BSA Hornet Hammer

[Dangerous Brian]

Hi All

I bought a pretty rough BSA Hornet a few months back and have been fettling it. The problem is a power spike as it drops off the reg. I have fitted a new one but the problem remains. I would like to change the hammer to something a bit lighter but can't get it out of the housing. Does anyone have an idiots guide for this?

Thanks

[Shed tuner]

sounds like you should reduce the reg pressure a bit, and back off the hammer sping Or reduce its weight - a bit too...

[Dangerous Brian]

Hi Shed turner.

Already going through the process. I fitted a HuMa and have reduced the pressure from 75psi (set as the norm for BSA .22) down in stages to 55psi and still get the problem. The only difference is the hammer spring adjustment is wound out so far the end cap won't go on anymore. Next option is a lighter hammer as the one in there could be used to knock fence posts in. The only snag is I am not sure how the hammer and spring is removed from the tube without damaging anything. Any tips on separating them would be appreciated.

[Shed tuner]

is the TP too large ? Otherwise yeah, lighter hammer...

[Dangerous Brian]

You are right- it might be worth a quick look at the transfer port. I am pretty sure someone has had the gun apart before so may have been messing.

[greenwayjames]

Hi All

I bought a pretty rough BSA Hornet a few months back and have been fettling it. The problem is a power spike as it drops off the reg. I have fitted a new one but the problem remains. I would like to change the hammer to something a bit lighter but can't get it out of the housing. Does anyone have an idiots guide for this?

Thanks

Why dont you give Bowket a ring . 0121 745 4287. Leave your number and he WILL ring you back. The Hornet is based on one of his designs. Very helpful and I.m sure he would be only too willing to give advice.

[riku]

Hi Shed turner.

Already going through the process. I fitted a HuMa and have reduced the pressure from 75psi (set as the norm for BSA .22) down in stages to 55psi and still get the problem. The only difference is the hammer spring adjustment is wound out so far the end cap won't go on anymore. Next option is a lighter hammer as the one in there could be used to knock fence posts in. The only snag is I am not sure how the hammer and spring is removed from the tube without damaging anything. Any tips on separating them would be appreciated.

Take off the endcap and spring comes out. Open a grub screw at the rear of the hammer and hammer latch pin can be removed allowing hammer to come out. Replace with Scorpion hammer from XTX and use heavier hammer spring. While you are at it get a shorter grub screw for power adjustment in case you need it.

[greenwayjames]

Take off the endcap and spring comes out. Open a grub screw at the rear of the hammer and hammer latch pin can be removed allowing hammer to come out. Replace with Scorpion hammer from XTX and use heavier hammer spring. While you are at it get a shorter grub screw for power adjustment in case you need it.

One of the nicest features of the Hornet is the very short hammer travel. Using a Scorpion hammer will more than double that travel. That will bring far more problems. The Hornet could then be re-named Zebedee.

[riku]

One of the nicest features of the Hornet is the very short hammer travel. Using a Scorpion hammer will more than double that travel. That will bring far more problems. The Hornet could then be re-named Zebedee.

I wouldn't call the setup nice, the hammer is massive and the hammer spring way too soft and too long resulting quite a bounce. I actually managed to make 100 fpe with a shortened Hornet hammer in my .224 BSA To put things in perspective here's a comparison of Scorpion hammer, R10 hammer with PEEK tip and Hornet hammer:

IMG_2832 by abbababbaccc, on Flickr

[Dangerous Brian]

Take off the endcap and spring comes out. Open a grub screw at the rear of the hammer and hammer latch pin can be removed allowing hammer to come out. Replace with Scorpion hammer from XTX and use heavier hammer spring. While you are at it get a shorter grub screw for power adjustment in case you need it.

Thanks Riku

That build up the picture quite a lot. The gun is an old design; the endcap is glued on and comes off with a knife easily. I ran into problems with the metal bit that sits in the tube (with a couple of bolts through it) but by the sound of it that should come out. Time for a bit of heat on it.

[Dangerous Brian]

Thanks everyone for your input. I have a plan and a few areas to avoid now, plus JB's number if all else fails.


Now for a long weekend of fettling...…(I wish).


Cheers guys

[riku]

Thanks Riku

That build up the picture quite a lot. The gun is an old design; the endcap is glued on and comes off with a knife easily. I ran into problems with the metal bit that sits in the tube (with a couple of bolts through it) but by the sound of it that should come out. Time for a bit of heat on it.

That's actually the endcap I meant, screw off the pellet probe end/push button and you'll get access to the top screw. Apply some heat if needed.

[greenwayjames]

Hi Shed turner.

Already going through the process. I fitted a HuMa and have reduced the pressure from 75psi (set as the norm for BSA .22) down in stages to 55psi and still get the problem. The only difference is the hammer spring adjustment is wound out so far the end cap won't go on anymore. Next option is a lighter hammer as the one in there could be used to knock fence posts in. The only snag is I am not sure how the hammer and spring is removed from the tube without damaging anything. Any tips on separating them would be appreciated.

What calibre and length of barrel is your Hornet. The psi figures you quote cant be right. Speaking to Bowket he tells me the hammer is quite heavy so that a weaker spring could be used for user friendliness. In production you have to allow for all. There is little bounce on a standard Hornet due to the short hammer travel of only 6-7 mm. Its easy to check yours with a fine felt marker pen and a rule. The production regulator settings he told the factory to use gave a slightly lower shot count out of the many tried but produced no spike when coming off the reg. The count was more than adequate from a 75 cc air reservoir. The standard acceptable figure he gave BSA to comply with for the carbine was 65-75 for the .177 and 90-100 for the .22". Port size doesnt matter apparently if all other settings are OK and was the same for all calibres and power levels.
The R10 hammer travel was increased to try to overcome the problems caused by the BSA designed magazine indexing system rubbing on the hammer.

[Dangerous Brian]

That's actually the endcap I meant, screw off the pellet probe end/push button and you'll get access to the top screw. Apply some heat if needed.

Cheer riku

I already have the hammer tube separated from the rifle on the bench. The end cap is off exposing the adjusting screw for the spring pressure. The problem is the metal bit that holds the spring in the tube is fixed and I am not sure whether it's glued or screw out (or both). From what I have been reading in here it is likely glued in.

[Dangerous Brian]

What calibre and length of barrel is your Hornet. The psi figures you quote cant be right. Speaking to Bowket he tells me the hammer is quite heavy so that a weaker spring could be used for user friendliness. In production you have to allow for all. There is little bounce on a standard Hornet due to the short hammer travel of only 6-7 mm. Its easy to check yours with a fine felt marker pen and a rule. The production regulator settings he told the factory to use gave a slightly lower shot count out of the many tried but produced no spike when coming off the reg. The count was more than adequate from a 75 cc air reservoir. The standard acceptable figure he gave BSA to comply with for the carbine was 65-75 for the .177 and 90-100 for the .22". Port size doesnt matter apparently if all other settings are OK and was the same for all calibres and power levels.
The R10 hammer travel was increased to try to overcome the problems caused by the BSA designed magazine indexing system rubbing on the hammer.

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).