im building an m-4 based on a large pin colt lower. ive purchased a daniel defense flattop upper designed for the large hole colts…now i have to decide what barrel assembly to buy and what twist…ill shoot primarily 55 gr rounds. price isnt really an issue…ive looked at bushmasters and stags…any input??
Check out Bravo Company USA
seen that… i see lots of dif barrels jus need some input
What length are looking at getting? Gas system? Profile?
When you say building and M4, I assume you want to build one that looks exactly like the military weapon? A good weapon but if your minds not set on that config, you can have something better…
BCM has several to choose from and they are top notch so I doubt you’ll need to go anywhere else unless you decide to go with another manufacturer.
Get a barrel that has known variables. True 5.56 chamber, 1/7 twist so you can shoot heavier bullets if needed. Any of the BCM barrels or DD barrels would be good. You may also getting a Noveske barrel as well.
I wouldn’t buy a Stag or BM barrel, that’s just me.
If you’re shooting primarily 55 FMJ go with the slowest twist you can find, these days that seems to be 1/9 but a 1/12 would be better. BUT! As Iraqgunz said, a 1/7 will give you more options for heavier bullets should you choose to go that route in the future.
Why do I suggest a slower twist with 55 FMJ? Two reasons; Supersonic bullets are steered by the base of the bullet. FMJ bullets are formed in a die from the nose back leaving an open base with lead exposed and are much more difficult to form a consistent base compared to a hollow point that is die formed from the base forward resulting in a much more consistent base. Also, and as a result of how FMJ’s are formed, they suffer concentricity issues (out of rotational balance). A fast twist exacerbates out of balance and tends to cause the down range performance (accuracy, which should actually be refrred to as “Precision”) to suffer. A 1/7 and even a 1/9 imparts a high rotational speed (high RPM) to 55 grain FMJ bullets (similar to an out of balance tire at highway speed it will oscillate).
With that said, what I described with 55 FMJ’s (or nearly any FMJ bullet) from a fast twist barrel mostly shows up at ranges beyond 50 yards i.e., 100 yards and further. If most of your shooting is close in then it may not be an issue so really depends on your accuracy (precision) needs.
Don
I have fired 55gr. through my 11.5 SBR and was easily able to hit targets out to 220 yds.
And in a one off case that proves what? What was the target at 220 yards? Did you hit it with every round put down range? Did you shoot for group at 220 yards, if so, what was the group size?
Why is it that I offer my first hand experience to this forum and it is continually called into question? Is it because I am new here? Be that as it may, I have 30 years of experience with the AR, experience gained long before most here had any interest in the AR.
My advice stands and is based on 30 years of experience dealing with the 55 grain FMJ (and heavier) .223 bullets in twists from 1/6.5 to 1/14.
Don
Relax, it is just a discussion. No one is questioning your manhood. Personally, if what you told stick the other night about your experience is true I am very interested in what you say, and so will most others. But that said, this is a discussion board and sometimes opinions will differ, or be questioned, even between those who are the experts
I am relaxed, and it ain’t about my “manhood” as stupid as that statement is. I just can’t figure out why others here can’t relax and except someone new who might offer some additional experience.
Be that as it may, I came here to learn as well as try to offer some first hand experience. Obviously that experience is not needed nor wanted here.
Adios!
Don
Iraqgunz is one to trust, he knows whats going on. I have as well shot 55gr XM193 thru my 10.5in 1/7 Noveske barrel’d SBR and 200yrds and all 90rds I shot were in a steel 7in diameter plate. I wouldnt want to shoot any farther, as 10.5in isnt a distance barrel length. my 18in noveske barrel’d SPR holds 2MOA at 200yrds with 55gr XM193
Bravo Company has a sale right now with their barrels. I just picked one up and saved about $60.
My point was (and there are others here who have had similar results) is that a shorter barrel can still reach out. Though if I needed to make that shot I would select a different tool from the tool box. However, I at least know that it can be done.
I don’t care about group sizes. If I can hit a mansized target at that distance then that’s all I care about. The target in question was a little steel pig (I am sure that markm can tell us the size.)
There are many M4C members who use 55gr. ammo in their 1/7 twist barrels for training and most seem to confirm that the ammo is accurate to at least 100 yds.
Personally I know nothing of your experience or how long you have been dealing with AR’s. My point was that your statement doesn’t really match the day to day reality. Unless I misunderstood you and the point you were making.
This is the first time I have seen someone argue that a 1 in 7 twist rate will actually cause reduced real world accuracy with 55gr FMJ loads.
This past Sunday I was shooting on the 200yard line Federal 55gr FMJ out of an LMT 10.5" 1 in 7 twist barrel. Accuracy is excellent I have shot sub MOA, actually sub half MOA, groups using 55gr FMJ ammo from that LMT SBR at 100yards. I also shot about 10 or 12 5 and ten shot groups through a Daniel Defense SPR (Lothar Walther 1 in 7 twist barrel with a wylde chamber), and that rifle was able to hold 5 shot groups at right on MOA at 200yards, I have frequently shot 55gr FMJ and lighter weight HP and V-Max and consistently got sub 0.5 MOA through it.
I don’t buy that a 1 in 7 will cause your accuracy to be reduced shooting 55gr FMJ loads, no matter how old the proponent is.
Cameron
either way gentlemen thank you very much for all the input. i understand what everyone is saying…now to decide what to buy…lol
another thing i failed to mention is that i already have a 1\7 colt 20. ive never had problems with it at 200 yards…however i wasnt sure about shorter barrles and stability
The length of the barrel is not the issue. Barrel length will really only effect velocity. In fact a shorter barrel can be more rigid than a similarly contoured longer one and consequently shot to shot accuracy can be better out of a shorter barrel. If I was buying a new short(er) AR I would buy a 1 in 7 twist for the ability to to able to shoot weights from 50-77grs without an issue. A 1 in 9 twist would be I good twist rate to consider as a second choice.
I have:
16" SPR Lothar Walther Wylde chamber 1 in 7 sub MOA accuracy with quality ammo weights from 45-77 grs
16" HBAR Colt with 5.56 chamber and chrome 1 in 9 twist a decent MOA barrel with weights from 45-69grs.
10.5" LMT 5.56 chamber and chrome 1 in 7 twist not shot a lot for accuracy but amazingly it has produced sub MOA groups at 100 yards.
The differences in shot to shot velocities due to the ammunition variances will effect your accuracy much more than the twist rate or the barrel length. To answer your initial question I would use a 5.56NATO chambered chrome lined 1 in 7 twist 16" barrel for your purpose, I would not be bothered if I bought a 1 in 9 twist barrel either.
The real question is what weight of barrel to you want, HBAR, pencil or something in between. Reliability, balance, accuracy, durability would be the things to consider. If I was in your shoes I would probably buy either a BCM BFH™ 16" Mid Length Barrel or Daniel Defense 16" Mid Length Gas Barrel Assembly 1/7 Twist.
Cameron
Get a DD A1 barrel or a Middy barrel (which will be out shortly).
C4
Off case?? I shoot 55gr 90% of the time through 10.5’s and 11.5. Hitting targets out to 300yds (the size of a gopher) is of no issue.
Typically, I can get 55gr ammo to group .75 to 1MOA at 100yds from an SBR with a 1/7 twist.
C4
I applaud your prowess with 55 grain FMJ through your AR, although I’d like to see confirmation of consistent .75 MOA results because they would be the rare exception from my experience. You must have found an exceptional lot of ammunition.
Don