Here is one of Shawns smaller diameter 1/2" thread brakes. They are slightly longer then the Holland but will also be closer to the muzzle diameter as well.
This is the side view(obviously [img]/ubbthreads/images/graemlins/grin.gif[/img]) compared to a Holland 1/2" threaded QD brake.
The ports are round instead of oblong on this small brake design and the top of each port is releaved to offer JUST enough vertical muzzle control on light weight rifles but not so much that it will pin the barrel down into the stock.
This the top view also compared with a Holland 1/2" thread brake. You can see the relief on the top of each port. This is the brake that is on my lightweight 7mm Allen Mag(7.5 lbs) which is currently with Shawn getting teflon coated flat Black. It will soon be put through its paces and I will report fully on the performance of that brake and rifle for that matter.
The 5/8" threaded brake is very simpliar to the Holland in appearance except that the ports are slightly different in size and position in relationship to each other. Also, the 5/8" brake comes untapered and in that state will match up nearly perfectly with a #8 Lilja contour barrel with a muzzle diameter in the 0.875" range. For all smaller diameter barrels you can easily taper the brake to match the muzzle diameter. The ports on these brakes are not releaved at the top of each port. The barrels these brakes are designed for are relatively heavy contoured barrels so muzzle jump is really not a concern. Recoil reduction is the main chore and this design works very well, at least equally as well as the Holland.
This is the brake I have tested on my wifes 6.5mm Allen Magnum. I do not have any detailed pics of it yet but I can get a few taken and post them.
I have yet to get any of the new 1" diameter brakes but will be soon.
Not the best pics but they give you an idea.