Stupid Q: How to determine twist rate in barrel rifling

M

Markit

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Hi All,

I'm trying to figure out the twist rate in the rifling of an NEA15 parts gun (insert hatred and disparaging remarks here) I put together last year with all parts sourced here on EE.

I know this is a stupid question but anyone know the easiest way to figure out the twist rate in a barrel?

Upper and lower are NEA and barrel might be an NEA, the rest of it is Frankengun.

With cheap AE 62 gr ammo (.223) and with PMC 62 gr 556 it prints 1/4 to 1/2" groups at 50 yrds, but with 55 gr AE 223 the groups open up to 1" and sometimes 2" @50 yards. It clearly likes heavier bullets.

All I know is it is a 223 Wylde chamber 14.5" barrel. I think it might be an NEA barrel but am not sure - bought it used. No Bayonet lug and no step cut for grenade launcher. It is .750" profile from gas block to muzzle.

Reason I want to know is I plan to start reloading for it and though twist rate would come in handy when I start selecting components and powder.

Many thanks in advance.

Marc
 
Cleaning rod, patch black marker, tape...
Make a line with the marker along the rod, then insert in barrel from muzzle, make a mark with the marker after about an inch, push down until ligitudinal line have make a 360, mark again at this point, mesure between the 2 marks, you have your ROT... JP.
 
If it's an NEA it's probably 1:7

But if you have a cleaning rod try this: Take a cleaning rod and mark one side of it. Lightly pull it down the barrel, so that it rotates with the rifling. Use that to ballpark how much twist there is. If it makes 2 or very close to two full rotations, it's a 1:7
 
Thanks all.


Unfortunately no marks on the barrel that I saw when I assembled it and I don't want to take off the foreend.

Guess i'm going to have to get a .22 cleaning rod. Been using a boresnake.

Thanks again.

Marc
 
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