I've also got a Disc, had it since ???96...It's the 22 inch barrel model...

Anyway...Mine is a little picky (actually I am)...I not only clean with 3 patches dampend with alcohol and then dry but I also lube with oil and then dry...I found if I didn't lube and dry my groups opened up...Now, I'm a picky sob when it comes to groups, more than a inch and a half at a 100 to me has to be corrected...

Now...You will not find a bullet that will out group that Barnes 300gr MZ...Trust me, I tried...

I have also got a load that works with the 250 SST...That's the bullet to try if you want a flatter shooting bullet...In my Knight, the pet load was 100grs Pyrodex and a 300 gr Barnes...With the SST it is a 250 SST and 90grs Pyrodex...With both of these loads sighted in 2 1/2 inches at 100 yards the Barnes hits 6-8 inches low at 150 and the SST hits 2 1/2 - 3 inches low at 150...It seems wierd, less powder, flatter shooting...It's in the design of the bullet...

As stated, a 240 hollow point pistol bullet will not shoot much flatter than the 300gr Barnes...If you want flatter shooting, look at the SSTs or the Dead Centers...(My Knight didn't like the 220s)...

Have fun...