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放放电影By BarryinIN

放放电影Trapdoors are one of those rifles that don’t get the respect theydeserve. There are Trapdoor collectors out there, but few compared tocollectors of other US martial arms.
Most of us never even glance at one lying on a gun show table.

Yet,the Trapdoor had a pretty good service record in some trying times.After some initial trouble with the early brittle copper cartridgecases, it usually worked and did so in some crummy conditions. Of greatimportance was that due to being cheap and easy to transition to, itallowed the US Army to convert to breechloaders after the Civil War whenthe country was flat broke. It served in several battles and wars,including two that had a tremendous impact on our country- the IndianWars and the Spanish-American War.
There was a war or conflict going on during almost all of it’s career.
It is the gun that won the west.

But it’s history is another story.
I’m going to ramble on about the gun itself.

Peopleusually call it a “weak action”. Well, it isn’t as strong as a Ruger#1, but that does not make it faulty. Some seem to think that way. Ithink we have to compare it to guns from it’s period. I wouldn’t shootanything in a 45-70 Sharps or Remington Rolling Block that I wouldn’tfire in a Trapdoor.
The Trapdoor was made to handle a specific loading, and it DID handle it.
Ihave found nothing saying a Trapdoor failed in service due to not beingup to the task.The fact is, it’s cartridge was made more powerfulduring it’s service.Originally loaded with a 405 grain bullet over 70grains of black powder, the bullet was increased to 500 grains over thesame charge in 1881.
Duplicate of M1881 on left, duplication of original load on right.

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The fact it cannot contain a load that is pushing .458 Winchester Magnumlevels that was dreamed up 90 years later is of little bearing. Ahundred years from now the much-loved Remington 700 may not be able tohandle a typical load from the time, but that doesn’t mean it is a badaction then or now.

The Trapdoor has some mechanical details andfeatures I find interesting, and I don’t know how many people arefamiliar with them.

By outward appearances, it looks simple asdirt. You might not think there would be anything of interest about it’smechanism, but there are a couple of things that stand out once youknow about them.

By the way, it was not called the “Trapdoor”back then, at least by the military. It was the Springfield Rifle (orCarbine), Caliber .45.

Breech Locking
I thought I knew how thebreech was locked until I got one and then got a copy of the old Armymanual.Then I found out there was more to it than I previously knew.

Youopen it by unlatching and swinging the breechblock up, and you close itby swinging it down where it latches in place.When the breechblock islatched closed, there is a latch (called the “cam latch”) that holds itclosed by keeping the breechblock from being pushed up and open by thefiring pressure. That much was obvious from looking at one, and Ithought that was all there was to it.
Well, there is and there isn’t.It is designed so that when fired, the pressure holds it down and latched tighter.

Take a look at this diagram from the manual. Our two main points of interest are marked “E” (Hinge) and “F” (Cam Latch):

 

 

 

 

 

 

 

Item “E”, the hinge pin, runs through the hinge pin opening in thebreechblock. The hole in the receiver is round. BUT, the hole in thebreechblock is slightly out of round. It is elongated fore and aft.
Hold that thought.

Item“F”, the cam latch, is what latches the breechbloclock closed. Noticethat the center of it’s pivot point is lower than the contact surface ofthe latch.

When the rifle is fired, the elongated hinge pin holeallows the breechblock to push backward just a little. It hardly moves,but it does move. As it comes back, the cam latch rotates slightlysince it’s contact point is below the centerline of it’s pivot point.This rotation cams the breechblock down, holding it closed tighter.

Small detail, but one that is simple, clever, and an important one.

Rear Sight
In1884, the “buckhorn” rear sight was replaced by a new design called theBuffington sight (named after the Colonel in charge of SpringfieldArmory at the time). Compared to the previous sight, it is both simplerand more complicated. It offered an easier windage adjustment and abattle sight that blocked less of the target, but its also had five different notches or apertures that can be aimed through and was adjustable from 200 to 2,000 yards.
But there was something else.
Take a look at one, and see if you notice anything peculiar about it:

 

 

 

 

 

 

 

Can you see that the sliding “ladder” runs in a track that angles to the left as it goes up? Closer look:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This is a built in compensation for bullet drift.

When a bulletis fired from a rifled barrel, it has a tendency to drift in thedirection of it’s rotation. A bullet from a RH twist barrel will tend todrift to the right. I think the theory is that the larger and heavierthe bullet and perhaps the lower the velocity, the more it will showthis effect, but I’m not sure.
The new sight compensated for this by sending the aperture and notch to the left as it is raised.

Accordingto the manual, SA had the best marksmen test rifles at various rangesusing some rifles having RH twist barrels and some with LH twistbarrels.At each range, the groups got farther apart laterally due tothe rifling twist causing drift.SA then halved that distance betweenthe groups to determine the amount of drift caused by the rifling, andused that info to know how much to make the sight compensate.

How much drift could there be?
Themanual lists the results in 100 yard increments to 1,000 yards. At 100yards, the bullet has already drifted 1.29 inches. At 300, it’s 5.1inches. At 500, it’s 11.5 inches. It’s almost 4 feet at 1,000 (whichtakes 3.29 seconds to arrive at).
With the rifle, that is inside themean accuracy standards, so I suppose it was worth addressing. With theCarbine, I’m not so sure since at all ranges, the Carbine’s accuracyacceptance standards exceed the amount of drift. I don’t know if thepossibility of 5″ of drift is worth worrying about when the Carbine isshooting a group of almost 12″.
I don’t know how far they ever shot them in actual combat either.
But I still find it all rather interesting.

Other Details
There are other small details to it if you look for them.

Thethumbpiece used to unlatch the breechblock has an arm that blocks thehammer from the firing pin if the latch isn’t completely closed. Thehammer can be cocked and the trigger pulled if the breeckblock is open,but it will fall on this arm.

It has an actual ejector, not just an extractor. Regardless of how fastor slow the breechblock is opened, the ejector will “fire” the emptycase out of the chamber. A part called the ejector stud in the bottom ofthe receiver acts as a deflector to send the case flying over theshooter’s right shoulder…if right handed. It should just about catch aleft hander square in the face.

I’ve read this cartridgeejection was quite impressive to Army officers who examined earlysamples. Apparently, they thought it was just the neatest thing. I’m notsure why, since there were ejectors on arms before, but I guess thatdoesn’t mean it didn’t happen.

And it’s a simple ejector system.The ejector is basically an extractor with a spring bearing against it.The key is how that spring is located. The ejector pivots around thebreechblock hinge pin. Most of the time, the spring is applying pressurejust above the centerline of the pin and keeps the ejector retracted.As the breechblock is rotated open, a tab contacts the ejector androtates it slightly. That is just enough movement to “free” the springto bear against the ejector on the other side of it’s centerline andkick it out.
They made use of cams and overcenter principles in this rifle.

Therewere near-constant improvements being tested or applied to the Trapdoorthroughout it’s service. You have to remember there was almost always ashooting war going on. Even though money was almost nonexistant, theyhad people counting on these rifles so they never stopped developingthem.
The breechblock got some strengthening changes, the receivergot widened just a little, the firing pin material changed, the sightschanged, the trigger was re-shaped…Literally everything from thebuttplate to bayonet got changed at some point. Even the ramrod wentthrough a few changes (yes, they call it a ramrod even though it’sreally a cleaning rod).

So as you can see, it may look simple as a hammer, but there is a lot more to it than first appears.

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