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Lane

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About Lane

  • Rank
    100
  • Birthday April 23

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  • Gender
    Male
  • Location
    Upstate New York
  • Interests
    Machining, Building, Shooting, Reloading.

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  1. The biggest concern left is tempering my expectations in terms of speed. I'm going to need to plan a barrel removal/swap every month or so; maybe even every two weeks. Barrels arrived yesterday, though I didn't even unwrap them right away. Just now got around to bluing them both, and finished the lower assembly for the 24". Can't show the barrels off quite yet because they are in a heat bath for 24 hours. Then I clean off the leftover bluing solution; and oil them. Also need a new buttstock (on the way), because of the resonance concerns with an adjustable stock. It was neat to play with a reduced size AR like that though; I can certainly see why you all like your pistol builds. Had to order the second upper receiver BCG combo. While I had earlier considered a side; or dual charging upper, I don't think that offers a great side by side comparison of the 21.750" barrel. I found an Aero Precision upper on sale with Toolcraft BCG; so that's going to be for the 21.750 when it arrives (it has already shipped). That gives me a pretty straight comparison between standard upper receivers with different forge marks. I'll be sure to weigh both first, and note any physical differences. Close to the last thing on my list is a pair of scopes. I haven't ordered them yet; but may have the funds soon. Looks like a bunch of rainy days coming up; so that gives me time for mold making, test assembly, chamber casting, etc. I also still need to finish milling the aluminum lower; carefully of course... To answer some other questions; yes, I've seen a bolt action BCG, but didn't like the arm. Seemed way too long to use in this project because of the resonance questions at play. It also didn't seem to actuate the bolt directly (though I may have missed something). In terms of charging handles; I've made some progress. If everything works out, I may be able to modify a 7075 handle. While inspecting these clearance issues I came across a roller cam pin (again). That alone might be enough to satisfy my desire to reduce friction (and force required), to manually remove cases. They are typically used in piston builds; which is relatively similar in terms of function to a gas free build. For all I know, the reduced surface area of these 300 Blackouts will make it a null issue; but there are other builds where I want this. I have melted some modeling wax for casting. Found a tube of silicone to make molds; the fun part here will be moving the handles enough to make the mold oversize. Shrinkage is a serious consideration when making copies this way. Then on to modify waxes, gate, and invest for casting. There is little sense in pouring just one part if I'm going to melt metal. Might as well iterate a few designs in the same batch that can be modified later for various reasons. I'm not pouring aluminum for this because I don't have the ability to temper aluminum parts of that size at the moment...
  2. Can't stop thinking about the charging handle. I have a new design in mind (read: five or more), but haven't fully worked out the details. Not sure whether to call it the tickler, stripper, or... the ripper. The idea is, it needs to do the work of the gas system all by itself. Can't really show off any pictures or drawings here. There are many possible solutions; more so if you are able to remove the gas key (aka UK build)... This may be the first bronze casting I do here. I have a small crucible that would be perfect for casting about 5-10 charging handles. Cast them a bit fat, and mill them down to specs. It's MUCH smaller than the 90 pound crucible I'll be running later on; so it's a perfect experiment in this case. I already have a furnace capable of doing exactly that once I work out an alloy blend. I try to recycle as much as possible, and might need to buy an ingot or two to make that just right. I also advocate for silver in a good bronze for many reasons. Never much; but just enough makes everything right... If you didn't figure this out yet; there is a re-introduction of the ambidextrous charging handle design here. It needs to actuate upstream via some kind of control. And some other things. Pretty sure a few of you could beat me to this if you tried.
  3. Since it's a quiet night; so here is a slightly better color comparison. I really can't tell the difference if I weren't looking at it from 3" away under a bright light. After closer inspection of the aluminum lower; I think it's pretty nice... But still want one that has a flawless interior finish for this particular build. Since I'm free-styling the milling on this lower; I'm rethinking the rear cutting constraints (outside of the blueprint). I think I only need a slot wide enough for a trigger. Also; Polymer80 recommends leaving a bridge behind that for strength; apply that to an aluminum lower... And given the laws here; it's not any kind of problem to block that area out. That MIGHT change resonance enough to notice in testing; though at this point, I don't even know if the polymer lower will make a barrel react differently... That's why I need more than one for all this fun. Aluminum lower still needs quite a few thou taken off the walls, more off the front; and whatever I decide on the rear pocket. Then of course the pin holes; but those are fast if setup correctly. After turning the dials for hours; I think I could install some heavy duty servos on the jog wheels to drive this rig CNC. If I can run it slow enough, it should be highly capable. I've been cutting at 0.1mm per second in many cases, and would like to go even slower for fine detail work.
  4. Not quite finished milling out the (black) aluminum lower; but getting pretty close. I spent some time calculating and testing the feeds and speeds that work in my setup. That got me pretty excited unfortunately, and I created a few tiny flaws I would prefer didn't exist. The cost of a replacement is low enough that it's worth the effort to make one look superior. I'm sure if I place this one in a box, hidden inside a drawer; that something good will come of it later on. It also allows me to mill the next one when I'm not pressed for time, rushing, or getting overly excited by my progress. I also need one or two replacement end mills, because I've been working these hard from time to time. I do plan to shoot this lower in the short term; but it's not the gem I wanted. I also started working on the purple lower. Despite seeing reports it wouldn't work, I tried painting on the dye cold. Even with a heat gun, the application seemed lackluster at best. Multiple coats and sitting overnight produced something with a few dark splotches, and a slightly darker overall hue. So I put the whole thing in a pot of boiling dye as recommended. I waiting a bit more than 30 minutes; but the results I achieved were almost exactly what I wanted. I might have taken it out five minutes sooner had I been paying more attention; but it's better this way. It appears black as any factory black polymer lower; until you see it in bright sunlight. If you look very closely you can see a violet glow emanating from the texture of the surface. It is actually a bit brighter inside (mag well and FCG) where I didn't brush on the dye the first time. Truly stunning; midnight blueberry. Looked over the numbers I can get in terms of FPS to projectile weight between 7.62x39 and 300 Blackout in long barrels. Adjusting for everything; it appears they are nearly a 1:1 comparison. I may have to use a different powder in one cartridge or there other; but FPS number are almost exactly the same for any given projectile weight between the two calibers with long barrels in use. This is good! I took a picture of the epoxy filled area of the trigger hole to prove it was the same lower. Bonus; the plastic epoxy was all black with just the cold brush application of dye; it was only the lower itself that needed the full on hot bath treatment. I hope this still qualifies as a black rifle...
  5. Decided to go back to my roots on this next aluminum lower. I inspected the blueprints and took the important numbers down on paper. Did a few calculations, and planning to scribe the FCG pocket layout in the coating this time. That is; as opposed to using any kind of jig, or applied template. I'll just start measuring with calipers as I get close, and try to get a nice interior finish with my final passes. This will be the lower for the 21.750" barrel build. I'm planning to start the 24.000" on the polymer lower, but will have to swap those around at some point. I'm still considering my options for upper configuration differences; especially early on. There are some constraints that cannot be understated in these builds. The strain gages may require a modified barrel nut (quite likely with a 300 Blackout chamber length). That also may prevent future barrel removal without removing or ruining the strain gages. It may also mean no handguards with strain gages installed. So; it's either a do it once process; or a calculated effort to take measurements at exactly the right time in the experiments. Haven't come to any conclusions here; but it may pay to wait on that part, and experiment on some other build short term. I took case measurements with micrometers and haven't really decided on a path forward yet. I may still drop back to neck only sizing soon if it functions at all; that means more new dies. I also don't have scopes for the 300 Blackouts yet, so that's going to be a constraint early on. My final build concern at the moment is the strength of the rear charging handles. With a gas free straight pull build; that may become a problem. The heaviest weight handle available would be ideal, without any ambidextrous features (or pivots that reduce overall strength). Don't want to be too optimistic on delivery date; but both barrels are a few hours drive away from here already... Not sure if they require finishing; if I do have to blue them, that takes a solid day all by itself.
  6. Lane

    My first 7.62x39 AR

    I can not reverse engineer your chemistry here. I still think you have it a bit wrong. But it's all in good fun.
  7. Lane

    My first 7.62x39 AR

    It was an experiment. I don't think anyone cares either way. I haven't photographed the fun for you all; but local stores sell binary targets.
  8. Not sure which kind of "irons" you mean here. I have a lot of metals in the fire these days. The element Fe is just one component in the mix; and I can't remember the last time I even welded steel for fun. Coming soon though; there is a casting furnace going in this year. Should be capable of around 30 pounds of aluminum, or 90 pounds of bronze; give or take... I do still need to forge a few tools to make that a seamless operation. Who wants .308 silver projos?
  9. Sounds good. I mentioned JB Weld as the simple solution... I wouldn't trust that with stainless steel mags; but it should hold up to Polymers just fine. Finding someone to weld on a bit of material should also be no problem. A MIG or TIG could do that in seconds. Not sure I would torch a part that small; but perhaps there are welders out there that could do that. That's my problem lately; this "1 at a time thing"... Sometimes it helps to have more than one for comparison sake.
  10. I don't think it's that bad in this case. I'll admit; I will need to read through this entire thread again to try and get a handle on where you are with this 80%. Looks like it's not milled yet, so you might want to save task in terms of flexibility. What were your plans for that? A jig? Blueprints of some sort? I mentioned some time back; there is a way forward with a modified magazine catch if that is really your only issue here. It's not a perfect solution; but I think it's much better than modifying every magazine you have (or want to use). From what I can see, the lower will need a minor "enhancement" as well to make it possible to install. The maximum spread I saw across the mag catch height was ~0.060" (from memory); which is a bit more than a dime in thickness. Hell; if you want the simple solution? JB Weld to thicken the top, and some way to grind it back down flat (a metal file would be fine). Same amount of adjustment needs to be done to the bottom of the catch (not even the whole profile) if the magazine catch slot in the magazine doesn't fit. Then you would need an access port where it plugs into the upper; on the left side so you can install it. That would also require a bit of filing. I don't think you need anywhere near that full 0.060" though, so in both cases it's a very tiny adjustment. Here is a rough CAD sketch of the maximum deviation listed. As I mentioned; I still need to re-read all this thread to figure out how far off each of your lowers is. A modified catch for you would look a lot less extreme from what I can tell (red part shifted down, smaller amount of modification needed).
  11. That explains it. I wasn't half as worried about which way the went in; only that they were too short. Carry on.
  12. It's an unfinished 80% lower; they are just holding the two parts together for fit; and haven't been installed in a formal sense. What really confuses me is those hexagonal bumps on the other side (and it looks like pins are going to be short as well). I don't think this should totally dissuade you from building 80% lowers. It really depends on the upper you wanted to begin with though. There are some Armalite style 80% lowers available; but then the compatible uppers are much fewer. I'll admit; I love 80% builds myself. If you pick either an upper or a lower to start with; it shouldn't be too difficult to figure out which other components will work. As you can tell from this measurement poll; it's not hard to get a whole bunch of numbers from people who have a few of these things around.
  13. INCOMING! Well not quite yet... I got an email today from Compass Lake Engineering; and they want more money for shipping. The barrels are both complete and ready to ship. I can't really complain about the added cost, considering their custom fabrication price was only $125. I had to go make a deposit once I saw that; but I should be able to call them back in the morning, pay for additional shipping costs; and get both custom barrels heading this way. That means I'll have lots of new projects running sometime next week. And I already had a lot of projects on the table; so I'm going to have to get serious about buttoning things up around here. I honestly haven't even begun to break down the order of operations on these 300 Blackout builds. Chamber casting seems like a logical first step. Headspace check; and making some ammo. I've got powder and projectiles in spades for these new builds; and a small handful of factory loads...
  14. Lane

    My first 7.62x39 AR

    I'm still crushing through reloading data on these new powders with 7.62x39. Both of them were on my compromise powder list, for this particular reason. I think the large vs. small primer issue in 7.62x39 may be a part of the complications in these matters (brass can have either one); and some people specify magnums especially for H110. There is also the variation in projectile size to consider; and who knows what else yet. Some speculation that I might be BETTER off with heavy projectiles in one or both powders. Of course most people messing around with this just stick to 123-125 grains. I've seen the anecdote a few times around here; that "300 Blackout is hard". Pretty sure this trumps "hard" in almost every category. In terms of compatibility, simulation, accuracy, etc. I will still be buying one 4198, and Accurate 1680 to compare in the long run (probably next week at this rate). Today was my first time visiting this particular shop where I found any powders on my list. I used to live out that way; and I really wish I still did in terms of access. They have an actual gunsmith (working and laughing along with everyone else); and at least a half dozen employees. They are all very friendly and knowledgable. I saw a few other customers run through the store; and you have to wait in line... Because every employee knows the customer and has to get an update on things. It's truly a fun place to go. And it's chocked full of things I can't even begin to describe. I didn't even ask about all the pistol grips attached to ARs on display. But they have other things nobody else displays too. I even saw a pentagonal magazine mount (filled with 5 ten round magazines). Sure you have to rotate 72 degrees on each reload; but that's still better than the 180 degree duct tape flip. There was of course the anal probe at the end when they had to take my information because I bought powder. It was worse than the other place; in that, it happens in secret. It also looks like the same spreadsheet printed on paper. Funny thing is it both spreadsheets appear to be printed intentionally small, so that any writing is nearly illegible to begin with. The other places lets you fill it out yourself, and you can pretty much guarantee everyone writes too messy to read in that case. The real question is; WTF would the police even do if you bought 24 pounds of powder at a time? What does that kind of call even look like? Do they come at 4AM with spotlights? Do they stop by at dinner time and ask about what calibers you enjoy shooting? This is either a mandate from the SAFE act, or a protective compliance measure for the shop. There was supposed to be a state-wide database of all ammo sales; but it was deemed to complicated for the police to implement, and completely unfunded. I'm not worried about it (yet), but it's amusing to me given the current situation. I believe this shop is in a county where the sheriff has, since it's inception; declined to enforce any part of the SAFE act. There are plenty of counties where this is the case; and they may all have non-compliance compatible gun shops. It was furthermore apparent to me, that they are moving 10; maybe even 100 times the amount of powder that my local shop does. They even offered to order anything and have it in stock within a few days (the other shop orders every few months). Gun friends...
  15. Lane

    My first 7.62x39 AR

    Thanks for the rundown. I don't want you to give up your secret on this; but I do have two questions to ask. Are you just topping off the load with wheat germ? Or, are you a true voodoo practitioner (duplex/triplex loading)? Took a long drive for no good reason today; other than to get the F out of the house. I picked up H110 and IMR4227. H110 especially seems like some kind of quiet riot in the 7.62x39. A lot of people say be VERY careful; and others reporting success without providing load data. Furthermore; I'm almost out of 303 caliber projectiles, so whatever I discover here is likely going to drive my next purchase. Saw only 174 grain locally; which don't have any published load data... But I came across more than a few SKS boards where people talked about shooting up into 220 grain projectiles; and 174s should work with H110. I'm certainly going to tread lightly in this area to begin with. Yes; I'm aware of the simulation ability with H110, but I would like to collect more anecdotal data before I experiment on my own. I saw more than one report of blowing a firing pin out the back of an SKS; which doesn't seem all that easy to do. I'll have to inspect the SKS construction more closely when I feel like getting dirty again...
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