BSA Hornet Hammer

[greenwayjames]

Hi greenwayjames

The barrel is a 15 inch .22 and the gun is a single shot. The pressures I gave should have read BAR not psi. I bought the HuMa ready set up at 75 BAR to simply fit and forget. Turns out it's not that simple. I assume it was a production reg that I took out of the tube. This suffered from the power spike which is why I was replacing it (previous owner had set the power to 9.5FPE so it didn't go over when dropping off the reg).

When I spoke to JB the other day he told me the regulator settings for all calibres and lengths of barrel. The .22" 15" carbine setting is 700 psi (divide by 14.7 for bars) to avoid the velocity spike as the rifle comes off the reg. Without a reg tester you are p*ssing in the wind unless the Huma reg is marked up accurately. Good luck. James.

[Dangerous Brian]

When I spoke to JB the other day he told me the regulator settings for all calibres and lengths of barrel. The .22" 15" carbine setting is 700 psi (divide by 14.7 for bars) to avoid the velocity spike as the rifle comes off the reg. Without a reg tester you are p*ssing in the wind unless the Huma reg is marked up accurately. Good luck. James.

The reg has a finely calibrated scale on the side. No wait- it's a sticky label with some marks on!! The chances of that being anything close is remote. If I assume the scale is halfway accurate I probably didn't reduce the pressure enough (700 BAR being 47ish psi). Looks like I am probably better off ringing JB to sort something out. Even if I get the power spike smoothed out I still have the problem of the adjustment screw being wound out too far for the rifle to go back in the stock.


Thanks very much for your wisdom on this. What started off as a quick drop in replacement is turning into something a little more than I am comfortable with.

[riku]

The reg has a finely calibrated scale on the side. No wait- it's a sticky label with some marks on!! The chances of that being anything close is remote. If I assume the scale is halfway accurate I probably didn't reduce the pressure enough (700 BAR being 47ish psi). Looks like I am probably better off ringing JB to sort something out. Even if I get the power spike smoothed out I still have the problem of the adjustment screw being wound out too far for the rifle to go back in the stock.


Thanks very much for your wisdom on this. What started off as a quick drop in replacement is turning into something a little more than I am comfortable with.

That scale should be close enough to get you going. The end piece with power adjuster is attached with two screws, one through trigger block and another one under probe.

[greenwayjames]

The reg has a finely calibrated scale on the side. No wait- it's a sticky label with some marks on!! The chances of that being anything close is remote. If I assume the scale is halfway accurate I probably didn't reduce the pressure enough (700 BAR being 47ish psi). Looks like I am probably better off ringing JB to sort something out. Even if I get the power spike smoothed out I still have the problem of the adjustment screw being wound out too far for the rifle to go back in the stock.


Thanks very much for your wisdom on this. What started off as a quick drop in replacement is turning into something a little more than I am comfortable with.

Having already bought a Huma regulator why dont you contact them and ask if they can alter it or get their distributor to set it to the correct level? JB wont fit a Huma reg.

[Dangerous Brian]

Hopefully one more go at it tonight. Plan A: Drop the reg pressure to 47BAR (or as near as I can get) and wind the adjustment screw all the way out and see where we are. If all goes well I will just need a shorter adjustment screw. If not, then plan B: take the HuMa off and see if JB can work his magic.

I think someone might have put a drop of locktite on the end cap so it needs something a bit more than harsh language to shift it. I am not sure what I would do if I got the hammer out anyway after seeing the various shapes and sizes.

Update: Turns out JB knows a thing or two about his air rifles! After a lot of trial and error (and half a tin of pellets through the Chrono) I managed to find the sweet spot somewhere between 47 and 50 BAR on the reg. Any higher I got the spike and any lower I ran out of adjustment on the hammer spring. I now have a Hornet running a nice 563fps with 16grn AADF and even managed to get the end cap back on.

Thanks for all your help guys.