Got a 21J Dominator 5 weeks ago.Tried H+N 10.5 gr.and CP. 10.5 gr.without obtaining proper groupings.The nearest to anything worth while was with 8.5 gr. JSB,s. Adjustment of powerlevel , tampering with stockscrews ,different pressurelevels, nothing brought improvement.Then got 10.2 gr JSB,s.At first 10 out of 40 shots were proper.I then increased the powerlevel to shoot at 850 ft/sec. and avoid any form of lubrication and at last I can say that I am the proud owner of the LG 300,getting 15mm 10 shot groupings at 65yards with ease.I own 3 different makes of competition rifles ,all F.A.C. models,and all perform best with different pellet types.I do believe that every adition of a quality pellet type must be applauded.