Underhammer receiver problem

I use the H&A actions for competition shooting, table and chunk, and besides changing barrels and sights I have figured out how to make an adjustable trigger. The trigger really made a difference. I also have one that has 4 barrels including a 12 GA trap and a 20 GA field barrel. Great and simple little actions.

Mark would you share with us how you made the adjustable trigger?

Will do. These changes are done on my competition rifles so when I do them they will not have a safe notch. I start by cutting off the safety notch on the hammer and creating a flat on the hammer edge. The flat is drilled and tapped for a small set screw so that it aligns with the full cock notch on the trigger. The screw can be screwed out to adjust the amount of engagement between the trigger and the full cock notch thus adding or reducing the trigger pressure. The hammers are hardened so they have to be annealed to work and then re hardened. It also helps to stone the engagement surfaces for a smooth let off before re hardening. Hope this makes sense.

I think the names you are calling the parts might be a little misleading.
Most people agree, the hammer is the external part on a lock that hits the percussion cap. It is attached to the tumbler.
The tumbler is the part with the safety notch and full cock notch in it. It is either thru hardened or case hardened to resist wear.
The sear is the part that engages the notches in the tumbler to hold it in the "half cock" or the "full cock" position. The sear on most sidelocks has an arm that sticks out at a 90 degree angle with the lockplate. It is this arm that the trigger pushes against to release the lock and fire the gun.

Using these words to describe the parts your quote becomes,

"Will do. These changes are done on my competition rifles so when I do them they will not have a safe notch. I start by cutting off the safety notch on the tumbler and creating a flat on the tumbler edge. The flat is drilled and tapped for a small set screw so that it aligns with the full cock notch on the tumbler. The screw can be screwed out to adjust the amount of engagement between the sear and the full cock notch thus adding or reducing the trigger pressure. The tumblers are hardened so they have to be annealed to work and then re hardened. It also helps to stone the engagement surfaces for a smooth let off before re hardening. Hope this makes sense."

Thanks Zonie. Being an UH lock I tend to use generic rather than usual names. I hope the content made sense to those that asked.

Zonie, on an H&A underhammer there is no tumbler. The trigger directly engages the half and full cock notches on the hammer. Mark, made sense to me. The half cock notch can be a problem on these guns. It's very deep and with a slow easy trigger pull it's possible for the edge of the notch to strike the part of the trigger that forms the sear and break it off. I've done it myself and have a couple of guns that have been damaged that way. Cutting about half of the notch off helps and still leaves enough to be safe. The set screw for depth of engagement would go in the hammer by the full cock notch and bear directly against the sear portion of the trigger. These are not Numrich parts but are nearly identical.

Why take the half cock notch off? A set screw could positioned else where.

Leaving the half cock notch in place would mean relocating the set screw to a different location and could interfere with the hammer fall. On strictly a competition rifle it should not be necessary, the rifle is not cocked until you are on the line or at the bench.

Mark Herman said:

Leaving the half cock notch in place would mean relocating the set screw to a different location and could interfere with the hammer fall. On strictly a competition rifle it should not be necessary, the rifle is not cocked until you are on the line or at the bench.

Click to expand...

Ok but why not put the screw in the hammer just past the sear or in the hammer so the screw touches the frame. Or an adjuster in the frame that bears on the hammers full cock position?
Personally I would of stoned the sears untill happy.
Best wishes all the same.

B.

Brit,
All good thoughts and may work, this is what I did. Drilling into the full cock notch ,it seems, would be difficult at best between the space available and hardness. I can see some broken hammers. Try it.

Mark Herman said:

Thanks Zonie. Being an UH lock I tend to use generic rather than usual names. I hope the content made sense to those that asked.

Click to expand...

Sorry. I didn't notice this thread was about underhammer locks.

I have 2 Hopkins & Allen Underhammer Kits. One in 45 Caliber and one in 58. They have the tapered pin that hold the barrel to the receiver. I made the mistake of tapping the pin in and I cannot get it out to blue the barrel and receiver. There looks to be a small pin on the opposite side but it is not in-line with the tapered barrel pin. It is slightly forward of the barrel pin. I tried a nail puller from the top of the pin but only buggered up the pin. Any suggestions?

Never mind, I looked at the barrel pin again. It lines up on each side. A previous contributor was correct. I will need a hydraulic press to get this pin out. Tried a bronze punch and dead blow ball-peen hammer. Then tapered punch and engineer's hammer - nuthin, didn't budge.

I have done the same thing. The tapered pin will, indeed, go in from both sides (right to left being correct on the one I had at the time). Hydraulic press is EXACTLY what's needed. Trying other methods buggered up the pin, which required a replacement. Don't feel like the Lone Ranger. At the time I did the deed, several others admitted it also. Good Luck !!

Wow! Old thread, and is the OP still around? The H&As are about as simple as any rifle could get including matchlocks. And yes, a hole should be in the receiver where the pin goes through to connect the barrel to said receiver. Drilling this hole one's self could be problematic and I would get it done by a smith or machinist, this part is critical. I've had an H&A in .45 since the mid 1960s. It doesn't get fired now since the trigger guard/hammer spring/trigger return spring is dead and will not return the trigger forward.