Posted on 10/14/2020 1:10:18 PM PDT by Blueflag
I am looking for advice on getting an older Marlin 336 to strike the primer hard/deep enough to fire the round. ie fix a soft primer strike.
I have refinished a Marlin 336 RC, built 1964 per serial number, that I bought used at a gun show. I bought it knowing that it would not fire a round when the trigger was pulled and the firing pin would only dent (soft primer strike) the primer in the cartridge. I paid just over $100 for the firearm with the Nikon scope (worth more than $100) with the intent of refinishing the stock and grip, and getting the rifle back into working order.
I am comfortable working on/ disassembling/re-assembling lever action rifles, and know the 336 is easy to work on.
When I took the rifle apart, the two-part firing pin was badly worn where the (short) rear firing pin strikes the front firing pin. There was also a burr on the rear firing pin. The firing pin retaining spring appeared too flat to secure the rear pin well. These were all obvious issues.
I replaced the front and rear firing pins, Firing pin retaining spring, Extractor, both firing pin retaining pins, and hammer spring and hammer spring adjusting plate. Not the original breech bolt Not the original finger lever.
I soaked the breech bolt overnight in Hoppes and used an aluminum 'dental pic' to remove any stubborn carbon left behind inside the bolt.
I thought these updates would enable proper firing pin function and length AND also provide a more forceful strike from the hammer in case the old spring was weakened.
... and the symptoms did not change. I tried Hornaday, Federal and Winchester cartridges (30-30) with exactly the same result-- a dimpled primer.
FYI, I cannot see any damage to where the cartridge seats at the breach of the barrel.
I welcome your thoughts on what to try next?
On that thread there was this post I saw, which asks good questions:
here are a couple of things I might check:
1) Hammer engagement of the firing pin, does it strike square and fully engage the fp?
2) How far does the fp tip protrude from the bolt face when the rear of the fp is flush with the back of the bolt, or where the hammer pushes it at the end of it’s fall. (this is with the bolt out, and the rear half of the fp moved up into the position it would be in when the locking lug is up) <— Well if it needs to protrude farther, maybe I did not get the bole clean.
3) Is the locking lug raising far enough to properly align the back half of the fp into a firing position? <— good question but how could it not?
4) How stiff is the hammer spring? <— new and replaced
5) Is the headspace Kosher? <— Rabbi did nt say so ;-)
6) Is the fp hanging up on anything, burrs, etc? <— will inspect again
Hang in there, you’ll find the gremlin.
New spring.
In reverse order.
It NEVER fires. And thus could be out of battery. On a 336, I would think a bolt not fully closing, that points me to a worn or mis-shapen finger lever tip. But D@amn, you’d have to really abuse a rifle to wear out a finger lever tip.
A longer firing pin makes sense, but I’d rather fix the ‘why’ of what calls for a longer firing pin.
It appears you’re not alone, so I’d bet the answer is somewhere in the gun-internet universe.
New firing pin.
That is my thoughts, too.
Replaced old one already with a new spring. Heve not yet tried the technique of adding a washer to shorten the spring and increase its ‘push’ on the hammer.
Bought a new firing pin set already. The 336 of that era uses a two part pin for a safety feature. Not wanting to go non-original and install a single unit.
I agree. Just thought it wise to put this out there on the FR-universe.
Off the internet I have a long list of “try this” items, most of which make sense, but thought someone here might come up with something I had not thought of.
I appreciate your responses.
It boils down to: the hammer isn't striking hard enough, or the pin isn't reaching far enough, with few possible causes for either case.
How about the pin protrusion, where the hammer strikes. Could that be somehow worn down?
I will go back to that - ensuring the pin DOES travel far enough when struck.
Could be a weakened old hammer spring, pin channel may be dirty, and the tip of the firing pin could be work down a couple thousandths of an inch
This gent’s business is highly regarded in the Cowboy Action community.
https://www.longhunt.com/storelh/index.php?route=product/product&path=88_93&product_id=227
Haven’t seen anyone recommend this before on this thread, but have you tested the headspace using go/no go gauges? That would be my first step in verifying the full lockup of the action before doing anything else.
If the headspace is good, the lever is closing the bolt fully and the problem lies with something in the firing sequence.
If the headspace is excessive, consider herself fortunate the primer strike is shallow - the barrel will need to be set back and rechambered.
Worn*
Also inspect the hammer face. You said the rear firing pin had a burr; maybe the hammer face has some subtle damage.
Has it been dry fired a lot?
If the chamber is too deep you would have to have the barrel cut and turned in one turn then the chamber reamed to the correct depth.
I used to shoot cowboy action matches. The guys with marlins often replaced the duplex firing pins with single pins to increase lock time. But like you said there is a safety issue. I have a 1977 vintage 336C. No safety. You lower the hammer to the half cock position for a safety. But that’s not safe really. I tend to leave the lever slightly openfor safety. Or even better leave the chamber empty till you’re ready to shoot. If I’m on stand while hunting I do keep a round in the chamber and the lever closed the hammer at half cock. Of course I’m standing stock still and watching the muzzle. If I go off stand I open the action
Someone else, had the same exact problem.
https://www.thehighroad.org/index.php?threads/marlin-30-30-mod-336.868886/#post-11512555
Captain Obvious is here helping me out.
He says take it to a professional gunsmith... He’s still saying something about headspacing or some such thing.
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