I was able to get to the farm this morning... it was a cool sunny day here and as usual the wind was blowing fairly well at the farm, but i really wanted to test this latest conversion of mine.
Most know I took a Knight Power Stem cut the stem off and installed a Lehigh Vent Liner. The purpose of the conversion is/was to reduce the amount of blow back collected in the bolt and reciever area. The theory was to increase the 'flash channel' to just over 5/32's in diameter and also to increase the length of the 'flash channel' - the end product should be an increase in volume that the BP can contain. With the increased volume possibly the bullet would leave the barrel before the blow back volume increased to the point that it pushed its way back out of the FPJ. If the timing were right the bullet exiting the bore would cause the blow back gas to leave the same way.
I honestly think - I may have come very close to accomplishing that goal. I shot 20 shots this morning. 12 at a target and 8 at dirt clods in the field. I really felt I was getting much less blow back than I had with my previous use of the FPJ. To further complicate the problem I was using FPJ's that have been shot at least five time already - so they were already stretched. While shooting I kept looking at the bore area, and yes it was getting dirty with a reddish brown residue. It never did build up a black carbon deposit anywhere in the bolt/receiver area. When I got home and started cleaning - everything on the bolt/receiver area cleaned with a wipe of a Windex patch. Even the scope was undamaged - very little residue being blown up on the scope. (i forgot the scope cover)
Here are some pictures of the bolt/receiver area....
This is the target and velocities.
