Home Forums Hunting & Shooting Hunting Rifles .308 22" vs 18" barrels

For the 308 the loss is typically closer to 25 fps per inch.

For Colorado hunting in your place I would get the 22" because you guys out there don't climb trees for you deer and elk hunting. We do that here in the Midwest and the 24" on my 7mm RM hit every limb and got hung up with it on a sling over my shoulder pointed up or down. The 18.5" barrel on my .308 was way handier for tree climbing and bullet velocity was never a consideration. That 7mm RM still has that 24", but when I built up a custom 7mm-08 it has a 20" for these parts. I'm more of an in tents hunter these days and a 22" like on my .300 Savage works just fine.

For the 308 the loss is typically closer to 25 fps per inch.

elocity loss is about 170fps compared to a 22" barrel, Remington 150g loads.

These statements need to be put into perspective. Individual rifles even with the same barrel length can yield VERY different MV. I've seen as much as 130 fps difference from 2 different rifles with the same length barrel shooting ammo from the same box. I've seen a 20" rifle shoot faster than another 22" rifle and match a 24" rifle. Somewhere between 25-50 fps from the same barrel length is common. It might be accurate to say that rifle "A" shoots the same loads 170 fps slower than rifle "B", but not all of that 170 fps can be attributed to the shorter barrel.

The 25fps/inch number is thrown around on the internet a lot, but I've never seen any documentation to support it, even with magnum cartridges. In fact with 308 class cartridges 10-15 fps/inch seems more accurate. There have been lots of tests done where a longish barrel was tested for velocity and velocity measured again as it is cut shorter. Using the same barrel is the only way to get meaningful numbers. With a barrel 20" or longer velocity loss with ANY center fire rifle cartridge is a lot less than we've been told. Especially with anything over 24".

Once you get below 20" velocity does drop off at a greater rate. My 18" 308 doesn't give up much at all to my 22" 308's but that may just be the individual rifle. I've never worked with a 16" rifle, but wouldn't be surprised to see a bigger difference at that length. But with a 308 a 20" barrel isn't a bad place to be.

... It might be accurate to say that rifle "A" shoots the same loads 170 fps slower than rifle "B", but not all of that 170 fps can be attributed to the shorter barrel.

The 25fps/inch number is thrown around on the internet a lot, but I've never seen any documentation to support it, even with magnum cartridges. In fact with 308 class cartridges 10-15 fps/inch seems more accurate. ...

My Remington 660 carbine wears a 20 inch barrel. I had a smith glass bed the barrel channel and lighten the trigger a little. Otherwise, everything is same as the day I bought it. Accuracy and deadly power is quite impressive. This South Dakota muley was taken at approx 225 yards or so. I would not want a longer barrel than 20 inches.

Sherwood

Charlie_Sisk
Campfire Ranger


Reged: 02/21/02
Posts: 1321
Loc: Dayton, Texas Been doing a little more experimenting.........
#88566 - 09/14/02 03:15 PM Edit Reply Quote



For a long time I have wondered about how barrel length affected velocity. I had always been told you need a certain length barrel for certain calibers. I have read when folks compared one gun to another with different lengths but I always thought that was not an apples to apples comparision. So I did a few test myself.
All these were Shilen barrels. I used the same brass through out the whole test. All weighed to with 1 grain. Bullets were tested on the Juenke machine. Powder charges were weighed to .1 grain. The same rest, chronograph, Redding press, primers all from the same lot, bullets for the same box, same lathe, same crowning tool, same cutoff tool, and each rifle done from start to finish on the same day. Ambient temperature was the same because I shoot from inside the shop. I held the rifle the same way on the rest every time. I shot ten rounds first to break in the barrel. Then cleaned with Sweets and fired one fouling shot. Then shot five rounds and took the average. I used a midrange load fron the Nosler book, not too hot but certainly not a reduced load. Here is what I got.

22-250 Hodgdon 380 34 grains Federal GM210M Remington brass 55 grain Ballistic Tip
27 inches 3469 fps
26 3451
25 3425
24 3407
56 fps from highest to lowest

270 Winchester Hodgdon 4350 54 grains Federal GM210M Winchester brass 130 grain Sierra
27 inches 3115 fps
26 3093
25 3071
24 3054
23 3035
22 3027
21 3001
114 fps from highest to lowest

300 Winchester mag Federal GM215M Winchester brass 74 grains of Reloder 22 180 grain Partition
27 inches 3055 fps
26 3031
25 3024
24 3003
23 2984
22 2960
95 fps from highest to lowest

340 Weatherby Federal GM215M 250 grain Sierra
81 grains Reloder 22 Wby brass
27 inches 2837 fps
26 2817
25 2809
24 2791
23 2777
22 2755
21 2731
106 fps from highest to lowest

I think I will do a little more thinking before I recommend a barrel length in the future. What do you folks think ?
Charlie



.338 Winchester & .257 Roberts

Here is the info about the 338 Win and the 257 Roberts.
338 Win mag
Winchester brass
Federal GM215M primers
Reloder 19....73 grains
250 grain Partitions
27 inches.....2806 fps
26 inches.....2787 fps
25 inches.....2761 fps
24 inches.....2743 fps
23 inches.....2716 fps
22 inches.....2697 fps
21 inches.....2676 fps
20 inches.....2656 fps
150 fps from 27 inches to 21 inches

257 Roberts
Federal GM210M primers
Remington brass
H-4350....45 grains
120 grain Partitions
27 inches.....2860 fps
26 inches.....2834 fps
26 inches.....2815 fps
25 inches.....2815 fps
24 inches.....2798 fps
23 inches.....2775 fps
22 inches.....2760 fps
21 inches.....2739 fps
20 inches.....2717 fps
143 fps from 27 inches to 20 inches

I want to test this on the next 450 Marlin I build and on a 222 Remington. If I get the same results with those, in my mind the test is over. I think this will be enough data to support the findings. Are there any folks out there who have a degree in this sort of thing ? Maybe explain how many data points would be needed to be able to say this would work with the majority of calibers ? Someone with experience in statistical (spell check) quality control?
Charlie



--------------------
Sisk Rifles
400 County Road 2340
Dayton, Tx 77535
www.siskguns.com
charliesiskguns.com
1-936-258-4984

The data and opinions contained in these posts are the results of experiences with my equipment, componentry, and testing methodology ONLY. As your equipment, componentry, and methodology is different, NO CONCLUSIONS SHOULD BE DRAWN FROM ANY DATA PRESENTED, nor should any data presented form the basis for any load development. DO NOT, UNDER ANY CIRCUMSTANCES, ATTEMPT TO REPLICATE THESE RESULTS, as doing so could be extremely dangerous.

I don't think the elk will care..... but I bought a Vanguard in 30-06 during the Wally World big sale last September. It is the first rifle I have owned with a 24 inch barrel. Maybe I am crazy but it seems significantly quieter than my other '06's with 22 inch barrels when I have fired it at game and the time I forgot to put my ears back on when sighting in....it was 90 degrees then and I took them off while waiting on the barrel to cool. Other than that I haven't noticed the two extra inches on the barrel as making the rifle "unhandy".

An 18 inch barrelled .308 must be a loud rascal. If you are gonna use it for a loaner, maybe loan your friend some earplugs with it....or use a can.