My first 7.62x39 AR

[Lane]

5 minutes ago, CRracer912 said:

You may or may not care about this, but field and stream is owned by Dick's. Dick's made a statement by destroying their remaining stock of 'assault rifles', hiring anti 2a lobbyists. They've taken a hit financially as us pro 2a tend to no longer patronize them.

Oh I do care; I was at the Dicks only location the other night and they didn't have any 7.62x39; the clerk recommended Mom and Pop shops I had already been to. I Just remembered that the Field and Steam location had a much larger ammo selection... Certainly not worth the gasoline to find out they are not going to have it either. The Dicks store I was at keeps the .223/5.56 under glass at the counter where every other caliber is on the shelf; I never understood that. I've not bought any ammo at Dicks in a long time; their prices usually aren't very good, it is close to my last resort buying locally though.

[98Z5V]

Here's what I do to make my own 300BLK brass from 5.56 NATO Lake City brass:

The steps I take on this stuff is as follows.  It's also subject to change if I can find any other steps that will make other steps easier...

 

Steps for my 300BLK manufacture:

 

1.  AR-15s get the $hit shot out of them at the range.  All brass policed up.

2.  All AR-15 brass (.223 Rem and 5.56 NATO) goes into the tumbler once it gets home.

3.  Sort out Lake City 5.56 NATO brass - that's the only stuff I'll turn into Blackout ammo anymore. 

4.  Run the Lake City 5.56 brass through the mini chop saw.  I was cutting it right at the neck, but that leaves ALOT of trimming.  I've been cutting it a little further back now, so I have less final-trimming to do.  I'll get pics next time I chop a batch up.

5.  Chamfer those now-straight-walled cases heavily, with VLD chamfer bits - this is important later, and for the next step. 

6.  Run them through the tumbler for about 15 minutes, to clear out all the brass shavings from chopping them - don't let that stuff tear up your 300BLK dies.

7.  Pull from tumbler, shake 'em out, and lube 'em up on the pad (or whatever you use).  You can hit straight-walled 5.56 cases with some pretty heavy lube, and it won't hurt the brass.  Typically, if you use too much lube, you're gonna dent in the shoulders of brass that you're just resizing.  That's one sign of "too much lube."  You can run this stuff heavy and it won't hurt new-made BLK cases - you're forming a brand new shoulder, where there wasn't one before.  I've yet to have a problem on a heavy-lubed pad, and any shoulder issues when making new BLK brass.

8.  Run 'em through the sizer/deprimer.

9.  Leave the lube on there - don't sweat it.  There's still alot of steps to go here...

10.  Change dies in the press - Run them through the Swager now - get rid of those crazy Lake City primer crimps.  Be aggressive with them in this step, because the new Lake CIty primer crimping is a 4-Corner affair.  Lake CIty wants to make sure you never blow out a primer in their brass, and they're damn good at the primer crimping process.

11.  These things are going in for final-trimming now.  Put them in your trimmer - lube still on them - and cut them back to 1.363" OAL.  I've been cutting them shorter now so I have less to trim.  If you chop them right at the shoulder, they'll be somewhere between 1.900" and 2.000" long when you start trimming - THAT'S ALOT TO HAND-TRIM!!!  I chop under the shoulder now - still experimenting - and my initial length, to start trimming, has beenin the 1.800"-something range.  That's not bad.

12.  You may need to hit them with the VLD chamfer tool (inner and outer) while you're trimming them down.  Measure often - if you have alot to go, chamfer those fuckers.  It makes it easier to trim them down.

13.  Once at final trim-to size, chamfer those bastards again, inner and outer, with the VLD chamfer tool.  This must be done in order to make it easier to get a good, light crimp on them later. 

14.  Once they're all trimmed to 1.363", they go into a small tupperware of hot soapy water.  Run them all around in there, make sure you wash them good.  They've got lube on them, brass shavings, gunk.  The hot soapy water makes that stuff go away fast. 

15.  Toss in a squirt of Real Lemon, right into the soapy water, for the last 10 minutes.  Makes 'em pretty.

16.  Out of the water, into a small collander - hot water bath, right under the faucet, to clear all that soap and lemon juice out.

17.  Onto the paper towels, out into the AZ sun, to dry out.  Takes less than 10 minutes here, in the middle of the day, in the summer...

18.  Into the tumbler again.  Polish 'em up.

19.  Clear them out from the tumbler, take them back inside ('cause it's summer in AZ...).

20.  Prime those bastards up.  I'm running CCI 400 small rifle primers in mine.

21.  Measure/drop powder.  I'm running 150 grain Hornady FMJ BT projectiles, so I'm running 16.1 grains of H110 powder under them.  It's very, very damn close to a compressed load in this small case.

22.  Seat your bullets. 

23. Toss on a light taper-crimp, if your dies don't already do this for you.  I've been using the RCBS AR-Series 300BLK Small Base Die Set.  The seater die has a crimp function built right into it - all in the same motion.  Once you hit that final depth on the seating, it crimps it, too.  No separate action the their AR-Series Dies. All in one.  Saved one step that way...  <lmao>

 

There you go.  That's the process I take to turn Lake City 5.56 NATO brass into 300BLK ammo.  Might seem excessive, but those steps are there for a reason.

[98Z5V]

1 minute ago, Lane said:

Oh I do care; I was at the Dicks only location the other night and they didn't have any 7.62x39; the clerk recommended Mom and Pop shops I had already been to. I Just remembered that the Field and Steam location had a much larger ammo selection... Certainly not worth the gasoline to find out they are not going to have it either. The Dicks store I was at keeps the .223/5.56 under glass at the counter where every other caliber is on the shelf; I never understood that. I've not bought any ammo at Dicks in a long time; their prices usually aren't very good, it is close to my last resort buying locally though.

Here's some background on Dickheads Sporting Goods.  THose fuckers will never, ever see a penny from me.  Just like CTD.

 

[Lane]

4 minutes ago, 98Z5V said:

put it in the drill, and run it (slowly) down onto that cutting jig

Alrighty then... I think I'm going to need to make or buy one of those. Seems like the Unimat lathe could do the spinning, if I mounted the right things on the tool mount or tail stock for necking. That device looks pretty well thought out though; I can see click stops on the one adjustment, I presume they are in something like .001 increments (or whatever increment is functional for that job)?

[98Z5V]

14 minutes ago, Lane said:

Alrighty then... I think I'm going to need to make or buy one of those. Seems like the Unimat lathe could do the spinning, if I mounted the right things on the tool mount or tail stock for necking. That device looks pretty well thought out though; I can see click stops on the one adjustment, I presume they are in something like .001 increments (or whatever increment is functional for that job)?

True - that's exactly what they are.  One piece I'm not showing you in that pic, is the one I keep in the die set box.  There's a special neck sizer that you run it down on, before you do any cutting.  Also, that cutting tool is precisely sized (in this case, to 6.5mm) to support the neck from the inside, while you turn down the outside.

Money is money, but it would be way easier to get the tool, rather than try to figure everything out to make your own jig for this job.  It's only a controlled explosion, inches from your face.  I'm just sayin'...  

Also, get the carbide one. 

https://kmshooting.com/neck-turning-tools.html

Their instructions:

https://kmshooting.com/kmshooting/media/pdf/97.pdf

Edited January 2, 2019 by 98Z5V

[Ravenworks]

When I was building computer cases I bought a bunch of stuff from Mouser.

Their shipping was pretty good

[Lane]

51 minutes ago, 98Z5V said:

It's only a controlled explosion, inches from your face.  I'm just sayin'...  

That's why I didn't run outside and fire my 7.62x39 build real quick. I know for a fact it would function just fine the first time I shot some Wal-Mart ammo. Right? Just use that old barrel nut and some whatever anti-sieze in the threads?

You saw my Ceratac first fire photo. Seems like you might play with motorcycles too?

46 minutes ago, Ravenworks said:

Mouser

Definitely good with Mouser too. I really need to crack down on that shot timer programming; it's all boiling in my head lately.

[98Z5V]

15 minutes ago, Lane said:

Seems like you might play with motorcycles too?

 

Absolutely - but only the ones that will kill me. 

[Lane]

13 minutes ago, 98Z5V said:

Absolutely

Do you have a Turbocharger? I've always been a bit scared of them in a bike. Never even tried one...

[Ravenworks]

38 minutes ago, 98Z5V said:

Absolutely - but only the ones that will kill me. 

I've been hit 3 time.

The one in 88 almost did me in,40 fractures and 6 months in the hospital.

Lady ran a redlight and I tee-boned her,ended up in the back seat with my Panhead with me

 

[98Z5V]

26 minutes ago, Lane said:

Do you have a Turbocharger?

Do I have one?  No.  Have I built and tuned them?  Yeah, LOTS of them.  This was 10 years ago:

[CRracer912]

Midsouth shooters supply has a Trinity for a 15" keymod rail, 49.99.

https://www.midsouthshooterssupply.com/item/00250ygm515km15nl/15inch-echo-keymod-hand-rail

They sell other gun related/reloading stuff as well?

[Lane]

21 hours ago, 98Z5V said:

This was 10 years ago:

And that is why I asked about a turbo... That is precisely the kind of machine that I might have too much fun with on the wrong day. I had been riding a 1978 XS400 for a few years; until winter riding last March fried my electrical system (salt/water is the likely culprit of course). I still swear the ColorTune spark plug is the only reason it ever ran as well as it did (made fuel tuning visible and accurate). I have another pair in various states of finish, but different years of course (79 and 81).

On 1/1/2019 at 9:40 PM, 98Z5V said:

https://kmshooting.com/neck-turning-tools.html

I'm going to have to read back through your procedures a few more times; but this looks like a very well designed tool. So you run a regular sizing/depriming die on a case that was raw chopped and chamfered? The KM tool is only for final trim; or does it do some shaping too? The documentation only seems to discuss cutting; but I might have missed something having not actually used one yet.

 

I've begun coding the menus for the shot timer prototype's display. I have a case design in mind that I'm about to sketch out in CAD. I ordered a pair of final microcontroller modules with the larger screen already mounted and wired to the same board. I'll design a slightly different case for that one once I have it in hand to measure up. I should have a handful of prototypes once I figure out the final audio input choice... Currently have a few options on the way, along with the initial piezo sensors I had on hand. Each of those have different size and mounting requirements of course. 

Just about to finalize the 7.62x39 build order. There isn't much left; but I want to make sure I don't have to pay extra shipping costs for no reason.

[98Z5V]

56 minutes ago, Lane said:

I'm going to have to read back through your procedures a few more times; but this looks like a very well designed tool. So you run a regular sizing/depriming die on a case that was raw chopped and chamfered? The KM tool is only for final trim; or does it do some shaping too? The documentation only seems to discuss cutting; but I might have missed something having not actually used one yet.

My reference for this is only on .260 Remington, as it's the only load that I have that needs it.  I'm necking down Hornady .308 Win Match brass to a smaller caliber, and confining that brass dimension (neck diameter of .308 Win brass)  to a smaller outside diameter, overall, through the .260 sizing die - that's all it takes to make .260 brass from .308 Win brass - or so one should think.  There's no chopping and chamfering - even though I VLD chamfer all of them, inner and outer.  It's not like cutting down 5.56 brass for 300BLK case manufacture.

By doing that, I've increased the wall thickness at the neck - same amount of brass, displacing a smaller diameter, and internal is sized by the sizer die, last, as it comes out of the sizer die - that means increased outer diameter, in some instances.  Depends on the brass, really.  I'm using the best brass I can for this, to make my own cases - and when I run them through the neck turner device - they don't always have the same trim marks.  That's the byproduct of downsizing extremely accurate brass for another caliber. If it makes a difference on Hornady .308 Win match brass, downsized to .260 caliber, it would have a huge difference on range-trash 7.62 pickups, out there.

I wasn't aware of it initially, until I had problems chambering some of my early .260 brass conversions.  Some chambered, some didn't.  All from the same once-fired Hornady .308 Match brass.

I run the regular Hornady Match brass through the .260 Rem RCBS sizer/deprimer die.  I then switch dies to the KM sizer die - this is important, for the internal dimensions for cutting the necks down.  I then lock it into the KM tool, and turn down the necks. The cutting tool both supports the internal support for turning the necks, and turns the external diameter to what you need to not stick the round in the chamber. You get to adjust this dimension, to what you need, with this tool.

When you neck UP brass, this is almost never a concern - you're turning the same amount of material into a larger diameter - the neck thickness will be fine, thinner,actually.  This is the first caliber I've turned down, with exceptional quality brass - and it caught me a few times.  I invested in the right tool immediately.

[Lane]

9 hours ago, 98Z5V said:

By doing that, I've increased the wall thickness at the neck - same amount of brass, displacing a smaller diameter, and internal is sized by the sizer die, last, as it comes out of the sizer die - that means increased outer diameter, in some instances.  

I wasn't aware of it initially, until I had problems chambering some of my early .260 brass conversions.  Some chambered, some didn't.

This is the part I hadn't fully thought through (wall thickness increasing too much); so essentially the KM sizer die is turning the cases like a lathe? Do you use something like a Lyman case length/headspace gauge to check cases; or just measure with calipers? 

[98Z5V]

1 minute ago, Lane said:

This is the part I hadn't fully thought through (wall thickness increasing too much); so essentially the KM sizer die is turning the cases like a lathe? Do you use something like a Lyman case length/headspace gauge to check cases; or just measure with calipers? 

Just measure with calipers on this one - the .260 - Lyman doesn't have anything like that for this one.

Yep, it's a mini-lathe, of sorts, while supporting the inner diameter at the same time.  That expander die they have - that's different from the regular expander die - you have to set that thing at a certain depth, in order to create a "ring" to machine through, to make the brass right.  It's way more complicated than I thought, until I talked to them on the phone.  After talking to them, it's not complicated at all - with the right tools.  I bought everything they said I needed, and I didn't buy any of the extras (an ergonomic hand-hold tool, etc.).

This is the first case I've had to neck down...   from .308 brass.  if I was necking UP 243 win brass, it wouldn't be an issue.  I just have a mad base of 308 Hornady Match brass that I've accumulated. 

[Lane]

Things are starting to settle down for me here (for the time being at least). All the rest of the 7.62x39 build parts are on the way now. I'm about to take the barrel back off the upper and touch up the last bit of Perma Blue application near the barrel extension. I also "accidentally" ordered a bunch of reloading dies; even a set for a gun I don't have; oh well. Powder was a no-go though because I'm not paying $10 for hazmat and $11 for shipping when everything else was going to ship for free. 

Finally ready to start coding the audio input routines for the shot timer. This really isn't all that difficult but I do want/need to compare the results to audio recordings made nearby. Without attention to that detail the microcontroller could record timings that are off by a few milliseconds due to execution times and delays in the ADC; best to plan for and account for all that early on.

I scratched out a few CAD drawings of the minimum case design for the shot timer with these parts. It could be made wider and thinner; but everything would stack inside this design. The grey objects are a single quarter, and a $1.00 stack for scale reference. I haven't finalized any button arrangement, or placement because of all the other constrains involved. The microphone and buzzer placement could possibly force my hand one way or another still. 

[98Z5V]

This is such an awesome project, to watch happen.   Impressive.  

[shepp]

You may have stated in here and I missed it, what are you planning for a trigger? 

 

Im running the hyperfire 24c ended up having to order their heavier (x39 recommended) springs for commie primers, Havnt had an issue since 

 

FYI

[Armed Eye Doc]

43 minutes ago, shepp said:

You may have stated in here and I missed it, what are you planning for a trigger? 

 

Im running the hyperfire 24c ended up having to order their heavier (x39 recommended) springs for commie primers, Havnt had an issue since 

 

FYI

I am running the Larue MBT with the heavy spring and I have had no problems. 

[Lane]

1 hour ago, 98Z5V said:

This is such an awesome project, to watch happen.

Thanks, I'm having a good time with it so far. I do have a question about how a handheld timer listens for shots. I've seen at least one timer with a big green "Go" button. I presume there is some already programmed time to record shots in that case; say 5 seconds total, or 35 seconds? Does a handheld timer usually have the ability to count the shots and stop automatically?

I had tried earlier today to write data to the flash memory, but kept crashing the microcontroller. There was apparently a bug in some previous version of the software, so it is possible I found that. For the time being I'm just barfing the data into some arrays that can be written to flash in bulk later in the code (if absolutely necessary). I was kind of hoping to use the flash write as part of the echo rejection delay; but optimization will have to wait.

Here is a debug screen showing the raw time, amplitude recorded, and split time (not my real splits yet; but it is actually recorded data). It's not your eyes; the text is overlapping a bit simply to give me more data on screen at the moment. I'm considering auto threshold on the audio input based on the recorded peaks; simply dropping anything that's 10% less than the highest peak, first shot, etc... I'll have to see what kind of data I get when it's out in the field of course. 

4 hours ago, shepp said:

heavier (x39 recommended) springs for commie primers

I'm still on the fence about shooting steel case ammo in this build. I have a bit on hand but might save it all for the AK or SKS. I bought 7.62x39 reloading dies recently, but still need to acquire suitable powder and a lot more brass. I've also seen a longer firing pin that is supposed to help on the harder primers.

I actually run mil-spec triggers with a smile on my face. At this point I don't see my trigger slowing me down very much, but perhaps a shot timer will prove me wrong. This particular build isn't even semi-auto, so cycling the gun is going to be a much bigger distraction for me. 

Been meaning to try out some nicer triggers at the local gun shop, but almost every time I go they have more customers than they can handle. I think I was wandering around for an hour before getting help the other day when I stopped just to pickup a 7.62x39 magazine.

[98Z5V]

2 hours ago, Lane said:

Thanks, I'm having a good time with it so far. I do have a question about how a handheld timer listens for shots. I've seen at least one timer with a big green "Go" button. I presume there is some already programmed time to record shots in that case; say 5 seconds total, or 35 seconds? Does a handheld timer usually have the ability to count the shots and stop automatically?

 

The Go button on mine can do a few things - it starts the countdown to a preset delay, before it beeps and starts counting.  The beep is the audible for the shooter to go.  I set mine for a 3-second delay, then the beep will sound, and timing starts, as well as shots recorded.  You can turn that delay function off, so as soon as you hit the Go button, the beep sounds and timing starts.  You can also set it up to run a PAR time.  Say you want to get 10 rounds on target, from holster, and you give your self 3 or 4 seconds to do that.  You set up the PAR function, and it beep at the beginning and at the end, letting you know you reached the time limit.  The Go button starts that activity.

My timer won't stop, until it shuts itself off from inactivity, or I physically turn it off.  Once you hit that go button, it'll record shots until it runs out of battery power, if that's the case.  If there are shots going, it's recording, once it's started.  We've shot through courses before, with it clipped to my left pocket.  We run the last one, and start doing different things.  I'll look down, and it's still on, recording the 100th shot and 900 seconds later, for example...

[Lane]

I looked back at my own post and saw I wasn't actually displaying the split time. Fixed that and went down a few more rabbit holes. Now the debug shows: raw time, amplitude, time from buzzer, split time, stored memory location.

Current menu options are: Go, Mode, Program, Settings, WiFi, Shutdown. Menus are actually animated without any significant code or memory usage.

The web interface isn't much use in programming without being able to write shot timing to flash memory, though I do recall some kind of file writing option. There is certainly a work around here one way or another.

17 minutes ago, 98Z5V said:

for example...

The other image is a fast and dirty web based form for configuration of a program. I believe it can handle every scenario you described and then one. They can be chained together, or run individually with the go button. You can also just set a super long recording time for your last case; with one total program like this.

Still working out a few details, but the buzzer plays, and times are measured (real split times now too).

[98Z5V]

THIS IS SO COOL, MAN!!! 

[Lane]

1 hour ago, Lane said:

(real split times now too).

Not really "real" split times. That debug measures the slop in timing from: code, a delay function, and some other nonsense with the ADC, etc... I'm actually running a ton of code in the display loop and still getting decent numbers. I even tried clocking up to 160MHz from 80 and didn't see many changes in those numbers. 

Taking the shot timing functions out of the main display function, and doing display updates only on shot input could bring me well below 1ms resolution. The clock cycle time on an 80MHz clock is 12.5 nanoseconds. Even at 10 clock cycles per execution it could be 1/8 millisecond resolution. For reference; CD quality 44.1kHz sound is sampled every ???. Does anything currently qualify 1ns resolution?

Edited January 7, 2019 by Lane
ns I don't even know now..