# HPR Mk. I

971

8

24

My personal war gun, and favorite I've used thus far, this is my High Performance Rifle (tentatively Mk.1).

### Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

## Step 1: Explanation

In 2014, Zak designed a trigger system for TRs that is capable of reducing dead space to a bare minimum. Dead space is basically the amount of length on a firing pin that does not contribute to its acceleration. A firing pin that only accelerates 3 inches before stopping has more dead space than that of one which accelerates for 7 inches before stopping, assuming they are both the same length. Naturally, more length to accelerate means more power.

The latest TR is perfect for wars, but it has some drawbacks that I attempted to address with this gun. The first issue is the amount of dead space it bears: 5.5 connectors (though I prefer to use the term 'units', and will do so from here on), where my attempt landed me at a comfy 3. Another issue, though mostly conjecture until tested and proven otherwise, is the pin guide.

Oh I can already hear the angry mobs screaming at my door, but let's think about this for a minute. A pin guide requires at least one unit of a pin's length for a connector to tether the two. Generally, a guide is used to keep the pin from bending when it is being held in its cocked position, and when it is traveling to a lesser extent. In motion, I thought the pin would be traveling too quickly for the bend to affect power more than a pin guide's friction and the extra dead space. As such, if the pin can be held in position when it's cocked, a pin guide becomes unnecessary and redundant. So I scrapped it.

The absence of a pin guide left some extra space to play with, so I installed an ammo holder in its place. This provides ease of access to 24 extra pieces of ammo. After using the ammo holder in a war, I don't think Ill ever want to use a gun without one again!

Through several iterations and collaborations between Zak, ooda, and I, this gun is my contribution to the performance pool, and hopefully we'll see many more iterations down the line as I fix its problems and refine its strengths.

## Step 2: Gather Parts

Note that these parts are listed in K'nex's standard colors, though I used a slightly different color scheme on mine.

RODS

• Green: 186
• White: 53
• Blue: 23
• Yellow: 4
• Red OR Tan*: 2
• Tan: 1
• Gray OR Black*: 3
• Black: 5

*As always with performance guns, the stronger rod is preferred, but either will suffice in these cases.

CONNECTORS

• Metallic Blue Clips: 17
• Tan Clips: 31
• Dark Gray: 21
• Light Gray: 46
• Red: 23
• Green: 8
• Yellow: 106
• Blue: 4
• White: 11
• Orange: 16

OTHERS

• Hinge (black end): 10
• Hinge (blue end): 5
• Blue Spacer: 19
• Silver Spacer: 9
• Ball Socket: 1
• Y Connector: 20
• 1" Black Wheel: 6-18
• Bendy White rod: 3
• Small Wheel: 5
• Black Cap (see picture): 4

Before we move on, I'll assume that these numbers are not 100% accurate, as I just counted what is seen in the pictures rather than the gun itself. As always, be sure to go over the instructions thoroughly to figure out what parts you may want to substitute or subtract from your count (18 1" wheels may be out of reach for some people).

## Step 3: Barrel

Now then, let's get started with the build. The HPR was designed first and foremost with performance and efficient
use of space in mind. Every part of it serves some purpose, and altering it (for the most part) would make the gun worse. Be sure to follow these instructions as closely as possible, as most alterations would hamper its effectiveness.

Some surface details could be slightly modified to accommodate for comfort or lack of parts, like the 1" wheels on the handle or any of the extra connectors on the blue rods throughout the stock. The end of the stock is really the only part that could be modified, but all the main structure must remain intact.

Throughout the instructable I have placed several notes on images pointing out key information, so be sure to check every image for them!

## Step 4: Shoulder Rest / Stock

This is a bit extravagant I admit, but it's the most comfortable I've made for it. You could just as easily make it a square instead, so long as the main structure remains intact.

## Step 5: Body

This section is where most of the gun's strength comes from. The 1" wheels are not necessary, but they add a great deal of comfort to the gun. I believe the tires KILLERK uses on his handles will fit this gun as well, so you could use those as an alternative. Personally, I like the tape. If you choose to use tape, put a layer on upside down first, then cover it with a second layer so it doesn't leave a sticky residue on your parts.

## Step 6: Bits

I didn't take any extra pictures of the turret because it is very straightforward. If you need any help, follow this link.

## Step 7: Assembly

Here we will assemble the gun. I have included several important notes in the pictures, be sure to read them!

## Step 8: Firing Pin and Banding

Fairly straightforward.

## Step 9: Turret Functionality and Finishing Up

This is a short and simple step demonstrating how to attach the turret to the gun.

## Step 10: Problems and Future Changes

The biggest issue with the current iteration of the gun is the slide. It is not nearly as sturdy as I would like and there are also some user-related problems; it is NOT foolproof. When you charge the gun for the first few times, learn where the back of the slide goes, because it will hit the pin stopper if you're not used to it. I have a few ideas to fix this, though have yet to implement them. Another thing to note, you do NOT want to pull back the slide from the wheel. I use the wheel purely for comfort, and it is not sturdy enough to support the force put on the slide.

Above is a video demonstrating how I fire the gun.

## Recommendations

• ### Lamps Class

9,673 Enrolled

## 24 Discussions

:'( It's been too long...

*exhales for the last time ever*

my take on that trigger placement

Not what I was expecting to see this morning, good to see you. Very interesting take on the TR. I like how you all manage to make each one look so different despite being the same concept. I noticed pin on the TR KK sent me had some pretty bad friction. I could feel it while cocking and decocking the gun. I could see the pin still bent inward too. The simple solution is figuring out how to mount bands in such a way to prevent bending in the first place. Albeit, it does get harder to do so the less "dead space" you have.

Now, a further challenge. You could eat up yet another "unit" if you were to make a system to draw the pin without being around the pin. Perhaps draw the rubber bands.

7 replies

new tigher design should reduce friction not as far back as this trigger due to the guide rod but still very efficient. With that being said I'll have pictures tomorrow. The friction you where feeling was entirely from the older design trigger pin wearing out due to the grooves that get dug into the one slot connector sliding against the firing pin.

Hmm possibly, though I usually hold the trigger down to decock the weapon, which I did a lot while testing out the comfort of different slide and handle configurations. I'll double check it. Let me know when you got pictures.

That got me thinking, wondering if we should attempt making diagonal firing pins so the grooves aren't always a problem. Would be nice for magazine guns too. Of course would be tricky if you intend on keeping pin guides.

I posted a video on youtube showing off the new trigger design and firing pin band placement. The trigger now uses 1 part instead of 2 to both stop the trigger from setting too high and also not be overly pulled. The trigger also reduced the wear on both the trigger pin and firing pin allowing for less maintenance and more consistent shooting. Finally a combination of both the new trigger and firing pin band placement should aid in a smoother overall charging of the gun and reduced friction making for a more consistent easy to use smooth firing gun. Yes it is true that Mepains gun does have a further pin draw by 2 to 2 1/2 units but the lack of a guide rod in my opinion may add the friction and or hit the back of the slide to charge the gun resulting in worse inconsistent shooting and lots of stress on the firing pin. That being said in any gun design one needs to weight out the pros and cons to figure out what the best solution is for the need of the gun and its uses. I can say that I love Mepains gun the stock is very sturdy and comfortable and the design is superb. That being said it is a preference thing. I designed my gun strictly for reliability and ease of use so even kids and can pick it up and shoot it repeatedly without any trouble or breaking it. This point has been proven to me by giving one to my wifes cousins that are 5-10 years old and it has lasted almost 2years without a problem. To me that is impressive. What is more impressive to me is that at last years war I supplied 4 or 5 TR8's of my design to my friends and brother who never use it and they had zero issues with it other than my brother who had the front rubberband mount shot and literally broke the Knex part. Again I would like to improve the stock but I also keep in mind those using it usually younger kids with short arms so a short compact design is both ideal for them and also for ease of use in tight spots including indoors. There are so many little things that are good and bad with every little change brought about to the gun. So as I said Mepain has built an excellent gun that looks very reliable whether or not he uses it consistently with 5 new size 64 rubberbands as I do as a standard for part wear and gun wear I do not know. I use my gun primarily to shoot fin ammo which is why I do not have the front wheel thing because with fin ammo it would be unusable and impractical at best. So anyway I am going on and on. Go check out my new trigger try it out with the new band placement on the pin and if you get a chance built Mepains gun Im sure you'll love it hes an excellent builder.

I appreciate that you're more thoughtful about your builds, you've got certain mentalities in your guns that you don't always explain, so that's all good and fine. I'll check out your video when I get home. There're definitely a lot of pros and cons to balance with TRs. Personally, you know me, I've always been a bit against focusing so much on range in the first place. Ease of use is right up there.

I posted a video of both the trigger and new firing pin band placement I also never gave you my new firing pin but I think I posted a video for that as well under my KILLERK youtube channel

I left a comment on you new (ish) TR8 ible you might want to read. I still have it built and the new trigger is doing great after at least 800 shots.

great gun still prefer my pin guide but there are so many great features this gun has to offer. All preferences at this point! It's been awhile and u changed my name to something a bit less threatenin lol

3 replies

On your next version of the TR, please try a different handle, one more like the one on the HPR, since I find the handle on your TR to be sorta flimsy. With a very solid handle it would be a lot better.

if you've built my most up to date TR the handle is very strong not sure I'll make it much stronger however I plan on testing out my new trigger tomorrow which should reduce friction and wear

I like this much better than KKs TR, I think it's really overrated. Good job, I actually like this even though I'm not a fan of the TR set up.

3 replies