Monday, November 17, 2014
Saturday, November 15, 2014
Thursday, January 23, 2014
I recently saw a search that set me back a bit. It was "Trapdoor Springfield Sucks".
I am well aware of the trend to add "sucks" to any subject to try to find a site dedicated to a subject's belittlement. I'm sure "Justin Bieber Sucks" or "Miley Cyrus Sucks" will bring up plenty of fodder about poor singing, poor life choices, and mediocre twerking. But "Trapdoor Springfield sucks?" Surely there isn't a trapdoor hate site? Well, where there is a need, there is a supplier. What follows is a list of the trapdoor's failings, in my experience.
1) It was built to a price point. There is no doubt, that when the government started with the Allin Conversion, the main goal was to use up all of the muzzle loaders they had sitting in the armory. The ability of the trapdoor concept to use up these free parts was surely a major selling point. After that, even when making rifles from scratch, the trapdoor is a simple piece to make. Remember that the trapdoor was never the active arm during any major conflict. It is hard to spend money on rifles during peacetime.
2) The rifling is off. I have to agree on this one. Current BPCR guns use 18:1 twist for a reason. 22:1 is surely better than the 4 foot twist of some muzzle loaders, but still not quite there. I can't think of a good reason why 3 lands is worse than any other number, but people have surely landed on 6-8, so there may be something to it.
3) The trapdoor barrel is too whippy. Sure enough, a rifle built to be carried across America on foot or horse is not going to have the heavy bull barrel of a target rifle. Plus, steel costs money, see #1.
4) It is unreliable. I call this one false. The troubles of Custer are well documented and certainly stem from the balloon cases of the time. In my 1000s of rounds I have had zero fail to fires and one case failure that didn't stop it from functioning. Even my broken firing pin was still functioning when I changed it.
5) The trapdoor is weak. I give this a 50%. the trapdoor is fully capable of supporting the round it was designed for. The fact that technology marched on and created incredible pressures in the 45/70 doesn't change the rifle. The same can be said of all the straight walled black powder cases. This is why the revolvers tended toward a longer, high pressure version. .38 to .357 mag. 45 to 454 Casull. 44 to 44 mag, etc.
So there you have it. The truth is out. The Trapdoor Springfield sucks and there's no way to deny it.
It also can't twerk worth a damn.
Sunday, January 19, 2014
There are 3 competing requirements in the load. One is that the initial pressure needs to be strong enough to upset the bullet into the rifling, without upsetting it too much and deforming it out of round or leading the barrel. Two is that the combustion needs to be regular, steady and clean. Lastly, the final muzzle velocity needs to be in a range where the bullet is happy aerodynamically.
There are lots of ways to play around with this. More powder raises muzzle velocity and the initial upset pressure. It can make a burn more regular, or more erratic, it just needs testing.
Coarser powder decreases the initial pressure, and might decrease muzzle velocity, but with my long barrel it may not affect velocity much.
Balancing off a powder change with an amount change could give me exactly what I need, or just the opposite.
All of these options can have base wad thickness modified to affect compression. There are at least 100s of possibilities. On top of all that, a slight change in bullet hardness might alter the results concerning the initial pressure.
So, a pretty picture:
All tests were at 200 yards, bench rest, 320 grain 30:1 bullet, .060 wad, 40 grains measured, very light compression that varied by load to meet the same OAL.
For the data below I'll give maximum group size and then "9 shot" group size. A big difference between the 2 indicates a "flier". I'm not much into calling fliers, as they are still a miss, but the existence or lack of them can point at combustion problems, or bullet quality control issues.
In none of these did I run a chronograph, so we'll need to hold that for a later day.
Powder 10 shot group 9 shot group.
KIK FF 9.3 6.6
KIK F 8.5 6.9
Swiss 1.5F 8.8 6.8
Olde Eynsford 1.5F 7.2 6.9
Olde Eynsford FF 5.2 4.8
Goex F 10.1 8.9
Goex FF 6.6 5.6
I should comment that the first load, the KIK FF is my standard go-to load (or it was until I saw the Olde E result), and usually shoots about 7.5 inch groups. No excuses, a test is a test, but it shows how variable a single round of testing can be.
That Olde Eynsford FF is looking pretty good right now...
Calipers are set at 5 inches.
In the match today it was rather foggy, so my cross stick shooting was not up to my bench rest results in the sunshine. I did, however, have a bit of excitement. Near the end of practice, this ejected:
The trapdoor is a very difficult gun to inspect. After trying to push the chunk out with wads, we ended up driving a bullet down from the muzzle. The spooky thing, nothing came out but the bullet. It seems the ring of brass formed itself into a crude gas check and went out with the original shot (high and right, by the way). I've only seen one other case like this in a BPCR, and it left the ring in the chamber. There were no unusual effects, and the reline job didn't give way, so I'm still happy, if concerned. A thorough brass inspection is in the works. Cracked brass can be an indication of headspace issues, which I'm not expecting, but I'll check. Usually a headspace crack is closer to the base.
Have fun. Be safe.
Sunday, November 17, 2013
I shot this today in the match. 5 in the black, and the other 5 floating about 1/4 inch away. A 5% reduction in group size should do the trick. Of course, if I'd just adjusted my sights up 1", that would have worked too. Hopefully, I'll be updating this blog a bit more frequently now that I'm shooting the old girl again.
Sunday, March 31, 2013
The shot above is the drill being held with the pilot in the chuck for alignment, being pushed onto the end of the steel rod that has been bored in the lathe collet. The rest of the rod is about 3 feet long and rests inside the lathe spindle.
If the old action had good headspace, a simple depth measurement from the end of a seated cartridge to a fixed feature like the thread shoulder is all you need. If you want a different headspace, some corrections can be made from there.
Cost totals (Some are guesses):
Old barrel, receiver, door. $75-100
Liner $5.39/inch Track of the Wolf.com
T slot Cutter $15
Crown tool $85
Headspace gauges - cheap, but a total waste. In bottleneck cases they measure something difficult to measure and important for safety. In rimmed cartridges, they are glorified washers, and you should learn basic measurement techniques instead.
Thursday, December 20, 2012
The result was a trigger pull of 36 ounces. This sounds light, but in the offhand position it feels terrible.
But this is a blog about Trapdoors, right? Here's a shot of the same concept applied to the Trapdoor lock:
The wire loops around the mounting post and an extra loop slides into the slot that holds the stock spring.
How does it work? Trigger pull is down to 21 ounces and feels very nice. This is the same setup I used to win the offhand competition a few months ago. By comparison, my Izhmash Ural 5-1 target .22 is set at a pull of 6 ounces and feels like it isn't there at all.