I was wondering what type of muzzle velocities are attainable in a 20" barreled 308 Win.

With safe maximum loads, and the appropriate powders, how fast can you push the following:

130 gr.
150 gr.
165/168 gr.
180 gr.
200 gr.
220 gr.(if it is even done)

The rifle would be a strong action, and have a 1-10" twist. Most manuals show data for 24" tubes, and I hear you can loose 25-50 fps per inch. Just looking for some actual numbers out of a 20" barrel.

i own the remington 700 ltr. in 308 win. it has a 20 inch barrel and 1-12 twist. i found out that the shorter barrel in 308 win. doesn't reduce the velocity by much(if any). take for example the factory loaded federal gold match bullets. they state that the velocity is 2600 fps from a 24 inch barrel, when i chroned the round in my rifle i got min. velocity of 2570 and high velocity of 2594 fps. then i loaded some sierra 165 gr. bullets and i got the same velocity published in the reloading book which specify 24 inch barrel used in testing. it's amazing but it's true

sambo

Tod, you will never know exactly what YOUR rifle is doing unless you chronograph it, but with the smaller, more efficient cartridges like the .308, your velocity loss will be less for each inch you chop off than for larger, less efficient cases like the magnums. In a .308, you might lose as little as 15 to 20 FPS per inch you cut off of a 24" barrel, but the "standard" amount usually subtracted for a cartridge like the .308 is 25 FPS per inch.

I had a 220-grain .308 load, 48 grains of N205, then later, 48 grains of MRP, that gave 2350 FPS, and was one great deerslayer in the thick woods of Virginia!!

[ 02-10-2003, 18:52: Message edited by: eldeguello ]

19" bbl'd SS M70 / RL15 / WLR / WW Brass:

150's / 2,820 fps

165's / 2,750 fps

180's / 2,610 fps

Brad,

Do you have the data to add up a M1999 with a 19" slim tube in .308 Win, MacMillan, light mounts and say a 10 oz scope for me?

I am most interested in the weight of the M1999 with a short slim barrel in say .308. The choice of the stock is not fixed and I don't know much about composite stocks.

M99... I believe the M1999 action is a couple ounces heavier than my SS SA M70, so I'd bear that in mind.

The M70 type actions are tough to get light because of the basic action weight, so it's important to get all the details correct as ounces add up rapidly and make pounds!

First, I'd send the action to either PacNor or Dave Olson in Plains, MT (I believe he's been working in conjunction with the MT Rifleman Co. working on these action's) and have it barreled in the USRAC featherweight pattern. Either can mimic the original fwt. contour. I love the fwt contour as it's a brilliant compromise to lose weight yet remain stiff. In equal barrel lengths the fwt is 6 oz's lighter than the standard M70 Sporter wt. bbl.

Next comes the scope. On a carbine I'd do a matte black 1x4 Leuold (9 oz's). With a 22" bbl. I'd do a 2x7 (10.1 oz's) or a 3x9 compact (9.3 oz's).

Bases and rings are a big decision... I've generally used aluminum (ss) Weaver's. In low they'll go 3.2 oz's (bases and rings). I've recently swithced back to Warne Maixima bases (Weaver style, all steel, silver finish) and low (sivler finish) Burris Zee rings. The Zee's are better made than they used to be and are narrower than the Weaver's (more mounting flexibility), as well as MUCH better looking and all-steel. The bases and rings go around 4 oz's. I'm wiling to cash-in a little weight here.

The stock is the next big decision. I've made mistakes in the past with fiberglass stocks and have actually GAINED (or not lost any weight) with them.

The McMillan will not lose any weight over a standard "tupperware" M70 stock and will generally weigh in at 32 oz's.

Mark Bansner's "High-Tech" stock is apparently the way to go for a quality, stiff and light stock. I'll be ordering three next week! You can cut out a section of the forearm on the High-Tech stock and re-attatch the tip to shorten the forearm to be in keeping with a short barrel as well as shed weight. With a nice 3/4 -7/8" decelerator with a section removed from the forearm the stock should com in at 25 oz's (or thereabout's) finished.

Five rounds (180's) weigh 4.8 oz's.

Unlce Mikes "Mountain Sling" weigh's 3.4 oz's (this is another area where weight stacks up... a lot of guy's put 8 oz leather slings on their rifles... the Uncle Mikes is stiff enough to use as a shooting aid and has a "grippy" patch sewn on it so it won't slide on your shoulder.

Your "all up" weight (scope, sling, five rounds) should come in at 7.5 to 7.75 lbs assembled as per above.

Me, I'd go with a 20" tube... I've had six 308's with 18.5, 19, 20, 22 and 24" bbl's... I think 20" is "perfect."

Hope any of this helps!

Brad

[ 02-10-2003, 23:51: Message edited by: Brad ]

Brad,

Thank you very much for all this work.

I am going to use rifle weight however without a sling or ammo. It's just easier to add them up that way. A old pre 64 Featherweight goes 7lb 15 oz on average that way. It seems that the new one will weigh less.

MRC estimates that the short action will go 2.5 lbs. Jack Belk weighed a long at 2.95 lbs.

What does a 19" .308 featherweight barrel weigh?

How much does that stock weigh with the pad on it?

I like the old M-70 Featherweight barrels a lot also and have three pre 64 M-70 Featherweights in .30/06, .308W and .358W.

[ 02-11-2003, 00:45: Message edited by: Savage99 ]

My sons is a Classic Compact M70 20" and with all the testing I've done, a good rule of thumb is about 50-100 fps slower than 24" tube data in the books and on the factory loads.

I have notice quite a few Ruger rifles shoot the same box of ammo 50-100 fps faster than my 700's do as well, just an observation not definate with all though.

I have quite a bit of data on the 308 in my sons testing with the Oehler 43, if you would like some specific bullet comparisons etc, I might be able to give you an idea of what you did what in this gun.

M99, The Bansner stock completely finished should go 24 - 26 oz's depending on which pad you use and the forearm length... if you have Mark Bansner do the bedding, painting, etc., he'll cut and finish the forearm length to whatever length you'd like. I plan on doing everything except the final paint job myself. Rick Bin at 24hourcampfire seems to do an excellent job painting and is reasonable so I'll have him do that part of the job.

I currently have a 22" SS 308 fwt take-off barrel on hand... it weigh's 2lbs 2.3 oz's. Somewhere around here I have the 3" piece that was cut off my original ss fwt. bbl. If memory serves, that piece weighed 2.8 oz's... sooo, your 19" bbl. should weigh in at a smidge under 2 lbs.

The 308 is a GREAT cartridge... in my mind it's attained "classic" status!

BA

I have only looks at Norma out of my brothers 18 inch 308 and they got 2500 fps

I took a FAL in 7.62mm, the barrel was 21", cut it to 18", I lost 84fps with military 147gr ammo.

On the M1999 weight issue with a short 20" Featherweight barrel and light synthetic stock it's totaling 2.5 for the action, 2.0 for the barrel and 1.5 for the stock or 6.0 lbs which is the same weight as a new Ruger Ultra Light which also has a 20" barrel!

The Ruger Ultra Light that a friend has in .308 does not group all that well and falls apart with the Hornady high energy load. I gan get a Ruger UL for maybe $600 or less retail.

The M 1999 will cost me $350, the stock $250 and a barrel $440 or a sub total of $1040. Add $75 for bead blasting and some for shipping and FFL costs and I am in the $1200 range for this dream rifle.

It was more fun before I added it up.
Just rambling.

I see no problem with the velocity from a 20" barrel. It will be plenty.

quote:

Originally posted by Brad:
19" bbl'd SS M70 / RL15 / WLR / WW Brass:<br /><br />150's / 2,820 fps<br /><br />165's / 2,750 fps<br /><br />180's / 2,610 fps

Hi Brad
I realise that thios is an old post but how the hell did you get that velocity from an 18" barrel & 150 grn. Best I got so far is 2685

Hi Galloway,

If it's any consolation your velocities are much closer to what I have been able to achieve loading for the AR member Boghossian's 20" .308 culling rifle.

A load of 45 grains of H4895 under a 150gr Horbady BTSP ( 2.740" OAL ) proved to be maximum in that rifle and chrono'ed 2680 FPS. The 44.5 grain load was more accurate however and we settled on this at 2640fps. This load achieves 2800FPS in my 24" Sako.

IMI 180 grain factory ammo measures 2380 fps from the 20" barrel and 2510 from the 24"; I'm sure you could get it a little higher with some judicious hand-loading.

Reloder 15 seems to do very well in the 308, certainly better than H4895 and Varget in my experience for velocity. It must be said however that I get 2765fps with a max load of RL15 and 165 grain bullets from a 24" barrel, the gentleman above seems to have an extremely fast barrel...