Folding Stock Bullet-bow Project

This build was an idea inspired by the Victorian era bullet bows as well as a mix of ideas that came from this forum's community. The design of the tiller is a copy of a flintlock circa 1750, the kind that French colonists would trade to the Indians of north America for furs. Heres the first drawing I did for the overall design

I've already trashed a lot of this design but it gives you a general idea on what I'm going for.

I had my heart set on something that could throw .50 cal steel at about 200FPS and was quick to draw and load, so I cut the barrel to accomodate a power stroke of 11.5" however the prod will only be about 90lbs, as I understand, with light projectiles its the powerstroke that does most of the work rather than the draw weight. I came up with a sort of tube magazine built into the tiller similar to a Girandoni air rifle and I plan to have a little lever or bar that will trip a ball into the barrel when activated. I wanted a rifle-sized crossbow, but I also wanted something compact and portable to take on woods trips, at first I decided to settle on a short musketoon style of tiller but later I discovered some really nice flintlock rifles that were designed with collapsible stocks to be portable on horseback, so I decided on something similar.

Here's a few pieces of cherry I'll be laminating together with a red oak core to make the tiller, and the slotted barrel next to it, which looks really bad in some spots where I botched the cut (was using a small dremel tool with no sort of guiding jig), however all of the rough spots are parts that will be inletted into the stock and wont be visible in the final crossbow.


I'll have more progress to post in a few days, hope you like my idea.

Awsome! Watching your progress with interest!

Thanks Andy!

Made some progress on the trigger assembly, just need a few tension springs installed and it should be ready for a test.


And the rear of the stock in profile and ready for shaping.

I like your trigger! Looks a bit different than your drawing! LOL I think it will be a big improvement. I didn't think of it until I saw your picture but you only need a single claw for a bullet bow.
That three part design should result in a very nice trigger pull.

jaeger22 wrote:I like your trigger! Looks a bit different than your drawing! LOL I think it will be a big improvement. I didn't think of it until I saw your picture but you only need a single claw for a bullet bow.
That three part design should result in a very nice trigger pull.

Yeah haha like I said the initial design will not accurately represent the final product since I had a lot of time to think about changing things while I was waiting for my lumber to get shipped and then reshipped when HD sent me the wrong dimensions. I was going with the early lever trigger because I had more of an arquebus tiller design with a flashy sweeping fishtail buttstock, but eventually settled on the more generic musket profile. Glad you like it!

Inletting trigger assembly into the core lam of the tiller

Awesome!

A first look at the magazine space and mechanism for chambering a ball


I'm clearly in need of a metalworker, but how it works is on the side of the stock there will be a lever that turns that little metal piece under the first ball,pushing the ball upward into a hole under the barrel where it hopefully is grabbed by the magnet inside the shuttle (think of the shuttle as a plastic sabot that rides on the string) that rides inside the barrel. The magazine holds 7 rounds.

Hello X, Those balls you show, are they steel or, lead. I have never shot steel. I can tell you lead is awesome.I know ,all the bs that goes with handling lead.I also have my own molds. Great idea you have . Take your time and it will come about.You know , if you make a piece and it's not so good, all is not lost CAUSE, you now have a pattern.Use it more carefully in the area that didn't come out to your liking.

c sitas wrote:Hello X, Those balls you show, are they steel or, lead. I have never shot steel. I can tell you lead is awesome.I know ,all the bs that goes with handling lead.I also have my own molds. Great idea you have . Take your time and it will come about.You know , if you make a piece and it's not so good, all is not lost CAUSE, you now have a pattern.Use it more carefully in the area that didn't come out to your liking.

Thanks for the feedback. Those are steel bearings, .50 cal. I realize lead has better energy potential but my design uses magnets to get the round seated in the shuttle. I have plans for making another shuttle that will hold the round with slight clamping force  rather than magnets so that any ammo can be used, the downside is that it will also need to be muzzle loaded each round, so the magazine under the barrel will be useless.

X I still think you have a great idea. You could load lead just like you do steel xcept, You would use the side spring pressure to keep the over load back. Very similar to a modern pellet gun. You reliease one ball ,fire, grab the next one in line . I t amounts to a thin spring with a light side pressure ,to capture the rest of the balls. Coarse you have to have gravity help here, in other words if you want to load , raise the mussel , balls fall against the spring keeper, and you release one, into the firing zone.

[size=32]That's a pretty nice idea with the simple spring tension to keep the magazine rounds from falling into the chamber, i had something similar planned.[/size]


[size=32]Here's the buttstock and forestock end almost fully fitted and ready for the latch and hinge hardware.[/size]



[size=32]This cherry wood darkens up really fast, can't wait to see what it looks like in a few months. I'm leaving it natural unstained because of this. I hope the oak doesn't ruin its look.[/size]

X ,that's a great piece of wood you have. You have a good Virginia or Kentuck style. I do front stuffers once in a while. Nutin authenic, just hunters,in 45 or 50 , or 54 cal. I can't wait to see your creation. Chuck

Thanks again Chuck! Glad you noticed the inspiration for the tiller profile, a mix of Pennsylvania/Kentucky and French 'Fusil De Chasse'. I never shot or put together a real muzzleloader but I do think a few are the prettiest firearms in history.

Started to inlet the barrel into the stock today and it's coming along very quickly thanks to a trick i discovered, which is that you can use a sharply sawn piece of pipe with the same diameter as your barrel as a planer to carve the channel for the barrel to almost exactly the right size, hehe no expensive inletting tools needed. Soon I'll be able to drop in the trigger box and hopefully things will line up right without much difficulty.

Something else I need to start worrying about is how to reinforce the prod area which will be very thin by the end of all the tiller shaping. The prod will only be about 90lbs in draw weight but the wood will still be stressed by the constant shock of the prod firing just above its dry firing limit. I might need to do similar to a 'padre island' bow and reinforce the sides of the hole in iron. Any suggestions or alternatives are welcome!

I like your iron idea. Also you might consider hogging out a goodly portion of the inner front stock , and then pouring it with fiberglass resin. The stuff can be purchased almost any where.It can be scrapped with the same pipe deal you are using,although may be a little slower going. That should make the front end very strong indeed.A couple of metal pieces ,one on each side to bear the prod still sounds good also.At any rate, make all attempts to keep this kind of approach "resin" covered and out of sight.

Xamllew
It is fun to work out all the variables, kind of like a pioneer swimming through a “catch 22” soup. 
Your barrel slot looks long enough. From my experience the string shuttle combination travels past brace quite a distance even when you get the occasional dry fire. My delrin shuttle is at just about 400 grains, so dry fire is not a factor but it still goes close to 1-1/2” past brace. As I mentioned in PM the mag keeper does not travel with the payload. The reason for the delrin is wonderful to machine and drill but much heavier than hdpe on the first bow. Incidentally neither of these bows has a barrel!

Hey Septua, thanks for the info. About how much heavier do you think delrin is compared to hdpe? I reasoned that delrin would be a good choice because of its low coefficient of friction on steel. I recall you mentioning that your crossbow's holding magnet wasnt in the shuttle so I'm curious where your crossbow holds a magnet? I will likely drill out a spot in the shuttle for a magnet since my design offers very few alternatives unless I were to put the magnet above the barrel. If only i were a machinist I would try to come up with a rear sight that contained the magnet inside the sight.

Chuck, I'm definitely digging the idea of filling the hollow below the barrel inlet with resin to reinforce the tiller at the front, i think this might have the added advantage of dampening vibrations from firing. Thanks for the idea.

My shuttles have a flat top which at full cock engage a pressure pad mounted overhead and that also holds a 4 pack of mini rare earth magnets. The plastic pressure pad keeps the shuttle from buckling under tension.The disk pack of magnets are in the hole at top front of metal frame. The delrin shuttle is 26 grams, poly one is 10 grams but the former is slightly beefier. Delrin finishes (machines) very smooth and is very slippery like teflon. 

Hey X; you could use a modified version of the whole thing also. Think of a way that you could incorporate a steel rod along with the resin. Maybe even go so far as to have this tie into your bow irons. Just thinking out load here.

Oh lordy, didn't realize delrin was such dense stuff. I might try to skeletonize the shuttle wherever I can to bring the weight way down.

Hey Chuck I might instead fill the core with silicon adhesive, while it won't be as strong as fiberglass resin it will be much like rubber and act as a damper against the shock and noise of the prod as well as reinforcing the prod area. Kinda like how blades are tempered hard but the core of the steel is kept soft and flexible.

Here's a view of the trigger assembly and barrel fully inletted.

X;The only way I would just jump into the skeleton job would be if I had lots of extra material. The stuff seems tough enough but, I'm not really impressed with it. I would reccomend you try it first . Only after you think it's bothering,would I start chopping.You take where you drill for the holding pin ,that area for me was weeker than I like.Under full cock I could see deflection caused by  drilling the hole for the holding pin.

Thanks for the insight Chuck, I decided to just buy another rod of hdpe given the large difference in weight between the two, not to mention the rod I bought was slightly oversized and I found that reducing the diameter by Sanding would have taken a very long time and would likely result in a lumpy uneven and loose fitting shuttle.


Here's the beginning of some sort of hinge mechanism for the folding stock


 It will work similar to a folding table hinge, which is able to fold 180 degrees without needing the hinge pivot poking out awkwardly because it is made out of three pieces so you end up with 2 pivot points that both rotate 90 degrees.

Xamllew
That hdpe is a pain to work with, but I have it for my trackway. This track will eventually be replaced with a delrin one waiting in the parts box.
Tom       

SEPTUA wrote:Xamllew
That hdpe is a pain to work with, but I have it for my trackway. This track will eventually be replaces with a delrin one waiting in the parts box.
Tom       

I wanted to ask you if you've tried putting the retaining magnet inside of your shuttle, because that is probably going to be my only option with my setup, my concern is that the magnet will hang on to the ball at the end of the power stroke and possibly reduce velocity.

 I will be using a very small rare earth magnet so weight shouldnt be a problem.

Xamllew
I just checked your idea and if you used one magnet embedded at front of a shuttle and flat to the ball will work if it is about a quarter inch away. If mounted edge to the ball center that distance can be closer. My disk mags are 5/16” dia. By 1/8” thick and weigh 1.2 grams each. The ideal method is somehow mounting several magnets at the exterior of the steel barrel. Once the ball is launched the mags stay in place. If you use a conical front on the shuttle it will improve accuracy.
Tom