Knight DISC 50 with Conversion @ the Farm

[sabotloader]

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.

[cayugad]

It really looks like you might have that thing licked. Also some nice shooting there. It was a beautiful day here also for shooting. But I (as usual) went traditional.

You said the scope was not getting a lot of blow back. That is good. Although my Disc is not too bad on the scope. Ignition must have been instant. So how does this vent liner work? I know nothing about them.

[sabotloader]

cayugad

So how does this vent liner work? I know nothing about them.

One the vent liner is suppose to replace the flash hole in the BP, the only reason I got interested was from talking about gas cutting their 'flash holes' - loosing accuracy and requiring a replacement BP. It was my point that drill, tapping, and installing a vent liner would sometimes be a lot cheaper.

The vent liner designed by Lehigh is suppose to have the optimum flash hole size for ignition of BH (.032). The liner is hardened and should last many shots especially a person using a normal primer and a BP sub. I shoot T7 and it is a very hot temperature powder - but not even close the the burning temp of BH or the heat and force of a Fed 209 primer. Tom has over 300 shots on his vent liner and it is still going strong.

The next thing that attacted me was the cone design of the vent liner - it would make sense that some of the blow back pressure coming back the the BP would be deflected to the sides by the cone instead of it all being directed down the flash hole into the BP... that has got to help reduce some of the pressure hitting the bottom of the spent primer.

The next thing I like since you can remove the vent liner - it really makes cleaning the BP pretty darn simple and the cleaning the liner as a separate part is also easy.

Probably one of the most important things to me is that vent liners are $5 - considerably cheaper than replacing a plug.

I have not proved this yet, but I really think I am getting a boost in velocity with the vent liner - I know the numbers are indicating a greater velocity - but the numbers are coming from a new Chrono that I have been using lately. I question Jim Bailey at Competion Electronics (maker of the Pro Chrono's) if I should expect a difference in velocity between the Pro Chrono 'Plus' and the Pro Chrono 'Digital' - he indicated they were basically the same electronics with the newer 'Digital' be more user freindly than the 'Plus' but the velocities indicated by both should be very close... More testing - more shooting.... PROBLEM - Rhondy shoots arounf here a beginning next month and I need to get started shooting my Renegade and PRB's...

[lemoyne]

Mike
I notice that the varence and standard deveation are much better than I got from T7, I noticed an improvement with BH also. Have you conducted any efficency tests on where the peak preformance is compared to volume of the flame channel?
I also notice thjat when the SD is reduced that I can see the diference in accuracy at 200yds and over.

[gregrn43]

Thats some good groups, looks like your have a winner there.

[sabotloader]

lemoyne

What you see is what i have done with these conversions. I just picked 110 grains out of the air and said that is what I am going to shoot. The 110 grain load is my normal hunting load except with Knights and I do move to 120 grains with them.

If the gun can not shoot 110/120 grains accurately - i do not have the gun very long. But, I am hoping to get a lot more shooting in - except for one problem - local area Rhondy shoots begin 3/7 and go through July - so I do need to switch over to shooting the Renegade and PRB's to get some practice in...

[lemoyne]

sabotloader
Since I also do a lot of my work with 110 as a base that in it self is interesting. The increase in velocity by itself is not enough to get excited about, when you put it with the improvement in SD and better groups at long range it appears to me that we are dancing in circles around a a few improvements in breach plugs that could really amount to something if we go to the trouble of graphing it out in detail.
One of the problem as I see it is that different 209 may affect the length and volume needed for best efficiency.
Have you noticed any difference in cleanness of burning or hardness of residue?
I may have to buy a can of 777 as I am interested in seeing how this affects those of us who have to deal with major crudring problems.

[sabotloader]

Lee

I may have to buy a can of 777 as I am interested in seeing how this affects those of us who have to deal with major crudring problems.

I would not do that quite yet... I am going to put the new conversion in the used 45 that I bought in December. It has what appears to be a grease stain in the breech area of the bore that i can not get out without resorting to a lapping process. That stain in combination withthe heat and residue of T7 does create a 'crud' problem. I want to try the conversion there and see if it makes any difference. Hope to get to shoot again on Friday.

I was not going to shoot that 45, I was going to shoot the new one, but your post has me interested... was the lack of any notible fouling in the 50 a result of the new BP or just a fluke? Guess I need to find out...

Have you noticed any difference in cleanness of burning or hardness of residue?

I really think I have. I know when I dropped that first windex patch in after the first shot - the thing dropped right to the bottom - surprised the heck out of me. I did continue to patch after each shot - 20 of them - but never felt much of anything. In fact I only used 2 windex patches all morning. So I really think the burn was more complete - maybe another reason that the velocity moved upward... well, at least until I started heating the barrel there at the end...


But time is running short for my inline shooting got to get into a different frame of mind and start shooting some PRB's...