JASmith Wrote:Ref Posts #52, #55, and #57: Too bad the gel test in the first frame wasn't reduced to a sketch to allow a more direct comparison with the results sketched in the second frame.If you're referring to the pics in post #52, neither bullet breaks up. Both are non-fragmenting projectiles.
We need to establish a consistent set of experimental data -- comparing a stoutly designed FMJ bullet in one caliber with one that breaks up in another caliber is not a consistent check.
I got to thinking about the topic this morning. Wound profiles of the majority of FMJ rifle bullets show undesirably late yaw. This is especially true of FMJBT projectiles, regardless of caliber (the notable exception being the 5.45x39 M74 round). So it should not be surprising that the 6.5mm Norma 120gr FMJBT also displayed late yaw; the same would almost certainly be true of the 6.5mm Lapua 144gr FMJBT, as well as the Swedish military 140gr Ball and 113gr AP bullets.
I question if the RUAG design (shown in post #57) -- scaled up to 6.5mm, per Tony's suggestion -- would provide the desired results. Gel tests of M855 show the late yaw typical of FMJs, when the bullet has a very small angle of attack (see right pic at http://www.itstactical.com/wp-content/up...7/pic4.jpg)
Those FMJs which show relatively early yaw are typically short-for-diameter designs -- 7.92x33 Kurz, 7.62x39 M67, 6.8x43 SPC -- and they are hardly spectacular in this regard, with onset of yaw at ~3 inches.
The only example I've seen of early yaw in a streamlined, long-for-diameter bullet -- which is the configuration needed to give an intermediate caliber the necessary long range capability -- is the Russki 5.45x39 round (see attached). AFAIK, that's the only proven design; either copy it, or spend a lot of time and money trying to reinvent this particular wheel.