LaRue AR-15 16" 18" or 20" ?

[rightwingdad]

In a few days I'm going to order a complete upper and lower LaRue AR-15.
it will be used for plinking, home defense, and possibly hunting south Texas
Whitetail Deer.

I am leaning towards the 18" upper simply because it is in the middle. Thoughts and comments please....

 

[HOLY DIVER]

18 is what my next build will be i say go for it!

 

[Z-Michigan]

18" is a great compromise length for many AR-15 uses. Go with it.

 

[Rokman]

I thirdly recommend the 18" length for what you want to do.

 

[inherentical]

I went with a 20" for my LaRue AR, but I only use it from the bench.

 

[Shadow Man]

With an AR chambered in 5.56x45mm a barrel length of 18-20" is necessary to achieve the full velocity, terminal effects, and performance of the round. With either of those barrel lengths you should be just fine.

You should also check the twist rate on the barrel. A faster twist rate, such as 1:12 will only correctly stabalize the lighter grain weight bullets, such as the 55gr loadings. A 1:9 is a compromise, able to acceptably handle any loading from 55grs to 62grs or even the heavies at 77grs. If you plan on shooting only heavy grained rounds, the 1:7 twist rate is best, and would work better the longer barrel you have on the rifle. I may have those numbers wrong as it is late, and my CRS is in full swing, but I'm pretty sure they are correct.

 

[rightwingdad]

You should also check the twist rate on the barrel. A faster twist rate, such as 1:12 will only correctly stabalize the lighter grain weight bullets, such as the 55gr loadings.

I just checked LaRue website and the twist is 1:8 twist polygonal rifling.

Not sure what polygonal is though.

 

[praharin]

I believe that means it's not the typical "lands and grooves" type rifling. It's more like the inside of a socket (wrench) but twisted.

I could be wrong, but that is the way I understand it.

 

[Coronach]

What barrel profile are you considering? If you are looking for handy and well-balanced, a pencil barrel in any of the three will be fine from a weight & balance perspective. I use a 20" A1 on duty and it balances like a dream. The shorter length will be handier indoors, though.

If you're going with a thicker profile, length will matter more in the balance department.

Mike

 

[rightwingdad]

What barrel profile are you considering?

I'm not sure what the profile is the web site does not talk about barrel profile.
but here is a pic like the one I am considering.

 

[Maverick223]

Personally I wouldn't own a 5.56NATO/.223Rem. under 18", and really prefer a 20in.+ barrel. A ≤ 16" bbl really limits the velocity and thereby grossly limits the lethality of the wee .223 (that relies almost solely on velocity to get the job done). This is why I think bullpup configuration carbines are ideal for this cartridge in particular...you get a little bit of everything, short OAL and long bbl.

FWIW, your photo looks like a 18" HBAR to me (fairly heavy, but manageable).

 

[Shadow Man]

What Maverick just said. He hit it spot on.

If it is a 1:8 rifling, I'd be happy with that. Slower twist, able to handle the heavy loads that are becoming more popular, but still fast enough to handle the light loads too.

Polygonal rifling is the reverse of traditional "lands and grooves" that you see; it ppears to use raised ridges where you would normally see the groove. Very common in GLOCK pistols, and ancient artillery.

 

[Z-Michigan]

With an AR chambered in 5.56x45mm a barrel length of 18-20" is necessary to achieve the full velocity, terminal effects, and performance of the round. With either of those barrel lengths you should be just fine.

Most .223 loads gain significant velocity in barrels at least to 26", and I think you would need 30"+ to truly get "full velocity." However, 20" will get you roughly the velocity that is quoted for 5.56mm military-pressured rounds (M193 and M855) in an M16.

All barrel lengths are a compromise. You just have to pick the best compromise for you.

 

[Dr. Tad Hussein Winslow]

Yeah, 18 or 20, +1.

Having said that, I've had a couple of 16s.

 

[atblis]

How much does this rifle cost from Larue?

 

[rightwingdad]

Thanks for all the info, I just placed my order for the 18" upper. it certainly was a compromise. I really wanted a 20" but that is just too much for home defense.
I was told that the upper would take 4-6 weeks to produce and ship, the the lower would be cut and shipped 2 weeks after that. So i'm looking at 6-8 weeks for production and shipping....

How much does this rifle cost from Larue?

The LaRue is a very high end AR platform, they will only sell you the lower if you already own one of there upper assembly.
The upper assy. will run $1200-1300 thats less sights, after that the stripped lower is $250. Then you will still need a stock and sight system.
I went with all LaRue parts the furniture and iron sights plus fwd. hand grip.
total package shipped for $2200..
I will still need to get a lower parts kit from someone else as they do not stock the parts kit. .... Not sure why...

 

[Shadow Man]

Most .223 loads gain significant velocity in barrels at least to 26", and I think you would need 30"+ to truly get "full velocity." However, 20" will get you roughly the velocity that is quoted for 5.56mm military-pressured rounds (M193 and M855) in an M16

That may very well be true. I just know from my research on the platform that Eugene Stoner reccomended that the rifle use an 18-20" barrel to achieve the desired results. I imagine that you could gain significant advantages in velocity from a 30+" barrel, but your handling would suffer dramatically from such a large rifle.

 

[Coronach]

Just remember that the velocity drop when going from 20->18->16->14.5 is most critical when using ball ammo, which uses fragmentation for a lot of its wounding potential. As civvies, we can (and in many instances, probably should) be using ballistic tip rounds for "real" use, which are far less velocity-dependent for proper terminal function. I'm not saying slower is better, just that slower is not nearly as bad, when you use non-ball ammo.

I have no problem with using a 16" AR as general purpose weapon. The way it handles is superb, and if you're using an RDS the reduced sight radius only matters if your dot goes down.

Mike

 

[Shadow Man]

An excellent point Coronach, and I feel now that I must clarify that most of my experience is with ball ammunition, which does suffer from shorter barrel length.

 

[HOLY DIVER]

coronach i agree %100 a ballistic tip coming out of a 16inch barrel will get the job done most deff!

 

[Maverick223]

Very true, V-Max, A-Max, TAP, et al won't benefit nearly as much as standard ball, but if you want to use everything (including the cheap stuff), and maintain a better trajectory (not a significant difference IMO) longer is better. 18" is probably the best compromise in the AR; that said: make mine 20+...but put the magazine behind the trigger please.

 

[Shadow Man]

that said: make mine 20+...but put the magazine behind the trigger please.

You bullpup freak!

Never have put in much time on a bullpup, well, not nearly as much time as on a traditional platform. Always was a little slower on the reloads, but nothing some serious range time won't fix.

 

[Maverick223]

You bullpup freak!

Yep.

Never have put in much time on a bullpup, well, not nearly as much time as on a traditional platform. Always was a little slower on the reloads, but nothing some serious range time won't fix.

Mag changes are a little slower...mag dumps (aimed fire) a little faster...it all works out. I really like the handling/short OAL, but they are definitely not for everyone (especially lefties until recently). They both have their place...right in my safe.

 

[Shadow Man]

I'm never too old to learn, Maverick.

Variety, after all, is the flavor of life...or some such.

 

[Coronach]

Very true, V-Max, A-Max, TAP, et al won't benefit nearly as much as standard ball, but if you want to use everything (including the cheap stuff),

Well, assuming you use ball on paper or steel and ballistic tip on living things you wish to make dead, there's still no barrel length problem

and maintain a better trajectory (not a significant difference IMO) longer is better.

That's undoubtedly true. Longer=faster=flatter, but yeah, the difference isn't that huge.

18" is probably the best compromise in the AR;

Probably, in an all-things-else-being-equal sort of way, but once you figure in the use of non-ball ammo for "serious" use, things get murkier. However, like the trajectory debate, the length debate isn't that big of a deal, either. The difference between 16" and 18" is still just 2". And, if the OP isn't intended to clear rooms or run a barricade course very often, the main advantage of the 16" falls away completely. Either will work, for sure.

that said: make mine 20+...but put the magazine behind the trigger please

nooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo!



Mike