River's Consolidated Custom Built Bullpup Thread

Discussion in 'Hi-Point Carbines' started by riverrover, Sep 22, 2020.

  1. riverrover

    riverrover Member

    62
    37
    I know there's a HTA bullpup "In general" thread, but I hate to dive into 1300+ replies to search for scattered answers and discussions of this topic.

    So, I going to build a custom 995 bullpup! OK, stop laughing. I bought a beater, monkey stock 995 for THAT purpose and win or lose, I will try. If I win, cool. If I lose, the remains / parts will be sold here at a great discount!!

    Sight lines:
    The sight line of the 995 is about 1-3/4" above the cheek rest area of the classic stock.
    The cheek rest area of the HTA MBS is about 1" higher than the classic stock CR area.
    It appears on the HTA that the top rail is just slightly above the cheek rest area.
    Will AR15 rail sights be a proper height for the HTA stocked HP? Are AR15 rail sights offered in different heights? I've researched this some and it seems a sight is a sight regardless of AR configuration and caliber. Anyone know the general sight line height of AR sights above the rail? Will a rail riser need to be used on a HTA to get the sights to a taller height?

    Optics:
    Same as above. What do you use on a HTA MBS and/or what lines up properly?

    RE: My custom BP, at this planning stage time.
    I'm looking at using the Leapers UTG flip up sights.
    Metric FAL grip and sectioned lower w/ custom built trigger.
    Mini forward grip
    Square barrel shroud will have full length Picatinny rail on top and sides will be machined w/ M-Lok slots.
    Metric or Inch FAL forward mounted charging handle.
    Frame cover, slide and barrel shroud - misc square tubing and farm junk.
    Optics?
     
    Last edited: Sep 28, 2020
  2. If the sights are mounted to the same rail, or at the least, on the same plane; then it should be good to go regardless of sight height over bore. The only possible issue is if you're trying to keep the original front sight on the barrel and align the rear sight on the rail. Otherwise, nah, you're good to go, just get it zeroed when its all installed :)
     

  3. riverrover

    riverrover Member

    62
    37
    It may not be too critical on a 9mm carbine, but bore to sight lines can be pretty tricky.
    If you chop a FAL barrel from 21" to 16-1/4" your sight line, sight adjustments are out of spec. You cannot bury the front sight low enough to make up for the loss of bullet velocity to cross the sight line and hit the target based on the graduation of the rear sight. You generally have to put on a taller rear sight. Or you play the guessing game of: Put it on 3 to hit 200 yds. Put it on 4 to hit 380 yds. 5 is 450, etc.
    If a 9mm carbine barrel and the sights are on a parallel plane, you will never hit the target. The rear sight must be high enough for the bullet to pass through the sight line at "say" 25 yds then drop back down on target at 100 yds. And once you get a set of sights calibrated and sighted in to your rifle, do you have to add a cheek riser to see the sights or take a rasp and carve a hollow into the stock to get you cheek low enough?

    I figured there are some Hi Pointers who have used the HTA stock and already figured some of this out. I'm was just curious, but sure, I can build the cheek comb as I need or more likely add risers to adjust the sights as needed which is the easier path. The top of my BP will be pretty much like the HTA BP. Full length rail from rear sight to muzzle.
     
  4. Weird thing is... when Colt did the XM177 series of carbines, they had to use a taller front sight post until the M4 Carbine came out with the taller F marked carbine front sight base so that the M16 and M4 can use the same front sight posts. Taking this into consideration, a shorter sight radius would require a taller front sight post or base, depending on the setup. On the other hand, the AR15 flip ups are already compensating for the sight radius and parallax alignments for the AR. FWIW, the F marked base is 1.98" tall from the edge of the 0.750" diameter to the machined surface between the ears, while the A1/A2 Rifle FSB is 1.94" from the same diameter to same surface. Adding the radius of 0.375 to 1.94 means a sight line height from bore centerline of 2.355".
     
    riverrover likes this.
  5. riverrover

    riverrover Member

    62
    37
    Thanks CD
    With the FAL, they were just shortening the bbl, but the sight radius was the same so that threw the sight base adjustment/ battle zero at 200m + the 3-6m bullet drop graduations off. The adjustable rear sight were only for a 21" I assume as when FN made 18 & 16" bbl FALs that just used a non adjustable fixed sight or a 0 - 200m "L" type flip aperture.

    A company called Precision Armament sells Picatinny rail blanks that are 9/16" tall. I assume you drill and machine them to the height you need. Not cheap, so will have to shop around. I really don't like to have clamp on sights to clamp on risers, but that would work too.
     
  6. riverrover

    riverrover Member

    62
    37
    We all know what the bolt retainer is. Now, just behind the bolt retainer is a vertical strip that is part of the trigger frame. I noticed there is a gap between the 2 parts. I would have thought the vertical frame strip would have supported the bolt retainer to keep it from bending back?

    Then again, looking at the Numrich Arms parts diagram of a 1st Gen Hi Point carbine the frames vertical guide strip wasn't even used then!

    HP Gen 1 bolt retainer.PNG
     
    Last edited: Oct 8, 2020
  7. riverrover

    riverrover Member

    62
    37
    I've been working on my monkey stock 995 to DIY bullpup and had to figure out the max bolt travel during recoil. Yes, seems like the bolt stop is via hitting the inside of the stock. Outside of the stock, the bolt travel is a bit further even w/t recoil spring installed.

    On my bullpup, I'm installing a 3/8" thick recoil buffer that will be about 1/8" forward of where the bolt currently stops in the monkey stock. Hoping the overall travel at full recoil will end up the same. The buffer will be accessible to trim the rubber down or add a flat washer behind if need be.

    Any chance the TS stock could have a buffer of some sort installed for the bolt to impact?

    IMAG0001.JPG IMAG0002.JPG
     
    Last edited: Oct 14, 2020
  8. riverrover

    riverrover Member

    62
    37
    This must be the most secretive feature of a HP carbine other than the rare NATO Stanag offset NV mount made in the Federated States of Micronesia when they were considering the HP 995 for their civilian militia.

    I've seen old discussions about the bolt catch. Never have seen any pics of or how the catch actually works. Is the assembly all internal where you have to pull the mag from the carbine then pull the bolt back to release the catch? No external thumb gripper to release the bolt?
    Is the catch attached to the frame or to the bolt?

    Thanks
     
    Last edited: Oct 15, 2020
  9. cicpup

    cicpup Resident PITA Supporting Member

    15,834
    5,595
    Vermont
    Yea. That one.
     
    fatal-bert33 likes this.
  10. riverrover likes this.
  11. riverrover

    riverrover Member

    62
    37
    Thanks Adam! That pretty much explains everything. While my 995 frame has the square hole for the LRHO arm to reach the mag follower, the HO assembly was never installed. The bolt also has the clearance for the assembly.

    As my bullpup conversion will have a open frame on the LH side, I should be able to fabricate a HO that can be externally tripped after a fresh mag is installed! I won't be able to mod and install an original HO assembly as my conversion will be using Beretta 92F mags.
     
    Last edited: Oct 15, 2020
  12. undeRGRound

    undeRGRound ROLL wif Da MOLE! Supporting Member

    25,296
    1,524
    INDY
    Ok I suspect you have another post about this "project" and I am intrigued...
    I did a work-up (pix and measurements) of this exact combo but in the Fouhty-S&W.
    So a 4095 and a Beretta 96 mag combo. Beretta and most other, what I call "Euro-Spec"
    double stack magazines (Browning Hi-Power, Beretta, CZ, Tanfoglio and other knock-offs)
    are about as slim as a 9mm double stack gets. Many American 9mm use it as well.

    I still saw a need for receiver clearancing, and there was a pesky linkage on the left
    side. Without going back over it, I suspect that is the LRHO and that is why you are
    on this current track. I also believe you are using the Monkey Gun stock??
    @riverrover
     
    riverrover likes this.
  13. undeRGRound

    undeRGRound ROLL wif Da MOLE! Supporting Member

    25,296
    1,524
    INDY
    I have a lot of Pic Rail "extras" but not sure if any are quite that thick. Doubtful.
    But I have some really long rails...
     
    riverrover likes this.
  14. Rachgier

    Rachgier Administrator Staff Member

    Yes, @riverrover is cross posting everywhere about his project. Up to 8 threads now?
     
    fatal-bert33 likes this.
  15. riverrover

    riverrover Member

    62
    37
    Actually, I have not posted even one dedicated "build" thread on my project. I have commented about my project in other threads authored by other people. And I have authored a few threads inquiring about specific carbine designs and functionality that will help me with my project.

    I find that addressing certain aspects of the carbine results in quicker answers, than just a cover it all thread about my pet project. Example: If I'm 8 pages into my (Building a bullpup) thread and I have a question about the LRHO, what are the chances that adam01364 will be following my build thread and be able to give me the helpful info that he provided?

    As a newbie it's also fun to keep you all guessing who I am and what I'm up to!!
    If I'm overwhelming the board with discussion and violating the rules I can leave. Sure don't want to cause too much trouble!!
     
    Last edited: Oct 15, 2020
  16. riverrover

    riverrover Member

    62
    37
    Thanks
    Haven't actually started a dedicated thread on the build. Just gathering up design specs and functionality ideas. Yes, the original trigger, sear lever and safety will not be used and trying to build a new design around a magazine/grip seems like more work than just mounting a forward grip w/ linkage. The HP design lends itself well to a bullpup. BP's are cool and I don't have one so....
     
  17. riverrover

    riverrover Member

    62
    37
    Thanks
    There has been some design changes on my project that I assume at this time will be permanent!? LOL.

    The top of the bbl shroud will sit about 1/8" lower than the receiver cover. I will probably attach a Pic rail to the receiver cover, but cut M-Lok slots into the top of the bbl shroud so I have the option of attaching Pic rail to M-Lok sections or other accessories that use M-Lok. This should give me more options than doing a semi-permanent rail right to the shroud. From what I've seen though. Most BUIS's and Optics still are set up for Pic rail and not M-Lok direct. I don't think it wise to M-Lok the receiver cover and that would allow rain, dirt, etc to get into the action more easily.

    I WILL be in the market for about any Pic to M-Lok rail piece just to have a test part for finishing up any M-Lok cuts. I found the M-Lok slot specs online, but best to has a test part for fitting.

    Based on my design, I'm also going to be able to run the stock tube down to the buttplate at an angle putting the top of the buttplate about 3/4 - 1" below the top of the receiver cover depending upon how long I want to make the stock tube.
     
  18. Rachgier

    Rachgier Administrator Staff Member

    Covering it all in one thread is more cohesive and effective, plus cross posting about the same subject, ie your project, is technically against the rules.

    And Adam is a moderator, so if he's doing his job he should be reading every single post that's made... just like I do.
     
  19. undeRGRound

    undeRGRound ROLL wif Da MOLE! Supporting Member

    25,296
    1,524
    INDY
    @riverrover you need to make your own thread, so I can use this on you:

    :pics:

    But this GIF is worthless w/o THREAD! :rotfl: