Brocock Bantam Tuning

[BigTinBoat]

"Element"I second that, great info trying to keep up lol thanks bigtin your the compatto goto guy!

Thanks Steve - but it was actually Dr Putz who took it apart first. I just kinda theorized, based on what he found, that reducing the spring and increasing the hammer weight should work, and it does. It seems intimating at first, but once you open it up you see how elementary it really is.

 

[Element]

Yes they are simple to wrk on I've had my compatto apart a few times never thought about the inner valve spring, I new it was stiff as all get out. Makes me wonder why they don't leave the factory in better tune it's not like they don't have the experience at building these things...

 

[BigTinBoat]

"Element"Yes they are simple to wrk on I've had my compatto apart a few times never thought about the inner valve spring, I new it was stiff as all get out. Makes me wonder why they don't leave the factory in better tune it's not like they don't have the experience at building these things...

I would think 90% of their guns are under 12fpe, where the SSH likely works well.

 

[DrPutz]

I applied the same formula from my 177 to my new Bantam 22: 0.054" wire 1.75" long hammer spring, 0.026" wire diameter valve spring 1" long, 0.075" hammer pin out (plus 2 turns) and I am getting 860 fps with JSB 18.1 for 29.9 fpe and 1.38 fpe/ci efficiency; and 880 fps for JSB 15.9 for 27 fpe at 1.16 fpe/ci efficiency. The transfer port on the 22 is already 4 mm. One interesting note is that 18.1's are quiet without a LDC - backyard friendly. The 15.9's are a bit loud. I am suspecting that the 18.1's are under powered - that is using up all of the air before exiting, hence no real report. I could probably push them faster, but I like the current speed for accuracy. 

One fun note is that the 15.9's on low power, make just under 20 fpe, so I might compare them to the 177 for field target in windy conditions.

 

[BigTinBoat]

I think I'll have to test the 18.1's when I get my rubber mulch target back together.

 

[noblett56]

Guys, I realize this is an old post, but I'm desperate for information and trying to do some research. I have one of the early Bantam's. It's been fine for my application but lately it's become randomly inaccurate. I'm shooting quarter size groups at 50 yards killing every pest invading my habitat and then without any indication I can't hit an invasive species from 15 yards away. I'm a newbie as it goes with PCP's and haven't made any modifications to my Bantam. Before I start down that road I was wondering if you could offer some guidance.

What modifications do you recommend that I begin with? What research can you point me to that would raise my confidence that I won't wreck my rifle

 

[L.Leon]

@noblett56, you should probably start a separate post, you'll get more responses that way. You could also provide more information, like pellets used, scope, regulator setting (if any), etc. It might simply need the barrel cleaned. Good luck.

 

[Navyblue]

It would help a lot if you can get some fps measurements too.