Hey is there a big difference down range say 200 to 300 yards between a 20 inch  and a 24 inch 1/9 barrel. I,m  thinking about ordering a Flattop from M&A parts or Model 1Sales.Any suggestions.Newbie from tampa

No difference, and the 24 inch barrel wont really get you any extra velocity. Get the 20, it may actually be a little more accurate.

ya what he said  

Quoted: No difference, and the 24 inch barrel wont really get you any extra velocity. Get the 20, it may actually be a little more accurate.

Please show me some links or data on this ?

Quoted: Quoted: No difference, and the 24 inch barrel wont really get you any extra velocity. Get the 20, it may actually be a little more accurate. Please show me some links or data on this ?

Glen Zediker's book about loading for high power competition, 20-26 inch barrel gains 120 fps. essentially negligible, in my opinion. He also states that shorter barrels are more accurate.  The Army has used 14 inch barrels for 500m shooting. Their groups were impressive.

All ive heard about M1S has been bad, dont know if ive ever heard anything good about them. Might want to keep that in mind and look into them a little more before you decide to go with them.

Quoted: Quoted: No difference, and the 24 inch barrel wont really get you any extra velocity. Get the 20, it may actually be a little more accurate. Please show me some links or data on this ?

Why would a longer barrel be more accurate?  

As to velocity, Derrick Martin of Accuracy Speaks  (a top AR smith for highpower competition) did a comparison between a 28" barrel and a 20" barrel using the 80gr. SMK loaded with the plenty-slow VARGET.  

The difference between them was 120 fps.   With an M855 or M193 load with a lighter bullet and faster powder the velocity difference would be even less.   Thus, Combat_Jack's on good ground IMHO when he says the 20 vs. 24" barrel with normal ammo will not be significantly different.  

As to why shorter barrels are a bit more accurate than longer ones, no one knows why, it's just an observed phenomenon.   Take two barrels of equal quality (NOT manufacturer, materials, or anything else but quality) - say, a pair of air gauged Obermeyers - and I doubt you could find a significant difference in accuracy between the 26" and the 16" barrel.  

Reasons why highpower shooters go for longer barrels is due primarily to the better sight radius, balance, and somewhat greater bullet velocity (for match rifles shooting .308 or magnum calibers this makes a difference).    I'm told that serious competitive bechrest shooters (i.e. $4000 guns using things like "6mm PPC" and "Panda-Stoll actions") prefer short, stubby barrels when they're going for their .3" 100 yd. groups.  

Ref:

Derrick Martin Book
Glen Zediker's The Competitive AR-15


Anyway, dogdirt, get the one you like the best based on looks, or other considerations.  There's no significant accuracy or velocity difference between a 20" and 24" barrel from M&A or Model1Sales.  

Good info.

get a 20 inch, get a 1/8 twist if you can find one


i have a 20 inch ss 1/8 barreled a4 rifle, match sights, std trigger, pwa lower, all the rest was a kit i got from model 1 sales, i make good solid chest sized groups all day at 500, and 600 yards, i must be the lucky one with all of the model 1 sales kits that work, all 15 or so of them



model 1 kits are fine, but if you must shoot itty bitty bug groups get a model 1 kit without a barrel and buy a 1/8 ss 20 incher from woa

The reason shorter bbls are more accurate is because they are stiffer and have better  (read as less) harmonics.  The longer BBl you get that does not have a directly proportional increase in diameter whips more.  That is the whole point of a Bull Barrel-  stiffer.  Well, not the whole point but you get the point.

   My Oly ultra goes sub 1/2 minute with 69gr Sierras and sub minute with Lake City.

Hope this helps and your mileage may vary.

Debo

ETA-  chunk this question into the competition accuracy board and get some really good info.  Those guys are a little sick.