AR BBL length

ndb86

ndb86

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Before I start, yes I searched it! If you can find a thread that answers my questions then my all means point me to it.



With that out of the way. I'm still in search of an AR-15. I really like the remington r-15 and have used one quite a few times. However I want a "badass" AR. And while i do like the camo, black is more badass lol. Yes i realise how bad that sounds.

Here is my question. I plan to shoot to 100 yards or much less the majority of the time. Does bbl length make a huge difference in accuracy? If i got a 10.5 inch norc or NEA will there be a noticable difference from a 18-22 inch r-15? As far as I can tell a shorter bbl looks better and makes more noise, especially with a nice brake on it. However like one cgner's sigline says "only accurate guns are interesting".

So I'll ask again, just to be clear of my question since as you noticed I like to ramble on. How big of a difference does bbl length make on accuracy of an AR under 100 yards? And is there a substantial change from 100-200 yards?aside from the obvious bullet drop.
 
I would say no difference inside 100 yards. Technically you will have more wind drift but at 100 yards it will be hard to tell really. An AR is not a bench rest rifle, how much accuracy are you looking for?

My 14.5 Norc puts my "match" hand loads into about 1.5-2.0 inches at 100 yards. Plenty for what I use that rifle for.

If you are only shooting 100 yards and like to look and feel of a shorty, go for it.

That being said, I know a guy at our club that is getting sub-moa with his R-15 (22 inch) with hand loads.
 
If you have to ask, you probably won't notice a difference.

The only real difference is muzzle velocity and sight radius, if you're using iron sights. The loss of muzzle velocity from the shorter barrel will be much more noticeable at longer distances, but I doubt you'll see much of a difference at the short ranges you're talking about.
 
I'm sure a longer barrel is more accurate in most guns. Assuming same build quality and twist on both.

However in my experience with 1:7 twist 16" and 1:9 twist 7.5" barrels there is no significant difference in accuracy out to 100m. All other things equal (same optics, ammo).

Having said that, I have recorded a 700 fps difference in the muzzle velocity so at longer ranges this will have an impact on accuracy.

The shorter barrel is easier to shoot unsupported and adds to practical accuracy.

My thought is that the AR platform wasn't designed primarily as a benchrest firearm. So I can't see the big point in a 20" "accurate AR... For the same money you get a choice from a heck of a lot of good true long range platforms.
 
Our range holds 3 gun matches a couple times a year and this year we had an "action rifle league" as well. That is what i'm using it for. 99% of my targets are under 100 yards and 80% of them are 40 yards or closer. Basically I'm planning on throwing a red dot on it and calling it good. The r-15 i was borrowing had a bushnell acog red dot on it and i was picking off bowling pins about 90 yards away with it. So as far as accuracy that's what i'd like out of the shorty. Assuming i do my part do any of you see a reason why it can't be done?
 
I should mention. when I say "picking off" I mean hitting 6 pins with 1 LAR mag. not precision, but good enough for me. I don't blame the gun for that I blame my finger for jerking on the trigger even after i specifically told it not to! lol
 
Barrel length has a big effect on velocity. It also has an effect on accuracy, albeit an indirect one. I.e. the stiffness of the barrel increases as it gets shorter and the resonant frequency goes up. You can get the same effect by making a barrel 'heavier' in profile.

So for shooting inside 100m, it doesn't really matter what your barrel length is. The quality of the barrel such as the rifling and crown will be more important as will the appropriate rate of twist for the ammunition you use.
 
ESQ said:
Barrel length has a big effect on velocity. It also has an effect on accuracy, albeit an indirect one. I.e. the stiffness of the barrel increases as it gets shorter and the resonant frequency goes up. You can get the same effect by making a barrel 'heavier' in profile.

So for shooting inside 100m, it doesn't really matter what your barrel length is. The quality of the barrel such as the rifling and crown will be more important as will the appropriate rate of twist for the ammunition you use.[/QUOTE]

Funny you mention that. I generally shoot 55 grain cheapos... 1:7 or 1:9? i always get confused on which is better? slower (1:7) is better for a ligher grain like 55 right? fast (1:9) for 62grain?
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You're over-thinking the issue. You'll do well with whatever you buy as long as you practice with it and get to know that platform whether it's a 20" bbl topped with a fixed 3.4x sight, a 16" bbl with a shortdot or a 10.5" with an aimpoint. I find the biggest issue is knowing my hold overs close up for the action rifle matches at LFGA. And FFS, get to know your trigger :D

RUN WHAT YA BRUNG

Also, I've had no problems thus far with 55gr ammo and my 1:7 barrel.

For service rifle where you start shooting out to 500m+ you'll want that extra barrel length. But when it comes to local 3 gun and action rifle, don't think too hard.
 
Ar180shooter said:
If you have to ask, you probably won't notice a difference.
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In case you missed it. Short and to the point.

If you're asking such a question, you likely aren't the type of shooter that will split hairs over minute accuracy changes that different barrel lengths will have. Especially if you are at or under 100 yards. Barrel length won't be a factor.
 
I never said I did bad at the rifle league. In fact most nights i was in the top 3 and I even won a few nights! But the riffle I used was the club gun. And while it is very nice to have access to a gun to borrow I'd always rather have my own! But if i'm getting my own i want to make sure that i get all teh opion like i want it. and I want a short an relatively accurate gun, it's no fun if i can't at least hit something!
 
Look out chubby girls of Lethbridge???? -
Meanwhile, back on topic: Guys are shooting Service Rifle matches with 14.5/16 inch barrels, thats waaaaaaaaaaaay out beyond the range you're looking at.
 
ndb86 said:
ESQ said:
Funny you mention that. I generally shoot 55 grain cheapos... 1:7 or 1:9? i always get confused on which is better? slower (1:7) is better for a ligher grain like 55 right? fast (1:9) for 62grain?
Click to expand...

For reference, you math is a backward. 1:7 is faster than 1:9 (1 turn in 7 inches compared to 1 turn in 9 inches).

In theory if you are limiting yourself to 55 gn bullets 1:9 might be better, or not. 1:7 twists are for longer heavier bullets like 77 Gn SMKs. If you are shooting 100 years you don't need high BC bullets. That being said the 1:7 will work fine with 55's too.
Click to expand...
 
The 1:7 was standardized to shoot the very long NATO tracer bullet.
It is also necessary if 90gr VLDs are to be used. Think you will ever be shooting single loaded 90gr cartridges?
It is very popular with the tactikewl crowd, just because.
1:8 will stabilize most any bullet that would be appropriate for use in an AR, including the 80gr SMK. The 80 won't work through the magazine, the 77gr SMK will, although it is not a VLD. Will probably shoot better in the wind at 500m than a 68/69.
1:9 is fine for 68/69gr bullets, and will shoot some 75s.
55gr bullets can be used in any .223; lower quality ones will do worse in a quick twist barrel than high grade ones, although will shoot well enough with a slower twist. Rifles intended for the 55s and lighter will often have 1:12 or 1:10 barrels.
For 100 and under, bullet choice isn't that important. Most short range matches, CQB, FIBUA, involve snaps and rapid fire; precision accuracy isn't much of a factor. Probably a waste of match grade bullets of any weight.
Good 55gr ammunition will perform at longer ranges, although as ranges increase, and the wind picks up, the frustration level will increase.
 
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