Those with AR's with 16" barrels with 1:7 twist I need your input

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montgomery381

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Hopefully tomorrow I will be going and either picking up or placing an order for an AR. What I need from you all is your first hand experience. One of the two rifles that I am looking at has a 1:7 twist. PMC 55 gr. is readily available where I am at and that is what I usually shoot. What I would like to know is what kind of groups do you guys get out of your 16" 1:7 twist barrels using factory loaded 55 gr. ammo at 100 yds?

Varmint hunting is non-existent around here so I have no intention of shooting anything less than 55 gr.

The barrel twist is not a huge selling point but I do kinda like the ability to shoot heavier bullets.

In advance, thanks for all of your input, I really appreciate your help.
 
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I shoot a fair bit of that ammo in 1/7 barrels and it works fine. Groups are maybe in the 3-4" range at 100 yards (I'm not usually shooting for groups). That is about what you can reasonably expect from inexpensive ammo and non-precision barrels.
 
The 55gr will work in the 1/7 barrel but if that is what you will be mainly shooting i would go with a 1/9 twist. 1/9 will still handle bullets in the mid to upper 60's.
 
G.barnes can you tell me what kind of groups you are getting with which twists? Thanks you guys for your posts. Keep it coming.
 
I don't do a lot of precision shooting but my best groups are with 62gr ammo. I have a ddm4v5 with the 1/7 twist. 55 is not bad but 62 works better. my groups are around 1.5 to 2 moa at 100yds. my rifle is set up for 100 yd or less though.
 
Thanks for the quick response, G.barnes. Could you give me a guess on the 55 gr. groups? If you can't don't sweat it. Thanks again.
 
I have a 16" barrel with a 1/7 twist on my AR. I've shoot a lot of 55 gr. ammo through it. I'm putting a scope on it next time I go to the range. Hopefully this weekend. It might be to late to help you, but I'll post the results.

NYH1.
 
I have a Stag Model 3 that will give me on average .900 groups at 100 yards with my reloads using 52gr sierra match, some groups as low as .500 when I do my part. The Stag is a 1/9 twist, honestly all the 223's I've owned have been 1/9 and they all did best with the 52gr however up to 69gr will give fair accuracy.

I know many disagree but find the 70 and above grain defeats the purpose of a 223 aka small bullet fast speed. The military selected the 1/7 twist for shooting tracer rounds from what I've read.

If you plan on shooting long distance with the 223 say over 300 yards then no doubt the larger gr is the correct answer but personally if I want to reach out that distance I will use a 6mm perhaps the 308.
 
What I would like to know is what kind of groups do you guys get out of your 16" 1:7 twist barrels using factory loaded 55 gr. ammo at 100 yds?
Click to expand...

I typically get about 3-4" 5-shot groups from a stable position (prone or bench) with most 55gr ammo (Remington UMC, PMC, Federal XM193, Guatemalan, Q3131). Opens up to probably 5-8" with Russian 55gr FMJ.. Best shooting is the Hornady 55gr FMJ training ammo or the Hornady 55gr VMAX, which averages 1.5"-2" and produces the occasional sub-MOA group.

My general experience is that the bullets in most 55gr ammo leave a lot to be desired if a high-level of accuracy is your goal.
 
Exactly. 55gn ammo is plinking ammo. I rarely see target grade ammo of that type.

Usually the pricier ammo is 62gn+. You really can't sweat accuracy with plinking ammo. If you want sub moa, you have to buy the good stuff.
 
I only get about 3" with PMC from my 1/7 Colt 6920.

I've used that same ammo to get hits at 425 yards on an IPSC target. PMC is decent ammo.
 
I have an HK MR 556A1 that I pull 3-4" groups at 100 yards with that same PMC ammo. I actually shoot 1" groups or less with a 55 grain handload on that same rifle as well.

On my SCAR16S, it performs about the same, with half the recoil of the HK. The groups are slightly larger at 100 yards with both the handload and the 55 gr PMC.
 
Really appreciate all the posts please keep it coming. I do have a follow up question, though and I probably should have asked it earlier. How do you guys do with the M855 stuff? Thanks again.
 
According to US Army FM 23-9, M193 (55 GR FMJ) groups with equal accuracy out of the M16A1 (1:12 twist) and M16A2 (1:7 twist). If 55 gr is the lightest you want to shoot there's no reason not to get a 1:8 or 1:7 twist bbl so you shoot the really long stuff too.

In my experience quality of bullet and barrel manufacture will have much more affect on accuracy than 1:9 vs 1:7 twist will on most 69 grain and lighter bullets.
 
wingman said:
I have a Stag Model 3 that will give me on average .900 groups at 100 yards with my reloads using 52gr sierra match, some groups as low as .500 when I do my part. The Stag is a 1/9 twist, honestly all the 223's I've owned have been 1/9 and they all did best with the 52gr however up to 69gr will give fair accuracy.

I know many disagree but find the 70 and above grain defeats the purpose of a 223 aka small bullet fast speed. The military selected the 1/7 twist for shooting tracer rounds from what I've read.

If you plan on shooting long distance with the 223 say over 300 yards then no doubt the larger gr is the correct answer but personally if I want to reach out that distance I will use a 6mm perhaps the 308.
Click to expand...
The longer heavier 223 caliber bullets will have a better BC as well as more reliable yawing and fragmenting out to further range than lighter bullets.
 
The limitation on the accuracy with that ammo is the bullet itself, and the rate of twist of the rifle has nothing to do with it. Don't sweat the twist at all. Routine 2-3" groups are about all you should expect from it. If you want better accuracy shoot better bullets. The PMC 55gn FMJ isn't a bad bullet but it's accuracy is simply limited by its design and the inherent limitations of the open based bullet construction. Plenty of people have gotten sub-MOA accuracy out of 52gn match bullets from 1:7 twist rifles, so don't believe that the faster rate of twist is in any way a hindrance to practical accuracy. The benchrest crowd MIGHT notice a difference of 0.1" or so but their rifles are actually accurate enough to note that difference. ARs are not.
 
I don't have much problems holding 3"-4" groups with pmc 55gr fmj, but winchester M855 throws groups at 1.5" with a daniel defense m4v1 with a red dot.
 
It's NOT an AR, but it is 5.56mm with a 1-7 twist, 16.14 inch length. I had 55 grain Hornady 55gr FMJBT handloaded over 22.5 grains of H-335, gave me 3 inch groups shot like this at 100 yards, iron sights. :)


vz556braced.jpg
 
NYH1, I should have posted earlier, but I look forward to hearing or seeing what your results are. Thanks.
 
montgomery381 said:
Really appreciate all the posts please keep it coming. I do have a follow up question, though and I probably should have asked it earlier. How do you guys do with the M855 stuff? Thanks again.
Click to expand...

When shooting my Bushmaster 20" HBAR with 1 in 9 twist from prone position, with iron sights I will typically get 3" - 4" groups (10-shots). That's with Federal M-855 and Serbian PPU-M855.

Could probably improve on that a bit with scope, bench and sandbags . . . but I never shoot like that :D
 
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