The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Medium Bore Rifles velocity vs. barrel length experienceGo | New | Find | Notify | Tools | Reply | |
| velocity vs. barrel length experience | Login/Join |
| One of Us |
While shooting yesterday, I saw something that I found quite interesting. I shoot a load of 46 grains of Varget powder uner a 165 grain Hornady in my 18 1/2 inch barrel .308 for a velocity of 2650-which is great for that short barrel. My buddy chrono'd the load through his new Remington mountain rifle with a 22 inch barrel and the load was only 2700 fps in his-with a 3.5 inch longer barrel! 50 fps for 3.5 inches more barrel doesn't equate to me. I'll take the short one! I have found that the Varget really does well in short barrels. | ||
|
one of us |
Your experience is anecdotal, one has nothing to do w/ the other. It's not uncommon for rifles of the same manuf. w/ same length bbls. to be off as much as 100fps. You have a tighter chamber/bbl. specs. than your buddies 22". Example, I had a 2 3/4" Ruger 357mag that used to run an avg. 100fps faster than my 4"M19 regardless of powder or bullets used. Varget is a good powder for the .308, but it really is no better for short bbls. than any of the others. You are fortunate to have a "good" bbl.  LIFE IS NOT A SPECTATOR'S SPORT! | |||
|
| One of Us |
The .308 is an efficient designed case. If you had been shooting something on the order of a .257 Weatherby or .264 Win Mag you would have seen more velocity difference due to the expansion ratio (case capicity:bore volume). I would estimate an average of 30 fps per inch of barrel length for rifle cartridges in general. This is not linear. From 25 inches to 26 inches you will see very little change. But, from say, 16 inches to 22 inches a large margin. | |||
|
One of Us |
SCI Life Member NRA Patron Life Member DRSS | |||
|
One of Us |
Barrel length is far more relevant to compactness and handling than velocity but it seems we want to get excited over velocity. Most cartridges do not produce differences of velocity that are truly significant until the barrel is reduced to under 18" and more. It remains one of the most discussed and of most useless discussions as it makes no difference to almost anything we shoot at. /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
|
| one of us |
I have seen as much as about a 100 FPS difference in barrels, all things equal. so that does not surprise me. I think some calibers benifit from long barrels and other do not. The .270 can really handle short barrels and maintain velocity. The 9.3x62 really cooks with a long barrel. Ray Atkinson Atkinson Hunting Adventures 10 Ward Lane, Filer, Idaho, 83328 208-731-4120 rayatkinsonhunting@gmail.com | |||
|
| one of us |
If you guys tell me I wasted 2-4 inches by putting a 26 inch tube on my .257AI I think I will cry.  It's a field gun so it don't need to be handy though.Don Nelson Sw. PA. | |||
|
| One of Us |
Nah, it's much easier to shorten than lengthen a barrel  . Generally speaking, longer barrels offer less velocity advantage in underbore capacity calibers and/or faster powder loads. "You can lead a horticulture, ... but you can't make 'er think" Florida Gardener | |||
|
| One of Us |
I believe the only time the barrel length really matters is with magnums. If they don't have the length to burn the powder, it takes away the magnum advantage (if there really is any). | |||
|
| One of Us |
and that truly is debatable....! /////////////////////////////////////////////////////////////////////////// "Socialism is a philosophy of failure, the creed of ignorance, and the gospel of envy, its inherent virtue is the equal sharing of misery." Winston Churchill | |||
|
| One of Us |
Using the same barrel chambered in 7.62/308 Win I lost 160 to 200 fps, depending on ammo, when the barrel was shortened from 22" to 18 1/2" with the same ammo. Larry Gibson | |||
|
| one of us |
Larry I would say that is quite a bit. In my opinion I would be very happy to gain that much by adding a couple inches of barrel. Don Nelson Sw. PA. | |||
|
| One of Us |
If it performs the duties you designed it for, who cares whether you've got a few inches more barrel than "necessary"? Lets say the rifle produces 75 fps more than you intended but groups great. So you cut off 4 inches of barrel and groups open up. If you knew that was going to happen ahead of time would you still cut it? If not, then there's no reason to cry. There's some famous saying about artists that goes along the lines of "the difference between good painters and great ones is that the great ones know when to stop." Applies to rifle nuts, too, IMHO. Another way to look at it is that whatever velocity gain you get from an extra 2-4" is "free" in the sense of requiring no additional powder and no additional pressure. Whether you're getting 25 fps or 100 fps for free, its probably a good deal either way. And a lot of old safari guns had 25 and 26" barrels. Hell, look at an 18th century flintlock; its so "unhandy" it must have been a literal miracle for frontiersmen to have ever harvested a Virginia whitetail.  | |||
|
One of Us |
I'd agree with that. No game will ever not die from an 18" bbl that would have died with a 24"! If given the option, I personally like longer barrels because I think they steady and aim better. I can also appreciate the additional distance between my head and the muzzle blast. It just makes for more comfortable shooting, IMO._____________________________________________________ No safe queens! | |||
|
| one of us |
Couchtater, My shortest flintlock has a 32 1/4 inch barrel so a 26 inch rifle is no big deal. I don't see me cutting any of the barrel off as I am expecting the longer length and heavier profile to make the rifle balance good off of bags. Did I mention I often hunt off of a table and bags? that is how this rifle will be used and I have no idea what velocity I should get but am hoping to get close to 25-06 velocities. My software shows the AI getting about 300 FPS more than the standard Roberts and about 100 fps less that the 25-06 with 117-120 grain bullets. Test barrels went from 22 inch for the Roberts, 24 for the AI and 26 for the 06. If going 26 with the AI can give me even 30-50 more fps it puts me darn close to max shown for the 06. That is fine by me. Don Nelson Sw. PA. | |||
|
| one of us |
Sisk did some tests on thsi subject. He cut barrels and fired them over a speed trap. I downloaded the results for my ow inforamtion. The notes are for my own edification. Here are the results: 270 Winchester H4350 54 grains Federal GM210M Winchester brass 130 grain Sierra 27" inches 3115 fps 26" 3093 - 22 FPS 25" 3071 - 22 FPS 24" 3054 - 17 FPS (Down 39 fps from 26 inches.) 23" 3035 - 19 FPS (Down 58 fps from 26 inches.) 22" 3027 - 8 FPS (Down 66 fps from 26 inches.) 21" 3001 - 26 FPS (Down 92 fps from 26 inches.) 114 fps from highest to lowest Charge 27†to 26†22 FPS 26†to 22†66 fps drop. 24†to 22†27 fps drop. 300 Winchester Magnum 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 warthog1134.com | |||
|
| One of Us |
I am about to see what the difference is for myself. I have Rem 700 LTR w/20" barrel. A buddy of mine has a Rem 700 PSS w/26" barrel. As soon as I have time I am taking both to shoot over the chrony & see what's what. | |||
|
| One of Us |
All the posts are correct. But the only real way to get the change in velocity for a given rifle is to cut off THAT barrel. Normal variations from one rifle to another, even those of the same model, largely void the comparisons. While Mr. Sisk's excellant tests are general indicators but the actual results are really valid only for THOSE TWO RIFLES! And, there is another BIG factor in varying speeds in different length barrels: the cartidge's "Expansion Ratio", a ratio between the case capacity and the bore diameter. Basically that means large capacity cases (.270, .300 Win., etc.) with smaller bores will lose more when they are shortened. Smaller cases (.30-30,.308, etc.), especially those with larger bores (.35 Rem., .358, etc,) lose less speed as the barrel is shortened. Also, cartridges with lower chamber pressure will lose less velocity per inch than those with higher pressure. So, the observations of "...all things being equal..." are true enough, if thing are actually equal. Fact is, things are rarely equal even when it may appear they are. The .308 is an excellant cartridge for a short barreled rifle. For that, it's much better choice than a .243 but not as good as a .358, all because of the different expansion ratios. All three of those cartridges are based on the same parent case and same SAMMI pressure but the bore size changes make a LOT of difference in how they respond to shorter barrels! | |||
|
| One of Us |
Good explanation, Jim. I guess that I never knew that concept before, but it make sense. | |||
|
| One of Us |
I have cut of several other barrels (.223, '06, 6.5 Swede, 6.5 Jap, 7.57 and a couple other military calibers and found pretty much the same type of velocity loss. The velocity loss is one of two very good reasons I won't shorten a barrel less than 22" - you can give up a good amount of performance with shorter barrels. Some say it doesn't mean a lot and I suppose that's right if all your shots are short range. If your shots might be long range (200+ yards) the extra velocity equates to more velocity at longer range which gives better bullet performance on game, i.e. they kill better. The other reason I don't shorten barrels is because I've found no need to. After I went through the "short barrel is handier" phenomina a few years back I found no difference in the use of 22-24" barreled rifles in the jungles of Central America and SE Asia, the dense hardwood forests back east or to the dense rain forrest of the Pacific NW. If you're banging your barrel around on things then it'syour poor weapons craft that's at fault not the length of the barrel. My opinion based on my own experience. Most all of my serious hunting rifles have 24-26" barrels on them and I prefer the 26". Larry Gibson | |||
|
| One of Us |
Fred Bullberry http://www.bullberry.com/barrels.html has done similar testing with barrel lenght on the 17 hmr and 204 ruger. with the 204 he found that max vel was at 23" and he only lost 50fps at 21". Based on this I had my Cooper 204 cut back to 21" when I had a supressor fitted. My load was 28.3g of AR 2206h with the 39 sierra was 3950 fps in the 24" bbl. When I chronoed it after cutting it back to 21" it went 3650 fps. So I lost 300fps for 3"!! wasnt happy! But I have since played around with BM2 and am now back up at 3900fps. i had previously tried bm2, but wasnt getting any mor vel thant 2206h and it wasnt quite as accurate. so the different burn rates of 2206h and bm2 (which are pretty close) are obviously sensive enough to be effect by the different bbl length. Cheers Grant | |||
|
| One of Us |
My experience of the 243 is that it loses or gains a lot more velocity than commonly thought. 18/19" barrels lose about 300fps from 24" ones 26" barrels allow factory loads to reach claimed velocities. | |||
|
| one of us |
The best reason for a long tube is off hand shooting, especially when one is winded from running up a hill and taking a shot. That extra length and weight out front do make a difference. I don't much care for short tubes, but I do have a .416 Pre 64 with no. 5 barrel cut to 20"s and its heavy enough to get that weight where I want it. I really like this particular rifle as it holds well off hand. I don't shoot over sticks, I grab a rest on a tree, rock or whatever or take the shot off hand. Light short barrels suck!~ Ray Atkinson Atkinson Hunting Adventures 10 Ward Lane, Filer, Idaho, 83328 208-731-4120 rayatkinsonhunting@gmail.com | |||
|
one of us |
BTW, sbhooper, how many rounds did you shoot through each of those two rifles? Extreme spread of velocities in a group fired through the same rifle with the same load can be quite a bit. If you happened to get a fast shot with the short barrel and a slow shot with the long one, it might appear to be a lot closer together than the true average difference. "A cheerful heart is good medicine." | |||
|
| Powered by Social Strata |
 | Please Wait. Your request is being processed... |
|
The Accurate Reloading Forums THE ACCURATE RELOADING.COM FORUMS Rifles Medium Bore Rifles velocity vs. barrel length experience
Visit our on-line store for AR Memorabilia