Re: 375CT at 2000Y and 2500Y
"Drag bands" is the correct terminolgy we used back then. Dean and I started testing on or about 1999. If he says he shot 100K rounds of 408's, that is very conservative. He and I were shooting partners the whole time, and still today. I also shot just as many then. I still have the orginal experimental rifle here, which is on it's 14th barrel. It still "drives tacks".
The above term comes from us studying Yuma Radar Data. Looking at the Doppler Dope, where we could study the meter by meter down range of a specific bullets flight, caused us to shy away from any driving bands.
There is a very common photo out there of a shadow graph picture showing a 7.62 NATO bullet in supersonic flight. It shows the very prominate Primary Shock Wave from the nose, but also look farther back, a lesser shock wave is coming from it's very small cannalure. Imagine 3 or 4 deep driving bands cut onto that same bullet.
I will not answer, here at SH, anyone who wants to dispute this as I believe what I see by actually shooting all possible projectiles. Even though I do have an Aerospace Engineering degree. It's still all about the shooting and final results. Then it's up to the Ballisticians to explain why.
Barrels. We decided on a specific bullet first (through very extensive testing). Then we wanted to test different barrels to fire that specific bullet. We decided on Barney Lawton to make all barrels for us. The 1st few test barrels he made for us were all different twist rates/land/groove configuration, etc., because we wanted to test and shoot all ourselves, and settle on the most optimal twist/configuration we could...by simply shooting them. For the 408 we decided on the 1x13 twist, 8 groove. For the 375/350 gr. we made the 1x11.5 twist.
Bullets. The solid 408/419 gr. and 408/305 gr. along with the .375/350 gr., and .338/270 gr. were all CheyTac designed. We contracted LRBT to make these on our machines using our material, at one time. LRBT fell on hard times. So we moved our machines to Jamison International(CheyTac owned).
Like I said, this is just past history and probably old. Technology has made leaps and bounds. Just wanted to "clear the air" as Dean was fond of saying!
Dave
CheyTac
