ perm FH.  there's a few things that i need clarification on:  is 14.5" (w/o perm attachment) what is actually issued to infantry?  will a standard bayonet mount in the right spot on a 14.5?  what about a 16?  what are downsides to a perm FH?  does that mean i can never take off my FSB?

i appreciate any ifno on the good and bad points of each.  i know for the issued rifles, i could just get 14.5 w/o the attachment, but we want to keep all of are guns civilian legal so they're easier to sell when we upgrade.

Never go below 16".  That should be the min.

Any shorter and you lose too much velocity.

There is no advantage over the 16" and you have to make your attatchment permanent.  Just never sounded like a good idea.

If you are working inside buildings and clearing smaller spaces on a regular basis, then the 14.5" barrel is a good idea.  If you can't go legally smaller, it is as good as it is going to get.

However, if you aren't using your weapon for a specific & dedicated use, and on a regular basis, the 16" is a better all around length.

14.5" M4 profile looks really cool

i was thinking that a shorter barrel would be more manueverable when entering and exiting a patrol car in a hurry.  honesltly, the "cool factor" was a considerationhe

but, after calling M1S, i found out that you can't a chromlined b&c with a perma FH.  they said the heat of the weld would destroy the chrom lining and that you'll never see the two together.  decision madethanx for the input, tho.

Quoted: but, after calling M1S, i found out that you can't a chromlined b&c with a perma FH.  they said the heat of the weld would destroy the chrom lining and that you'll never see the two together.  decision made thanx for the input, tho.

might want to double check on that. there was a thread about this in the AR discussions debunking that "myth".

I like the 14.5 because I think its best to use a Phantom or Vortex, and the 16 with those is friggin' long. I know its only 1.5", but it makes more of a difference than I would have thought.

16in bbl

its the best mix b/w best velocity and compactness

Quoted:

But it's a new week and ...............................

Quoted: i was thinking that a shorter barrel would be more manueverable when entering and exiting a patrol car in a hurry.  honesltly, the "cool factor" was a consideration. i also like the idea that i could stick a bayo on it but, after calling M1S, i found out that you can't a chromlined b&c with a perma FH.  they said the heat of the weld would destroy the chrom lining and that you'll never see the two together.  decision made thanx for the input, tho.

I have a 14.5 w/ Phantom from Bushmaster, It is pinned on. So yes you can get them. Im not to sure about the welding thing, but They make them.


Why on Earth would a LEO put a bayonet on his carbine in the line of duty?Is it not bad enough that you shoot the family dog before you burn the house down, that you have to stick the thing to?...Are you waiting for a lawsuite?

I've never had to stab a dog, and I've been doing the cop gig for quite awhile.  

Quoted: I've never had to stab a dog, and I've been doing the cop gig for quite awhile.

Im a Dispatcher, ...If you are local I can hook you up!

Quoted: Why on Earth would a LEO put a bayonet on his carbine in the line of duty?

who said anything about on duty?  that's for when i'm showing it off to friends or antishe
if ya can't answer, now, no problem.  i'll ask again next week just to bother the repost nazis.

oh, yeah, is there really much of a velocity drop with just an inch an a half difference?

Take the 14.5 w/ birdcage,remove and add (1) extra washer,pin and tack= 16"and legal.

In answer to your question, the bayonet will fit the 14.5" barrel but not the 16". The 16" barrel is not military issue, but the 14.5" is.

Now if you were to get a 16" midlength barrel, then the bayonet would fit. The trouble with the midlength is that it's relatively new and there aren't many manufacturers doing them. To find barrels made of 4150 steel, with chrome lined bore and chamber, with a 1/7" twist in the 16" midlength (milspec) is almost impossible unless you get into a group buy/special order like the one going on in the group buy forum right now.

Keep in mind that there have been many complaints coming in from the sandbox about the lack of stopping power from the 14.5" barreled M4's using the issue M-855 ammo. The shorter barrels don't produce the necessary velocities for the 62gr bullets to perform as designed. The 20" A2's on the other hand don't seem to be experiencing the same problem with the same ammo.

I have an M4gery with the 14.5" barrel and a P/A Vortex that I like very much. I'd use either the M-193 or the Black Hills MK-262 MOD I ammo in it if I ever had the unpleasant task of using it for real though.    

I'd say go with a 16" barrel. By the time you add a Phatom or Vortex to a 14.5" barrel there's less than a 2" difference in length anyway. I seriously doubt that 2" will effect your egress from a patrol car.

One of these might negate the barrel length being an issue for mounting a bayonet.

.725 diameter

OR

.570 diameter

It might look a little funky, but it will still freak out the neighborhood kids on halloween.

Quoted: Quoted: I've never had to stab a dog, and I've been doing the cop gig for quite awhile.   Im a Dispatcher, ...If you are local I can hook you up!

Don't tell me you are one of my dispatchers, I didn't think any of my people liked guns.....

14.5" w/ A2 flash suppresor is standard M4 issue length.  A2 FS is not permanently attached, it is torqued and timed.  Standard bayonet mountable.

If you use a 16" midlength, then yes, a bayonet will be mountable, if using a standard front sight block/tower with bayo lug.

See here for velocity vs. barrel length.  MD AR-15 shooters site
14.5" = 2900 to 3000 fps
16"=3000 - 3150/3200 fps  (all dependent upon ammo used)

Hope this helps.   For yourself, hell, buy a 14.5" carbine and a 16" midlength.   Then you only have to decide which to use!  :)

Quoted: i'm going to be building a carbine for myself and putting a couple together for my dept. (to be issued to the guys that don't already own one). for MINE i had decided on a 16", but have started to considered the 14.5 w/ perm FH.  there's a few things that i need clarification on:  is 14.5" (w/o perm attachment) what is actually issued to infantry?  will a standard bayonet mount in the right spot on a 14.5?  what about a 16?  what are downsides to a perm FH?  does that mean i can never take off my FSB? i appreciate any ifno on the good and bad points of each.  i know for the issued rifles, i could just get 14.5 w/o the attachment, but we want to keep all of are guns civilian legal so they're easier to sell when we upgrade.

Quoted: Quoted: Quoted: I've never had to stab a dog, and I've been doing the cop gig for quite awhile.   Im a Dispatcher, ...If you are local I can hook you up! Don't tell me you are one of my dispatchers, I didn't think any of my people liked guns.....

Anything is possible, but where I work, there are a lot of us that CCW

Word to da dispatcher!! I thought I was the only one on here.

Quoted: Word to da dispatcher!! I thought I was the only one on here.

Word to the vanilla_gorilla


Redneck_Indian 14.5 will take a bayo, the 16 will take it, but it will look like you have a drooping dick on the end of your bbl.

Originally Posted By AMTRACS Take the 14.5 w/ birdcage,remove and add (1) extra washer,pin and tack= 16"and legal.

I never thought of that, I will check it out and see if it works out...If it does, I may have to try it on another build.