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My first 7.62x39 AR


Lane

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Electrically speaking; I'm pretty sure hard attaching it to the gun could fry the input on the chip with a piezo sensor. I really want to triple input with a MEMS, Electrolet, and Piezo sensors; given the budget so far, any or all of that could be carried into a final build.

Does anyone trust a phone app for shot timing purposes? I saw some complaints about timing ,and turning on airplane mode with those; I haven't even tried one myself. 

7.62x39 barrel is outside, with all the chemicals; I just have to glove up and clean. The barrel has nice lathe marks on it; but dirty as you would expect from a machine shop. Not too much lateral scratching, so I'm going to try and make it nice during the bluing cleanup process. Stainless steel wool is my first option on hand; but who knows what I'll end up using before I finish it.

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1 hour ago, sketch said:

steel wool will take down small lines.

The barrel is gross with oil and grease; full of metal particles. I think I want to spin it in the steel wool to make it look alright after cleaning though.

I usually wipe the blue on the barrel the long way; but this barrel won't likely work that way at all.

1 hour ago, sketch said:

clean it well

Very much so...

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After scrubbing the barrel down with carb cleaner a few times, I tried stainless steel wool. That actually did next to nothing to get any of the marks out of the metal. I moved on to 1000 grit sandpaper and that seemed to take out everything I was concerned about at first. There were some strange liquid streaks running the length of the barrel, presumably something acidic dripped down, but wasn't wiped around. Those long flowing marks were embedded in the lathe tool marks on the barrel, so while they did clean up a bit; they were still visible.

Knowing the bluing process is a chemical reaction; I applied the blue over the streaks while spinning the barrel and hoped that would take them away. The marks did not appear to dissolve as I was applying the solution, but perhaps after sitting warm for 24 hours it will look different. I could also try another coat after the 24 hour warming if I'm still not happy with those results. If it's really bad I can always sand it down and finish the outside profile myself, but then all those tool marks will be my own, and not how it came from the factory. That would nullify the idea of the raw finish I was hoping for with this. 

I'm honestly curious what could have made the dripping marks; the barrel was well lubed when I got it. I might give them a call and ask when I'm in the mood; not because I'm mad about it, but I would just like to know. They sent me a sticker and a nice thanks for buying a barrel letter that just showed up in the mail today. It was truly a nice touch, and I'm certainly happy with the overall quality of this barrel. 

Pictures of this and that tomorrow night; when the barrel is cured.

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Here is what it looks like with a broken barrel nut, no hand guard, on a lower from another build. It is surprisingly balanced at the barrel nut in this configuration. I don't think it will look right without a 15" hand guard, so I think that's the next pickup. Not sure why I thought I was getting a C-Products magazine, it was an ACS brand. It is also not very good quality; much worse than my .308 ACS magazine. I want to beat it with a hammer and I haven't even cycled rounds through it yet. Spot welds look terrible, there is a gap where the stainless sheet metal is supposed to overlap. It doesn't slide into the magazine well freely at all. I will certainly be ordering a C-Products magazine sometime soon as well.

The barrel blue job came out pretty rough, and only looks alright from a distance. I don't see any harm in heating the barrel lightly with a torch to do another application in hopes I can darken it up some more. I suspect in the end I'll just have to polish the whole thing and start again. As such, I haven't wiped it down with water or oil yet; no sense making it harder to get clean when that time comes. 

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I cleaned the barrel with CRC brake cleaner this time, then warmed it up above 200 degrees with a torch very slowly and carefully. I cleaned it again with brake cleaner and then applied the Perma Blue again. The first few coats of solution steamed off during application, but a few more after that went on smoothly. It looks a lot better already, but I'm not sure it's absolutely perfect. Surprisingly the torch heating seems to have cleared up most of the remaining defects in the barrel; the extra bluing did darken it up nicely though too. Back to sitting for another 24 hours, but I will certainly run it this way for a while.

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I'll look around and mock up hand guards at different lengths before I spend the money; it's certainly worth considering a 17".

The reverse grip is at least pseudo-legal here on a semi-automatic (the local gun store sells a commercial product like it). That particular lower is from another gun which needs that anti-feature. Since I don't have that gas port on the 7.62x39 build I can run a real pistol grip, and even any kind of fore grip I want. I'm not sure a forward grip is helpful, but at least it would be legal. 

I have yet to build a lower for this; it doesn't seem like it will need to be anything special, other than bolting on the regular grip.

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24 minutes ago, blue109 said:

Reverse grip and low-pro magazine for super ninja prone shooting.

I've actually come to appreciate the sleek look of the legal build here. The other options are a pure sawed off "spur" grip, or the sideways "boar" pistol grip. All of them are great for prone shooting. I'm kind of mad I can't find short .22lr magazines for my CMMG conversion. The kit came with 25 round magazines pinned out to 10 rounds, even the Black Dog ten round magazines are much longer then necessary, and plastic welded closed (tougher to modify).

I held up a yard stick and 15" is the hand guard length I want for this. The marks on the barrel tip are some kind of lathe work; but it makes a 17" look bad. I have to wait a few days for that, and also delivery of parts for the shot timer. Since Radio Shack is gone, I can't get a zener diode easily without shopping on eBay.

Barrel looks great, and almost 100% in my mind. The hot blue application worked out just as I had hoped; actually better.

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12 minutes ago, Lane said:

 Since Radio Shack is gone, I can't get a zener diode easily without shopping on eBay.

 

Fry's Electronics - if you have to order it anyway, they'll have it.  I'm lucky enough to have two of them near me, but I didn't see any locations listed in your state.

https://www.frys.com/

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2 hours ago, 98Z5V said:

Fry's Electronics - if you have to order it anyway, they'll have it.  I'm lucky enough to have two of them near me, but I didn't see any locations listed in your state.

https://www.frys.com/

 My go to is https://www.digikey.com/  If I ordered by 10am west coast time I'd see it the following afternoon.

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13 hours ago, 98Z5V said:

Fry's Electronics

 

11 hours ago, Cunuckgaucho said:

 My go to is https://www.digikey.com/

I will actually check out Fry's; I've never ordered from them before. Digikey has great prices on components, but I always feel like I need to order $100 or more to justify paying the shipping costs. My last Digikey order was three years ago, and I paid $10 shipping and $5 tax on $45 in parts. 

I have absolutely no idea how the chinese ship things in to the US for such low costs; but even US eBay sellers have 10-20 packs of components for $1.95 with free shipping; or in this case, an assorted 300 pack for $5 and free shipping. That keeps me from blowing ten times the money on parts that I would likely put in a box hidden in a drawer until next year. 

Finding the MEMS microphone is a bit more challenging apparently. For a component that only costs a dollar or so, one mounted on a breakout board is closer to $10; still cheaper than paying Digikey to ship one though.

 

On 12/30/2018 at 11:29 PM, CRracer912 said:

If you're gonna shoot steel cased ammo

I looked all over town for 7.62x39 and boy is it tough to find in brass at a reasonable price. Almost everything is steel case berdan primed for at least $0.25 a round; brass starts at $0.75 and goes up over $1.00 a pop. I pay less for .308 when I shop around, so I think that means another set of reloading dies if I can find projectiles at a reasonable price.

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3 hours ago, Armed Eye Doc said:

Even with shipping, you can come out ahead by ordering online.

In NY we have to have ammo shipped to the FFL, and they charge a fee just like buying a gun. I believe the local store I do business with charges $35 flat rate for each shipment if I order online. Had they been open today I would have asked if the same fee applies if they order it for me.

I ran the numbers though, and with those prices (roughly $0.40 a round);  I would only need to buy about 100 rounds to break even if I paid the FFL fee too (so I would pay $0.75 a round for those first 100 rounds). That really does look like the best deal when I'm ready to stock up on brass. Who am I kidding; that will probably be next month at this rate... 

Interestingly a 3 die set for reloading is only $27 at Midway right now. I see 123 grain .311 projectiles as cheap as $0.11 elsewhere which would let me reload for less than I would pay in bulk ordering online. Cheapest powder charge is $0.12 for a starting load, through $0.16 for a max load (buying 1 pound at a time and paying hazmat fee); plus four cents a primer is $0.31 or less per round with reused brass. Given the laws here now, and what they could be in the future; I might as well do both. Order ammo online; likely paying the fee, and buy the dies to reload all that brass.

1 hour ago, CRracer912 said:

Winchester white box 7.62x39, brass cased.

I stopped by there twice today; at first I scoffed at the $15 for a box of 20 of these, but after hitting another gun shop it seemed like the best deal in town. Field and Stream is the last store around here I haven't been out to look at yet. 

While I could rush through a headspace check and fire this build, I'm waiting for the last few things parts this point. It gives me more time to work on the shot timer, and also try to finish up my long running AK-47 build. I'm honestly most nervous to press the front trunnion rivets; once that's done it will be smooth sailing to finish it up.

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10 minutes ago, Lane said:

Given the laws here now, and what they could be in the future; I might as well do both. Order ammo online; likely paying the fee, and buy the dies to reload all that brass.

That's the way to go, honestly. You'll recoup the cost of the reloading equipment in no time, really.

I load .338 Lapua Magnum for about 90 cents a round.  That gun is chambered for $6 bills...   :laffs:   Where it doesn't work out is manpower, versus cheap ammunition like 9mm.  I can buy 9mm for about as much as I can load it, and I don't have to spend the time loading it.  If you load your own, it'll certainly be more consistent than regular bulk ammunition.  That's the greatest benefit, bar none, right there.

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18 minutes ago, 98Z5V said:

manpower

That's one thing I have going for me. I have plenty of free time for the most part; and I absolutely love the process of reloading. With .223, I can reload my brass for the same cost as steel case ammo; I much prefer to reload. I get pretty good milage out of even Remington UMC cases, which seem to be the worst quality out there. Hell; I would try reloading steel cases if I could find it with Boxer primers around here. 

I don't have anything in 9mm yet; but perhaps one day. I'm sure you know; the laws here make that difficult (some counties in NY flat out reject pistol permits if you don't have the right connections). I have toyed with the idea of a 9mm AR-15, but I simply can't justify it for any logical reason. Might as well shoot some other caliber out of the same platform.

Any thoughts on what other calibers have benefits? I know a bunch of you have some AR-10 style guns in different calibers. Unfortunately I don't have any good long range shooting here for most of the year. In the winter I could thread the needle through the trees to a target way up the mountain; but in the summer I can't see more than 10 yards into those same woods. I saw Lee made a limited run of .50 Beowulf reloading dies, and considered that for an AR build; but haven't run all the numbers yet.

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3 minutes ago, Lane said:

Any thoughts on what other calibers have benefits? I know a bunch of you have some AR-10 style guns in different calibers.

My two favorite are .338 Federal and .260 Remington.  I make both from used .308 Win brass.  I'd say it's as easy as passing them through the sizer die - and it is for the .338 Fed.  For the .260, I'm only using Hornady .308 Win Match brass (downsize it), but then I turn the necks on that "new .260 Rem brass."  For the .338 Fed, I'll make that out of any old .308 brass I find.

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13 minutes ago, 98Z5V said:

I make both from used .308 Win brass.

I had been meaning to read up on that. You said you turn down the necks; how does that work exactly? I would certainly be interested in other calibers I can work up from modified .223 and .308 brass.

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1 minute ago, Lane said:

I had been meaning to read up on that. You said you turn down the necks; how does that work exactly? I would certainly be interested in other calibers I can work up from modified .223 and .308 brass.

Now you got me on .223 brass...   :laffs:  I do 300BLK and Sharps 25/45 from .223 brass.  The 25/45 is brainless - just neck it up in the sizer die and load it and shoot it.  Only take a barrel change.  300BLK is the same way (just a barrel change), but there's more work involved in converting the brass.  I'll try to find the longass step-process I wrote up on it.

.260 Rem.  When you neck down the brass, you have the same amount of material in the neck, you just make it smaller - and it's usually thicker neck walls, because of that.  Sometimes too thick to chamber.  Hornady .308 Win Match Brass is the best I've found for this task, and I still need to turn the necks on about a third of them.  I use a KM Precision jig to do this - they sell a really, really good kit, by caliber.  Fully adjustable.  It's another $100+ bucks to get into it, unless you find it somewhere cheap, but it's worth the frustration of having round not chamber on you.  If you need it, you need it.  On .260 Rem, you probably will, if you're converting .308 brass.

I lock the converted brass down onto that shell holder, put it in the drill, and run it (slowly) down onto that cutting jig.  Turns the neck diameter down to whatever I set it to.

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