Vietnam era M193 ball 1:12 twist vs. Modern M855 ball 1:7 twist

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RugersGR8

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Test: Vietnam era M193 ball 1:12 twist vs. Modern M855 ball 1:7 twist
Military Arms Channel
Aug 8, 2020 31,307 views

 
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dennishoddy

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No shat. Earlier designs did not stabilize the Bullet

It was tumbling in flight with a 1:14. At combat distances during that conflict it was acceptable.
The early issues were thought to not need cleaning kits. We all know different now.
Lots of soldiers were found dead with their broken down AR’s in their laps while needing cleaned during a firefight.
The military started to issue cleaning kits later on.
A 1:12 will stabilize a 55 grain just fine.
 

Shadowrider

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This thread came at an uncanny time. Just yesterday I was helping my BIL zero his RDS on his cheapo Anderson AR. It has a 1:7 barrel. He had Fed AE green tip and some Black Hills 55g soft point. At 25 yards it was shooting about a 6" group with both loads. Completely unacceptable. I checked all the normal stuff and didn't see anything wrong. It shot the same for me, but when I checked the target after I shot it I noticed a round went through the target sideways. Ahha! No wonder it won't hit.

Went back and pulled the BCG and looked in the barrel. Looked good, nice bore, nice rifling, nothing out of the ordinary. Checked the crown. Same. Nothing stood out as being the culprit. So I stuffed some of my reload Hornady 55 FMJBT in it and put 3 rounds in a nickel sized group not really trying. We zeroed it with my ammo.

I have no idea why that 1:7 barrel won't shoot those two other rounds. 6" at 100? Yea maybe in a crap Anderson barrel, but at 25? ---> :scratch:
 

swampratt

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I have seen those 12" groups at 50 yards from many AR rifles in 223-5.56 with store ammo and the owners were happy.
That was years ago before I ever owned that caliber.

Store ammo could just be crap or that ammo in that gun is.
I have 1:9 and 1:7 twist and they both shoot 55gr and other sizes up to 77gr just fine.

That is why I hand load.
 

SMS

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My 1:7 shoots 193 accurately out to 500 all day long if I do my part...that's gotta be a crappy barrel for sure. I get that some barrels "like" some ammo differently, but like you said, at 25yds?
 

Glock 40

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I am no a fan of 55gr or smaller in ARs I prefer 60-62gr and have found box ammo shoots better in multiple ars and my hand loads with 60-62gr shoot great in anything I have tried them in.
 

Shadowrider

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My 1:7 shoots 193 accurately out to 500 all day long if I do my part...that's gotta be a crappy barrel for sure. I get that some barrels "like" some ammo differently, but like you said, at 25yds?
I'm really wondering if the barrel needs lapped to the upper. It's a Anderson upper and lower and may be a complete Anderson gun. It runs fine it just doesn't seem to shoot. I've seen Anderson receivers built with decent pieces shoot great but I'm sure turds do get out into the wild. Haven't took it out past 25 yet. He only has it for close range "pig work" for the most part.

I am no a fan of 55gr or smaller in ARs I prefer 60-62gr and have found box ammo shoots better in multiple ars and my hand loads with 60-62gr shoot great in anything I have tried them in.
I know a couple of 3 gun guys (pro, national level) that shoot 52 and 55 grain exclusively out to 600'ish in matches. One shoots Hornady 52s the other Nosler 55s. They don't need special custom 77 grain LR loads and different dopes to hit at distance.
 

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