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?
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?
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Most gunmakers are very helpful.
However, on my bolt, there is a section near the rear of the bolt that has a transfer pin that must be pushed up by the lever before the hammer blow will transfer energy to the firing pin. It is an out-of-battery safety.
Is your lever fully lifting this piece? Here is a pic of the transfer piece that I'm talking about. It is shown dangling at an angle at the left side of the bolt. The picture is not mine, but an internet picture:
If that transfer pin isn't fully lifted, it could be causing drag on the transfer of energy into the firing pin.
I’m no expert, but is the bolt seating all the way?
Maybe a weak hammer spring. You said it’s an “older” Marlin. Was it stored for years with a cocked hammer?
Never mind. I just saw that you replaced the hammer spring.
Maybe the headspace is off and the cartridges are seating too far forward in the chamber.
Another helpful thread.
I thought about this when I chose NOT to replace the finger lever, in that MAYBE the finger lever doesn’t quite push the bolt forward far enough for the mechanism at the rear of the bolt (locking bolt et al) to properly position the firing pin assembly. I am trying to keep the rifle as original as possible.
I will look for wear on that rear pin, since the burr on that rear pin was consistent with what might be called ‘not really flat’ wear.
Yours is a good thought.
Reading that thread, it could also be a weak hammer spring.
Indeed - RTFM/ call tech support ;-)
Also on the ‘hmmmmm’ list. It’s possible if the finger lever is not pushing the bolt fully forward or there’s a burr of other obstruction there, perhaps from someone manhandling a jam out of the chamber. Will inspect again. Didn’t originally see any issues. But definitely on my list.
Could be the firing pin. The hammer spring. Perhaps the chamber is reamed too deep.
Did you try recocking and firing it a second time.
If there is oil/grease in the chamber it can cushion the firing pin blow preventing it from Firing.
I replaced the sping and adjusting plate, but have not yet tried the trick of adding a washer to give the spring more punch.
Thought about that. Not SURE, but I think fixing that would mean replacing the barrel, presuming the seat is integral to the breach. The other side of your idea is “does the bolt fully close”?
Worth a real gunsmith’s opinion.
I did re-fire each cartridge at least twice. No joy.
re grease in the chamber: I can check the chamber and seat again to make certain there is no grease cushion or ‘bounce’.
yes and thx. previously found that one.
Replacement would be the fix is the chamber is reamed too deeply, as suggested by Vauquero in #15. Others have suggested a longer firing pin which was my first thought.
The other side of your idea is does the bolt fully close?
Possibly. Yours could be very slightly out-of-battery. Does the rifle fire at all? Does it never fire and just ding the primer?
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