Light Weight 6.5 Grendel Upper

[Rainman]

I am about to order an Alexander Arms light weight 16" upper and am trying to decide between the Incursion and the next level up called the "16" Lightweight Complete Upper". (Weight difference between the two is inconsequential to me.) Any opinions on which might offer the best accuracy potetial with handloads I will develop primarily with 129 and 130 grain bullets (Hornady, TMK, Berger, Nosler, etc.)? This upper will be used on paper out to 400 yard and steel out to 1100 yards, coyotes and possibly Mule Deer within 300 to 400 yards max. Black Friday pricing, if any, may help make my decision but I am interested in input on accuracy potential from the experts here. (Current upper is an 18" stainless fluted varmint weight 1:9" BHW barrel.)

[1075 tech]

If you are into building your own upper, Alexander Arms is selling their 16" lite barrel individually. They also have a 20" and 24" barrel available.

[Klem]

Your current 18" varmint (heavy) profile barrel is geared to do a better job of punching paper and steel out to 1,100.

A light-weight 16" will be good for short range hunting but no better at anything else when compared to your heavier, longer barrel. Especially when the bullet from a 16" goes transonic at around 700-800yds it gets buffeted around passing back through the sound barrier. This translates into bigger groups and harder corrections beyond that range. Your 18" will experience the same at a 100-200 more metres.

Truth be known neither the 16" or 18" is suited for steel at 1,100yds.

[cory]

Klem is correct. However, he's selling the 16" and 18" short. It'll really depend on where you're at in correlation to sea level. At just about sea level, 123gr pills from my 16" are sonic until roughly 1100 yards.

[Klem]

Not at all Cory, I think an 18" is a perfect compromise for both hunting and long range. But for the longest range target shooting or the shortest range CQB a mid length barrel will not be the best choice. And getting a slightly shorter second barrel is not going to change much.

I don't believe there is much practical difference in velocity between the proposed 16" and an 18" barrel and the op might be better off with a heavy long barrel (e.g. 24") and dedicating the short light weight 16" barrel for hunting. That might mean mean selling the 18" heavy barrel if two 6.5GR uppers is elegant sufficiency. Or dedicating the lightweight 16" barrel with light-weight furniture for hunting and using the heavy 18" for the long range target shots.

A point of clarification. My experience shooting F Class competition at 1,000 for a few years is that when the .223 approaches transonic the group size blows out. Not just in my gun but everyone's gun. The diameter profile of the group is like a blunderbuss. You can still hit the target but it's like the bullet is drunk. Making adjustments is like driving jelly. While the sound barrier at the ambient temp/pressure might be say 1,100yds for a particular bullet/velocity the instability starts about 100-200yds prior and builds. My view is that if you are regularly wanting to shoot predictable results then you need to be comfortably supersonic, not on the raggedy edge.

What velocities are you getting from your 16"?

[LRRPF52]

There is something to be said for a tight twist. My 16" AA barrel has 1/7.5", and was scary predictable when I first shot it at 1200yds, much to my surprise. Of course, I'm supersonic well past 1200yds up at the lowest elevations here.

If you look at Predatordown's ELR videos with his Grendel, he rapid-fires onto 12" plates at 1000-1200yds, with only 2500fps.

My 16" does ~2450fps with factory AMAX and Scenar. My hand loads with CFE easily do 2500fps without pushing it. Interestingly enough, I'm not seeing any real differences in velocity between 16" and 18" guns, across many 18" now.

I've seen 20" .338's that wouldn't hold together after 1500yds, because the twist wasn't tight enough. Todd Hodnett seems to be a big fan of shorter pipes with tight twists, and he gets very good results with 20" .338 and a tight twist at ELR.

[cory]

Not at all Cory, I think an 18" is a perfect compromise for both hunting and long range. But for the longest range target shooting or the shortest range CQB a mid length barrel will not be the best choice. And getting a slightly shorter second barrel is not going to change much.

I don't believe there is much practical difference in velocity between the proposed 16" and an 18" barrel and the op might be better off with a heavy long barrel (e.g. 24") and dedicating the short light weight 16" barrel for hunting. That might mean mean selling the 18" heavy barrel if two 6.5GR uppers is elegant sufficiency. Or dedicating the lightweight 16" barrel with light-weight furniture for hunting and using the heavy 18" for the long range target shots.

A point of clarification. My experience shooting F Class competition at 1,000 for a few years is that when the .223 approaches transonic the group size blows out. Not just in my gun but everyone's gun. The diameter profile of the group is like a blunderbuss. You can still hit the target but it's like the bullet is drunk. Making adjustments is like driving jelly. While the sound barrier at the ambient temp/pressure might be say 1,100yds for a particular bullet/velocity the instability starts about 100-200yds prior and builds. My view is that if you are regularly wanting to shoot predictable results then you need to be comfortably supersonic, not on the raggedy edge.

What velocities are you getting from your 16"?

Ohh I completely agree with this. I wasn't trying to say that his 18" was ideal, just that it was capable. I do think having a 24" and a 16" gives you best of both worlds. I've got a heavy 24" and a lightweight 16". This quickly produced an 11.5" child. HAHA OP don't be surprised if this happens to you.

OP I'd consider a pinned 14.5" barrel for your lightweight hunting rifle and stick with your 18" at 1000 yards.

[Rainman]

All of your input is much appreciated. I do want a 16" and where we can shoot beyond 200 yards is 2,200 feet above sea level so I am anticipating being able to safely push 129/130s in the range of 2,450 to 2,500 with accuracy taking precedence over velocity. My 1:9" 18" BHW barrel groups them under 1 MOA @ 100 yards with first loads tried but I'm not sure stability will hold up beyond perhaps 200 yards so I may go longer in that upper with a tighter twist at some point down the road. I'd like a 14.5" 1:7.5" twist but that is not available from AA and I definately want to try one of their uppers so it will be a 16". I am aware of all the positive comments about Precision but want to express my appreciation to AA for developing this great round by buying one of their complete uppers. I've played with a number of rifle cartridges over the years and this is one that has kept my interest for pure enjoyment of shooting as well as accuracy from the AR platform for which I'm still on the marksmanship learning curve.

[Double Naught Spy]

Well, all I can tell you is that we got the Incursion and it works very well, happy with the quality of the build.

[EPeterson]

Well, all I can tell you is that we got the Incursion and it works very well, happy with the quality of the build.

I've got a Incursion on order. What kind of accuracy are you getting with yours?

[am4966]

All of your input is much appreciated. I do want a 16" and where we can shoot beyond 200 yards is 2,200 feet above sea level so I am anticipating being able to safely push 129/130s in the range of 2,450 to 2,500 with accuracy taking precedence over velocity. My 1:9" 18" BHW barrel groups them under 1 MOA @ 100 yards with first loads tried but I'm not sure stability will hold up beyond perhaps 200 yards so I may go longer in that upper with a tighter twist at some point down the road. I'd like a 14.5" 1:7.5" twist but that is not available from AA and I definately want to try one of their uppers so it will be a 16". I am aware of all the positive comments about Precision but want to express my appreciation to AA for developing this great round by buying one of their complete uppers. I've played with a number of rifle cartridges over the years and this is one that has kept my interest for pure enjoyment of shooting as well as accuracy from the AR platform for which I'm still on the marksmanship learning curve.

Call AA and find out the weight of the uppers or rifles and maybe that will help with your decision. The incursion might light enough for you and the light weight might be too lite. If it was me that's what I'd do and shooting at 2200 ft would help tremendously in your quest and let us know what you decide.

[TomSawyerNW]

I am new to this, so my question might seem a little naive. For distance shooting (750-1,000 or more yards), I assume something like the 123 gr Hornady is more preferred than a 100 gr Wolf? My thinking is that the heavier bullet would be less affected by windage and such, whereas the 100 gr could be buffeted around more so, which would lower the accuracy. I am using a 24 inch heavy barrel 1/9. I have used the lighter 100 gr at nearly 300 yards with good accuracy.

Is my thinking right?

[customcutter]

TSNW, yes your thinking is correct. The heavier bullet will give you a higher BC (ballistic coefficient). The higher the BC, the better the projectile can overcome the effects of drag and crosswinds. However, you are limited in the AR 15 platform by the magazine length, and therefore maximum length that you can load projectiles too, when you get into reloading.