Merkel Rear Trigger Problem I hope someone has a solution to this problem…

Subject: Merkel 140AE double rifle. I posted in the more frequented shotgun forum since this is a trigger problem.

Problem: Double trigger boxlock ejector Merkel 140 AE rear trigger increases from 6 pounds to almost 12 pounds after a few shots. I fire this gun by alternating the barrels right to left. On my 16th shot (attempt) I could not pull the trigger.

I took the gun to my gunsmith who disassembled it and set the triggers to 4 and 6 pounds.
Next time shooting with less than another 15 rounds, the rear trigger suddenly increased to almost 12 pounds.

Back to the gunsmith who disassembled and inspected it for a possible cause to include possibly the stock binding. He could not find anything.
Reassembled and return to range. Once again after relatively few shots fired from each barrel, the rear trigger suddenly increased to almost 12 pounds.

Has anyone seen this problem before in any boxlock rifle or shotgun?

Wow that's a tough one ,can't wait to hear the solution.could it be a linkage problem with the safe.cant imagine it getting hot enough to effect the trigger.

It could be a sear problem.

Could be the scears. Did the mechanics stone the scears? What about the Safety? Is it automatic? Can you take it out of service & try?

Serbus,

Raimey
rse

The problem first occurred prior to anyone opening up the rifle.
The gunsmith checked the safety, it the wood maybe had caused it, the triggers and sears but found no evidence of anything wrong.
He adjusted the pulls to a crisp 4 and 6 pounds.
Firing the gun again everything was great until a dozen total right and left barrel shots.
Then, "presto", a 12 lb pull was once again required for the rear trigger.
Back to the smith for another inspection. After nearly an hour he found nothing.
Pulls were 4 and 6 once again for less than a dozen shots...
Now, I am seeking information from all...

Thanks!!!

I wonder if the problem would be caused by dry firing on snap caps or spent cartridges. Not because I have a specific mechanical problem in mind, but because if so it would allow cheaper and more convenient testing of any interventions.

In other words,
The rear trigger jumps from a 6 to 12 lb pull required.
The stock and trigger plate are removed to inspect for anything abnormal. Nothing found, twice.
Reassemble the gun and like magic, the rear pull is back to 6 lbs.
Shoot each barrel half a dozen shots, more or less, and the rear trigger pull suddenly jumps to 12 lb.

We did put a trigger gauge on the rear trigger when it was/is heavy.
The weight varied from 10.5 to 12 pounds. Maybe this indicates something like two parts (sears maybe) rubbing against each other?

Thanks in advance!

I sure cannot even guest, but if GSI is still the importer for Merkels, I would give them a call for starters. Long ago I had my nearly new Merk doubling on me and they took it back and did a little work as well as replaced some parts which solved the problem.they may have some ideas.

Mark,
I'm wondering if the action heating up from firing is causing some sort of binding. Just a thought.
Karl

Being >>Captain Obvious<<, the issue is recoil dependent. I wonder if somehow on of your fingers is affecting the performance?

But I would remove the Safety, or disengage it if possible, & see if the situation repeats. How much recoil are we talking about?

Serbus,

Raimey
rse

GSI dropped the importation of merkel several years ago

John Boyd
Quality Arms

I’m by no means a Merkel or German gun aficionado, but I recently worked on a late 90’s 147E. So I’ve been into a couple of these types of actions.

I’ve been thinking about your dilemma, it’s an odd thing that’s happening for sure. Has your gunsmith checked he position of the over hanging sear guide (the cone shaped rod that the sear spring rides on). Have you confirmed that the guide is in the correct position, is it straight or slightly bent….and that the coil spring moves (contracts and expands) smoothly? Obviously he’s removed the Sears and tumblers to work on the trigger pulls, so we can pretty much rule out burrs, bent, etc.
Highly doubtful the action is getting so hot with a few shots fired that heat would be an issue. Can you confirm that there’s not any gas leaks from pierced primers that is blowing into the action maybe causing an issue??
These actions are not overly complex. Your guns issues are really odd.
Have you actually seen the work he’s done to your sear and tumbler?

Thanks for letting me know. Does anyone import them now? GSI might still know something about them, if GSI is still in business, but could be a bit of along shot.

Now, there is an understatement.

Mark, is there any pattern that you can see when this occurs? Does it begin after a random number of shots fired, or after a right then left (or vice versa)? Try to determine that to help figure if it's recoil related, or otherwise.

If all else fails, and it were mine, I'd send it to Phillip Crenwelge in Emory, TX. He is a gunsmith of German descent and is the finest trigger man I've ever known. He has sorted out many, many issues with triggers on all types of guns. It may even be worth a call to him just to talk about it. He doesn't always answer during his working hours but he'll usually return the call. His number is 210-313-5988.

The problem occurs after about a dozen shots total from when the back "was" functioning at 6 Lbs.
The stock and trigger place have been removed for inspection twice after the first malfunction (on total shots since brand new (15)) and the problem reoccurred at about a dozen shots total.



Great information!!!
I cannot answer all of this by I will forward to my gunsmith.
There is another flaw with the rifle that as you mentioned may be causing this. I didn't think that gas was entering the action but maybe I was wrong...
The image below of the left side of the standing breach is after less than 25 rounds fired from that barrel (50 rounds total).
Admittedly I did not anneal my brass before reloading. The primers were not blown and there was no noticeable blow by marks on the brass. Still, this is ugly...

Gosh, I thought I was Captain Obvious...
After the first 12 pound trigger problem, my smith shortened the automatic safety connecting mechanism. He said that he could not remove it but that shortening it would remove the auto safety function while allowing manual safety operation.
We also checked that the 12 pound trigger is not tight against the sear. There is a little play in it when cocked.

As for recoil, this is a 11.5 pound 375 H&H. Recoil is just a positive reassurance of its powere going downrange.
For me, a 416 Remington's recoil gets my attention. My .458 WIn Heym 88B double rifle has significant recoil.
Then for some strange reason there is a 450 Rigby on a Vektor magnum length Mauser action- that followed me home that is down right impolite concerning recoil! A 500 grain bullet at 2450 fps is more than I enjoy!

As I posted earlier, this problem occurs after disassembling and reassembling the rifle. 6 pounds to start then after a dozen shot total (both barrels, alternating) the left trigger is at 12 lbs.

Thanks for Phillip Crenwelge's contact info. Trigger work is an expertise all its own.

Well, there’s definitely something causing some gas to escape and leave marks on your breach and action face. You’re right, that’s definitely no Bueno. Next thing I would do is check the condition of the tumbler to see if there’s any signs of that gas making it back into the action….if it is, the face of the tumbler will also be scorched.
You said the trigger wiggles and isn’t tight when it switches to its 12 lbs pull phenomenon……has your gunsmith checked to see that the tumbler is at full cock or is the sear resting in the intercepting/safety bent instead of being in the bent at full cock? If that’s the case, somethings gotta be causing the tumbler to come out of full cock and resting in the intercepting bent which would definitely explain the heavy trigger pull.
If the tumbler and sear are dirty, I’d highly polish them both, reinstall without lube and try and see if you can see any abnormal drag/friction marks. It would explain a lot seeing where the parts are resting when the 12 lbs pulls are happening.

Just FYI….JJ Perodeau is a very good mechanic when it comes to issues like this. The escaping gas on the left barrel is fairly concerning.

Mark, not familiar with Merkels or boxlock guns but I still think it is a sear problem. I agree to what Rainey states, disconnect the safety as I think the recoil has something to do with it. Reading up on a few sites the only thing I saw on this model was "doubling. I would contact Merkel and asked them.
Why it only happens after 12-15 shots is the $100 question.

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

Thanks for the good thoughts and prayers everyone.
Mike