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Bill D
09-25-2009, 06:47
I have a couple of SP1 AR's. Does anyone know what the rifling twist is on these?
Thanks in advance.

Bill
RCS
09-25-2009, 07:03
The SP1 has the 1 in 12 twist, very early ones had the 1 in 14 twist.

Early and very early flash hiders
Bill D
09-25-2009, 07:40
I guess mine aren't quite that early, they both have the birdcage suppressors. They were some of the first to be so equipped.
BTW, do you also know the twist on the M4?

Bill
RCS
09-25-2009, 08:11
The AR-15 barrel twist changed alot on the SP1, best thing to do is check it yourself. Using a tight cleaning patch, mark your cleaning rod with a dot or something and when one complete revolution is made mark your rod again.
Then measure the distance between the two marks on your cleaning rod, that will be your barrel twist.

Early cartridges, left is 224E2 Winchester, right is 222 Remington Special which became the 223 Rem
Litt'le Lee
10-04-2009, 11:14
this is to stabilize the long tracer rounds
lyman
10-05-2009, 09:03
this is to stabilize the long tracer rounds



not really the tracers, so much as the newer, heavier 62gr standard ammo, (green tip)

just happens to work great with the 77/80gr SMK's too
jaceglarek
10-07-2009, 04:44
Sorry, but I believe you're wrong. The 1/7 twist is to stabilize the long tracer bullets that were introduced alongside the new "green-tip" ammo. The 62gr SS109/M855 bullets don't need that fast a twist to stabilize them...but the long tracer bullets due.