Best method to find unknown barrel twist

[TaylorS]

So I was reading on a box of black hills ammo and it was saying that the heavier bullets needed a faster twist rate to be accurate. That got me thinking what’s the twist on my DMR AR? I bought the barrel off I think brownells years ago and apparently they have stopped selling them it is a 24” extra heavy bull barrel with what I thought was a 1:12 twist but I really don’t know and wasn’t thinking about twist rate much when I built it.

Anyway dumb story short it’s got me thinking how can I find the twist rate of my barrel?


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[Hossfly]

The way I check the twist of my rifles, is to take a solid cleaning rod and a tight patch, mark with marker or masking tape and pull thru barrel with carful measure 1 turn in so many inches. Simple.

[country gent]

I do it similar to above. I use a brush with patch cut to make a tight fit. insert rod thru muzzle and screw it on. Pull into rifling. put a masking tape tail pointing up right against the muzzle and pull out for 1 revolution. measure between muzzle and flag you twist is 1 turn in xx inches. You need a free spinning rod, I try to use a new brush and cut the patch to wrap around the brush so it fits tight, you don't want it to slip. Locking the rifle / upper in a vise is a big help here also. Last is do this 3-4 times to make sure your getting good readings.

[country gent]

As a side note a lot of AR barrels had the twist stamped on them somewhere usually ahead of the extension or at the muzzle end

[TaylorS]

As I recall only markings were by the breech end and the hand guard is a booger to pull off I’ll give the spinner patch a go to see what I end up with the ammo in the box called for a very fast twist so I’m hoping that’s what I had the foresight to purchase when i built it. But the best load I had worked up with the 70gr Serra bullets was slower than published material but sub moa out to 400 yards


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[lefty o]

if your shooting 70gr bullets, and they are punching clean holes in the paper, you dont have 1-12" that much is for sure. you more than likely have a 1:7 or 1:8.

[DCM]

The way I check the twist of my rifles, is to take a solid cleaning rod and a tight patch, mark with marker or masking tape and pull thru barrel with carful measure 1 turn in so many inches. Simple.

This, Simple and true.

[oldracer]

I use the tight patch as noted above. I have a cleaning rod used just for this with a center line scribed down the rod and inch marks made also. I pull the or measure the rod turning at both ends since I bought a muzzle loader barrel that turned out to be gain twist! So now I pull from one end and measure and then reverse the barrel and pull to see if the readings are the same.
John

[Nobade]

A tight brush on the rod and a spring type clothes pin. Get the brush started, pin goes against the muzzle and oriented straight up as I sight down the rod. Pull rod, pin spins, when it's up again I measure from the muzzle to the pin with a rule. Works great!

[Texas by God]

I use a non threaded slot tip rod with a tight fitting patch. From the muzzle end I start it in a few inches, then drag a sharpie on its side down the rod to make a line. Mark a witness dot on the muzzle face at the line. Mark the rod circumference flush with the muzzle. Push the rod down the barrel till the line hits the witness mark again, mark around the rod again. Measure mark to mark for your twist rate. I use a solid rod for this so there is no chance of loose connections.

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[fourarmed]

If it has a right hand twist, measure by pulling the rod through. If left hand, push the rod through. Otherwise, the jag or brush can unscrew from the rod, and mess up the measurement.