Tuning Brocock Commander Hi-lite power increase tips?

Thanks. I don’t think there is a plenum issue as there are versions of the Commander that do over 50 fpe.

I suspect it they might get different hammer weights and springs.

What I find strange is adjusting the spring stop tighter seems to have little effect over a wide band of adjustment. There is a large gap between the spring and hammer. Only the last 30% of the bolt travel loads the spring. The power slowly climbs over a wide range of winding down the spring stop then switches to wasting air and losing power which can clearly be heard.

The spring stop itself is very loose. Someone had red loctited it. They should have used blue. I had to apply heat to break it loose.

One other thing I noticed is the regulator is almost instantaneous at 140 bar, but at 150 bar you can hear the fill sound for about a second or two after a shot. If I can't find a spring setting to increase velocity I'll turn the reg back to 140.

The gun is super accurate. Really impressed with that. I’d just like to be able to turn it up for pushing slugs at longer distances.

After the regulator settled it is at about 155 bar. That only yielded another 15 fps or so but interestingly filled faster (vs. the second or two it took to recover at 150 bar.) Predator Polymags are moving about 930 fps. Hades at maybe 5-8 fps faster than that. So 30.7-30.9 fpe. JSB Jumbo Monsters do 810 fps for 36.8 fpe.

Back to slugs I'm getting 885 fps from .2165 17.5 gr. NSA hollowpoints for 30.4 fpe and they seemed to be as accurate as pellets out to the 42 yards I tested them at. .217 20.2 gr. NSA's are good for 840 fps and 31.6 fpe. I had feed problems with the slugs unless I seated them into the magazine a bit. If not, they would fall backward out when I cocked the gun and jam going back in.

Going to play more with the 17.5's and see what I can get the group sizes down. They have half the BC of the best pellets which will have them shooting flatter and retaining more energy downrange.