Page 3 of 4 FirstFirst 1 2 3 4 LastLast
Results 21 to 30 of 40

Thread: Another 7.62x25

  1. #21
    Gunco Rookie rk5n's Avatar
    Join Date
    Feb 2009
    Posts
    11
    Feedback Score
    0

    Default

    Quote Originally Posted by Coils View Post
    Ar you getting a lot of fouling on the bolt & in that area while shooting it? Sounds like the bolt is starting to open while the powder is still burning in the barrel. Might want to try a stronger recoil spring?
    I just came across this problem when I went shooting on Sunday. After about 50 rounds of polish surplus, the gun would short stroke and mis-feed almost every other round. I'd wipe everything down and oil the rails and the gun will be back to normal. On the plus side, normal was a short stroke or misfeed every 20-30 rounds. I ended up putting 120 rounds through it.

    I'm thinking that the bolt and carrier are too light. If anything I've reduced 10-20% of the bolt carrier's mass and SMG's have heavy bolts. I'm going to replace the piston with a solid steel rod to fill up the gas tube to try and add a few ounces.

    Also I need to replace the feed ramp with a steel one slightly lower than the current aluminum one. The second magazine I modified is slightly loose and too low and misfeeds more often than the first one I made.

    The third problem: the charging handle broke off... again. Trying to operate this gun when dirty without a charging handle and with the bad magazine is one of the most frustrating gun related experiences I can think of. Every other shot I had to undo the top cover, remove the magazine, clear the jam, pull the bolt carrier back, insert the magazine, let go of the carrier and close the top cover. The problem is that welding on the funky alloy the bolt carrier is made of is very very hard. I'm planning on making a new charging handle and either bolting it in or pressing and staking it in to avoid it ever breaking off again.

  2. #22
    Gunco Member BIG 54R's Avatar
    Join Date
    Apr 2006
    Location
    Metro Houston-Galveston
    Posts
    207
    Feedback Score
    1 (100%)

    Default

    rk5n how thick are your magwell adapter plates on either side and the front?
    they look about 5mm?

  3. #23
    Gunco Rookie rk5n's Avatar
    Join Date
    Feb 2009
    Posts
    11
    Feedback Score
    0

    Default

    Thats about right, I remember I used 1/4" thick 7075 aluminum and had to mill it down slightly.

  4. #24
    aka: SDK1968 dutigaf's Avatar
    Join Date
    May 2006
    Posts
    4,088
    Feedback Score
    14 (100%)

    Default

    COILS,

    just wanted to throw this at you for consideration......

    you mentioned the bolt may be opening too soon and letting a lot of the powder foul up the set up...

    YEP that could be very possible on a blow back gun, happens all the time if the bolt is too light.

    and while a stiffer recoil spring will help with what he already mentioned about the "too much" recoil.

    it wont really help much on this. if he gets one stiff enough it will. but what really is the issue on blowback guns and especially 7.62x25 guns is the BOLT WEIGHT.

    the bolt mass has to supply the dampening effect for just that mili second.

    this is the most important part of a blow back operated gun. lots of guys try to just control it with a spring, and sometimes its real easy to cover the stretch, which meant your weight was only off a tiny bit.

    thats why when we do conversions of fixed pin bolts to floaters we try to always make sure the weight is back to where it started. that way the mass is right for the power of the round.

    by just adding "more spring" a lot of times the spring has to be so strong to do the job that it causes feeding issues after that.

    a good way to ad mass to an AK bolt is to put some lead into where the recoil spring went up at the top. he obviously doesnt need to cycle as far as the original set up.

    its just an idea to think about.

    but for manageable recoil on a 7.62x25 with a 16" barrel in blowback.... your bolt should weigh near 550 - 600 grms or so.

    thats where the pps41,43, m56, p7 and others all come in at.

    sdk
    say what you mean & mean what you say


  5. #25
    Gunco Rookie rk5n's Avatar
    Join Date
    Feb 2009
    Posts
    11
    Feedback Score
    0

    Default

    Quote Originally Posted by dutigaf View Post
    but for manageable recoil on a 7.62x25 with a 16" barrel in blowback.... your bolt should weigh near 550 - 600 grms or so.

    thats where the pps41,43, m56, p7 and others all come in at.

    sdk
    Thanks for the info. I was about to ask that question while reading your post.

  6. #26
    aka: SDK1968 dutigaf's Avatar
    Join Date
    May 2006
    Posts
    4,088
    Feedback Score
    14 (100%)

    Default

    if that helps then im very happy!

    you kept the piston as a guide rod so its gonna be pretty close already.
    say what you mean & mean what you say


  7. #27
    Gunco Member petro116's Avatar
    Join Date
    Mar 2007
    Location
    CT
    Posts
    78
    Feedback Score
    0

    Default

    Quote Originally Posted by dutigaf View Post
    COILS,

    just wanted to throw this at you for consideration......

    you mentioned the bolt may be opening too soon and letting a lot of the powder foul up the set up...

    YEP that could be very possible on a blow back gun, happens all the time if the bolt is too light.

    and while a stiffer recoil spring will help with what he already mentioned about the "too much" recoil.

    it wont really help much on this. if he gets one stiff enough it will. but what really is the issue on blowback guns and especially 7.62x25 guns is the BOLT WEIGHT.

    the bolt mass has to supply the dampening effect for just that mili second.

    this is the most important part of a blow back operated gun. lots of guys try to just control it with a spring, and sometimes its real easy to cover the stretch, which meant your weight was only off a tiny bit.

    thats why when we do conversions of fixed pin bolts to floaters we try to always make sure the weight is back to where it started. that way the mass is right for the power of the round.

    by just adding "more spring" a lot of times the spring has to be so strong to do the job that it causes feeding issues after that.

    a good way to ad mass to an AK bolt is to put some lead into where the recoil spring went up at the top. he obviously doesnt need to cycle as far as the original set up.

    its just an idea to think about.

    but for manageable recoil on a 7.62x25 with a 16" barrel in blowback.... your bolt should weigh near 550 - 600 grms or so.

    thats where the pps41,43, m56, p7 and others all come in at.

    sdk
    Tagged for interest. As a tinkerer, i find the this reply interesting.
    On my setup, i hadcut off an inch+ from my recoil spring. I do notice that after repeated magazines, my firing pin will start to freeze up.
    I bought a new spring during a KVar sale and will have to try it out.

    DOH! miss read it. But my bolt and carrier should weigh almost the same asthe AK carrier group.
    Going to try the new spring anyways.
    Last edited by petro116; 12-13-2009 at 05:33 PM. Reason: misread quote

  8. #28
    No Hope For Me Coils's Avatar
    Join Date
    Feb 2005
    Location
    PA Where the Amish Roam Free
    Posts
    14,039
    Feedback Score
    38 (100%)

    Default

    Quote Originally Posted by dutigaf View Post
    COILS,

    just wanted to throw this at you for consideration......

    you mentioned the bolt may be opening too soon and letting a lot of the powder foul up the set up...

    YEP that could be very possible on a blow back gun, happens all the time if the bolt is too light.

    and while a stiffer recoil spring will help with what he already mentioned about the "too much" recoil.

    it wont really help much on this. if he gets one stiff enough it will. but what really is the issue on blowback guns and especially 7.62x25 guns is the BOLT WEIGHT.

    sdk
    I know you have more experience with different model firearms then me, so I'm not saying anyone is wrong, just pointing out what I've seen and experienced.

    Yes the weight of the bolt does have a lot to do with it, but a few builders have adressed the issue with heavier recoil springs, sometime multiple springs.

    I remember one of the first people that did a home PPSH41 design used two stock recoil springs, one on each side of the bolt, and had a skinny hammer that swung up in between them. They did this for two reasons, 1-to control recoil of the bolt and 2-the thinking the extra spring would also balance the movement of the bolt so it wouldn't angle to one side while traveling.
    "Government is not the solution to our problem, government is the problem" Ronald Reagan

  9. #29
    GuncoHolic Rahatlakhoom's Avatar
    Join Date
    Jan 2005
    Location
    Indiana
    Posts
    2,317
    Feedback Score
    14 (100%)

    Default

    Quote Originally Posted by rk5n View Post
    The third problem: the charging handle broke off... again. Trying to operate this gun when dirty without a charging handle and with the bad magazine is one of the most frustrating gun related experiences I can think of. Every other shot I had to undo the top cover, remove the magazine, clear the jam, pull the bolt carrier back, insert the magazine, let go of the carrier and close the top cover. The problem is that welding on the funky alloy the bolt carrier is made of is very very hard. I'm planning on making a new charging handle and either bolting it in or pressing and staking it in to avoid it ever breaking off again.

    I feel guilty about the welding issues.
    Send the carrier back to me and I will try it again if you want to.
    No charge. You had the LH handle correct?
    Charter member-Busted Box Club est. 2006

    "I will adhere to the Patriot Act, the one signed in 1776"
    - Marc Anderson

  10. #30
    Gunco Veteran perry's Avatar
    Join Date
    Nov 2009
    Posts
    1,108
    Feedback Score
    0

    Default

    did u still use a mig amd how many amps took care of the job please/

Page 3 of 4 FirstFirst 1 2 3 4 LastLast

Search tags for this page

There are currently no search engine referrals.
Click on a term to search our site for related topics.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •