Trapdoor Strength

[StrawHat]

We all know the Trapdoor Springfiels is weak don't we?

http://www.assra.com/cgi-bin/yabb/YaBB.pl?action=downloadfile;file=Trapdoor_receiver _strength_article.doc

http://www.assra.com/cgi-bin/yabb/YaBB.pl?action=downloadfile;file=Trapdoor_blowup_a rticle_Guns_Illustrated_1996_pages1-2.doc

http://www.assra.com/cgi-bin/yabb/YaBB.pl?action=downloadfile;file=Trapdoor_blowup_a rticle_Guns_Illustrated_1996_page_3.doc

http://www.assra.com/cgi-bin/yabb/YaBB.pl?action=downloadfile;file=Trapdoor_blowup_a rticle_Guns_Illustrated_1996_pages_4-5.doc

http://www.assra.com/cgi-bin/yabb/YaBB.pl?action=downloadfile;file=Trapdoor_blowup_a rticle_Guns_Illustrated_1996_pages_6-7.doc

[NickSS]

The army when testing trap doors with Krag barrels and ammo found that the rifle would hold the pressure but after a couple thousand rounds the breach block was getting loose so they figured it was not soldier proof enough so never converted the guns to Krag ammo.

[Harry O]

Interesting photo of the barrel failure on page 67 of the second article. If there was a ductile failure, it would be smooth looking with part of the failure showing stretch marks. I don't see that here. It looks like the surface of the break was crystalline.

There are only two reasons (that I know of) that would cause a crystalline looking break in steel. One is that the metal is brittle like iron, or steel with too much carbon. The other is that it was caused by fatigue.

I don't believe it is fatigue in this case. First, the number of rounds that it would take to cause fatigue is more than could be fired in a gun -- many hundreds of thousands of rounds. The other reason is that if it was a fatigue failure, it would show the final failure as ductile. In other words, the break would look crystalline until there was not enough metal left to hold the pressure. Then it would stretch and pull apart. I don't see that in the photo.

The article mentions free machining steel. The free machining steel I have seen fails in a ductile manner. One of the most common ways to make steel machine more easily is to add lead. I believe that this is made from either iron or some kind of steel that has more carbon than it should have (essentially zero ductility in either case).

[StrawHat]

I was suprised at the load of Bullseye it took to destroy the trapdoor. I can't imagine what the recoil would have been!

I grew up hearing about how weak the Trapdoors were and believed them with out ever knowing what the test were that determined weakness. Then I read Waters article on the 45-70 in Rifle and Handloader magazines and he had four (4) load levels for the 45-70 with the trapdoor in the lowest tier. Several others also did loading guides and the Trapdoor was always in the bottom tier. Too weak, etc. I wonder what the basis for the determination was as reading these pages it seems to indicate the Trapdoor is a bit stronger, and safer, than was previously thought.

I guess my ideas of rebarreling a Trapdoor will get a fresh turn.

[StrawHat]

Does anyone know of a way to get the article printed on this thread? Instead of the links. If someone can do it, please do so, I am not that savvy with a computer. Thanks.

[Wayne Smith]

I just clicked on the links, told my computer to open. This opened a Word file with extra pages. I printed them out of Word.

[13Echo]

I'm not a super expert on single shot actions but I do have some experience with the Trapdoor, rolling block, Martini, and Sharps. Out of these the rifle with, by far, the most positive extraction and the only one with an ejector is the Trapdoor. The Trapdoor also has, by far, the best camming action to seat a stubborn cartridge. I haven't had a cartridge leak gas in any of these rifles, however I do believe I'd much prefer to be shooting a Trapdoor than a rolling block if it happened. For a battle rifle the good old Springfield seems better able to cope with bad ammo and dirt than any of the others. Its biggest fault as I see it is the tendancy of the breech block to bounce back when it's rapidly opened or to fall back if the muzzle is elevated. Very annoying. As for strength, it would seem it was perfectly suited for its day and was likely no weaker (perhaps much stronger) than a contemporary rolling block. The Trapdoor may have been a "stopgap" rifle but it was a pretty good one, and, I have come to believe, a better battle rifle than a rolling block if only for the extractor and camming action.

Jerry Liles

[StrawHat]

The Trapdoor may have been a "stopgap" rifle but it was a pretty good one, and, I have come to believe, a better battle rifle than a rolling block if only for the extractor and camming action.

Jerry Liles

Jerry, I agree with most of what you wrote. I think the "stopgap" idea was good up to when they stopped using old parts and started making rifles from scratch, 1870 or so.

As for the breechblock, I have taken to turning the trapdoor to the side when opening. It drops the empty in a pile (or my hand) and prevents the block from swinging back.

I prefer the trapdoor to the other single shots of the day.

[looseprojectile]

In the early 60s I bought a really nice carbine, about 95% at a gun show. I was able to chisel the guy down on the price as it had a broken extractor. He started at $50.00 and I was able to walk out with it for $35.00 along with a copious amount of ammo.
The ammo was a mixed bag of about a hundred and fifty original mostly milsurp and a few marked WHV. I figured it was worth about a nickel each or less.
After ordering an extractor from a place in West Hurley, New York and installing it I proceeded to shoot it. After shooting some of the copper cased ammo and breaking the new extractor, [copper cases stick] it found a new home as I considered it to be too unreliable to trust as a deer rifle. The military had to know. In those days nobody I knew thought of the trapdoor as being weak. I was a lot more recoil tolerant then.
If I just had that bag of ammo now I could sell it for enough to buy the carbine at todays prices. Maybe?
An other story has to do with a friend that told me the other day that his records show that I sold him a Sharps 45 70 Business rifle for $75.00 in that same period.
Who knew?

Life is good

[StrawHat]

In those days nobody I knew thought of the trapdoor as being weak.

An other story has to do with a friend that told me the other day that his records show that I sold him a Sharps 45 70 Business rifle for $75.00 in that same period.
Who knew?

Life is good

I started buying trapdoors in the 70s but remember the prices from the 60s and earlier. As I recall it was cheap but still a chunk of my weekly (weakly?) pay.

You are right, in those days no one I knew considered the TD action to be weak. It was understood it was not a bolt action but also not weak. I wonder who/when that myth started?

I have no plans to build one into a 300 Magnum but I have seen them in 30-30 and built one in 40-65. Maybe a 22 Hornet...

[missionary5155]

Good morning
Back to the order of strength... As we al know it is the weakest link that gives way. To me there is a BIG difference trying in short term to find destruction & the slow constant pounding a Breach system takes over thousands of rounds.
The hinge pin sytem & the locking lever are the 2 items I look carefully at on each Trapdoor I handle. My last fear is a barrel or Breachblock coming apart. Imagine where that breachblock will go if the hinge pin lets loose. If the locking lever fails where is that cartrige & pressure headed ?
I regularly shoot my 1868 caliber .50 when up here. I have never been concerned about the bursting ot the barrel or the fracturing of the breachblock... but I sure take a good look at that hinge pin area and locking lever.

[13Echo]

A Trapdoor can be fired without the hinge pin without disaster. The locking cam is another matter - it has to work or the breach will open as has happened with the H&R reproductions with the modified locking cam and lever.

Jerry Liles

[emorris]

I kind of hate to get off the "trap door" subject, but needed some info. I have a handi rifle in 45-70 (why im posting here) and looking to get some pointers for reloading. While preparing to start load development (studying manuels) i disovered 3 different load datas according to lyman #49. one is for the 1873 springfield, 1886winchesrte/1895marlin, and ruger #1/#3 rifles (hotter). The Handi rifle is new and my first thought would be that the later would work. I am worried that at the low pressure that it operates that the case would not show signs of excessive pressure and the gun will fail. I like shooting the rifle and from my research the 45-70 is a round the can be improved (velocity) by reloading. All of the factory ammo I have seen seems to be loaded for the weaker style rifles.

[HangFireW8]

I kind of hate to get off the "trap door" subject, but needed some info. I have a handi rifle in 45-70 (why im posting here) and looking to get some pointers for reloading. While preparing to start load development (studying manuels) i disovered 3 different load datas according to lyman #49. one is for the 1873 springfield, 1886winchesrte/1895marlin, and ruger #1/#3 rifles (hotter). The Handi rifle is new and my first thought would be that the later would work. I am worried that at the low pressure that it operates that the case would not show signs of excessive pressure and the gun will fail.

You could have started your own thread, but since we are here...

Start with the middle set of loads and work your way up. You may found what many Handi-Rifle owners have found, at a certain amount of recoil (not pressure per se) the rifle will become a self-ejector. :)

That is, it will spring open immediately after firing. Not unsafe, but very disconcerting. Or, it may not! The difference seems to be some receivers are springier, or stretchier, than others.

If it doesn't spring open itself, you may find yourself working right up into Ruger #1 territory. There, you will find the recoil to be terrific. Issues like rifle weight, balance, stock fit, stock shape, even the smoothness of the finish and the amount of stubble on your cheek suddenly become a factor in your recoil tolerance.



I like shooting the rifle and from my research the 45-70 is a round the can be improved (velocity) by reloading. All of the factory ammo I have seen seems to be loaded for the weaker style rifles.

Every cartridge can be improved by handloading, except the .338 Federal, which is factory loaded with magic faerie pixie dust gunpowder, which not only can not be duplicated by handloading, but crono and ruler owning handloaders shooting factory ammo. This cartridge is more powerful and flatter shooting than 7mm Rem Mag and .30-06 combined, all the gunwriters said so, all out of a case the size of the .308 and a bullet shorter in sectional density than, well, just about anything else.

For that reason, I won't buy the .338 Federal, because I know I'll never match that kind of performance with my handloads. Or any other kind of loads, for that matter. :kidding:

-HF

[StrawHat]

Let's see if this works.

http://i214.photobucket.com/albums/cc194/StrawHat/scan0002.jpg

Good, a little blurry but readable. I will get the other article scanned in and on the thread when I get the chance. Some interesting experimenting done in the 60s!!

[Sanchez]

Absolutely riveting info, gents. Many thanks.
Have always suspected as much since the mid-late '80s, after casually blazing-away w/ a newly-acquired 1875 date specimen of long rifle. Still have her, too - but we've always kept the 405gr cast reloads quite light .......

[No Good]

Looks like this is an older discussion but sure am glad to find it.
GREAT INFO!
Just started loading and shooting the trapdoor. Have to admit... (even loaded around 1200 fps with 405 gn berry's hardcast, and 23 gn IMR 4198) the first 2 shots were fired tied to the old tire with a LONG string tied to the trigger!
Call me a sissy if you must. But I believed the weak action stories too.
Havn't increased the load so far. It's just plain fun to shoot!

[StrawHat]

Not a thing wrong with soft loads. I stay strictly with black powder and lead boolits. But it is nice to know the is a bigger margin of safety than we may have been led to believe.

[No Good]

I agree StrawHat- about the loads and the safety margin.
I'm just getting set up to cast for the first time. The 45-70 will be my first boolit.
A lee 405 gn hollow base. I've been told that is a difficult one to get to work for a beginner.
Guess I will have to learn as I go like everyone did I'm sure.
Looking forward to it.
Did you know Winston Churchill is said to be the first person to fire an autoloader(a Mauser "broom handle") in combat?
He also has a cigar size named after him. Gotta love it.

[Ilwil]

I have an H &R Officer's trapdoor. Lately, the breech has been popping open on ignition. I've loaded my rounds to strictly "trapdoor acceptable" levels. Having it open is pretty disconcerting. I'd welcome any insights as to whether it is dangerous, can be fixed, or ignored.

[StrawHat]

I have an H &R Officer's trapdoor. Lately, the breech has been popping open on ignition. I've loaded my rounds to strictly "trapdoor acceptable" levels. Having it open is pretty disconcerting. I'd welcome any insights as to whether it is dangerous, can be fixed, or ignored.

The H&R did not follow the design of the Springfield 100%. The cam that holds the action shut was mounted on a round shaft rather than a square one. I believe parts from the Italian imports will interchange. You could also pin the cam to the shaft with a setscrew or just a roll pin. If I can find the article or link, I will post it.

[Larry Gibson]

IlWil

This sounds harder to do than it really is.

The cam must be positioned back to the right location on the shaft. A screwdriver was placed in the opening at the top of the cam to lock it in place while turning the thumb latch. I adjusted mine so when the top of the thumb latch is pushed forward as far as it will go (as in opening the action) the cam is rotated enough so its bottom will just clear the rear of the receiver and open. I then removed the breach block from the action and secured it in a padded vise with the left side up. Be careful not to move the cam on the shaft. If you do re-install the breach block in the action and re-adjust.

I removed the set screw and then inserted a drill bit. #43, that was a tight slip fit into the hole. This gave me a guide to line up a straight edge across the end of the shaft centering down the length of the drill bit. A line was scribed across the end of the shaft to use for reference, an idiot mark if you will.

A punch is then used to drive the shaft out of the cam and breach block. Out of the breach block the cam is then put back onto the shaft, the #43 drill bit put into the screw hole and the idiot mark lined back up. The original thread size on both of my H&Rs was 4x40, which is pretty small. I chose to go one size larger, which cleaned up some buggered threads and added some strength (maybe). I used a 5x40 tap and a #38 to drill the hole. Also I was able to find longer screws in 5x40 that would fill the entire hole in the shaft and the cam. The cam was secured in a machine vise on the milling table of my drill press. The job could be done on a mill also. The #38 was run down in front of the cam and shaft lining it up with the idiot mark and the #43 drill bit in the hole. Once lined up the #43 drill bit was removed from the hole and the mill table adjusted to drill the hole. A liberal amount of cutting oil was used, as there was some hardening to the parts. The hole was drilled completely through the shaft and out through the backside of the cam.

I then tapped the hole. Be very careful as it is easy to break a tap that small!!! Once again do not spare the cutting oil.

The new 5x40 screw is screwed in until the end just almost comes out the backside. Measure the excess screw length and remove the screw.

The cam and shaft are separated and re-installed in the breach block. Don’t forget to put the spring in. I initially eyeballed the alignment using the idiot mark and now the #38 drill bit through the enlarged hole. When it is lined up run the tap back into the hole to clean up any burrs created by the removal and re-installation of the cam on the shaft. When everything is lined up degrease the hole and blow it out with compressed air. The little cans sold for blowing off computers, etc. work fine. Put a little dab of lock-tite in the hole and then screw the 5x40 screw in until the measured excess amount that is protruding. Let the lock-tite dry and then cut off the screw and polish it smooth with the surface of the cam. Re-install breach block back in the rifle.

This modification worked for a while. As I was most often shooting sevice 1873 level BP loads it eventually failed and the BB began popping open again. Next post explans the ultimate solution.

Larry Gibson

[Larry Gibson]

My H&R LBH Carbine was the primary TD I 1st replaced the BB with using an original BB. It is not that hard to do if you have any ability while hand tools like a file. I was so satisfied with the BB replacement that when my Officer's Model popped open once i replaced the BB instead of messing with it. I have shot thousands of full level M1873 BP and smokeless loads through both since replacing the BBs without a single problem.

Fitting the original breech-block to the H&R Carbine. First thing was the hinge was a little larger in diameter than the H&Rs so the hinge-pin would not quite line up. I mixed some 220 grit lapping compound with cutting oil to thin it out. A small amount was put into the hinge recess in the receiver. Then with my left hand I put a punch through the left hinge-pin hole and exerted pressure pushing the hinge into its recess. At the same time with my right hand I moved the breech-block up and down lapping the hinge into place. Periodically I cleaned the hinge and checked the hinge-pin to see if it would go into place. It took three or four applications of lapping compound and about an hour to complete this. I did most of the lapping while watching TV. This went a lot easier on the next two breech blocks I fitted to other rifles. They line up a lot closer and took less lapping. On the third breech block fitted I used a small file and very carefully did the initial fit using it. Be very careful and go slow checking the fit frequently as you can't replace the metal you file off.

I then put a piece of flat stock steel across the flats at the rear of the receiver and measured the distance from the underside of the flat stock to the bottom of the receiver. I then ground the bottom of the breech block fore and aft of the arch that distance minus about .01as measured from the flange of the breech block to the bottom. I was careful to maintain the curvature of the bottom of the breech block.

With the breech block cap, thumb latch and cam-lock assembly removed I slightly ground of the hardened surface off the back of the breech-block where it fits into the receiver. A new 1” wide mill bastard file was used to file the back of the breech block down until it was a very close fit. I don’t know exactly how much I filed off but it wasn’t that much. I was careful to maintain the correct angle and used a “file a little – test fit – see where to file a little more, etc.” so the back of the breech-block fits the rear face of the receiver quite well. I stopped filing as soon as the flanges of the breech block rested on the flats at the rear of the receiver. On one of the H&Rs the recess for the ejector did not quite line up. the ejector was a little too far forward. Careful use of a Dremel tool with a small grinder in the forward edge of the breech block recess elongated the hole. One again it didn't take much for a perfect fit.

The breech block cap, thumb-latch and cam-latch assembly was re-installed on the breech-block. A scribe mark was made on the breech-block cap marking how much had to be removed from the end. The assembly was removed and that amount was ground and filed away. The breech-block was assembled and installed in the receiver. The cam-latch fit into the receiver recess perfectly but required a small amount to be ground (to hard to file) off with a large grinding wheel in the Dremel. Once again go slow here taking off only a little at a time untile the breech block closes and opens easily.

As there wasn’t any finish on the breech-block (on the first one I tried, other two had original finish and look pretty good) to begin with, cold blue was used all over giving it a “used” look. I then test fired the rifle with 50 carbine service loads of a 405 gr bullet over 25 gr XMP5744. The rifle has been fired hundreds of times since with no problems. I had some concern as to whether I should have the bolt re-hardened since I had ground and filed away some of the hardened surface. To date there has been no sign of wear on those surfaces. Total time for installation was 4-5 hours.
As the original H&R bolt was so poorly fitted and finished, which I believe is why nothing would keep the action from popping open upon firing, the replacement with an original Springfield breech-block was worth while. It made a dangerous rifle entirely safe, sound and serviceable.

Larry Gibson

[KCSO]

The latch is made different than the REAL trapdoor and you need a spring replaced if I remember right.

IF you mean unlatching, but POPPING open? Where's the hammer when all this is going on.

[StrawHat]

...My H&R LBH Carbine was the primary TD I 1st replaced the BB with using an original BB. It is not that hard to do if you have any ability while hand tools like a file... Larry Gibson

Larry, originally, the breech blocks were fit with some lateral play. Were you able to duplicate that?

[Larry Gibson]

Larry, originally, the breech blocks were fit with some lateral play. Were you able to duplicate that?

Yes, but I did not do it to the extent as many originals. I used and original cadet in very, very good condition (unfortuneately not mine) as an example of how much tight fitting should be done. Again I have fired thousands of rounds through both my H&Rs subsequent to this conversion without a single problem.

Larry Gibson

[trap4570]

The set screw has become loose. Tighten the allen head screw back in then screw another one in behind it. I've repaired a few H&R's with this problem. I also use a locking liquid to hold everything in place. If the set screw backs out far enough the latch will just swing then you have a stuck cartridge and it will require dental picks to release the cam. A very frustrating situation.

[Hang Fire]

HangFireW8
Start with the middle set of loads and work your way up. You may found what many Handi-Rifle owners have found, at a certain amount of recoil (not pressure per se) the rifle will become a self-ejector.

That is, it will spring open immediately after firing. Not unsafe, but very disconcerting. Or, it may not! The difference seems to be some receivers are springier, or stretchier, than others.

Back in 1982 I had a TC Contender in .223 that blew opened on first firing and ejected the case. I didn't try for a second go, but had the dealer I bought the gun and factory ammo from send it and case to TC. Couple weeks later I got a new Contender and barrel back but no explanation.

[44-40]

I was suprised at the load of Bullseye it took to destroy the trapdoor. I can't imagine what the recoil would have been!

I grew up hearing about how weak the Trapdoors were and believed them with out ever knowing what the test were that determined weakness. Then I read Waters article on the 45-70 in Rifle and Handloader magazines and he had four (4) load levels for the 45-70 with the trapdoor in the lowest tier. Several others also did loading guides and the Trapdoor was always in the bottom tier. Too weak, etc. I wonder what the basis for the determination was as reading these pages it seems to indicate the Trapdoor is a bit stronger, and safer, than was previously thought.

I guess my ideas of rebarreling a Trapdoor will get a fresh turn.
Hello StrawHat, I imagine you could blowup just about any modern gun with the amount of bullseye that will fill it's case. How much did it take to destroy the Trapdoor? I have two Lyman reloading manuals, 45th edition (c.1970) which was my first manual and the Lyman 47th edition (c.1992). Both list Unique 11gr. start and and 15gr. MAX for the 405 Jacketed bullet. The 47th edition gives 13.7 gr. Unique starting and 16.5 MAX for a #2 alloy 400 grain cast bullet. I have no idea what #2 alloy is! I load my 45-70's with 11 gr. Unique and 55 gr. Goex 2 FFG. That is about all the 2 FFG I can put in the case and compress it when seating the bullet with my press. I have not tried using an arbor press to get more powder into a case because I think the recoil is as much as I care to stand with 55 grains. I prefer shooting the 11 gr, Unique loads and they are accurate to my tested 100 yards. I would not be afraid of using commercial ammuniton but it will not be as accurate and I don't want the recoil.

[StrawHat]

44-40,

The article states the amount. Let's just say it was a lot. The whole gist of the reports was the Trapdoor is not nearly as weak as it is normally thought to be.

I believe the weak action rumors started with the 1866, which used old barrels and machined them to accept the action and new liners. By 1870, the action was newly made and for the 1873, all the parts were newly made. But the older actions were still available (I still use an 1866) and the rumor started/persisted.

[40-82 hiker]

I've had my 1884 TD since the late 60s. I've shot BP, Pyrodex CTG decades ago, but nothing has given me the accuracy that AA5744 does now. I resurrected the TD a couple of years ago as a project to help me with my disabilities, and I have been shooting the heck out of it since, er, at least when I can.

I don't worry about the strength of the action, as I have always shot the mildest loads I can to achieve the best accuracy. Also, I am very leery of the Hodgon tables, as I think they are a little overly heavy for the TD action. JMHO.

I would also recommend this load for any Handi Rifle, or other light 45-70 where the weight (or lack thereof) is an issue.

Lyman 405gr. boolit (1:20)
24.0 (or 24.2) grs. AA5744 (no filler per Johan Laubser - ballistician for Western Powder - not with them now)
Any good LRP (I use Winchester)
Lyman Moly Lube
My boolit sized to 0.459

I used to use the 500 gr. boolit, but recoil was getting to me due to my back problems. This load is nice to shoot in my Trapdoor, and very accurate. Certainly there are no pressure issues. My bore is good and shiny, but certainly not pristine.

I made a new front site for it out of German silver, but any steel will do. I regulated the front sight on with 6 o'clock hold at 100 yards, with the Buffington sight set in the down position.

As others have stated, it is not the looseness of the breech block that is a problem. They have to be loose. The pressure on the breech block face when firing has to be transmitted to the rear of the breech, and that takes the looseness of the hinge assembly to allow this to happen.

I have the one TD, and a RB in 40-65. I seem to enjoy shooting the TD better than the RB for some reason, though even with the Buffington sight the RB is easier to shoot with my 61 YO eyes. The TD is just a fun gun to shoot. Again, MHO.

My final thought on the TD is this: it is too fun to shoot to worry about the last couple of hundred feet per second you can get out of it. A guy at the range let me shoot my load through his Chrony, and the 405 gr. boolit was going 1420 fps. This surprised me a little, as I did not think it would be quite that fast. However, it is enough recoil for me to deal with, and I don't see any need to get it going any faster. I have to wonder if I have shot my weight in boolits through that gun in my lifetime :holysheep, and the action is as good as when my Dad bought if for me around '67. I just never took it to task. It may be a strong action, but over time I think it is prone to wearing out if using loads outside of its design strength.

As far as accuracy, I will put the TD up to just about any modern made .45-70. Period. However, even with the Buffington rear sight, it is not an easy gun to shoot. i find the rear sight is just not that easy to use with older eyes (again, MHO). While the sights may have been a marvel in their day, the Buffington rear sights do not match up to what we can put on RBs, Sharps, etc. Can't come close. JMHO again.

[RobsTV]

Started shooting an original Springfield 1884 TD before I had real black powder. Used 777 and 405gr lead. Always horrible accuracy. Then switched to full case of slightly compressed Goex FF and instant accuracy. Chrono'd these new black powder loads at around 1400fps, then chrono'd one of the 777 normal loads I was using, and these ran faster than 1800fps! I pulled all remaining and tossed out the 777. But, the original Springfield seemed no worse for wear after couple hundred of those hot 777 loads.