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Discussion Starter · #1 ·
I am going to be purchasing a new supressor for my Rem 700 .308 when I get home and will have to get the barrel threaded. I was thinking about having it shortened when I have it threaded. I have read a few different accounts online that talk about going as short as 18 inches with little to no change over a 24-26" barrel. I understand the theory that the barrel will actually be stiffer when it is cut short and therefore possibly more accurate. My concern is the velocity loss. The .308 isn't the fastest round around and I would like to keep it around 2700fps. I do not currently shoot anything over 500-600m though I would like to learn how to properly dope and shoot.

Looking for advise from anyone that can talk to this. Thanks guys.
 

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I built my 700's off of the M24 I used to carry, so I've got 24" of barrel out front. Shooting most "match" loads from a 26" bbl will get around 2600fps+ reliably, some might list 2700 but that's stretching. Military M118 Spec Ball and the M852 Match listed at 2550fps from the M14's 22" bbl. A goal of 6-700m isn't hard, it just depends on what accuracy you want out there and what you want the round capable of doing. A 7.62 at 1000m has about as much oomph as a small caliber gang banger pistol.

20" is a good length. If the Chandler's over at Iron Brigade Armory are using it then I'll take their word that it works. And the shorter barrel will work better with the suppressor otherwise it will stress the longer barrel in weird ways.
 

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Discussion Starter · #3 ·
I should have said I that shoot mostly handloads, that and I know that the .308 is about as fast as a school bus out there at 1000m. I was just doing some reading online and saw where a certain sniper school had cut barrels down to 18" and only saw a 3MOA difference at 920m over the same gun with a 26" barrel. I have always felt that the shorter guns handle better and I don't want the gun to be too long, especially after the supressor is mounted.
 

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At the sniper competitions and schools, I've seen 308 caliber sticks short enough to question if they were really pistols (HA!) - really, in the 18 to 20 inch category. And I've seen 'em long enough to wonder if a lanyard was needed to fire 'em (LOL!) - really in the 26 to 28 inch range.

Like M118SB said, the M852 and M118 most always gave me between 2600 and 2650 fps from my M14 based weapons. The M118LR was a bit more peppy under the Olin contract, before Alliant took over Lake City. Of course, then again, there weren't pin breakages in the M14 based weapons when Olin was making the M118LR either...... When Alliant started making the ammo, and pins started breaking, they decreased the pressure - instead of using a more suitable powder.

[Unlike what some character here said about the M14 being fragile as far as bending an oprod, the M14 breaks pins in the trigger assembly LONG before the oprod is damaged]

All that to say that my home-rolled M118LR is loaded to 2685 fps, to track my bullet drop compensator. Last year, for the advanced class, I "strayed" away from Varget. That mistake won't happen again. Using Varget, getting 2700 fps with a 175 SMK in a boltgun would be cake.

I'm limited to 2.820" COAL, due to mag restrictions. If you can load yours a bit longer, look into the 178AMAX. I can't stuff enough Varget in a Lapua casing (while keeping the 178 at 2.820") to get it up to speed - the bullet is SIGNIFICANTLY longer than the 175SMK, so I lose too much case capacity. Well, that combined with the fact this last Kreiger has so many round run through it the throat is WAY forward of where it should be......

Keeping those guidelines in mind, it's my opinion that your rifle barrel length will be the least of your concerns. The take-home message I got from the activities I've participated in is that the barrel length isn't any significant contributing factor - it's all the nut on the butt. I've never looked at a guy with a short barrel and thought "he's no competition to me, look at that barrel!" - then again, I've never looked at a guy with a telephone pole for a barrel and thought he had any advantage on me at all due to that.

And yeah, Norm Junior ain't building rubbish. He's got a reason, and his sticks are GREAT. Don't sweat the shorty barrel.......
 

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I shoot a 168 SMK out of RA military brass using 45g of AA2525. Velocity is bang on 2750 fps with very little velocity deviation. Max last string was 6fps. Barrel is 24"

You can drop a .308 down to 16" and still be ok for targets out to 500/600 yards but I wouldn't like to try for further than that. Ideal length is probably 20" as that covers you for length as well as velocity.
 

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Mickey, there better be some kind of something on the end of that 16" barrel or you'll need sunglasses to shoot it beyond the flash! That'd be something to see for sure! :D

I used to shoot the crap out of Varget but rediscovered BLC-2 when I noticed the store had it for a couple bucks less. I can mimic the Special Ball loading that my USO/Unertl is cammed for and it shoots every bit as accurate as I need it to. I bought a mess of the M72 173gr slugs from Jeff Bartlett at gibrass awhile back and am still going through them. But, the loading works just as good with 168 and 175 too. If I crank up the Sinclair tools I can usually coax an extra 1/4 MOA out of them. Usually do that during the winter when I'm bored though.
 

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Just pick a barrel that will keep whatever ammo you're using supersonic up to the range you're interested in. 5-600m is no problem even for a 16 incher. 1000 yard needs at least 19-20" depending on ammo.
 

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Actually, supersonic isn't much of a consideration.

Mickey - why don't you tell these guys what happens at Bisley. Beyond the ranges that bullets stay supersonic ;D
 

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We use the Remington 700 LTR and I really like the 20 inch barrels. If you have to carry the gun for any length of time or shoot it other than prone, I really like the LTR's. The 24 and 26 inch guns just don't feel "lively" to me.

I shoot a 16 inch barreled DPMS and haven't had a problem out to 500 yards.
 
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I've seen some really handy 20" 308 bolt guns. I was sufficiently impressed enough to not want to bother going shorter. kinda the best of both worlds deal.
 

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Actually, supersonic isn't much of a consideration.

Mickey - why don't you tell these guys what happens at Bisley. Beyond the ranges that bullets stay supersonic ;D
really? I was under the impression the bullet got googly as it went transonic... how long past that point can you retain good accuracy?
 

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So far out that the hole in the target is more of a tear than a hole.

The bullet is dropping (still nose-up in attitude) so rapidly out there that it looks like the bullet was tumbling LOL!

Or maybe a better term would be 'keyholing'. In any case, a 30 caliber projectile makes a hole 30 caliber wide and about an inch tall.
 

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You can hit targets beyond supersonic ranges, but the stability and flight performance become unpredictable as the round goes transsonic. you start getting very odd shaped holes in targets and very little hit guarantee.

Boat tail rounds handle the transition much better than anything else and trimming the meplat may give you some semblance of uniformity but if you want to shoot that far, either use a high BC round or buy a bigger gun.


M118, Aziator wants to use a surpressor with the short barrel so muzzle flash should not be an issue, but i'd definately look to use a quicker burning powder to maximize velocity.
 

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Oh, I was bustin' your chops Mickey! I remember shooting blanks from the M24 during field problems or stalking drills and seeing that chunk of combustion blasting out the barrel, always seemed way worse than shooting ball rounds at night with the PVS10.
 

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My advanced sniper instructor was taking a break from shooting one morning, when bambi decided to come up over the berm.

It was deer season, and he had a tag, so he thought "what the heck".

Since the deer was standing next to the 1K steel, he dialed 1K, and the guy that was spotting for him called the wind.

The first round went slightly aft, but knocked bambi to the ground. But the spotter was watching and when bambi started to get back on its feet, the second round was headed down range.

That one hit perfectly, and bambi went down for the count.

Anyone that says a 308 doesn't have power at 1K hasn't taken a round at that range - er, you know what I mean - seen what a 308 does at that range on living meat.
 

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Back in GW1 rangers were able to make hits out to 1400 yards. 168g hitting at 800 fps is still going to urt. It all comes down to consistency and whether you can hit it first time or without the target reacting to your sighting shots.

BTW: With a .308 SMK with a muzzle velocity of 2750 fps will, depending on environmentals, still be supersonic at 1000 yards....just.
 

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Never said a 7.62 round wasn't lethal at 1000 or even past that distance. When you're working the pits and somebody tags the stick on the Ernie you're walking you can tell the difference when the round was fired from, say 300m, to out there at 1000.

my goal was always to not get shot, even by a BB gun because I know it'll hurt! ;)
 

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Here's a great article by Daniel Lilja (owner of Lilja Barrels) that I think should help answer your question.

http://www.riflebarrels.com/articles/longrange_shooting/ideal_barrel_308_tactical_rifle.htm

The following article was published in the March, 2000 issue of Tactical Shooter. I've taken the liberty of including Editor Dave Brennan's introduction to the article from the magazine copy. DL

The Ideal Barrel For A .308 Caliber Tactical Rifle


By Daniel Lilja

(Editor: Recently a TS subscriber wrote to us, looking for some guidance on the barrel contour selection for a .308 chambered tactical rifle. We felt that the inquiry was a bit too broad-based in topic matter and while a scholarly discourse in depth might have been nice... to do the job properly would have taken perhaps a dozen pages... and been a rather dry reading dozen pages at that. Since we live in a "Be practical" type of world, we fired off a "Help!" missive to Dan Lilja, the honcho at Lilja Precision Rifle Barrels (P.O.Box 372, Plains, MT, phone (406) 826-3084), together with a cover letter that mused... "I'm looking for a good, technically-oriented response... but not a rewrite of Gone With The Wind ". The goodfellow, Heaven bless him, must have understood what I was trying to say... because his response was along just the very lines that I was looking for. The editor considers Dan Lilja one of the most knowledgeable of today's authorities on long range rifle shooting.)

To make a recommendation for a .308 caliber barrel to be installed on a Remington 700 action, there are a couple of questions that need to be addressed. The first question is overall rifle weight. For most tactical applications, a rifle in the 10-12 pound range is about right. This rifle weight allows a reasonably heavy barrel for good accuracy, but is not cumbersome when the shooter needs to make a quick entry or exit or a long stalk. And it is hefty enough to hold fairly steady.

Secondly, we'll look at both bullet selection and barrel contour/length in making a recommendation for a barrel twist rate and profile.

Using the .308 Winchester for a tactical situation, I would like to use a bullet in the 150-180 grain weight range. For longer range shooting, say out to 600 yards, a high ballistic coefficient is desirable to help offset the shooter's margin of error in estimating wind drift and, if not using a laser range finder, range estimation. With the lower velocities of the 308 Winchester cartridge though, the heavier bullets, with the high ballistic coefficient, tend to be a little too heavy, in my opinion. This extra weight keeps the muzzle velocity down. So a compromise of reasonable muzzle velocities and ballistic coefficient is necessary. The .308 just lacks the horsepower for truly long-range shooting. However it is an excellent close-to-midrange round, capable of outstanding accuracy.

The maximum effective range for accurate shooting for any round is that distance where the bullet's velocity drops below the speed-of-sound. Depending on the atmospheric conditions, that velocity is near 1120 fps. The 168 grain Sierra Match King is an excellent bullet in the 308 Winchester, and is probably my first choice for the shooting situation we're discussing in this article. This bullet has a ballistic coeficient of .475 and with a barrel of 26" or so, a velocity of 2800 fps is reasonable. Using these numbers in an exterior ballistics program, we find that this bullet will go subsonic past 1100 yards. If we were to go to a lighter bullet, like the 150 grain Sierra Match King, with a lower ballistic coefficient of about .440 and a muzzle up to 2900 fps, our supersonic range is no better. Individual rifles and longer barrel lengths will improve on these numbers, but the 308 Winchester is never going to be a 1000 yard powerhouse.

So, if we're going to settle on the 168 grain Sierra Match King or another bullet of a similar weight and style, then a 12" twist rate is the best choice. To keep the velocity up, yet keep the rifle handy, I'd opt for a barrel length in the 26-27" range.

Now the selection for a barrel contour needs to be made. We've made a number of barrels for Robar; a company which specializes in rifles of this type. The cover of the January, 2000 issue of Tactical Shooter shows one of Robar's SR-60 rifles. This special contour that we make for Robar weighs about 5 pounds in a non-fluted condition. It is similar to the contour found on the Remington Police Special rifles and our standard #7 contour. The barrel has enough diameter to remain stiff, and accuracy is excellent. I like this contour for a tactical rifle.

If it is desirable to make the rifle a little heavier, then I would suggest using one of the straight taper barrels, like the NBRSA Heavy Varmint classification or a close variation. We've made .30 caliber barrels like this for the Navy SEALS, theirs being a little lighter than the Heavy Varmint taper just mentioned. Finish lengths again would be in the 26-27" range. If we stepped up to a cartridge like the .300 Winchester, I'd consider going to a 30" length.

Some readers might wonder why I wouldn't suggest going even longer than 30", and there are a couple of reasons why not. One of the primary reasons goes back to our already mentioned requirement for portability. A long barrel just seems to always get in the way, banging against whatever obstacle there might be.

Another good reason is rifle balance. As the barrel gets longer the center of gravity moves forward, tending to make the rifle more and more muzzle-heavy. The rifle can be easily counter-balanced by making the stock heavier, especially in the butt area, but in doing so the overall weight of the rifle becomes higher. Also, too much barrel weight on a lighter-weight repeater action, like our preselected Remington 700, can affect the bedding and create problems that wouldn't exist with a shorter barrel. It is not unusual to see vertical grouping in a long-barreled, muzzle-heavy rifle. A maximum barrel length of 30" seems to be a good compromise.

There is one more good reason to stay with a 26-30" barrel, and that has to do with barrel stiffness. As a barrel gets longer it becomes more limber. The most accurate barrels are the stiffest, all other factors being equal. Increasing the diameter of a barrel has the opposite effect, making a barrel more rigid. But there is a weight penalty in going too large in diameter. If we take a look at the math involved in calculating the rigidity of a rifle barrel it can be modeled after the classic cantilevered beam. For a round beam, like a barrel, its rigidity increases with the 4th power of its diameter but decreases with the 3rd power of its length. The basic formula for calculation of muzzle deflection is:

D = (W*l^3)/3*E*Ix

Where: D is the deflection at the muzzle in inches, W is the force or load applied at the muzzle in pounds, l is the free length of the barrel in inches (not including threads), E is the modulus of elasticity or Young's modulus for the barrel material, and Ix is the moment of inertia for the barrel.

In plain English this translates into shorter lengths and bigger diameters being stiffer, and as we know, stiffness and accuracy are closely married. Like actual married life there are always trade-offs. Long barrel length means higher velocity but it also means lower stiffness values. Diameters that are bigger mean greater stiffness but the extra weight isn't always desirable. My wife has told me I can be stiff-necked but that isn't always desirable either.

Fluting a barrel helps with the compromise though. A fluted barrel retains most of the stiffness gained by increasing diameter, yet reduces the weight gain. And as a side benefit, fluting also increases the cooling rate of a barrel by exposing more surface area to the air.

I ran some numbers through a computer program I developed that calculates barrel weights and stiffness values. In this example I used the NBRSA Heavy Varmint taper. For those not familiar with this profile, it is dimensioned as 1.250" at the chamber end for 5". It then begins a straight taper to .900" at 29", a taper of .0146" per inch. In the examples below we'll start with a 22" barrel and go on out to 30". The table will show the weight for each barrel length, the deflection of the muzzle if a one-pound load were applied perpendicular to the bore centerline, and the diameter of the muzzle at the specified length. In all cases the model is for a .308" caliber barrel.

.308" caliber NBRSA Heavy Varmint taper barrel stiffness versus length table
Barrel length in inches Weight in Pounds & ounces delfection in inches muzzle diameter in inches
22" 5-14.9 .001143" 1.002"
23" 6-2.0 .001321" .987"
24" 6-5.0 .001520" .973"
25" 6-7.9 .001740" .958"
26" 6-10.7 .001983" .944"
27" 6-13.5 .002251" .929"
28" 7-0.1 .002546" .915"
29" 7-2.6 .002869" .900"
30" 7-5.0 .003223" .885"

So, we can calculate from the above that a 30" long Heavy Varmint taper barrel will deflect 182% more than a 22" long barrel will. The difference in length between these two barrels is just 36% and the weight increased just 23%, going from the 22" to the 30" barrel. The point is: increasing the length of a barrel quickly decreases its stiffness.

This graph was added in October of 2004 and was provided by Rick. It demonstrates the same information as the table above but in graph form.



Our experience has shown that for a .308 caliber tactical rifle with the overall rifle weight and shooting distances mentioned earlier, a barrel of 24-27" is optimum in one of the fairly heavy contours we discussed. Closer ranges or other considerations might dictate a shorter barrel. The vast majority of the barrels we make for the professionals, who have made their own decisions on barrel length and profile, also fall into these same parameters.

(As of February of 2004 we have added a new straight taper to our list of standards that we refer to as the Tactical. It was developed by one of our military customers. It is a 1.200" diameter cylinder for 4" and then a straight taper to .800" at 26". The weight at this length is 5.55 pounds in .30 caliber.)
 
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