20" AR question

C

cmdc

New member
I'm wondering if a standard 20" rifle with the carry handle is accurate enough for varminting? It is 1:9 twist.

I would put an optic on it as well.
 
Depends on the range and quality of the barrel. Length and twist have little to do with ultimate accuracy. You might not be able to shoot the heaviest bullets with 1:9, but you don't necessarily need them either.

Most guys don't want carry handles if they'll use optics.
 
Personnally, I don't mind using a scope mounted on the handle. I think you can get a solid mount and a cheek weld becomes a chin weld but it works fine for minute of crow at 200yds.
 
Heavier bullets are going to buck the wind better and drop less due to BC at further ranges. I guess if your shooting 300 and under it wont bet that big of a deal. Most of the time when think varminting I think rockchucks or gophers something of that sort. Depending on your application you should be fine. I personally like 1:8 or 1:7, not a big 1:9 fan.
 
Thanks for the comments so far. How much difference between 1:7 and 1:8 twist and bullet weights?
 
I think its all in what you practice with & known range.I use a stock stag 20'' with a 3x10x50 but thats just me.Mine is a 1to9 also it does pretty well up to 69gr.bullets but shoots 55gr. the best.It will shoot under a inch @ 100yds when I can & thats good enough for me.:D
 
1:9 will stabilize everything up to 69 grains.
1:8 will stabilize everything that will fit in an AR magazine (up to 77gr). I have a 1:8 twist 20" barrel, and I have pushed the 34gr bullets fast enough to vaporize them.
1:7 can stabilize up to 90gr bullets, but you either turn it into a single shot rifle to do that or you lose significant powder capacity and velocity. It's specified by the US military so they can shoot the long tracer rounds.

What shoots best really depends on the individual rifle.

Heavier bullets are going to buck the wind better and drop less due to BC at further ranges.
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You're half right. Heavier bullets with a higher BC will have less wind drift, but the higher velocity of the lighter rounds produce less drop.

556_comparison.jpg
 
I'm getting a Stag also. I'm left handed and am gong to get the 4l upper. It sounds as if I should just get it, shoot it and see what it likes, and go have fun. I already have several ARs but most are 16" barrels and I want to get the 20". I doubt I'll do much shooting over 200-300 yds with it.

Thanks.
 
The trajectory of the lighter bullet with lower BC at faster speeds is going to diminish velocity as it goes further. Now that being said shooting a 5.56 round out past 600m isn't the most ideal thing to do. But the 77gr @ 2750 will exceed the fmj @ 3240 eventually. Quick look at JBM is 850+ the 77gr retains more velocity. While that doesn't necessarily apply in this situation it has a greater effect in different calibers to extent.

Probably should've specified more but under circumstances we're both correct ;)

http://www.appliedballisticsllc.com/index_files/30cal_fullVersion.pdf

“Muzzle velocity is a depreciating asset, not unlike a new car, but BC, like diamonds, is forever.” --German Salazar
 
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I'm wondering if a standard 20" rifle with the carry handle is accurate enough for varminting? It is 1:9 twist.
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Yes it is. If you are really nuts you go with a 24 inch barrel, and yes it's a 1:9 twist.

Jim


IMG_0481.jpg
 
Nice setup, Jim243. What scope? For that matter, what would you recommend to put on top of the carry handle?
 
...wondering if a standard 20" rifle with the carry handle is accurate enough for varminting? It is 1:9 twist.
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Possibly.
Depends on what you call "standard."

161yofp.jpg


"Standard" 20-inch 1:9 Colt HBAR* before I rebarreled it w/ a Krieger/floated the handguard and squared up the bolt.

5/3/08 Sunny/moderate wind
Sierra 69HPBT/AA2520/25.5gr/BR4/WWCase/OAL=2.265"
Chrono = 2,833 ±13 fps / Leupold VXIII - 3.5x10/50mm
Results in bullet path PointBlank ±2" out to 225 yards


*(I admit I had to 'Tubbs'-finish the issue barrel first)


NOTE: This was a safe load in THIS rifle only, and probably only because I'd
smoothed the bore out w/Tubbs beforehand. 2,840fps generally maxes
out at 24.5gr/AA2520 in an ordinary chamber/bore.
 
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what would you recommend to put on top of the carry handle?
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That's a tough question.

With any rifle you want the axis of the scope as close as posible to the bore axis of the rifle. With the carry handle you are raising that axis by 2 inches.

I had a Armilite AR-15 with carry handle that a standard 3-9x40mm scope worked very well with out to 250 yards. One of the advantages of the carry handle is that you can put a 50mm scope on it without it hitting the hand guard.

If the carry handle comes off, then use the flat top and a couple of risers to mount your scope.

BSA Platinum 8x32x44mm w/3 inch sun shade
SAM_0543.jpg


SAM_0544.jpg


UTG 4-16x44mm
SAM_0545.jpg


Or you could use a red dot and a magnifier.

Jim
 
bedlatmite said:
And by that time they are both subsonic and way past their useful range.
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Which is why i said it doesn't necessarily apply in this situation. Yet it doesn't dispute the fact, and some people do shoot 77gr SMKs to that range.

It was a little out of context for the sake of this thread, but it applies to a greater extent in different calibers.
 
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