doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Merkel Rear Trigger Problem

Now that you have shown the photo where it indicates that your DR may be off face (left side gas escaping) and also that the trigger in question is the left side trigger, the issue with increasing pressure needed to pull the left trigger may likely be unrelated to the contact between the sear and the tumbler of the left side of the action. With your photo showing a problem on the left side the first thing I would check if I had this DR in my shop is contact of butt stock wood to the left sear.

In regard to the concern about the gas escaping from the left chamber and the DR may not be off face. I see two things from the photos. 1) there is no imprint of the cartridge rim on the left face of the action and 2) the rim depth of the chamber seems too deep. If the left chamber was reamed improperly then you have a significant problem.

JJ Perodeau is renown for his double rifle work.

I see that you are in Michigan and currently I cannot think of a double rifle gunsmith there, but I suggest that you telephone Brian Bilinski owner of Field Sports in Traverse City and ask him if he knows of such a double rifle and trigger expert gunsmith in Michigan.

Kindest Regards;
Stephen Howell

Del Whitman is in Michigan. If I recall correctly, he built double rifles for Rigby USA for a while.

Thanks Stephen!
The photo certainly looks like a very deep cut for the rim. This may be but please know this is a 375 H&H belted magnum. I have set of Go-No Go gauges for belted magnum. I will give them a try to check the depth.

I could see that it is chambered for a belted cartridge case.

When I chamber double rifles, I measure the rim and/or belt thickness of maybe 20 new cartridges and I also refer to the cartridge original design specs and then I chamber the cartridge for only a couple of thousands of an inch clearance between the back of the cartridge and the barrel flats. Then after shooting if I see that another thousand or so of clearance is needed I increase the depth of the cartridge rim into the chamber. This is a very critical clearance on a .375 belted magnum as the pressure of this cartridge is significant (max 62,000psi) versus the .375 flanged cartridge of 47,000psi.

I suggest to you that you measure the depth of the belt cut from the face of the barrel flat in the right barrel and do the same for the left barrel and compare the two measurements. Check to see how close the chamber cut is to the standard of the .375 belted mag which I believe is about 0.220 inch thickness. You can look up the standard for the brass on the web.

I just went back and looked at your photos again and I can see just barely an imprint of the cartridge rim of the left barrel against the action flat. Therefore my previous thoughts may be wrong about why there may be some gas escaping from that barrel---if there is any excess escaping.

Stephen Howell

Mark,
I've had Del Whitman do work for me that was excellent. Also, Steyr Arms is handling the Merkels after GSI stopped. My contact at Steyr was Einar Hoff and they have an Austrian trained gunsmith who services the Merkels.
Hope this helps,
Karl

I am curious as to whether the problem arises with snap caps or only when firing live ammo An experiment with snap caps would reveal if it is recoil related or not.

The stock is fastened with transverse stock pins. Something tells me that the problem is related to a change in internal geometry brought on by stock flexing.

Having just returned from the hospital, I haven't seen this thread before. The 375H&H is really a little too powerful for the typical 16 ga frame size many are made on. They pass proof testing, usually, so are considered safe. Continued use may bring up otherwise not noticed problems. Raimey's idea of disconnecting the safety makes sense, to see if recoil is causing the automatic safety to partially reset to "safe". Bushveld's discussion of chambering belted cartridges is great if you are building a new rifle, but the one under consideration is already chambered. For many years, I set the headspace in my loading dies by smoking the neck and shoulder of a case fired in the particular chamber and set the die to just "kiss" the shoulder of the fired case. This causes the handloads to headspace on the datum line rather than a belt or rim. On the other hand, I think this is a different problem having little to do with the heavy trigger pull. LeFusil's idea of recoil causing the sear to fall from full cock to the intercepting bent is worthy of consideration also. BTW, if setting the cartridge headspace with the sizing die, for a double rifle, the shortest chamber should be used to avoid having to load separate cartridges for each barrel.
Mike

I'm not sure if you've commented elsewhere, but welcome back Mike.

Mark Quellette;

I have sent you a PM

Stephen Howell

Glad you're "back in black", Mike.

Stan