Well, been waiting to write this for a little over a week. The metal adapter from John Hagan showed up last friday, and I got a chance to test it this weekend. You can see a comparison of the new metal shroud cap/adapter next to the original plastic shroud cap in the 2 pictures above. I originally wanted this to allow me to use a Donny FL suppressor on my Trail NP XL to cut down on some of the bark when using in town for pesting. However, one of the annoyance with the original shroud cap being plastic is it doesn't sit tightly against the barrel and shroud, and it strips as soon as you put any real tension on the shroud. The stripper holes for the original shroud are also perpendicular and 4- 2.5mm holes. When I designed the new adapter I wanted 5-3mm holes at 40 degrees rearward. After discussing with John, we decided to do 6-3mm holes at 45degrees to make it easier to mill. My hopes, other than aftermarket suppressor capability, were that the redesigned stripper holes would make the shroud more effective, and the metal shroud end would allow me to tension the barrel to improve harmonics.
I have to say. I made a measurement mistake and the internal threads were the wrong pitch forcing me to re-thread my barrel. So, if you go this route make sure you measure the threads carefully. The factory thread on the barrel was M12-1.25 fine thread, and I told John M12-1.5 common thread. M10 and M12 thread patterns are also available in 1.00 fine thread and 1.75 coarse thread So, if you don't know how to measure threads, definitely get an experienced friend to measure the threads for you, and confirm your thread measurement before ordering an adapter.
Okay, so overall I am completely thrilled with the final product. With the new stripper holes, the report is not only a more pleasant sound, but is significantly quieter. With the old cap I measured about 110db, and it was a snap sound. With the metal adapter, I measured 94db and it is more of a soft thud. At this point, I'm not even sure an aftermarket suppressor is all that necessary, but once I get one on the Avenger I will test it anyways. The barrel shroud is easily tensioned with this installed, and my groups improved signicantly at 100yds. Still some playing around with it, and it shifted my POI up. So I will continue to mess with it, but this is today's result at 100yds.
My adjustable scope rings got shifted about 50MOA, and I didn't have the tools to adjust them at the range. So I had to shoot by holding a consistent point below the target, and hoping to hit paper. I actually fired 5 shots, but was using a shattered clay pigeon as my consistent reference, and ended up using 2 different shard pieces. so the other 2 shots are grouped lower on the target. I will try to shoot a target card once I have it sighted in at 100 again and post as a reply as well.
Wanna say a big thanks and great job to John. This is just what I need to make this rifle worth shooting in the field.
Warning: I am using this as a barrel tension device, but be mindful that the barrels in break barrels are pressed into the chamber block. So over tensioning could potentially loosen the barrel and pull it out of your chamber block.
