Mike -

If your Bisley is a 45 Long Colt, it could be as fast as 1:15.

Snake RR -

We can WAG requied twist rates from multiplying the square of the bore times 150. This gives the rate of optimal twist for a bullet 1 inch in length. At .452 caliber we get a twist rate of 1:30.6 inches to start out, knowing nothing of velocity effects. From there we can scale up or down based on the actual length. All of this is for a reference velocity based on bullet shape.

The more mass carried in the outer portion of the bullet diameter, the better. Hence, hollow points are better, because they carry less of the lead in the portions of the bullet that are less than full diameter. The same holds true for pistol bullets of FN design. The reference velocity for FNs appears to be around 2000 fps, from what I gather.

So, if we addditionally correct for velocity, we take the square root of the ratio of the reference velocity to the actual velocity. Here, we are talking the sq root of 1100/2000, or about 0.74.

So, 30.6 times 0.74 gives us a twist rate of 1:22.6 inches for a 1 inch long .452 FN bullet. The actual length of the 360 GCFN is not yet know, as I have not selected it, but I may be OK at 1100 fps and 1:24.

If you do shoot some of these @ 1100 fps, please let me know how they work out.