Trapdoor ........... perhaps

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mdeland
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Joined: Mon Nov 20, 2006 1:47 pm

Re: Trapdoor ........... perhaps

Post by mdeland »

Mike, I'm going to open up an RCBS mold that drops bullets at .452 and 485 grains to probably .463 . I think it may be for a Sharps barrel is why it is such reduced diameter. Some one has hookybood the edges of the mold where they come together at some time and it leaves fins around the perimeter so this will be a good candidate to open and clean up. Most .45 cal molds I have encountered are .457-.458 range. I'll extend the nose a bit so hope it will drop bullets near the 500 grain mark.
It will be interesting to see what happens with this .457 bullet if they can expand, fill the grooves and shoot well without leading up the bore. I would like to trap a couple in some oiled saw dust and get a look at them.
Incidentally a .463 mold should drop a bullet of around .4615 figuring in some alloy shrinkage.
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alfajim
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Re: Trapdoor ........... perhaps

Post by alfajim »

Michael Johnson wrote: Fri Feb 26, 2021 7:10 pm Mike, I have two Springfield Trapdoor rifles. An 1878 and an 1884. Steve Brooks made me a mould that replicates the 1881 Armory bullet. It weighs 500 grains cast in 20/1 alloy and measures 0.460. It shoots well out of both rifles. You are correct, their grooves are deeper.
The grooves are deeper on purpose the Trapdoor 3 land, 3 groove barrel was adopted to allow the troops in the field to shoot a lot of rounds in a firefight without having an accuracy problem because of fouling upwards of 20 or so. There are a couple of molds available for the Trapdoor based of the original prints for the 500gr gov bullet and also for the 405 gr gov one too. The .347 dia bullet at 100 yrd target will look like a shotgun was used the Trapdoor requires a .459 or .460 dia to be accurate.
Again I highly recommend Spence's book covers all that.

Jim O
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

That is what I'm thinking as well Jim but I have them loaded and am curious as to what they will do. I will hardness test them in a few days but I think they will measure about 10 BHN if memory serves on this alloy I have.
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

Do any of you know how much ( column length) oiled saw dust it takes to stop a .45 cal bullet approximately. I have a 12 inch diameter sonna tube for pouring concrete pillars about 10 ft long . It mounts horizontally on two cross boards at either end, inboard about a foot, linked with two sections of plywood about 12 inches wide and eight feet long mounted on either side just below the cross, to keep them upright. I also have several 30 gallon trash cans full of oiled saw dust I made up several year ago to make a bullet trap but never got around to setting it up where I could use the thing. The idea was to make it with no metal and use my gold detector to find the bullet.
The entry port has about an 8 inch hole covered with tube rubber to shoot through and hold the saw dust in the tube. I can remove the rubber cover over the entry port if found to effect the nose profile.
The top will have two doors ( cut out sections of the tube itself) on leather hinges, separated in the middle and from each end for strength and to access the saw dust media and recover the bullet once located with the gold detector.
Now assuming the bullet will drive straight ahead( and not be deflected out the sides) it should be able to be recovered in pretty near the same shape it left the muzzle. No?
I have several bullets of differing calibers I would love to test this way. Probably will have to drag the whole shebang up to the cabin in Willow to test it safely but should be fun to do and interesting to compare with Kurt's snow bullets.
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

I put a sear lift in the trapdoor today and reduced the width of the sear spring . The pull dropped from 6 lbs to 3.75 lbs and breaks clean with zero creep. I'm pretty happy with it now.
I do think I need to put a wider front sight blade in as the factory blade is awfully narrow for good elevation hold at six o'clock in offhand work. I'll shoot it as is to verify the blade height from the bench then make a new one about .100 wide. The factory blade mic's .056 wide.
The short cadet stock fits me almost perfectly with a 13.25 inch pull.
We have a gun show this week end and a reduced clang and bang Sunday. Guess I'll go to the show Saturday and I might take the trapdoor to the match Sunday and see if I can hit anything without working up a load or getting sight settings before hand. That will either be wildly fun or exasperatingly depressing. :lol:
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

I learned something today from an older guy who is quite knowledgeable of Trapdoors in our guns and coffee group that meets weekly via Zoom. He said it was not uncommon for folks who do not know that the block hole is elongated on purpose to bore it out until it is round then match the ear holes in the receiver to it with a close fitting pin. The result is often cracked receiver ears.
John Bly
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Re: Trapdoor ........... perhaps

Post by John Bly »

I've seen the same thing on a Maynard. The front hinge hole is elongated as the rear lugs need to take the force upon firing. I've seen the hole bushed round with a close fitting screw. This usually results in a bent hinge screw that is extremely difficult to remove.
"Perfection consists not so much in doing extraordinary things as in doing ordinary things extraordinarily well"
Yellowhouse
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Re: Trapdoor ........... perhaps

Post by Yellowhouse »

mdeland wrote: Fri Mar 05, 2021 3:34 am I put a sear lift in the trapdoor today and reduced the width of the sear spring . The pull dropped from 6 lbs to 3.75 lbs and breaks clean with zero creep. I'm pretty happy with it now.
I do think I need to put a wider front sight blade in as the factory blade is awfully narrow for good elevation hold at six o'clock in offhand work. I'll shoot it as is to verify the blade height from the bench then make a new one about .100 wide. The factory blade mic's .056 wide.
The short cadet stock fits me almost perfectly with a 13.25 inch pull.
We have a gun show this week end and a reduced clang and bang Sunday. Guess I'll go to the show Saturday and I might take the trapdoor to the match Sunday and see if I can hit anything without working up a load or getting sight settings before hand. That will either be wildly fun or exasperatingly depressing. :lol:
I'd sure like to see pictures/video of that alteration!
Sam
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

I can post a picture or two of it Sam as soon as I get a new sim card for my digital camera but it is so easy I can just as well describe it to you.
Pull your lock and remove the main spring. Most folks say you have to use a spring vice but I have always used hawk billed vice grips with a leather pad and have never broken a V spring and I've removed and made a lot of them.
With the main spring removed you can now pull the hammer all the way back and make a note of where the sear nose winds up on the tumbler behind the full cock notch. Make a pencil mark on the side of the tumbler. Now remove the bridle , sear spring and sear lever. I took the hammer keep screw out as well but left the hammer on the tumbler still in the lock plate. I then padded both sides of the tumbler and hammer with thick leather and put the whole lock in a machinest vice making sure the pressure is all on the tumbler width and none on the plate or hammer arm. I was able in this fashion to position the tumbler behind the full cock notch at top dead center in the drill press. I then used a 1/16 th carbide center drill to drill a small vertical hole maybe 1/8 th deep into the hardened tumbler surface behind the full cock notch and behind the point the sear nose engages the tumbler at full hammer back swing.
I then fit a piece of piano spring wire into the drilled hole to keep the sear nose from fully dropping to the bottom of the full cock notch. Once the lift pin height was established I seated the pin with red lock-tite. This limits full sear depth engagement thus reducing sear contact, friction load and trigger creep. I also reduced the side to side width (not thickness) of the sear spring which also reduces trigger pull weight.
I chose not to reduce main spring weight as I want the hammer drop to be as swift as possible. I did how ever give the main spring my usual corner dressing treatment to eliminate any stress cracks sometimes occurring when the springs are heat bent.
The pin has to be seated behind the sear nose at full hammer retraction so it won't catch on the sear nose. The pin seated and red loc-tited in the tumbler hole will never come loose or wear out as occasionally happens with soldered on flat metal lifts.
It is important to test the sear engagement for knock off before final instillation. If it can be jarred off then the engagement needs to be increased.
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

Here is the pictures I promised of the sear lift Sam. In the top picture you can see how the sear is lifted out of the full cock engagement.
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mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

You may wonder what that item is in the back ground of the lower picture. It is a dry fire block I dreamed up for trapdoors. It holds itself on by looping over the locking cam lever and puts a 1/4 inch neoprene pad between the hammer nose and the firing pin. You can dry fire to your hearts content without any harm at all to the hammer, firing pin or block. It also is out of the way of the sights.
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

Well boys I feel I need to tell of a huge mistake i made that may save others the same. As I have been learning about trapdoors guns and working over things to make a shooter instead of a collector (which this gun never was) I decided I couldn't stand looking at the bore corrosion any longer. I decided to remove and lap it last evening. I was using my normal barrel vice with the closest fitting sleeves which are then filled with powdered resin and clamped down to my anvil. Wanting to clear the area where the Buffington sight is mounted I set the sleeve out in front of it a bit but still had plenty of barrel wall thickness to grip over. I tightened down on the vice as I always have and removed the action without incident.In removing the barrel from the vice i suddenly realized to my horror that I had ringed the soft steel barrel and destroyed it.
I have a new Douglas unturned blank coming in 22 twist so will turn to the same contour, length and machine on the front lug integral.
Odd this barrel ringed so easily from the barrel vice as the Rolling block I removed of approximate same diameter and lapped earlier gave me no such trouble and is shooting fine.
I've removed a lot of barrels in the last forty years and this was a new one on me. I would not have thought powdered rosin could do it as it so perfectly conform to existing barrel contour. It would never happen to modern barrel steel alloy of like diameter.
Hope this error saves someone else the same grief. Actually in my case it was probably a blessing to learn the lesson on this barrel as I would have replaced it sooner or later not being able to stand the bore pitting and brown rust color inside it.
So next time I need to remove a trapdoor barrel the sleeves will be positioned as close to the receiver as practical and no more tension than is needed to hold the barrel from rotating to break the receiver grip.
Michael Johnson

Re: Trapdoor ........... perhaps

Post by Michael Johnson »

Sorry to hear that Mike. That is harsh indeed. The good news is that the new barrel will give a better if somewhat more expensive result. This is how we learn. At least you are willing to admit and tell us about it so we do not have to learn at our own expense.
mdeland
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Re: Trapdoor ........... perhaps

Post by mdeland »

Yeah , about the time I figure I've made about every mistake that can be encountered in gun work I find a brand new one ! :lol: But then if you aren't making mistakes you probably aren't really doing much new to you either.
I've adopted a new phrase in the last few years, (why there ain't no end to the things I don't know yet)! :lol: Funny how it takes some years to realize the truth of that. I remember thinking at eighteen I had pretty well figured out all that was important to know . By the end of my four year service hitch that notion had changed some and has been in progression ever since.
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alfajim
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Re: Trapdoor ........... perhaps

Post by alfajim »

Yeah that was to bad you wouldn't think they are that soft being they are steel not iron. When I tried to get the new torch damaged barrel out of the receiver I taped it and used a three jay lathe chuck to hold it right at the receiver just tight enough to hold from turning but just couldn't get it unscrewed as it was slightly welded to the receiver when is was cut with the torch. There was no damage to the barrel didn't compress it.
Is the new barrel going to be three lands and grooves?

Jim O
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