doublegunshop.com - home Forums General Discussion DIY Gunsmithing @ doublegunshop.com Iver Johnson re-assembly

Over-hauling a 20 gauge Champion for a farmer friend. Used in the chicken coop to deter raccoons mainly--when you re-assemble the main spiral spring into the rear of the receiver, with the buttstock removed of course, how do you compress the main spiral spring on the main spiral spring plunger, and then re-fit the spring tension bar- the part with the countersunk hole and the two beveled edges, that lock into the milled slots into the receiver tangs-- any special tools required?? Many thanks.. RWTF

Drill a hole in the plunger, compress the spring outside the gun, put a nail in the hole, put it in the gun, remove nail. Next time the gun is taken down, cock the gun, install nail, release sear, remove spring/plunger.
Mike

OK- this plunger does have a through hole (about 1/32" dia. near the end of the shaft that located through the beveled tension block that is trapped by the milled notches in the receiver tangs. What trick do you use to compress the coil spring outside of the receiver, prior to installation? Thanks-RWTF

Put the plate in your bench vise to the side. Slip the spring over the spring guide (still attached to the hammer).
Shove the guide into the hole in the plate compressing the spring just enough to drop a short pin into the capture hole.
Doesn't matter where the plate and hammer are positioned in relation to one another as you can rotate either to their correct positions for installation. Use a short pin so it doesn't hit the frame in doing so when putting the assembly back into the frame.

Juggle the assembly into the frame and put the hammer pivot screw or cross pin back in place.

Most assemblys will still leave the plate just short of being able to slide easily back into the V slots top and bottom in the frame.
Use a pliers to pull one end , doesn't matter if top or bottom,,into engagement with it's frame V slot. Tap it in just slightly to hold it there.
Then again with the pliers pull the other end of the plate forward and into it's V slot.
You'll be pivoting it into the opposite end V slot and against the spring tension but the leverage easily allows it.
Now tap the plate into position in the frame. Cock the hammer back and remove the short pin.

Thanks- so the hammer and hammer cross pin have to be removed before you can properly insert the main spring and mainspring plunger? I have the spring on the plunger rod, with a small pin trapping it in place, so next I need to remove the hammer and hammer cross pin to insure a proper installation.?? Many thanks- RWTF

If the guide rod is the type that is attached to the hammer w/a pivot pin or screw,,you'll need to assemble the two outside the gun and then insert the assembly into the frame and do as above,

If the front of the guide rod only bears on the back of the hammer (rounded rod tip in a hollow hammer cut for instance),,put the hammer and it's cross pin/screw in place in the frame first.
Then insert the captured spring, rod & plate assembly up into the frame so the rod bears against the back of the hammer.
It'll be sitting at an angle now as the back end of the assembly is outside the frame tang(s).
This is where you have to push against the spring tension to get one end of the plate to engage it's V cut slightly,,then lever the other end to engage. Then tap the plate home.

My friend's is the second series or style you detailed--Boy Howdy, you know your stuff-- I have the parts schematic from Numrich- but that is not 100% a detail for dis-assembly or re-assembly. My friend's 20 has a 4 apha marking for the serial number- GxHY--28" choke bored barrel, but when I checked it with my Galazan choke gauge, it came up modified. punching out the bore-it came clean as a whistle, no signs of any tool marks in the muzzle area at all. Makes me think IJ marked all the Champion barrels "Choke bored"- whether they were Full or Mod. or whatever. Not in the same realm as a Ithaca or Parker SBT, but I'd like to have a dollar bill for all the game and vermin that were dispatched over the years with IJ Champion shotguns.

Following up- "Bingo" your tips worked like gangbusters. All back together and perfect function, as tested with a snap cap-- strong ejection system--trigger pull- not the greatest, but for a hardware store retailed single barrel shotgun from a long-ago era, not all that bad. Many thanks for your "spot-on" advice.