Actual .308 velocity from 16" barrel

K

Kor

Inactive
Well, thanks in no small part to the FAL and DSA fans here, I'm about to order a DSA STG58A "kit gun" FAL. My final dilemma has to do with the choice of the 21"-barreled rifle, or the 16"-barreled carbine version.

At present, I'm leaning towards the carbine, for several reasons: aesthetics, compactness, ease of handling, lower weight, feel(I'm sorry, but a full-size L1A1 sporter I handled years ago felt like a 10-lb sledge with a pistol grip ;) ). Unless DSA shortens the gas system on their "kit carbines," the sight radius will be the same as the full-size rifles, so that is not a disadvantage. Ordinarily, I would expect increased muzzle blast/flash, but since both versions will be fitted with muzzle brakes, I don't anticipate any meaningful difference in that area.

The final sticking point, though, is the velocity loss from the shorter barrel. The rule-of-thumb from Rinker's Understanding Firearm Ballistics says that you lose about 25fps per inch of barrel, and if saving 5" of barrel length only takes my muzzle velocity down to about 2650fps, I'd be perfectly happy with the deal. Thing is, that's still just guesstimation, and I'd much rather have hard data than a SWAG.

So, what I'm asking is if any of you good folk now own, have owned, or have/had access to a short-barreled .308, such as a FAL carbine, an M1A Scout/Bush Rifle, Remington Model Seven, or something similar - and if so, what(if any) chronograph results did you get? If you want to narrow the field, I plan to field my new STG58A with either 147gr. milsurp ball, or Federal 168gr. BTHP match ammo. Although I love the idea of a .308 carbine, if the short barrel drops it down to .30-30 ballistics, I'd want to re-think the whole idea. So, any info, insight or advice you can give on the subject will be muchly appreciated.

Thanks in advance - Kor
 
I have a Steyr Scout rifle [19" brrl] only load I have run over a chronograph so far is Hornady's 150 Light Magnum load which is supposed to do ~2900 in a 24" brrl IIRC. It did around 2755 in my scout at around 70 degrees.
 
Glamdring gave you his info with using Light Magnum loads in a bolt rifle. Most folks don't recommend these loads with a gas gun, even the strong FAL with the adjustable gas system.
 
Kor,

Why do you discount the muzzle flash issue?

If a post ban 16" AR with comp throws a big fireball, why do you think a 16" .308 with twice the powder will not? I would think the flash of the 16" would be far greater than the 21" inch since more powder burns while the bullet is still in the barrel. (Giving you your added velocity)

I'm also thinking of ordering a DSA rifle and the carbine is appealing for the reasons you point out. I just can't help but to believe that the flash signature from the carbine would be excessive.
 
Alex from Robinson is claiming the carbine length 20" veprs are more accurate then the 23 inch rifles...

Is there a rifling twist sweet spot for length?

dZ
 
I do not have data for a 16" FAL, but I have measured approx 2550 fps MV from an 18.5" FAL. Measured MV for the 20.5" FAL was 2750. Ammo was Radway Green surplus.

-z
 
The rule of thumb for cartridges of the .270 and .30-'06 type is around 70 ft/sec per inch of velocity loss from some known point. (In the "old days", this was always 26" for factory data.)

The .308 is supposedly a bit less susceptible because of its design, and my understanding is that around 50 ft/sec/inch is a somewhat accepted norm. smithz's data is 100 ft/sec/inch, so all bets are off. :) Glamdring's 30 ft/sec/inch seems "lucky" to me.

If it wuz me, I'd just assume 50 ft/sec/inch, until I got to compare both barrel lengths on a chronograph.

And that's about all I can guess; one test is worth a thousand expert opinions.

:), Art
 
I am also considering the very thing; 16" carbine or full size. A 20" barrel rifle is still a carbine size weapon.

I have heard that for .308 the powder is burned completely in 20"...there will still be a flash. There will be unburned powder with the 16" so there should be more flash.

Are you considering the lightweight carbine or the regular 16" carbine. The later is the same as the standard 20 barreled version less 4" of barrel...that 4" will benefit you more in shooting than it will bother you to carry it.

Here is what I may do. Purchase the 20" and remove the muzzel brake and crown the barrel. It should end up being closer in overall length to the carbine and still use all 20" of rifling. The muzzle break is really like a game show parting gift for the guy who can't have a flash suppressor.

As far as feeling heavy, a .308 is nicer to fire with a little extra fat. Handling and carrying is MUCH different than shooting.
 
When FAL Files comes back, search around over there. I'm 99.99% sure someone has chronographed one. Try leaving a message on the old-style forums over there; someone might know.
 
racegunner,
A 20" barrel is still a carbine size weapon.
Click to expand...
An FAL with a 20" barrel is about 40" long (with MB, 'bout 42").
An FAL with an 18" barrel is about 38" long.
An AR-15 with a 16" barrel is about 34.5" long.

A 40" long rifle is hardly a carbine!

The DSA Lightweight carbine has short handguards and thus a shorter sight radius than the standard 16" carbine, which has standard handguards. The DSA LW's gas system may be more robust than the regular 16" carbine's system because the LW has more distance between the gas port and the muzzle.

The muzzle brakes only add an inch or inch and a half to the end of the barrel. The original Austrian flash-hider, though it looks huge, only adds about 1" to the OAL.

One last thing to consider about the muzzle brake is that it can protect the muzzle crown.

The FAL is a pretty long design. I wish it were made in a more compact package. FAL bull-pup anyone?

regards
-z
 
OK folks, here's the facts. I have a 16" FAL (built by Arizona Response Systems) and a 21" L1A1 by Century. Chronograph numbers:

Radway Green:
21" FAL - 2693fps (30 shot average)
16" FAL - 2645fps (10 shot average)

Portugese FNM:
21" FAL - 2663fps (5 shot average)
16" FAL - 2599fps (5 shot average)

Obviously there is very little difference, at least in my experience. I've also shot the Radway Green at night. There is hardly any muzzle flash at all, just a very small, dim puff of orange light. And this was out of the 16" barrel. I think the Radway has a quick burning powder and/or some anti-flash stuff in the powder. So I think the muzzle flash concern is a non-issue.

I really like the 16" FAL. The handiness, better balance, and lower weight make it much more ergonomic, at least for me, than the full-size FAL. I also don't think you'll lose any accuracy. The other day I was able to score 10 out of 10 hits on a human silohette at 370 yards, with iron sights and shooting from an unsupported position. I just put the rear sight setting at 400 and I was still pretty much on target.

Also, only the "Light Weight" DSA FAL has a short sight radius. The regular carbine, has the same sight radius as the full-size FAL, as does my ARS 16" FAL.

Heard enough? If you haven't ordered that 16" FAL yet, what are you waiting for! :)

BTW, you might want to check out Arizona Response Systems. Their FALs are top notch and much more affordable than DSA.
 
Wow - my sincere thanks to you all, for so much good info in such a short time! Particular thanks to Chessman, Racegunner, Smithz, and Art Eatman for especially informative and insightful replies.

Hipower, I don't discount muzzle flash/blast so much as I am resigned to a good deal of it with either the rifle or the carbine - in other words, since both versions are equipped with a muzzle brake, I'm not sure that the the 21" muzzle-braked barrel would produce sufficiently less muzzle flash/blast to outweigh the other user-friendly qualities of the 16" muzzle-braked barrel.

Frankly, that just about decides the whole issue for me - I'm pretty well convinced that the merits of the 16" barrel outweigh its vices, on balance. I guess I'd rather not order that 21" rifle and live with any "buyers regret" when I could simply order the 16" carbine that I found more appealing to begin with. Anyway, Chessman's excellent info points out, among other things, that I can minimize potential velocity loss through careful ammo selection.

Actually, now that I think of it, I've got the perfect solution - get the carbine NOW, and then get a 21" rifle in a few months! So simple... :D

By the way, the guns in question are DSA's "kit gun" STG58A's - a DSA-made receiver plus 6 other U.S. parts and Belgian/Austrian surplus comprising the balance. The surplus parts are used so that the finished rifles will retail for $995 MSRP, as opposed to $1100-1500 MSRP for the 100% DSA-made SA58's. It's kind of an open secret, though, that DSA's actual dealer cost for the STG58A's is $795, and that a cagey FAL buyer can pre-pay DSA for the gun and have it sent to a friendly local FFL who would subsequently transfer the gun to the customer for a nominal handling fee. Since the AZ Response System guns are essentially the same product, price point would be the deciding factor - and from what I remember of ARS's prices at the local gun shows, DSA edges them out IF you've got that friendly FFL dealer handy.
 
There is apparently an "issue" with the ATF over the DSA brake on their "STG58 kit" guns. Look on assaultweb.net for discussion. DSA is recalling these rifles to retrofit a different brake.

-z
 
If you load your own you may want to check out Nosler's #4 (or later) reloading guide. They list 308 loads in the handgun section for a 14" barrel. Some loads were 400 below what is listed in the rifle section (24" barrel), but the loads for IMR 4064 were within 200fps.

150gr doing 2730 out of a 14" barrel is worth considering, but there is a tradeoff in accuracy. Best accuracy out of the 14" barrel was obtained by loading down another 200 fps or so with most powders.


Tom
 
Smithz,
Ok you've change my mind...I am also going for the carbine 16" now. Funny how I think of a 20" barrel and think of an AR-15, nice and light. But I have to agree that the FAL isn't much of a carbine regardless of barrel length (Unless one considers the lightweight version). Thanks for clearing that up.

I've never learned anything from anyone who agreed with me.
 
Read the articles on the DSARMS web site. I think these are the velocities...

22" barrel (i.e. M14/M1A) ~ 2800fps
20" barrel (i.e. std FAL) ~ 2600fps
16" barrel (i.e. 16 in FAL) ~ 2300fps

DS ARMS may have a 18" "para" barrel. The articles recommend that length. I read somewhere that 308 burns all of its powder at 18 1/2 inches which might take some of the flash out of muzzle blast
 
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