Crossbow modifications - Mission Sub One Lite

[yoderjac]

INTRO BACKGROUND: (Feel free to ignore this section. It just shows how I got where I am over the last 50 years.)

During most of my bowhunting career, I used compound bows. I started with a Bear Whitetail Hunter II. I had no idea what I was doing when I bought it. I did not use a pro shop and I could not hit the broad side of a barn beyond about 15 yards. Never got close enough to a deer to even get a shot. I knew nothing about bowhunting and only got the bow to extend my hunting season. When I moved to Virginia in the DC metro area, things changed. There was very little firearm hunting without a long drive. I found out that I could bowhunt at Fort Belvoir. I ended up joining an archery club there and learned a lot. Another important step was taking the International Bowhunter Education Class (IBEP) which was required to hunt at Fort Belvoir. It was a great class that include blood trailing and 3D walk-thru exercises.

I now knew enough to use a pro shop not a big box store and found out that bow fit was much more important than anything else a bow had to offer. I ended up going to the local pro shop and buying a used bow. I can't even remember the brand. The shop owner took plenty of time to work with me and get it set up to fit me. Suddenly, I was shooting pretty well. I never shot a deer with that bow, simply because I never had an opportunity when I did not get made by deer. I was just beginning to understand the importance of scent control.

By this time, I had learned the basics of setting up a bow. I ended up buying a Mountaineer bow. It was one of the first with 80% letoff. My shooting improved dramatically. With better scent control, I began harvesting deer, a couple each year. During this period, I also found another military facility near by that did allow shotgun (slug) hunting, Quantico MCB. I began working there as a conservation volunteer. This gave me a great opportunity to learn the base outside the season. I began harvesting deer there as well with both bow and shotgun.

I had become fairly proficient with a compound, or so I thought. The suburbs were having big issues with an overpopulation of deer, but there were few if any places where you could use firearms in Fairfax County. Most all of the land was privately held by homeowners. Developers developed the ridges and donated the stream valleys back to the county as parks where no hunting was permitted. Homeowners were having terrible issues with landscape damage from deer as well as deer/car collisions, but they had no concept of bowhunting and were concerned about liability, so most did not allow hunting.

I got together with several experienced bowhunters and we formed Suburban Whitetail Management of Northern Virginia. This volunteer organization, connected homeowners with deer damage with highly experienced bowhunters. To overcome the homeowner fear, we got liability insurance, ran bowhunters through extensive training and qualifications, and worked with the game department to obtain kill permits for out of season hunting. There was a high threshold for experience to hunt for the organization, because some lots we hunted on were 10 acres or less with sensitive neighbors. It was important that high probability kill shots were taken and every deer retrieved. We even provided tracking support to the bowhunters to help find deer, and a less than stellar recovery record was cause for suspension. Because one of our training requirement was the IBEP class, our members were putting a heavy load on the local classes held at Fort Belvoir, so several of us got certified as IBEP instructors and began to teach.

One of the other founders of this organization was an outstanding bowhunter, but also a state champion target shooter. She shot a Martin Scepter and was an outstanding bow mechanic with it. He knew it inside out. He was kind enough to take me under his wing and teach me bow mechanics. So, of course, I bought a Martin Scepter. My shooting improved even further. I started building my own arrows and even bowstrings. This guy was a great resource and teacher. I killed many, many does each year with that Martin Scepter.

I loved it and never intended to buy another bow. Then I made a HUGE mistake. One day, I was killing time waiting to attend a meeting and there was an archery shop nearby. It was a Mathews dealer. They had an indoor archery range, so I took my Scepter in to shoot. At some point the owner ask me if I'd like to try shooting one of the Mathews bows. I told him I was not interested in buying a bow, and did not want him to waste his time setting one up for me. He was persistent. So I told him that if he wanted to set it up, I'd take a couple shots. Needless to say, after the first shot, the bow was sold. I left that shop with a new Mathews Switchback.

Things changed dramatically. Using my previous bows, string jumping was always a potential issue. Sometimes they would and other times they wouldn't jump the string. It was always a gamble. The switchback changed that. Mathews focus on quieting the bow was key. I never had a bow jump the string using that Switchback, and I shot a lot of deer with it.

Over time, basketball, and my other athletic sports caught up with me and my rotator cuff got to the point where hunting with a compound became difficult. I could still shoot it at the range with no problem, but in cold weather, I'd stiffen up, and could no longer draw. I ended up having to pass several deer simply because I could not draw it. A few years earlier, they legalized crossbows in VA. By then, I had become a general Hunter Education instructor as well, and as part of the recurring training for that, several crossbow companies brought there crossbows in and we had training on them. We got to shoot multiple crossbows as well as having the safety training. The one I liked the best was a local VA company called Parker. I figured if I was going to train on crossbows in my Hunter Ed classes, I better shot at least a couple deer with one, so I had done that back then. At this point, with my shoulder, I began using the Switchback early in the season when it was warm, and then switching to the Parker mid-season. I used as much silencing accessories as practical, but string jumping still occurred with it.

Eventually, Parker went out of business. I was on my second Parker crossbow by that time. Knowing I could not get parts in the future, I started looking for a new crossbow. I found that Mission Crossbows were a spin-off of Mathews. Given Mathews focus on quieting there bows, I decided to go this route. I ended up buying a Mission Sub One Lite. There is a picture on this thread: Pic of Sub-One with Oracle X

Any string jumping issues disappeared when I got this bow. I like to play with technology, so one of the mods I made to the package was eventually replacing the red-dot scope with and Oracle X. A thread that includes an update on the Oracle X

THE ISSUE: (Start reading Here)

I killed lots of deer from treestands with the Sub One Lite. As I'm getting older, I'm limited to ladder stands, and I'm relying more and more on box blinds. They have presented a new issue with my crossbow. Because of the large distance between the scope and the riser on a crossbow, it can be difficult to get a clear site picture and be sure you don't hit the window seal. In fact, I've had several issues with the arrow nicking the window seal.

I tried building a device that I could fold forward under the riser to rest on the seal. It worked ok. Then I found out that Mission sells a stirrup for the Sub One Lite. Normally, you step on the riser to cock the bow. They did this so shorter folks can cock it and it does make the overall length shorter. I purchased one and installed it last season. I did not have any shot opportunities I liked with my crossbow last season, so this season is the first use.

I have now harvested 2 does with it. Both sort of jumped the string. Unlike a classic string jump where the entry wound is high or the arrow goes over the deer's back, both entry wounds were exactly where I aimed. Both shots looked good, Neither deer left a blood trail, and I was lucky to find both.

My post mortem showed the same thing on both. They both jumped the string as the arrow entered. In both cases the exit wound was significantly higher than the entry wound. In fact, on one deer the arrow was still in the deer when I found it, and during butchering today, I found the exit hit the very top of the far shoulder. The entry wound was in the lower third.

THEORY:

I'm thinking that the stirrup against the wooden window seal is causing a delayed noise that occurs after the arrow has left the bow. The in-flight trajectory is not affected and the deer is beginning the string jump just as the arrow is entering the body.

SOLUTIONS:

My next posts will include potential solutions with pictures. My first one will be to modify some kind of Limbsaver device modified to fit on the stirrup so that there is a rubberish stand-off between the stirrup and the window seal.

 

[1100LT20]

Enjoyed reading your archery evolution.

 

[swat1018]

You're making a couple hypothesis that may or may not be correct. It may have nothing to do with the stirrup, and it may not be string jumping, at all. What broadhead?

 

[yoderjac]

You're making a couple hypothesis that may or may not be correct. It may have nothing to do with the stirrup, and it may not be string jumping, at all. What broadhead?

Of course. That is what we do. We make an hypothesis, make small changes, test, and collect evidence and see if it supports the hypothesis or not.

To that end, the place to start is with what has changed. I did buy new broadheads to make a switch a year or so ago, but I have still not used them for hunting. I'm still finishing up my supply of Rage. They are the exact came broadheads I've been using for years and not having any issue like this. They don't open in flight and the bow shoots bullseyes at 50 yards at the range with them.

Your point is well taken, and I'm glad I haven't switched broadheads yet so I can eliminate that as a likely issue.

Tonight, the evidence has piled up to support my hypothesis.

First, I the dampeners came in today. I put them on the bow.

I never needed Limbsavers on this bow because it was so quiet. I just got them for the limbs just in case. The ones that I got to address the issue are the small ones for a youth bow. In the picture you see them om the bottom of the stirrup. Of course, I had very low confidence these would last. They are held on by adhesive and are intended to go on the limb face where there is a large flat surface. I'll need to find some way to attach them permanently, but I just stuck them on for a test.

At the range, the Limbsavers I put on the limbs had no effect on accuracy. The bow shot darts with no difference from before I added them. I needed no sight adjustments at all. I'm not sure they will help any, but with no change in impact point, I figure they won't hurt.

The first revealing thing was shooting the bow at the range. It was as quiet as ever to my hear (my hearing aids were in). It seemed significantly quieter than it was for the last two deer I shot. At the range, I shoot the bow the way I shoot it in an open treestand. I have a monopod that attached to the bow. In a treestand, I rest the monopod on my boot which give me greater flexibility in positioning the bow for a shot. At the range, where movement is not an issue, I just rest it on the ground, but in both cases, the front anchor point is the monopod.

The difference shooting in a box blind is that I would rest the riser on the window seal until I got the stirrup and now I rest the stirrup on it. I don't use the monopod in a box blind.

So, this supports the theory that my issue is coming from the way the front of the bow. The other thing that happened at the range, of course, is the two small limb savers fell off the stirrup. I didn't expect them to stay on with just the adhesive. I'll need to work on that.

THE HUNT:

I figured that I'd try one more hunt without the Limbsavers on the the stirrup. About 5:00pm a young 5 point entered the field and fed on my jujubes for about 40 minutes. He finally left and about 5 minutes later a doe and 2 fawns entered to do the same thing. I'm guessing she was waiting for him to leave.

Long story short, I had a shot opportunity at the doe. I rested the stirrup on the window seal. I paid very close attention when I released the arrow aiming slightly lower than normal. The bow was MUCH louder than at the range. I'm sure some comes from the fact I'm in an enclosed box blind, but it was more than that. I watched the doe intently. I saw her chest hit the ground and the arrow sail over her back. A very clear case of string jumping. She was more jittery than the other two does I shot and I think she reacted to the sound quicker and more violently.

I quit after that and headed out to verify everything while it was still light out.

NEXT STEPS:

I decided to bring the crossbow home with me and take tomorrow off to find a way to secure the small Limbsavers to it. When I grabbed the case for the sub one lite, I opened one of the pockets. I found the bag the stirrup came in. It reminded me of something that I forgot. In the bag, were the original rubber standoffs. When you install the stirrup, you need to remove the rubber standoffs from the riser. I'm now thinking that those rubber standoffs were insulating the riser from direct contact with the shelf. This further supports the theory that I need some kind of rubber buffer between the stirrup and the window shelf.

I'm thinking about tying them to the stirrup. Another thought might be to drill a hole in a limbsaver of some kind and thread it on to the stirrup, but it would need to be larger than the ones I got.

 

[Mennoniteman]

I have a friend who shoots a lot of crossbow deer out of hunting blinds, and he had the exact same issues, although a different crossbow brand. He walked a similar journey, losing a few deer. He blamed a part of his problem on spooky deer, which isn't much to be done about, but he was sure that the cause was the same, crossbow noise transferring through the windowsill.
After a few bunny trails somewhat similar to what you're on, he came to some truths, the root of the cause, and also a good solution. The truth is that certain models and combinations are quieter, but you can't get a crossbow quieter than so quiet. And noise transfer through the rest into the window sill the acts as a sound wave broadcaster may be a part of the problem, but it's the smaller part, the greater noise source is the general sound of the bow itself, directed out the end of the rail similar to a rifle, right at the open window.
So his solution is a three legged tripod that he sets up inside the blind to keep the crossbow further away from the window, thus containing most of the noise inside the blind. His success rate went way up, and he gets very vocal about the importance of a tripod set back from the window for crossbow hunting.

 

[yoderjac]

I have a friend who shoots a lot of crossbow deer out of hunting blinds, and he had the exact same issues, although a different crossbow brand. He walked a similar journey, losing a few deer. He blamed a part of his problem on spooky deer, which isn't much to be done about, but he was sure that the cause was the same, crossbow noise transferring through the windowsill.
After a few bunny trails somewhat similar to what you're on, he came to some truths, the root of the cause, and also a good solution. The truth is that certain models and combinations are quieter, but you can't get a crossbow quieter than so quiet. And noise transfer through the rest into the window sill the acts as a sound wave broadcaster may be a part of the problem, but it's the smaller part, the greater noise source is the general sound of the bow itself, directed out the end of the rail similar to a rifle, right at the open window.
So his solution is a three legged tripod that he sets up inside the blind to keep the crossbow further away from the window, thus containing most of the noise inside the blind. His success rate went way up, and he gets very vocal about the importance of a tripod set back from the window for crossbow hunting.

Actually, that is what led me to this point. I use a monopod from a treestand and it works great. So, when I started using my box blinds, I used it. Same principle as the tripod with more flexibility and less stability. My issue with it was having the broadhead clip the window seal. My blinds are elevated, so I'm shooting at a downward angle. I have multiple windows depending on the blind, so I monopod is more flexible moving around.

My windows are push-out type hinged at the top. We have more warm weather than cold here so my blinds are designed for air flow and not sealed up and insulated like up north. The push-out style windows work as sun shields letting less light into the blind to shine on me. The relatively large distance between the scope and the rail where the arrow sits means that it is difficult to have a clear sight picture with the scope and an arrow path that clears the window seal if you are shooting from inside the blind. I had several incidents where my arrow hit the window seal early on.

That is what lead me to buying the stirrup. I'm glad to hear I'm not the only one with this issue.

I may play with trying to tie the youth bow limbsavers to the stirrup today. I really don't think that will be a long term solution. I think putting my foot in the stirrup to cock the bow will eventually knock them off. I ordered some 3/4"x3/4 rubber spacers with a 1/4" hole through them. They should arrive tomorrow. I think threading these on to the stirrup will be a more durable solution. I'm not sure if this will provided enough height. Also, they are rubber, but I don't know how hard the rubber will be. I'm still looking at other navcom material limbsaver products to see if I can modify them similarly with a hole for threading on to the stirrup.

 

[yoderjac]

This is a temporary solution at best. I simply punched holes in the plastic base and used braided fishing line to tie them on to the stirrup.

 

[Mennoniteman]

My buddy has a mono-pod with three feet on the bottom, kindof like an old people's cane with three legs at the bottom. It's a little more compact than a full tripod for hunting inside a blind.
It sounds like your best solution to not cripple any more deer might be to start replacing hunting blind windows.
As far as new hunting blinds, most of the hunters in my circles are hunting out of 360HuntingBlinds, specifically because of their windows. I'm going to stick my neck out and say that 360 has the best hunting blind windows in the business, and also the most repeat buyers.
I will never own another hunting blind with any type of tilt out or tilt in windows, vertical or horizontal, there's so much wrong with tilt-out windows for close range archery hunting that I'm not even going to start getting into that.

 

[yoderjac]

My buddy has a mono-pod with three feet on the bottom, kindof like an old people's cane with three legs at the bottom. It's a little more compact than a full tripod for hunting inside a blind.
It sounds like your best solution to not cripple any more deer might be to start replacing hunting blind windows.
As far as new hunting blinds, most of the hunters in my circles are hunting out of 360HuntingBlinds, specifically because of their windows. I'm going to stick my neck out and say that 360 has the best hunting blind windows in the business, and also the most repeat buyers.
I will never own another hunting blind with any type of tilt out or tilt in windows, vertical or horizontal, there's so much wrong with tilt-out windows for close range archery hunting that I'm not even going to start getting into that.

My blinds are all custom built. I love the push out windows that shade from direct sun coming into the blinds. I would not want to change that, especially because I still use them to take kids out. As I said in one of the previous posts, I started going the monopod route and had issues with window ledge strikes.

Fortunately, I have not crippled any deer since this issue arose. I killed and fortunately recovered the first two and had a clean miss on the third one.

The rubber cylinders I ordered came in today. I did not even bother trying to install them. The rubber was way too hard, and I don't think it would dampen the sound enough. I have a couple Limbsaver target stabilizers on order that are supposed to arrive tomorrow. I plan to drill holes through them and install them on the stirrup. They are soft and flexible enough to prevent any vibration from the bow being transferred to the window seal. I'll post back ones I've doen that.

 

[Mennoniteman]

My blinds are all custom built. I love the push out windows that shade from direct sun coming into the blinds. I would not want to change that, especially because I still use them to take kids out. As I said in one of the previous posts, I started going the monopod route and had issues with window ledge strikes.

Fortunately, I have not crippled any deer since this issue arose. I killed and fortunately recovered the first two and had a clean miss on the third one.

The rubber cylinders I ordered came in today. I did not even bother trying to install them. The rubber was way too hard, and I don't think it would dampen the sound enough. I have a couple Limbsaver target stabilizers on order that are supposed to arrive tomorrow. I plan to drill holes through them and install them on the stirrup. They are soft and flexible enough to prevent any vibration from the bow being transferred to the window seal. I'll post back ones I've doen that.

Good luck, but you're barking up the wrong tree.
You're up against hard physics working with silencers that can only give you a small percentage improvement on what's already one of the quietest crossbows.
Working on figuring out how to pull the bow back into the blind could give you a large percentage improvement on projected sound waves outside the blind.

 

[yoderjac]

Good luck, but you're barking up the wrong tree.
You're up against hard physics working with silencers that can only give you a small percentage improvement on what's already one of the quietest crossbows.
Working on figuring out how to pull the bow back into the blind could give you a large percentage improvement on projected sound waves outside the blind.

Thanks. I do think the physics is on my side. I've never had string jumping before. I think there are two possibilities. One is that vibration from the stirrup itself is creating the additional noise. The second, is that is the interaction between the hard metal stirrup and the hard wooden window seal.

For possibility number one, you are right, the physics will only allow small improvements in dampening the vibration. I am discounting this possibility because of the audible difference in the sound of the bow when shot from a monopod with the stirrup attached and when it is shot with the stirrup on a window seal.

For possibility number two, I think the physics is in my favor. By insulating the two separate hard surfaces, I'm expecting a significant reduction in vibration transfer.

I guess time will tell. If this approach doesn't work, I'll look at alternatives.

 

[catscratch]

Shoot at deer that are closer?

I've hunted with bow my whole life. There's limitations. I'd rather stay well within those limitations. If the problem is consistent then why the push?

 

[yoderjac]

Shoot at deer that are closer?

I've hunted with bow my whole life. There's limitations. I'd rather stay well within those limitations. If the problem is consistent then why the push?

You are absolutely right about the limitations of bowhunting with compound or crossbow. With a compound bow, a lot more of one's personal shooting abilities come in. While you may be able to shoot bullseyes at the range at 50 yards, hunting is a different situation. Clothing is often heavier, you rarely will have perfect shooting form from a tree stand. Often you are shooting at odd angles. In fact, when I was using a compound bow, I would shoot a draw length about 1" shorter than for target shooting. This helps when shooting at awkward angles and still maintain upper body shooting form. My limit with a compound was 25 yards for does. For bucks, with a somewhat larger kill zone, I would extend that closer to 30 yards depending on conditions and the situation.

With a crossbow, the shooting form is primarily enforced by the rail, but you don't extend range over a compound in competent hands. When you get beyond 30 yards, you can't really see small branches with no leaves on them. It takes very little to deflect an arrow to cause wounding.

My limit, with a crossbow is 30 yards. Beyond that, too much can go wrong. All three deer were within range and presented good angles. This is a string jumping issue. When it comes to string jumping, close is actually a bigger problem. There are always noises in the woods like limbs falling and such. If deer reacted to everything, they would never get a chance to eat. They have what I would call a proximity zone. When they hear a sharp noise close by, they react by recoiling, dropping their chest, and then bound off. The sharpness of that noise and the proximity both come into play when it comes to what, if any, physical reaction they have. Sometimes noises further away will illicit an alert reaction rather than a recoil and bound reaction. Different deer in different situations have their own thresholds, so there is no hard number in distance as to when they will jump the string.

So, while you point of taking close shots is very well taken, that is not this issue in this case.

 

[yoderjac]

The target stabilizer dampers came in today. My original idea a drilling a hole 90 degrees to the existing hole and threading them on to the stirrup was not practical. However, threading them on to the stirrup through the existing hole seems to work pretty will. I had my wife hold the bow with the stirrup leaning against my desk at about the angle I would use in a blind. This first picture is taken from above looking down.

This second picture is taken from desk level. It shows I have about 1/2 of air space between the stirrup and the desk with it resting on the navcom material.

I'll report back after using this in the field as to how effective it is. There is a nice tight fit between the dampeners and the stirrup. They would be sliding around or anything. I'm anxious to cock the bow with my hunting boots on to see how much impact that has to the dampeners.

 

[swat1018]

How will you know it's effective? If you don't wound one? Quite the price to pay for the deer. Caldwell and other companies make tripods, quad pods, you name it. There are shooting bags you could put on the window ledge. A couple crappy pieces of rubber seems to be the worst solution I could think of. Those "dampeners" may help some on a stand alone bow or crossbow if you are shooting off hand or something, but they won't accomplish much in your situation.

 

[yoderjac]

I haven't wounded one since the addition of the stirrup initiated the string jumping. I'll know if it is effective, first, by shooting target arrow from the box blind and listening to the sound character. I'll know it is effective if the string jumping stops. These dampeners are not being used like normal dampeners which are intended to absorb some of the vibration reducing the amount of energy emitted by the bow. Instead they are intended to make the crossbow operate like I was shooting it off-hand or from a mono or tripod. The idea is to eliminate contact with the window seal. I won't be concerned about string jumping if I can the the bow to perform at the level it did prior to the stirrup addition.

I have in previous years shot a few that I did not recover, but that is the nature of bowhunting, and none were due to string jumping. We will, on occasion have an equipment failure or make a bad shot. I'm pretty confident in this solution, but time will tell. As I previously described, there are other issues that pods create. A shooting bag would require the entire front of the crossbow to stick out of the blind.