What the most effective / shortest barrel length for a 77gr bullet (using a 1/7 twist) out to 300M?
Printable View
What the most effective / shortest barrel length for a 77gr bullet (using a 1/7 twist) out to 300M?
Is 14.5" the ideal length for a 1/7 5.56 rifle using 77gr (SBR legal issues aside)?
I agree.
SBR and long range dont exactly go together...since 14.5/14.7" is the longest SBR length, I'd be incline to agree..
So the US Army made the best choice with a 14.5" barrel?
I thought I read somewhere that 16" is the best overall length, SBR issues aside.
A customer service rep from a manufacturer told me that most civilian SBR orders are for 12" instead of 14.5" because people feel that 1.5" isn't worth the tax stamp/registration.
If 'effective' for you is fragmentation max range, then 14.5" is the obvious answer.
If 'effective' for you simply means accuracy out to 300M, then there are other answers.
I think it has been answered above, but I will say that your question is apples and oranges........sort of.
you have 77gr pills, long range target and short barrels.
while any length barrel can get it there, the elusive part is "effective" at that 300 meter distance.
so the sum of your parts do not equal the total of the equation.
to get to the unqualified "effective" solution bigger is always better.
so within your parameters, as answered above 14.5 would be the best SBR length as it gives the best velocity down range.
but even better would be a 20-22 inch barrel with the same bullet.
even better would be a .50BMG at the same distance, and after that a 25mm bushmaster, and after that a 105mm sabot...see where this is going?
I thought there were diminishing returns past 18"?
I was interested in the shortest effective length for a 1/7 barrel using 77gr and a 1-4x scope out to 300M. I'd rather use a .308 any farther than that.
I'll SBR a 14.5" if it will be just as accurate and effective as a 16". Looking at the "Official SBR Picture Thread" it seems like most people that SBR go 12" and shorter.
Is it a waste to spend $200 + registration for 1.5"?
i think the OP is asking how long of a barrel is needed for effective fragmentation at 300 yards.
i don't have the data int front of me, but i'm sure someone does.
if you want as short a rifle as possible, while maintaining a 300 yard range, how long of a barrel do you want?
i'm thinking the 12.5 will probably do it.
I believe so. If you're going to be clearing rooms, or dumping out of vehicles, then shorter length is worth it, and in that case I'd be inclined to go 11.5 or 12.5".
Don't forget that SBR'ing it means that you'll have to get approvals to cross state lines and raise a host of other issues that go beyond the scope of this thread.
12.5" will do it and be just as accurate as a 14.5"?
Is there any benefit to a 16" besides it being the shortest legal (non-SBR) length?
Wasn't 16" the length used for the SEAL "Recce" Rifle?
No. You generally still gain significant velocity going from 20 to 24" barrels as far as velocity is concerned. As far as accuracy... :confused: I've ever heard of more barrel hurting accuracy.
To me a 16" barrel with carbean gas system is the most useless set up of all. So... No. It's not a waste to SBR to 14.5". Especially since you could buy a 11.5" upper to throw on the lower as well. And perming some aftermarket trinkett to a good barrel is a bigger waste to me.Quote:
Is it a waste to spend $200 + registration for 1.5"?
Less barrel length = less velocity...Not less accuracy. Accuracy can actually be a little better out of shorter barrels because they are more rigid.
I'm personally a fan of using a 14.5" barrel with pinned flash hider. No NFA required...just gotta be sure of what rail and flash hider you're going to want.
I once considered buying a Colt MT6400C, however I decided against it because of the carbine length gas system and the 16" barrel with the M203 step cut. I tried to explain to the Colt Customer Service rep that they should offer a mid length gas system with the 16" barrel.
I was thinking of a 14.5" with a pinned flash hider as well. I know the downside about pinning however I don't plan on changing the gas blocks or flash hider once they're on. I would SBR a 12", but I'm hesitant to do it with a 14.5"
Another interesting idea are the LMT MRP uppers, as you can can switch barrels. I could start with a 16" and change to a 12" if I decide I really want an SBR.
Oak,
If there's one thing I've learned over the last couple of years, it's buy whatever length you want right now. This disease will force you to buy several additional lengths and configurations in the near future. I started with a 14.5 (pinned). Then a 10.5 (SBR). Then a 16.1. Then and 18. Now I'm lusting after a 11.5.
You get the point. Enjoy
To me, the most versatile barrel on the market is a 16", chrome lined with a mid-length gas system.
It is short enough to use indoors, long enough to give you fragmentation out to 200M's and not too heavy to hump around all day.
With that said, if you are going to go through the pain of a tax stamp, get something short. Something between 10.5 and 12.5.
C4
A 16" using 77gr is effective out to 600 yards with a new shooter.
With that said, why is your requirement to engage out to 300m?
Do you see that as the max range that you will ever shoot the rifle or as the range that you will most likely do most of your shooting at?
Grant has good advice here.
In my opinion, a 14.5" with a permanently attached muzzle device isn't at all appealing. It limits your options and adds extra expense and time when it comes to changing parts around. For this, a 16" mid-length is probably a much better option.
By the time you go to the effort and trouble of getting a tax stamp, going with a 14.5" barrel doesn't make quite as much sense when you can go shorter. I'm willing to bet that most SBR owners have other guns to fall back on anyway.
I don't think a 14.5" SBR would be a waste on it's own. I'd just go shorter to start with, and maybe consider it down the road.
With standard military loads in the form of M193 and M855, yes. Barrel lengths over 18" typically provide no meaningful gains on velocity. This is true with Mk.262, though to a lesser degree.
Some commercial loads or hand loads may behave quite differently.
IMHO, if you want a short CQB rifle that you can (easily) hit with at 300, go 10.5"-12.5". If you want a rifle to be handy and still maximize the terminal effect of the 5.56mm at distance, go with a 16" mid-length and save yourself the tax stamp, wait and red tape down the road.
To the original question, the obvious answer is as close to 16" as possible, but ignores the length tradeoff.
If 300m is the expected maximum range, then something in the 12.5" to 11.5" range becomes the most practical option if maneuverability is key. If it's Almost always suppressed, shorter is always better, but this range (and the stainless 10.5") are the choices. As usual, Grant nailed it.
Any quality barrel free floated will work, and should keep 2" groups at 300yd, with Mk262 or something like TAP75gr. A Noveske 12.5" should be a great tack driver; a Sabre 11.5" is more affordable, but should still be more than up to the task, and the BCM CHF options across the range should all work great.
Consider a $200 premium and some fuss into the overall price of the weapon system. If you're spending over a couple grand (to include magazines, furniture, optics) then the tax stamp is a smaller concern. If you're well over that, then it seems trivial not to SBR it in the minds of many. If taxes and stamps are a small percentage of the cost (when lumped in with free-float system, aftermarket stock, triggers, grips, optics/mounts, etc.) then consider it a small investment - a one-time entry into the NFA club, and likely the first of many.
If it's your first rifle, and budget is key - then consider how much more practice ammunition that $200 will buy you - if that makes a 16" middy more attractive, or means not trading off important features, then stick with that. A quality 16" rifle will always be an improvement over a half-arse SBR.
Effective at what? There isn't any barrel that's going to produce enough velocity to cause fragmentation at 300M. If you're talking about accuracy, barrel length isn't really a determinative factor. The material, maker, chamber, etc. will all make a greater difference.
You'll have no trouble hitting any reasonably sized target at 300M with a 10.5" guns, even with 55 gr M193.
Get the 14.5" and perm attach a FH to bring you to 16" and save the $200 and some paper work.
I ordered a BCM 14.5" middy a few days ago, can't wait to get my hands on it.
I just got an email from my Class III dealer that my LMT SBR paperwork came in today! I'm like a little kid the night before his birthday. I could not make it up to get it today because of my work schedule. I will get it around 1030 tomorrow!
Get the best of both worlds; buy an AUG.
Apparently from what I have gathered from those "in the know" it is not just the barrel rifling but Noveske's chamber that make the Crusader barrel the "PMF" or "pure ****ing magic" barrel. I cannot fore see of any situation as a civie or if and when I go back LEO that a Crusader barreled upper would not full fill any roll in any situation I might find myself under.
When I wear out my LWRCi barrel, if I can't buy another one. I will be running a 12.5'' Crusader.
That said I'm looking to add a Noveske 11.5'' to my KAC.