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Benevolence

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Everything posted by Benevolence

  1. If you’re trying to just remove the ‘black’ aspect of it and make it shiny metal, just use rust remover (naval jelly) carefully. Don’t know why you would want to do that but it’ll make it bare metal-ish
  2. Just my two cents: watch your temps on the nitriding; you could get some distortion or make it brittle (400-580C). I've had some stainless medical devices that rusted after laser engraving as well. Also, nitriding is a surface treatment, not a coating. Would recommend laser engraving followed by DLC. I've had some distortion issues from CrN but DLC is usually quite a bit lower temperature.
  3. In addition to the posts above, I would recommend mosinvirus' videos on youtube. Those in conjunction with the Kunhausen books will help you understand the details. You need to fit the barrel hood, then locking lugs (~0.050" of vertical locking engagement on the hood), then the legs (aka lower lugs) of the barrel to the frame, and finish with some filing of the radius of the lugs to allow for the link pin to pull the barrel down. This is quite an indepth process and requires some 1911 fitting tools that can be found on brownells. It sounds like the radius on the lugs needs some relief to allow for the slide stop pin to clear it.
  4. This may show my ignorance, but I believe too much overtravel on a trigger can let the trigger bar push the sear reset leaf and you end up with a dead trigger or hammer follow?
  5. Earlan357 did some modifications on the disconnector as well as got different springs for the internal FCG (trigger return springs?) and it changed the trigger quite a bit. That’s a bit more involved than just a recoil/striker spring changeout but just to show more can be done. I’m having a hard time finding his thread but it’s out there, maybe on czfirearms.us
  6. If you’ve a good live center method of holding the tap/tap-handle aligned with the drill press chuck and hand turning it in I would do that. Keep the same X,Y location when tapping as drilled (don’t move between steps unless you’ve a good dial/DRO), and back out half a turn (or when you feel the thread chip break off). Pull it all the way out and clean it out every 3 or so full turns. Hopefully you’re working with 6-32 or larger? I never was able to get my 4-40 taps to not snap in 416 stainless.
  7. Not sure what design route you're going for, but I would start with a 80% or junky lower, drill some holes for retaining pins across the magwell to fit your magwell features/prototypes in. Design the prototypes in solidworks and find someone that can 3d print them out of polymer and ship them to you. Shouldn't be expensive and you avoid gunsmiths/FFLs.
  8. If I understand correctly, you’re saying the gas behaves incompressible until it begins expanding in the carrier, and restricting at the gas port only increases the velocity, decreases the delivered mass and doesn’t affect the pressure of the gas. And that the benefits of the gas length are two fold; decreased port (and delivered) gas pressure and velocity into carrier. I suppose the Fat Boy or (perhaps more gimmicky) pig tail gas tubes could be an option. Oh, and I don’t really see how measurements of pressure at the ports and carriers are irrelevant or table talk; I was just trying to present those as they seemed relevant and to demonstrate that there was a pressure decrease in the carrier chamber vs port. I thought it was due to pressure losses along the way and hoping to understand the gas pressure/velocity in relation to the bullet position relative to the gas port and muzzle.
  9. Thanks; I’ve read a fair amount and your posts seem to have some good content so I was hoping to get your thoughts. Also how easy it is to be flat out wrong with over analyzing things without actually trying it and overlooking things that are important. Just trying to understand the recoil from a fundamental perspective. I’ve got a 11.5” carbine (Spikes) JP SCS with white spring and thinking about replacing the steel weights with a Teflon spacer. That, and milling lightening cuts in a F/A carrier and putting in a POF cam pin. Hoping to use the AGB in conjunction with it to get the recoil tuned down. I guess I can math all day but it comes down to actually just trying things out.
  10. Huh, that’s interesting. This mil report (BRLR 1475) seems to show the bolt carrier pressures only hitting about 2.5ksi, which seems like there’s expansion and restriction of that metered gas to a lower pressure than the chamber pressure. I’d think further restriction by a restrictive adjustable gas block would lower that carrier pressure more? From another article showing gas port size (restriction) effects on carrier chamber pressure: Maybe @TonytheTiger has some input on this?
  11. I’m going to nerd out here a bit in order to describe my understanding of the gas operation and but I was hoping to have a discussion about the effects of barrel length on recoil and the methods of reducing recoil. The general consensus as I understand is that a 18” rifle gas length AR is the lowest recoil barrel-gas system combination. It has a 12” port distance, with 6” of dwell length and 0.13ms of dwell time. Pressures are 19.6ksi at the port and 14ksi at the muzzle. I would consider this the ‘working pressure’ range that is used to operate the carrier during the pressure stages when it is accelerating. Generally the carriers have an operating internal gas pressure of 2.2ksi (and an area of ~0.2in^2) and reach a velocity of 15ft/s. So, there’s a significant reduction in gas pressure between the port and carrier chamber even without an adjustable gas block. The rifle I’m trying to reduce recoil on has an 11.5” barrel with 7” carbine gas length, so 4.5” dwell length and 0.13ms dwell time but pressure of 33ksi and 22.6ksi for port and muzzle. As I understand it, the bullet leaves the barrel and gas pressures decrease before any carrier movement really occurs, and you certainly don’t have unlocking; I’m basing this off slow motion video and the relative velocity of the carrier to bullet (~0-15ft/s vs 2500+ft/s). The timing effects of the gas tube length don’t seem important because of how fast the pressure moves, even relative to the bullet speed and certainly the carrier. That acceleration of the carrier has to occur during the dwell length/time of the bullet between the port and muzzle, which for these two barrels are the same. With an adjustable gas block to act as a restrictor and decrease the gas pressure to the carrier, and similar dwell times, I don’t see how the gun would behave any different between a carbine 11.5” and a rifle 18”. The extra gas pressure at the muzzle certainly could contribute to recoil, however the bullet is also going slower; furthermore, more gas pressure helps operate a muzzle device (like 9mm minor vs major with a compensator). Then you can further do all the standard tuning to reduce the parasitic loss of energy from friction (carrier, bolt, feed lips and feed ramp polishing), followed by moving mass/spring ratio/gas block adjusting) to have the bolt hold open on last round but not have the buffer bottom out on the extension tube. With all of this done, why would the recoil be any more (if anything, less) than an 18”? I had a suppressed 10.3” that was harsh on recoil but was obviously overgassed. This link (https://www.ar15.com/forums/ar-15/How-it-Works-The-AR-gas-operation-and-how-everything-works-in-harmony-/66-266108/) has a great explanation of the gas operation but one thing I don’t understand is how the carrier and bolt can already begin to be extracting a round before the bullet leaves the muzzle (in an overgassed situation). The symptoms seem to agree with it but it is surprising; that’d have to move ~1/2” at an average velocity of ~100in/s whereas the bullet has to move 4” while it’s going ~30,000in/s, which is an order of magnitude more time... Thoughts, experiences?
  12. Try forcefully inserting a mag with the slide off, ejector on, but unpinned. Does it lift up the ejector? If so, that’s your problem and where you’ve got to remove material. Also make sure to try it with a fully loaded mag to see if the brass presses it. Just my thoughts, take it for what it’s worth.
  13. I had that issue and it was the magazine over insertion bending the ejector up and out into the slide. The dawson precision mag release seems to have fixed it after I replaced the ejector, but I took some material off the bottom to prevent it from happening again if I really slam a magazine home.
  14. Okay, thanks for the information, I appreciate it. I am returning the cylinder reamer and decided to rent a 460 Rowland reamer and do it right especially with how high pressure of a cartridge this is.
  15. I purchased a Clymer .45 ACP reamer with the intent to ream a barrel out to fit a 460 Rowland (I have the compensator and stiffer recoil spring, and this is in a fnx45T). Unfortunately, in my naivety I got a cylinder and not a barrel reamer so the solid pilot is larger and doesn’t fit (.455 vs .445 I believe). It also appears that the cylinder reamers have a constant diameter throat whereas the barrel reamers have a taper ‘lead-in’? I was thinking of turning down the solid pilot to fit in the rifling and use to ream the extra 0.063” required for the 460Rowland. My question was if the difference in throat (if there truly is) will increase pressures or decrease accuracy drastically. The bullets used for this are hard cast, powder coated lead going at a healthy speed (I suspect gas checked). If I understand it correctly, the jump should be good for lead bullets and perhaps even help decrease pressure relative to tapered?
  16. I think it was several things, and I took some material off of the front of the sear feet and put a tiny bend in the back of the trigger bow. This should allow the disco to raise when the sear is engaging the hammer. Whether it truly was the hammer/sear hole locations I’m not sure but it definitely wasn’t the best. Appear to have it working now
  17. True, I was kind of worrying about that as well. I’ve got a 3/16” ball nose carbide endmill I could bore out the sear/disco hole with, and turn some hard steel for a press in sleeve (have access to LN2 and a torch). Hopefully the endmill is rigid enough to keep center.
  18. Great, thanks. I hope the oversized pins are large enough and I can true up the sear/hammer holes in the frame. I feel like I did good on fitting the slide and barrel to the frame so this is a bit of a shame.
  19. Well, just to update that I feel like an idiot. Looks like the sear to hammer hole are a few thou out of alignment (drill bit wandering during drilling, not(?) during the first part. Should have undersized and reamed) and the sear legs are partially catching on the disco when it’s trying to reset. That, combined with the sear-hammer engagement is likely not aligned great. Hopefully redeemable by fitting the sear to accommodate. Not desirable though and frustrating. Should have just done a complete frame like I did on my first.
  20. Hi all, I hope to not make this too lengthy. I’m building my second 2011 and I did a 80% lower (mill rails, drill hammer/sear holes using center drill then drill bits on a mill with DRO so the dimensions should be accurate but I’m now maybe suspect). I am having some weird issues that are hard to replicate. Upon occasional dry firing, I am unable to ‘fire’ the gun and the hammer stays cocked. The trigger moves as it should and the disconnector moves forward and back. Upon inspection, the disconnector is staying down and the sear legs are too far towards the muzzle to allow the disconnector to be pushed up by the leaf spring. If I remove the thumb safety and grip safety, and pull the hammer unnaturally far back, it will allow the sear/disconnector to reset and it retains function again. I can’t seem to replicate this with the thumb & grip safety in; no malfunctions occur but this may be a false negative. I have also occasionally observed hammer ‘follow’ (fall to half cock) when hand racking it. I’m thinking there’s several possibilities: •I drilled the hammer/sear hole too far apart (but why not repeatable with safeties out?) •The safety detent spring is pushing the safety upward and that’s riding the sear? (but manually lowering it doesn’t let the fcg reset) I’m reading stuff online about leaf spring length, disconnector ‘shovel’ dimensions, and trigger bow length, but pushing down on the disconnector doesn’t allow it to reset; it seems like it has to be the sear being impeded by the hammer or thumb safety.
  21. I had this same issue and it was quite frustrating. I marked the points of contact in the thread below, but essentially you end up with a pivot point at the top of the barrel, about half way back, with the other two points of contact being the bottom of the barrel with the slide, and the barrel locking lugs trying to engage the slide locking lugs. You've got to either raise the pivot point (remove material from the top of the barrel), or lower the other limiting point (bottom of barrel with slide). I ended up electing to remove material from the slide (where the front & bottom of the barrel rests on) to allow the locking lugs to move up. As lmtdmster said; if it's got some "springy"ness to it then it's likely that.
  22. Personally I’d do DLC. It’s a PVD process that is relatively low temperature (low risk of distortion) and is thin. TiN distorted my frame. Hard chrome adds 0.003” of material and is an electrolytic process. Richter Precision does a lot of PVD processes.
  23. Titanium galls up like crazy. You’ve got to apply a coating to it, which is difficult to bond because of its oxide. It’s an incredibly difficult and funky material to deal with in every aspect. Nitriding or boriding the surface is likely your best option, but that has its own issues.
  24. The compensator doesn't need to come off on a 1911/2011. Unless you've got a bushing that you need to remove or change out, but most of these are bull barrels without bushings. Barrel pulls out the front of the slide.
  25. I think the issue with 45 open is having enough gas pressure to work the compensator and porting, as opposed to 9mm Major or 38SC.
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