.223 barrel length?

[Skofnung]

Hey guys.
I have a Bushnaster 20" A2 rifle. I like the velocity that the .223 attains out of a 20" tube. However, I have a desire to shorten the barrel back to 18" in order to shed some weight and make the gun handier.

I have stayed away from 16" barreled guns because significant (to me) velocity is lost, and when one is using a 55 grain bullet, one wants it going as fast as possible.

So, what kind of velocity would I get out of an 18" barrel? Who among you has done this conversion (or has another 18" .223) and how much velocity was lost?

Thanks

 

[Art Eatman]

A reasonable rule of thumb for short-action cartridges is a loss of around 40 ft/sec/inch. For '06-type cartridges and magnums, around 75 ft/sec/inch.

Roughly.

, Art

 

[ny32182]

I have bushys in 16" and 20". I love them both.

16" isn't a bad length. Many of the military barrels, and many of the civilian M4 profile barrels only have 14.5" of length to their name. To me, this is too short. But 16" can still generate over 3000fps, and with the superlight profile, its very light. The velocity dropoff from 16" down to 14.5 is much more signifigant than from 20" down to 16", IMO. 16" is still plenty effective inside 200 meters, and the 16" superlight is MUCH more quickly manueverable than the 20" HBAR, because all of the weight comes off the front of the gun.

Don't cut down your existing barrel. Get a 16" superlight upper, and switch it out with your 20" depending on your situation.

 

[Steve in PA]

Barrel Length vs. Velocity

Barrel Length (in) MV M193(fps) MV M855
20 3259 3100
16 3132 2989
14.5 3064 2970
11.5 2872 2738

MV: Muzzle Velocity (feet per second).

M193 - 55gr FMJBT
M855 - 62gr FMJBT

http://groups.msn.com/ThePennsylvaniaAR15ShootersSite/rifleperformance.msnw

 

[Skofnung]

Thank you kindly fellas.

 

[Onslaught]

The velocity dropoff from 16" down to 14.5 is much more signifigant than from 20" down to 16", IMO.

That's just because you have a 16"...

In reality, there's all of about 68 fps lost going from 16" to 14.5", while you lose nearly twice that (127 fps) going from 20" to 16". I've got experience with all 3, and on the range, you can't tell a spit'a difference between the two carbines.

Personally, I too would like to know the answer to your original question, as I'm quite fond of AR's, and the .223, etc... but I just never liked the 20" rifle (I have a phobia about naked barrel ). I was thinking that a dedicated scoped AR with an 18.5" barrel would make me very happy.

I currently own a pre-ban Bushy with a 14.5" bbl, so getting a 16" isn't going to scratch any itches. Plus, out to 500 yards, it does the same things my buddy's 16" does, so again, not gaining anything there.

BUT I will admit that I'm going to swap the14.5" for a 16" Wilson "mid-length handguard" barrel.... to cover up more nakedness

 

[ny32182]

That's just because you have a 16"

Actually, its BECAUSE of that, that I have a 16".

From ammo oracle:

Distance to 2700 fps (effective fragmentation range)
20" Barrel
16" Barrel
14.5" Barrel

M193
190-200m
140-150m
95-100m

M855
140-150m
90-95m
45-50m

Here, you lose ~50 meters of fragmentation range for a 4" shorter barrel, going from 20" down to 16".

And, you lose another ~50 meters of fragmentation range for a 1.5" shorter barrel, going from 16" down to 14.5".

After considering the above numbers (and others), combined with the fact that the overall barrel length has to be 16" anyhow, I just didn't see a reason to get a 14.5" M4 profile with a performance reducing fake flash hider on the front to bring the total length to 16", that weighs more than the 16" superlight anyway.

Mine is the legal minimum length, and lighter and better perfoming than a postban M4. I guess if yours is preban that might change things up a little since you can have a real flash hider. Does the 16" rule apply to prebans?

To me, the decision between a postban superlight and a postban M4 was a no-brainer when I was researching carbine options.

 

[mini14jac]

I think you have to have 16" unless you have a Class III, but I could be wrong.

I'm actually getting ready to send my Mini14 off to have the barrel cut to 16".

I originally purchased a Bushy with a 14.5 barrel, with a AK brake, to make it 16".
The brake made it really loud, and after researching the muzzle data above, (www.ar15.com has a lot of great info on this) I sold the AK upper, and got a regular M4 profile 16" barrel.
Seemed to shed about a pound of weight, gave me more muzzle velocity, and was quieter to shoot.
For a general purpose .223, I think 16" is the ideal barrel length.
Nice mix of length/wt./handling/velocity.

I miss my Bushmaster.

 

[JNewell]

Those numbers are pretty interesting. They tend to confirm something I've been thinking when I read the complaints about the "ineffectiveness" of the 5.56x45 cartridge, especially current issue M855: with the M4 (14.5") rifle, the genuine effective range is really short. I have a couple of 16" uppers and a couple of 20" uppers. The 16"ers are very convenient when you're out all day training, but the 20" is a somewhat more flexible rifle.
Actually, I think the services should go back to an almost-A1 configuration, but that's a different thread.

On the 14.5" question of legality, it's fine as long as the whole tube length is at least 16" -- so if you "permanently" (per ATF definitions) attach a muzzle brake (for example), you're good to go.

 

[bad_dad_brad]

I have the 16" Bushy for many of the reasons stated. I thought it a good compromise for civilian use. You really do not loose that much with a 16" over a 20" and with an HBAR you shave about a pound from the rifle. Eventually I want to get a 24" upper for long range varminting and target work.

By the way, the AK brake on a 14.5 is truly ear blasting. Looks cool though.

 

[JNewell]

I don't think that the shooter behind an AK-type brake feels any of it, at least not outdoors. Howevver, the shooters on either side really get blasted.

The thing to do at that point is get out the Marlin Guide Gun with the old-style ported barrel...

 

[mini14jac]

The local range has a covered shed for rifle shooting.
Using the AK brake under a roof, you get to enjoy all of the audio performance of it.
As do all of the other shooters.

Ever have someone ask "Hey, is that a .50 cal.?".

And, if you've ever stood off to the side of a gun with a brake, the blast will part your hair, and wake you up.

 

[Onslaught]

All comments and opinions below are written WITH A SMILE No flaming or insults are intended or inferred...

I just didn't see a reason to get a 14.5" M4 profile with a performance reducing fake flash hider on the front to bring the total length to 16", that weighs more than the 16" superlight anyway.

Actually, mine's a 14.5" because at the time (sometime in 1999 I believe), when I was replacing the 11.5" bbl that came on it, all Bushmaster had in stock was the 14.5", as the 16" bbl was backordered for at least 3 months or more. And as I mentioned, I don't like all that barrel sticking out past the handguards anyway, so I didn't mind. Also, no such thing as "super light" at the time. My barrel is fluted, so it's plenty light enough for me.

Yep, I do have a permanently attached flash supressor... the old style Phantom. The overall bbl length on my rifle is just a TINY bit over 16".

I personally think WAY too much "finite emphasis" is placed on that whole "maximum effective fragmentation range", ESPECIALLY (or exspecially ) for civilians. Even on the ammo oracle, they mention that it's only the distance to the magic "2700fps" that causes consistent fragmentation IN GELATIN. The 5.56 bullet is still tumbling, and fragmenting, below that range, just perhaps not 100% of the time, or as dramatically... IN GELATIN

If you're planning on hunting with your rifle, use soft-points. If you're a civilian planning on defending your life with it.... Well I don't think 100 yards or 150 yards of fragmentation is going to make a difference since that scenario just ain't gonna happen in real life... But even if it did, just use softpoints or some of the alternative suggestions for police and HD on the ammo oracle website, and there ya go.

64 gr Winchester (RA223T2).
68 gr Black Hills "Heavy" Match (BTHP).
69 gr Match King loadings.
75 gr Hornady Match (BTHP)
75 gr TAP (BTHP)
77 gr Black Hills Sierra Match King (BTHP)

And before anyone says that they use SS193 because it's cheap to stockpile or whatever... That's like using ball ammo in your .45 for home defense because Winchester White Box is cheaper than the same company's SXT's. It's your LIFE... use the good stuff

 

[ny32182]

All comments and opinions below are written WITH A SMILE No flaming or insults are intended or inferred...

Likewise, of course.

Actually, mine's a 14.5" because at the time (sometime in 1999 I believe), when I was replacing the 11.5" bbl that came on it, all Bushmaster had in stock was the 14.5", as the 16" bbl was backordered for at least 3 months or more. And as I mentioned, I don't like all that barrel sticking out past the handguards anyway, so I didn't mind. Also, no such thing as "super light" at the time. My barrel is fluted, so it's plenty light enough for me.

11.5" Thats the same length as the old Colt Commando. Now, I don't know what kind of NFA permits you have for SBRs, or what overall length rules apply to prebans. I can only speak somewhat knowlegeably from a postban, 100% civilian standpoint. And the applicable rule there is: 16" of overall length, or you get a few years of federally subsidized housing.

So, when I was looking for a carbine, I wanted the shortest length possible, and that was 16". I have nothing to gain from going to a 14.5", because the difference has to be made up with some sort of muzzle device, and none of the postban muzzle devices are useful, IMO. I figured that if I had to have 16" of barrel, I might as well get the performance of a 16" barrel, because a 14.5" wouldn't be any shorter, and wouldn't build up as much velocity anyway. And on top of everything else, the 16" was lighter, which is another key point of interest on a carbine.

The superlight does have some pretty short handguards, and thus a lot of exposed barrel sticking out the front. Perhaps a dissipator model of some sort would address this issue if you don't like the exposed barrel look, etc. Dissys also have the advantage of a longer sight radius.

If you're planning on hunting with your rifle, use soft-points. If you're a civilian planning on defending your life with it.... Well I don't think 100 yards or 150 yards of fragmentation is going to make a difference since that scenario just ain't gonna happen in real life... But even if it did, just use softpoints or some of the alternative suggestions for police and HD on the ammo oracle website, and there ya go.

I would like to go hunting with the 20", and have been watching the .223 on deer thread closely. As noted, a controlled expansion soft point seems to be the best choice for this purpose. I'm a little worried about the soft point being deformed or getting hung up during feeding. Guess the best thing to do is just buy some and see what kind of groups it can shoot. I think any 55gr fmj would be fine for SD out of the superlight.

64 gr Winchester (RA223T2).
68 gr Black Hills "Heavy" Match (BTHP).
69 gr Match King loadings.
75 gr Hornady Match (BTHP)
75 gr TAP (BTHP)
77 gr Black Hills Sierra Match King (BTHP)

I think the first 2 or 3 on this list are the only ones I'd be able to use. (1/9 barrels being the first limiting factor). Second, I've heard that some of the very heavy .223 loadings will not fit into a normal magazine, and have to be loaded one at a time. Do any of the above fall into that category? I was planning on trying to find some 64gr winchester power points to hunt with, as I think I can both stabilize them, and load them into normal mags.

 

[Onslaught]

because a 14.5" wouldn't be any shorter

Well, it sure ain't much, but the 14.5" barrel is actually about 1" shorter overall At least with pre-bans or post-bans with muzzlebrakes. 14.5" bbl + 2 3/16" fs = about 16 while 16"bbl + 1 5/8 fs = 17something... Muzzlebrakes are generally 2"+, so that moves it back into the 1.5" longer range.

They're all AR's, and that's what counts

 

[ny32182]

They're all AR's, and that's what counts.

Oh yes.

My muzzles are bare though, so the 16" really is only 16". It would be longer with a brake of some sort.

 

[Onslaught]

Sorry for being so slow to respond.... I've been spending more time with my family and less time online.

11.5" Thats the same length as the old Colt Commando. Now, I don't know what kind of NFA permits you have for SBRs, or what overall length rules apply to prebans. I can only speak somewhat knowlegeably from a postban, 100% civilian standpoint. And the applicable rule there is: 16" of overall length, or you get a few years of federally subsidized housing.

Yep... It was an 11.5" bbl with 5.5" permanently attached flash supressor. Back then, (after the AWB was signed but before the September deadline) it was the only AR15 I could find. Plus I didn't have the internet (Al Gore hadn't invented it yet ) so I didn't know about barrel length and AR's.

One thing before I give up the ghost on all this short barrel talk. One BIG drawback to shorter than 16" non-SBR weapons and all post-ban rifles with muzzle junk... You are STUCK with just about everything on that rifle from the barrel nut forward! If you want to add a free float tube, you can't... if you just want to change SIGHT TOWERS, you can't... Without spending $100 or more for a gunsmith to remove the offensive attachment and then reattach a new one... and that's NOT counting the work for adding whatever new part you wanted to add... Yet another reason I'm swapping my beloved 14.5" for a 16"... just too much hassle.

The only thing i may do for nostalgia's sake is at some point have a slip-over flash supressor attached to a 14.5" barrel on an A1 upper.... just so I can have the look of the old one back. But I'd definitely have the barrel turned to lightweight under the handguards...

Take care....