Quantcast

I've been developing a drop-in bullpup rifle chassis for your bolt action!

Discussion in 'Rifle Country' started by tykempster, Oct 26, 2015.

Thread Status:
Not open for further replies.
  1. tykempster

    tykempster Member

    Joined:
    Oct 26, 2015
    Messages:
    44
    Hi guys, new member here. I've had several people tell me there are some folks here who would love to see a project I've been working on.

    I'll tell you a bit about it, then there will be some pics at the bottom.

    I'm a long time precision, long range, and competitive rifle shooter. Through the past few years I've got to mess with Desert Tech (formerly DTA) bullpup rifles, and really like the reduced length, and features they offer. But their price is out of my budget, and that of many shooters. Which led to me developing my own chassis for popular bolt actions, starting with Remington 700 short action, including some features I think are pretty neat:

    Modular design, you will be able to interchange different parts to make the chassis how you want it. This includes rear sections, forends, rail placement, M-lok, keymod, rail cant, etc.

    Adjustable length of pull, recoil pad height, recoil pad cant, and cheekpiece horizontal and vertical adjustment.

    AICS and AW magazine compatability, I think they're simply the best in the industry. Eventually the plan is offer other magazine inlet types for whatever a customer prefers.

    Trigger and safety assembly comes installed in the chassis. You just unbolt your rifle from the existing stock, knock out the trigger pins, bolt in the barreled action, and reinstall pins to hold the trigger and safety assembly already in the chassis to your action.


    Here is a rendering of what the first chassis will look like

    ohJaRoU.jpg
    And here is where I'm at so far. Trying real hard to get this first prototype done by deer season in a few weeks, so I can carry it around and see what I think needs changed for version two

    BRPy5Q2.jpg
    Hope I didn't bore everyone! If you're interested in further developments, I'll post them here if there is good feedback, alternatively I have a facebook page at "MK Machining" you can follow for more information.

    Thanks,
    Tyler
     
  2. entropy

    entropy Member

    Joined:
    Feb 9, 2004
    Messages:
    8,606
    Location:
    G_d's Country, WI
    Nice looking design! :cool: George Lucas should hire you. There are several problems from the ergonomic perspective with bullpup bolt actions, the glaringly obvious one being manipulating the bolt is either very awkward while shouldered, or causes one to unshoulder the rifle. (Admittedly, most bolt actions are better worked unshouldered; the SMLE being the far superior exception.) Then there is the physical disadvantage/mechanical disadvantage encountered when holding the forearm regularly while working the bolt (with the rifle unshouldered) The rifle needs to be either held against the body for leverage, or the shoother must have a rather strong grip, particularly with that cylindrical forend.
    Next, we examine the trigger. Getting a marksman/sniper-level trigger in a bullpup is extremely difficult. The various semi-autos (The AUG & Tavor are the only two I have examined in detail) have acceptable combat triggers, but not in the league that a bolt action should have, and needs to have for such rifles' intended purpose.
    Which brings me to the crux of the situation. What is the purpose of a bullpup bolt action? I could see three possible uses for such a rifle, one of them somewhat nefarious:
    • One: A sniper rifle for use from within, or transfer of the sniper within, smaller armored vehicles.
    • Two: A sniper rifle for Covert/Black Ops types who will be transporting said rifle in populated areas, and want one that doesn't need to be 'assembled', like in so many Bond movies.
    • Three: A hunting rifle for all those Outdoors channel cowboys who currently use T/C Encores for ground blinds. But why mess with success there?

    You might want to reconsider the action you build on. The Remington 40 single shot would be a better choice, (Think XP pistol with a legal barrel and a stock) as there is no advantage to having the magazine on that rifle for the aforementioned reasons. It makes sense when you think about it. Getting five shots off with that Remington 700 in your prototype chassis would not be fast, and accuracy would suffer greatly (due to awkward postions or unshouldering and reshouldering ) when compared with a regularly stocked 700.

    I'm not trying to discourage you; on the contrary: I'd like to see a finished product. But I personally think taking the route of a single shot like the 40XB instead of a repeater, or a chassis to mount the Safety Harbor Firearms SHTF .50 AR upper in might be both more commercially successful, and a better solution for what you are seeking to do. i think if you could develop a bullpup lower for the SHTF .50 that incorporates some sort of recoil reduction, and a decent target trigger, and be able to market it under $500, you'd have a winner. I know I'd buy that. :cool:
     
    Last edited: Oct 26, 2015
  3. dh1633pm

    dh1633pm Member

    Joined:
    Apr 28, 2009
    Messages:
    2,016
    Location:
    Central New York
    Cool is all I can say. You have to figure out a mechanism to operate the Bolt from a more forward position. Without the Mag and on a single shot platform, you design would still be cool, just not as cool.
     
  4. MistWolf

    MistWolf Member

    Joined:
    Aug 17, 2005
    Messages:
    3,143
    So long as any part of the shooter interface (i.e. forearm) is made of metal, I'm not interested
     
  5. farmerboy78

    farmerboy78 Member

    Joined:
    Jan 19, 2010
    Messages:
    944
    I like the idea of a bullpup chassis... pm me please
     
  6. shootniron

    shootniron Member

    Joined:
    Jan 29, 2012
    Messages:
    518
    Location:
    South
    Looks like you have put a lot of work into it. Good luck.

    But, I ain't gonna be putting my head beside a rifle action...just me.
     
  7. gbran

    gbran Member

    Joined:
    Jan 21, 2003
    Messages:
    2,987
    Location:
    california
    I see this in a hunting application.....short overall length might be a bonus and in this application, I don't see the bolt location as being a problem. I hope it catches on. I'd try one in .308.
     
  8. adcoch1

    adcoch1 Member

    Joined:
    Oct 2, 2015
    Messages:
    2,147
    Location:
    Centralia Washington
    I have been over this idea myself probably 4 times, and the problem I run into is a Smooth and Light trigger. Bolt guns have great triggers and it is due to few moving parts. Add a linkage or trigger bar with any weight to it into the equation and it gets harder. Second problem is having your face next to the action. Not an issue when everything works, but if a case or primer fails you are closer to the escaping gas. Third is bolt ergonomics. That being said, I want one and would willingly help you in any way I could to see you succeed. Your prototype looks awesome...
     
  9. tykempster

    tykempster Member

    Joined:
    Oct 26, 2015
    Messages:
    44
    As several have stated, the bolt location and trigger are the big difficulties.

    Anyone who has shot a DTA knows a bullpup can have a nice trigger. I have a patented design on the trigger and safety function, with trigger feel being my number one concern.

    As far as the bolt, the chassis will work with no bolt modifications, although an optional bolt extension will optimize ergonomics, and put the bolt knob in a familiar position.
     
  10. Art Eatman

    Art Eatman Administrator Staff Member

    Joined:
    Dec 22, 2002
    Messages:
    46,547
    Location:
    Terlingua, TX; Thomasville,GA
    For a hunter, one favorable aspect is the ease of handling when inside a vehicle. This was true for varmint hunters, mostly, back in the 1950s/1960s. A friend of my uncle's built one with a Model 70 in .220 Swift. Ride the ranch roads, going for coyotes and jackrabbits.

    Yeah, the trigger is the main problem.
     
  11. jrexa

    jrexa Member

    Joined:
    Oct 10, 2014
    Messages:
    23
    Location:
    Nuuk, Greenland
    The trigger could be Solved, by using an electronic trigger, instead of a mechanical connection.
     
  12. MCMXI
    • Contributing Member

    MCMXI Contributing Member

    Joined:
    Jul 1, 2008
    Messages:
    8,251
    Location:
    NW Montana
    Bullpup bolt action designs have never really caught on for three reasons:

    1. Typically poor triggers (problem for bolt action and semi-auto designs)
    2. The location of the bolt relative to the shooter offers poor ergonomics and limited mechanical advantage
    3. The location of the magazine relative to the shooter makes magazine changes awkward

    Lightweight folding stocks are where it's at.
     
  13. tykempster

    tykempster Member

    Joined:
    Oct 26, 2015
    Messages:
    44
    I will post up some videos of the trigger in action. Negligible added friction or weight.

    Trigger will be excellent. Bolt extension is optional to put the bolt handle where you expect. The magazine is obviously further back, but the process is no different to put another one in, and your hand is already right there if it's squeezing a sandbag.
     
  14. dh1633pm

    dh1633pm Member

    Joined:
    Apr 28, 2009
    Messages:
    2,016
    Location:
    Central New York
    tykempster, Don't you dare stop updating us on your progress.
     
  15. Edarnold

    Edarnold Member

    Joined:
    Jan 8, 2012
    Messages:
    640
    Location:
    Northern Illinois
    One solution to the bolt-operation problem is a straight-pull action with an extension to the forend, making it a pump action. A couple have been built around the Swiss K31 action, apparently successfully.
     
  16. gunnutery

    gunnutery Member

    Joined:
    Jul 30, 2009
    Messages:
    1,682
    Location:
    Iowa
    I like the use of AR grips. With so many flavors, I don't know why any new pistol gripped guns aren't made to accept them.

    I've never bothered to check, but would it be possible to have different manufacturer's mounting holes in each chassis? Such as, chassis #1 has holes to mount either a Remington 700 or a Savage 10 (for example). Or are their mounting points too close together to be separate holes? Just asking.
     
  17. entropy

    entropy Member

    Joined:
    Feb 9, 2004
    Messages:
    8,606
    Location:
    G_d's Country, WI
    I thought of mentioning that, but the milsurp collector in me doesn't want to encourage sporterizing one of the finest milsurps made.
     
  18. TTundra

    TTundra Member

    Joined:
    Jan 6, 2015
    Messages:
    147
    Have my attention. I'll be following your progress.
     
  19. tykempster

    tykempster Member

    Joined:
    Oct 26, 2015
    Messages:
    44
    The answer to your question is maybe. But what about the diameter of the action? And the triggers aren't in the exact same spot, your operating rods need support. And the bolt isn't in the same position....it's easier to just make a separate center section for each action. You will be able to bolt in rear and forend sections from your Remington chassis to a Savage center section you buy. Modularity FTW!
     
  20. d2wing

    d2wing Member

    Joined:
    Nov 10, 2008
    Messages:
    3,660
    If you are not going to use a semi auto the only other action that makes sense is a pump action like the Remington 7600. I see no purpose for a bolt action bullpup but maybe others do.
     
  21. Hookeye

    Hookeye Member

    Joined:
    May 24, 2015
    Messages:
    2,696
  22. tykempster

    tykempster Member

    Joined:
    Oct 26, 2015
    Messages:
    44
    Update time!

    YCFHbek.png

    V2 is coming soon :) I think it looks fantastic, and I can't wait to feel this second prototype. Adjustable length of pull, cant, and cheekpiece with no tools. Recoil pad height takes an allen wrench, although I'm working on making that hand adjustable as well.

    Timney is going to be creating custom trigger units just for this chassis, and V2 is being sent their way as soon as it's finished. My prototype trigger increased pull weight on an Xmark trigger from 2.5 to 2.75lbs, and really pleased me with how it felt. Things are coming along really nicely, the plan is to be ready by spring for some preorders at a reduced price before full production.
     
  23. bikemutt

    bikemutt Member

    Joined:
    Dec 24, 2010
    Messages:
    4,480
    Location:
    Vancouver, WA
    nice, I'm in when you get it done, assuming reasonable price.
     
  24. mjsdwash

    mjsdwash Member

    Joined:
    Jan 14, 2011
    Messages:
    1,194
    looks like the bolt will be a few inches from the shoulder... sounds like a terrible idea, but if you pretend to hold it, and go throu the motion, its not that weird. Having the shoulder tension would likely make the bolt easier to work right there. May take getting used to, but i think it would be less work, than trying to reach out. The elbow would be bent, but the shoulder does not need to move, giving a solid grip. nothing wrong with new ideas
     
  25. goon

    goon Member

    Joined:
    Jan 20, 2003
    Messages:
    7,250
    I'd never discourage a guy from trying something new, but ergonomically, it's not for me. I think it might be adaptable to a straight pull design though - you could basically just stick the operating handle in a different place.
     
Thread Status:
Not open for further replies.
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice