Actual 308 velocities from 20" barrels

[handirifle]

Looking for chrono'd speeds from 20" barreled 308's, specifically using 165-168gr bullets. Would also like the load if possible. Thanks.

[handirifle]

Has no one ever chrono'd their 20" barrel? Or is it the bullet weight?

[GaCop]

The shortest barrel I've ever had was the factory 24" and I was pushing a 168 gr SMK 2735 fps. My new build this week will be with a 28" bull barrel. I would imagine you could get 2600ish from the 20" tube.

[jpdown]

I could get 3050 fps with maximum load of Varget and Barnes 130 gr bullets using a Savage Factory barrel cut to 20". Bad medicine for deer and hogs. Never looked at 165 to 168 gr bullets.

[handirifle]

Thanks guys, I was wondering. The books always give their speeds, but it seems most of the time we never see those velocities, kinda like ammo companies. Only reason I'm asking is of the idea of having one bullet for each caliber, ie. all my 30's use the 168 etc. So I was wondering what the external numbers would end up like, since my 308 wears a 20" tube.

I really like the short barrel for moving the rifle around and wasn't sure if it would be worth it to go longer.

JPdown
I assume that at 3050 that is near a top charge of Varget? I believe it's listed around 3150 or so. What kind of accuracy are you getting with the 130's. I read an article some time back of Barnes reps taking the 300Wm and the 130 TTSX's to Africa, and taking some pretty darn big animals with them. Kudu and the like. If I am correct those are not much smaller than elk, at least some species of elk.

GAcop
The 2600's would be good, since the lists are low 2700's. I was hoping for that anyway.

[jpdown]

Yes, 3050 was with Barnes 130gr, seated 0.050", and 50gr Varget. Got consistent 0.65" grps@100 yrds with Savage sporter barrel cut and recrowned to 20".

[helotaxi]

The good news is that the .308 has a relatively small case capacity for its bore and as a result doesn't lose that much velocity with a change in barrel length. Figure maybe 150fps lost from 24 to 20".

[handirifle]

Yea 150 is not bad at all, really, for a 4" shorter, more handy hunting rifle. My last range session wasn't super impressive in the accuracy dept. I will have to work on that a bit I suppose. I am moving to my '06 as my main rifle but want the 308 as a backup.

[Jamie]

A fellow on specialty pistol board said he only lost around 60to fps from 26" to 20".

[handirifle]

Wow, was it a 308? Got a link, I'd like to read his post?

[Jamie]

Yes, it was a .308 Win but can't find the threadI now. Maybe Tinkerer or Blue Avenger can find it since they are on that site as well.

That case size works extremely well in short barrels.

[Glock17]

Savage 10FP LEA1 20" Bbl
Lapua cases
168gr Hdy HPBT match
42grs IMR 4064
5-shot avg= 2569 fps
Extreme Spread=22.3 fps
Std Dev = 10.04
Group 100yds = .364 = Best Avg. = 1/2 MOA

[Creedmoorshooter74]

2405fps 168 a max 42gr rl15 210m and 2630fps 155 vld berger 44gr imr 4064 rem 9 1/2 out of Savage Precision Carbine

[acemisser]

good reading guys...my 20 inch has a 1 in 10 twist and will only handle the 175 gr for accuracy

[helotaxi]

What do you mean by "only handle"?

To add to the thread, I finally shot my 20" .308 over the chronograph. SSA factory loads with 168gn MatchKings: 2584fps with a max spread of 8. My handloads that were attempting to duplicate that load shot within 5fps or so average with a larger ES. Shot to the same POI out to over 300yds.

[Apache]

Partial cut-n-paste from 6mm.com

http://www.accurateshooter.com/cartridge-guides/308win/

Barrel Length & Twist Rate
You’ll see a wide range of barrel lengths and twist rates on precision .308 Win rifles. At one end of the spectrum, a tactical shooter who needs a compact, quick-handling rifle, may select a 20″ barrel. The popular Rem 700 LTR (Light Tactical Rifle) features a 20″ fluted barrel. On the other hand, Palma shooters, who need to keep a 155-grain bullet supersonic at 1000 yards, normally opt for barrels 30-32″ in length. The extra length also provide a longer sight radius–a big benefit when using iron sights. A shorter barrel definitely delivers less velocity, all other factors being equal. With most powder/bullet combinations, you can figure an additional 25-30 fps per inch going from 20 to 25 inches. From 25 to 30 inches, add an extra 17-20 fps. From 30-33 inches you may pick up 15-17 fps or so, with appropriate powders. Here are some velocity estimates projected by QuickLOAD for 44.5gr Varget (ADI 2208) and IMR 4064 with a 168gr SMK set at 2.800″ cartridge OAL, bullet not touching the lands.


QuickLOAD Projected Velocities in FPS with Increasing Barrel Length


Powder
20″
21″
22″
23″
24″
25″
26″
27″
28″
29″
30″
31″
32″


44.5gr Varget (ADI 2208)
2592
2620
2646
2671
2694
2716
2736
2756
2775
2792
2809
2825
2841


44.5gr IMR 4064
2628
2656
2681
2705
2728
2749
2770
2789
2807
2824
2841
2857
2872


Note: This is a software prediction only. Different barrels will perform differently based on a variety of factors including groove diameter, land configuration. Primers, seating depths, and powder lot variations can affect the numbers significantly as well.

[Curtis12]

With my .308 10FP 20" barrel
168 SMK's 2.800 OAL Win brass

41.0 gr Varget
QL Estimate 2426 fps ,
Chrono ave 2404 fps.

42.0 gr Varget
QL Estimate 2482 fps,
Chrono ave 2489 fps.

43.0 gr Varget
QL Estimate 2538 fps,
Chrono ave 2570 fps

All loads ave about 20 fps ES

Curtis

[jsthntn247]

44.0 grains of Varget gives 2580fps with 165 Hornady BTSP's in my 20 incher.

[memilanuk]

Sav 10 PC-SR 20" 1-10" tw

S155MK/45.6gn I4895/Federal case/210M primer = 2830fps

Factory Federal Premium S165GK = 2615fps

[pappy83]

I have a savage PC that has been cut back to 14.5 with a fixed brake, it will push a 175smk at 2580ish with a stiff load of Varget, and 130ttsx at 3000 with 50.5 grains of Varget. The rifle is very accurate with both loads. Brass is lapua that has been fired 4 times in kids palma rifle before I get it.