re-pinning a SxS shotgun

[Evanguy]

i have my beloved cheap as dirt Tradeex Merkel shotgun that as began to get a little loose. (its always been loose but lately i have the want to fix it)

i believe its the bites that need work as the lever sits hard to the right, it has no more travel to go. but i figured id start by replacing the pin so i can start fresh when i deal with the bites.

there are a few options and id like to hear form one one who has done it or knows about it

the pin isn't really bad, at most there is 0.001 measurable difference from highest to lowest spots (Starrett mics) it measure 0.298"

it is a lose slide fit into the shotgun action, tipping the action on its side, gravity will cause the pin to fall out.


so my options are,
order a 0.299" hardened ground pin and either massage the hole in the action a bit, or it may be a very light press in if it already doesnt tap in
or
go with something bigger like 0.304" even 0.312" (5/16") so i can rework the hook to mate with the new pin perfectly


this is mostly just to learn about setting shotguns back on face and tightening up the actions as I'm getting into building a few BP double rifles on sxs actions.


i added some pics because we all love pics

 

[tiriaq]

Brownells used to sell (maybe still do) tapered pins and matching tapered reamers in different sizes for replacing double hinge pins. Don't know if that would work on your gun.

 

[bearhunter]

Brownells used to sell (maybe still do) tapered pins and matching tapered reamers in different sizes for replacing double hinge pins. Don't know if that would work on your gun.

Use a standard straight reamer to make the holes a couple of thou smaller than a standard size piece of drill rod which is slightly larger than the hole. Then put the receiver into boiling water and the pins in the freezer or outside, whichever is colder.

When it's all about as hot and cold as it gets, insert the pin and when everything settles down to ambient temperatures, it should be sweated in place.

If the OP expects a smith to do it, he should make sure the shotgun is worth what the time and tooling will cost to do the job.

Many of those old shotguns just aren't worth it price wise and unless it has sentimental value not worth the price or effort to fix.

 

[mbatten]

Here you go (rejointing a fine English gun):

 

[Evanguy]

So to clear things up, I do want to do the work myself, I have most of the tools needed and most likely the ability too.

I just wanted to get a conversation going about doing it.

The taper pin would be neat, . I'll look more into that. That would be an easy fix and could use it on other guns

A straight pin 0.001" over size would clean it up as there is no real wear on the pin but it does slide with ease in the action so it would be tight in the action again. But that doesn't address any wear on the hook itself.

Using a larger pin and if standard size like 0.3125 or 0.314 I'd already have the reamers for that and buying hardened ground shaft In that size would be an easy find.

The file won't touch the pin from this shotgun.

 

[9.3mauser]

here are a couple more 'how-to' videos;

 

[B_noser]

Evan, Suggest you drop Oskar a line. He has tightened up a fair number of shotguns and I recall him taking about re-pinning and smoking in.

 

[cosmic]

Well - With that crossbolt locking mechanism, the game changes a bit. All adjustment to tighten up the gun must be done at the pin/hook interface. So, either keep the existing pin (it appears to be dimensionally correct, is there actually any play in the receiver??) and build up the hook. Or, install oversize pin and resize hook to suit.
In one of the Midway/Larry Potterfield videos, he puts a weld overlay on the hook, and then mills out the hook to the proper id. .The first step is to ascertain how much play currently exists. FWIW - I think this style of locking mechanism is more tolerant of being slightly hook loose compared to the common underlug system....

 

[boxhitch]

I have most of the tools needed and most likely the ability too.

I'd say, following with interest here
nice job on removing those old screws

curious, is there even a measurable end-play to the barrels when assembled, or does the hinge just have a wiggle that you want tighten?

 

[Ex3dy]

Is the pin still round or does it have some oval?

 

[Evanguy]

thanks for the videos guys, i used the method in post 6 to tighten up a 16 gauge i got that was slightly loose. i worked very well, it seem if its takes a few thousand shells to move the bite so the lock is on center, by peening it back in this method should last at least another 1000 shells. The lever is now just right of center and locks up solid, when holding the lever open the gun had zero side to side play in the barrels and with the lever closed there WAS only a little up and down ( just enough to feel it when you shook the gun with no fore stock)

but this 12g i made the post about has both side to side play and up and down play, the barrels are non matching set so there is good change the barrels and pin just worked their self's together over the last few thousand shots I've shot, over the last few months the gun has been noticeably looser so i figured the pin needed replacement and the bites can be tightened since the lever sits hard left when locked up

after taking the hinge pin out and measuring it, it seems fine and when smoking it to the barrels it mates really well. so i assume the pin is actually fine and the issue is in the bites. the open lever is hard over left so that makes sense.

the pin measure fine, less than 0.001" ((its actually 0.015mm) Half a thou) and seems straight. i can put it in the action and rotate it by hand it is also a slide fit. so it seems a little loose in the action really. the pin is super hard the action is not.


B_noser, ill give him a call to chat about this, good idea, its been a while since we last talked.

so to recap, the pin is fine, maybe slightly loose on the action but less then 0.001" out. the barrels did have a lot of looseness. a 0.004" feeler gauge just slide in from the barrel face to the action face if i was holding it hard one side or the other or forcing it open without the lever being pushed.


tomorrow ill be going to the shop and getting some work done, i have read a lot and watched a lot of videos so far. this is for learning purposes and the shotgun cost me $275, over a few thousand rounds and 5 years ago. so its a good one to learn on

my plan for tomorrow is

install the barrels, fore end, and clamp them together all square and level in the mill
remove the forearm, remove the hinge pin
pickup center
ream to 5/16" (0.3125") from 0.298"
remove barrels and re clamp the action level and square
ream to 8mm (0.315")
turn a 8mm pin from 4140, harden it
install into action and reassemble
smoke fit the barrel hook from 0.312" to 0.315"

then peen/ reset the bites on the barrel. Both the front, to make full contact and then the back to set the lever to the location, a little right of center so it has some ability to wear in


ill get pics as i go tomorrow and post them tomorrow night.

also during the process of taking the pin out and disassembling it, i managed to squeeze the action a bit, so even with no locks and the action totally dissembled the barrel fits well and there is zero play up/down or left/right when the action and barrel are closed together so the pin replacement isn't necessary it just need the locks/bites to hold it tight.

 

[Jonnyofalltrades]

Use a standard straight reamer to make the holes a couple of thou smaller than a standard size piece of drill rod which is slightly larger than the hole. Then put the receiver into boiling water and the pins in the freezer or outside, whichever is colder.

When it's all about as hot and cold as it gets, insert the pin and when everything settles down to ambient temperatures, it should be sweated in place.

You might want to check your math.
That's going to give you less than half a thou of thermal expansion.
Shrink fits start to be more practical once you are working with larger diameters.

 

[m1008]

Any decent welding supply shop has dry ice, they sell it at my local grocery stores in the summer. Canned air or even liquid propane is better than the freezer in your kitchen

 

[bearhunter]

You might want to check your math.
That's going to give you less than half a thou of thermal expansion.
Shrink fits start to be more practical once you are working with larger diameters.

In this case, half a thou is as good as a weld.

 

[Jonnyofalltrades]

In this case, half a thou is as good as a weld.

All I mean is that with a "couple thou" interference it is press fit, not a shrink fit. Nothing wrong with a press fit, but boiling and freezing gains you nothing when you're assembling this. Just makes assembly a pain.

 

[Evanguy]

^^ the regular size difference for shrink fit for is about 0.001" of interference per inch of diameter, too much of a fit and it can crack when the temp evens out.

On a pin this size I'd make the pin size for size of the hole, it would be a slight shrink fit

 

[bearhunter]

All I mean is that with a "couple thou" interference it is press fit, not a shrink fit. Nothing wrong with a press fit, but boiling and freezing gains you nothing when you're assembling this. Just makes assembly a pain.

Boiling and assembling is a pain, over press fitting, but a lot less can go wrong. When it goes wrong though, it quickly becomes a press fit situation anyway.

 

[m1008]

A toaster oven from the thrift store with a thermometer over boiling.

Temp crayons are cheap if using a torch and you don’t have a temp gun and your worried. The crayons melt at specific temps

The dry ice can be mixed with certain solvents to make a quasi ice bath. Acetone, methanol and others
https://chemtips.wordpress.com/2015...ly-thorough-guide-to-making-a-meohwater-bath/

Way easier than trying to source or borrow liquid nitrogen

 

[Evanguy]

ok so i got this done. it went very well and took about 8 hours total time, that includes disassembly and reassembly.

it fees like a whole new gun, the lockup is very tight and the action is very smooth even with the barrel open there is no play.

so i reamed the hinge pin hole with the barrels installed to 5/16"
then removed the barrels and reamed the action to 8mm (0.002" bigger)
turned a pin (8.01mm) from a cold chisel that was a tap in fit to the action, (like starting a finish nail)

smoke and fit the barrels to the action, basically was fine as it was and just needed a little file and debur
then i put the locks in the action and test fit the barrel many of time to make sure i was happy with it, it locked up solid and no a drop of play

so then i pushed the front bite ahead a bit until the gun would close with the lever full to the left but had slight resistance form the front bite
the i pushed the back bite so the lever was off set a bit to the right, then worked the bite until the lever was barely right of center, i used the back of the carbide endmill and did probably 100 little taps per bite, you cant notice a mark on the lumps. it was just the weight of the endmill from about an inch high

then i assembled the whole gun and test fired it, i put 10x heavy 1-1/4 oz no2's thought it and the it was a tight as before shooting them. but man did the gun shoot better, it just feels solid and even nicer to hold.


as seen in the last pic the lever sits just slightly to the right and the cross bolt sticks out about 0.020" but it has round edges so it doesn't catch anything and still has 0.040" of engagement on the right side of the cross bolt.

honestly the screws were the hardest part, one wrong move and its over

 

[Evanguy]