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grottulf

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Everything posted by grottulf

  1. The idea of using magnets is pretty clever. They give a truly progressive "spring rate", as the repelling force is proportinal to the inverse square of the distance between the magnets. (Up to a a limit, since it doesn't go to infinite at zero distance ) But if you can really tell a difference from a hydraulic buffer or a buffer with multiple springs, is another question. The most important part is probably that that you can tune the system and or ammo so it doesn't bottom out. I'm currently using two repelling magnets (25mm diam, 12mm long) at the end of my buffer tube together with a Kynshot hydraulic buffer and an A5 tube It had a good effect on my dot bounce/grouping. So using magnets definetely works. But since my magnets sits in series with the buffer spring, it slightly lessens the pressure on the bolt when closed. And thats not optimal... But with the Miculek-buffer that wouldn't be a problem, since it is only effecting the "spring rate" when it starts to bottom out. But I'm unsure how much repelling force it can have with such small magnets on the other hand. Even my big magnets bottoms out with factory ammo... (The is a thin rubber piece glued to one of them so the don't hit each other, since that can crack them) I'm working on lowering the power factor with port holes at the moment though... (I hate hand loading ) It would be cool if someone could do a comparison between the Miculek, Kynshot and Taccom buffers...
  2. Most ejector issues I believe are just because of the shotgun needs hotter loads to cycle the bolt reliably. The Tigris/Orthos works with really light loads however, due to the design with the rotating bolt, so that's normally not an issue with this one. In my case the problem was that the ejector didn't protrude enough, so it didn't get close enough to the bolt. This can be seen by just hand cycling the action and watch how close the ejector is to the bolt. I haven't heard of anyone else having this issue with the Tigris though, so I don't think it's common, and they have probably solved the issue by now. I made some shims to place between the ejector and the upper, to get it closer to the bolt. I don't have a picture of how it looked without the shim, but here's a pic of how the ejector sits close to the bolt now. And a pic of the shim. I also beveled a surface on the ejector, so it follows the inner contour of the upper better. Before that, it sat slightly canted. But again, they have probably fixed that by now.
  3. Yes, that ejector need adjustment. If it's new I would get a replacement
  4. There might be one drawback for 3-gun though... There are no 20-round mags for them as far as I know. But I've heard that there is a drum-mag in the works... (The Derya/Typhoon mags does not work, since this shotgun has a AR-308 compatible lower.) The Tigris 10 round mags works great however, and that's all I'm allowed to use for IPSC, so for me that's not an issue.
  5. That's a Tigris XR12 pro! Apparently they have started to sell them in the US now, but under a different name for some reason... I love the gun, but it might need some tweaking, like most turkish guns. After some tweaking of the ejector mine runs all ammo I've thrown at it, even down to 7/8 oz. And it shots super soft. You can read more about it here:
  6. Now I've shot a few hundred rounds at a competition this weekend, and I never had any slamfire. So I'd say my problem was due to my trigger modifications.
  7. Oil is a dirt magnet. I'd try less oil instead.
  8. I don't think they are any different from other AR-9's in that regard, so the same parts that works in others, works fine in a FM9 as well. I have a Kynshot (same as Blitzkrieg) RB 5015HD buffer in mine, and a 3G sports 6" comp (similar to the Brekke comp extension) Each of them made a significant improvement. But I would like to get it to shoot even flatter, so I'm thinking of porting the barrel, and I'm also a little curious about a magnetic buffer... I should add that I'm only shooting standard pistol ammo in mine. With handloading I could probably get it to shoot much flatter as it is.
  9. I should add that I have never had a single failure to feed with mine. I've only shot FMJ with it, and about 600 rounds so far though. I have however some problems with failure to fire, but I traced the cause of that to a too long headspace. And they will ship a new bolt to me, when Brownells finally gets their thumbs out of their ass...
  10. My problem was probably self inflicted... I had limited the over travel on the stock trigger. After I restored it to factory condition, I haven't had any issues. I haven't shot it enough after that, to say for sure though. But I'll get back to you if it starts again.
  11. Is the length of the buffer adjustable? So you can make sure it locks when the bolt is fully closed? Because I assume that there can be differences in how the threads for the buffer tube is cut in the upper (where it starts), and that would change where it locks.
  12. Yes, I'm having issues with intermittent 2-3 round bursts with my FM9. I just assumed it was trigger related, and since I'm planning on swapping out the stock trigger, I didn't look into it more thoroughly... Is there a way to tell if it's because of a week firing pin spring, or if it's trigger related?
  13. I have the same issue with some of my glock mags in my FM9. Did you sand the mags or the magwell?
  14. Crystal clear! Thanks for the clarifications, guys! It's strange that FM made the ledge so small. It's only about 1mm (0.04") on my bolt. The angled part could be much smaller and still clear the radius of the charging handle. And I suspect the tolerances between the upper and the bolt are a bit loose, because the charging handle slips of the ledge and pulls on the angled section instead, when the guns not loaded. I hope that has been fixed in their revised bolt, that they have promised to send me. I just have to wait until Brownells starts to export gun parts again, before they can ship it to me.
  15. How come some bolts have this ramp in the front part of the gas key dummy (not sure if that's the correct term for it, but dummy felt right...) My Foxtrot Mike bolt has a ramp like that, and when I pull the charging handle it pushes the bolt down slightly because of it. So if I pull the charging handle while there is no mag inserted, the bolt will drag slightly because of it. But when there's a mag with bullets inserted, it will push up on the bolt and counteract this. So it really isn't a big deal, it's just slightly annoying. I'm just curious why they would design it like that? It's not just FM. CMMG and even JP has bolts with this design. Some seems to have a design without the ramp, like the one in the pic from Angstad arms, and Taccom. That seems like a better design to me. But for some reason they then place it further back on the bolt... Is there a shorter charging handle you can use for these? Or should you just accept that there is some slack in the charging handle before the bolt starts moving...? Am I missing something?
  16. That's not a bad idea I've fixed it now though. I made a new shim from 0.001 stainless steel stock. First I test torqued it with oil and I got it to around 100 ft lbs. I deemed that to be enough as long as I add permanent threadlocker. When I applied a threadlocker, I applied it not only to the threads, but to both sides of the shim as well, for lubrication. (I noticed that shims this thin breaks easily otherwise, at least if they're home made ) But then I couldn't rotate it enough to get it to align... I hadn't considered that the threadlocker takes up some space as well. So I ended up removing the shim (and cleaned the threads thoroughly) And re-tightened it without the shim, and just thread locker, on both threads and the mating surface. It was enough to get just under 100 ft lbs. I think (hope) that will work fine. I'll never remove a comp without a barrel vise again anyway...
  17. I've gotten my hands on a sheet of stainless .001" stock now, so I'll cut out a new shim. I'll just have to find the time for it...
  18. Sorry, I totally forgot about this thread. I had a lot of stovepipes issues with it at first. But after I adjusted the ejector with a home made shim, it has worked perfectly. There was some other minor issues as well. I've emailed the factory with feedback and they have been very responsive, so I'm pretty confident they will have fixed all potential issues before they start to sell them in the US. All in all, I really love the shotgun. I mostly shot 28g shots due to the minimum power factor in IPSC, but it works fine with 24g as well. Not sure what that is in oz, you do the math. The recoil is really soft. I think it has a lot to do with the rotating bolt design. It's the first AR I've had that I don't feel the need to change anything about. I really like the pistol grip and the stock. And I love the handguard. The comp works great, and you can change chokes without loosening the comp. You don't have to loosen the comp when you remove the handguard to service the gas system either. I also love the low weight and the balance of it. But in all fairness, I haven't shot a Derya MK-12(RIA VR80) or Typhoon F-12, so I can't say how it is compared to them.
  19. In IPSC you can choose to have open action at unloaded starts.
  20. I have barrel nut shims but those are larger. I got my hands on some .001" brass foil, and made my own shim yesterday. But when I tried mounting it again today I only reached 80 ft-lbs when it reached the correct timing... When I disassembled it again I saw that the shim had cracked. I think brass is too soft, so it probably compressed under the load. I'll try to find some stainless steel foil instead...
  21. We ended up threading it M14x1 instead, and redrilled and tapped the comp to match. 1/2" just felt crazy...
  22. I have some questions for you gunsmiths out there. I tried to loosen my comp the other day, and managed to get the barrel extension loose. It didn't take much force at all, so I guess it wasn't torqued to specs from the factory... So I've learned the hard way to always use a barrel vise when removing a comp Now I'm trying to get it back on the barrel with the correct timing and torque. Turning it until it lined up, obviously didn't take enough torque... So I turned it until I got a satisfactory torque reading, and measured how many degrees past the pin it had turned. It was 14 degrees off, and with a little calculations I found that I need a .001" shim to get it right. I tried to Google it but couldn't find any shims for this? Does anyone sell these kind of shims, or do I need to cut it out myself from a sheet? If so would it be better to get a 0.001" steel shim, or should I use a slightly thicker brass shim, and allow for some deformation? And regarding the torque, my Midwest upper receiver rod was beginning to feel sketchy when it got over 135 ft-lbs. But I'm thinking that if I use permanent thread locker, it should be enough with 135... Or will it be too hot for thread locker? What do you think?
  23. Update: I got lazy and bought one of these instead https://www.3gsports.de/3g-pcc-compensator-3px.html
  24. Thanks, that would be really great!
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