I have had a handful of BAM50 over the years and also have a few Daystate Huntsman. The BAM can be a great rifle. Super easy to work on.
The big issue with them is out of the box they have WAY too much hammer spring. Left alone it will destroy the exhaust valve. Clipping the spring some will bring down the power ti a reasonable level and added bonus of a lower fill pressure.
The ones I had I polished everything up, trigger, crown, lead etc. I used a ban for a few years as my first pcp field target rifle.