Lane's: jtallen83 inspired 21.750" 300 AAC Blackouts

[98Z5V]

1 hour ago, ARTrooper said:

Now idk anyone that tries to conceal carry a 300blk pistol.

There's a minimum overall length, I'm pretty sure, otherwise it gets classified as an AOW.  For some reason, 26" sticks in my head.  It's the only way the Shockwave and TAC 14 get by - any shorter and they would be AOWs.  They made the barrels 14" long because that just gets it over 26" OAL, with that Raptor grip.

Edited March 2, 2019 by 98Z5V

[Lane]

1 hour ago, 98Z5V said:

There's a minimum overall length, I'm pretty sure, otherwise it gets classified as an AOW.  For some reason, 26" sticks in my head.  It's the only way the Shockwave and TAC 14 get by - any shorter and they would be AOWs.  They made the barrels 14" long because that just gets it over 26" OAL, with that Raptor grip.

I didn't even think about this because I don't have a pistol permit; but it looks like the SAFE act bans AR pistols in NY because of the weight. Only way to have one is to be LE, or have a strangely fixed magazine (bullet button isn't legal). The only one of those I'm aware of has special rivets into the magazine that destroy the lower if removed. I'm also not aware of any FFLs around here that are willing to play in that territory. Rifles are legal in NY... I'll see if I can clarify the SBR issue with my local dealer next time I stop in; I don't have any actual experience with it.

I read some more about suspersonic projectiles, but I still don't have a clear understanding why they would be more accurate. I can clearly see why I want to stay away from projectiles crossing back into subsonic territory though. Plenty more to explore in that department.

The wikipedia article on 300 AAC Blackout lists velocities in 24" barrels for a 78 and 90 grain projectile that I don't have load data for. One of them is listed as CQ, so they may not be very aerodynamic.

[Lane]

I played with a ballistics calculator in regards to the lighter projectiles I could find for sale. I'm not exactly sure what to aim for without any actual data in hand; other than favorable BC. I can only estimate the muzzle velocity based on some other off weight information at the moment.

Picked up a bag of 100 immaculate once fired Lake City brass a few weeks back on a whim. I had planned to reload those in .223; but I might as well convert them to 300 Blackout at this point. I will do a few in garbage brass first to get the rhythm. I know some people insist on case annealing; but that might not happen right away. I think a tight neck in chamber might help to protect against cracks. I don't remember seeing anything about annealing in the Houston Warehouse article; I'll check again before I make my decision on that matter.

I know I still need a micrometer, and a tube micrometer of reasonable accuracy. Also a case trimmer unless I can make the resize die do all the work for me... I kind of doubt it. Still all depends on what the chamber casts look like.

[ARTrooper]

7 hours ago, Lane said:

That is where the NY State law picks up though; anything below 16" barrel length must be put on your pistol permit, and thus treated exactly like a pistol.

I see, and I bet you guys have strict laws on pistols. you could always get like a 14 inch barrel and pin your muzzle device to make it the 16", or better yet pin a suppressor to a 9" barrel to get the 16"! 

[ARTrooper]

6 hours ago, 98Z5V said:

There's a minimum overall length, I'm pretty sure, otherwise it gets classified as an AOW.  For some reason, 26" sticks in my head.  It's the only way the Shockwave and TAC 14 get by - any shorter and they would be AOWs.  They made the barrels 14" long because that just gets it over 26" OAL, with that Raptor grip.

Not that I have found, you can have pistols under 26" in length, but NFA says if it is equipped with something like say a vertical foregrip, it is no longer meant to be shot single handed and therefore is not a pistol but rather an AOWs. So the vertical grip and other such things are the key, however angled foregrips are  approved by the ATF.

[98Z5V]

4 hours ago, Lane said:

Picked up a bag of 100 immaculate once fired Lake City brass a few weeks back on a whim. I had planned to reload those in .223; but I might as well convert them to 300 Blackout at this point. I will do a few in garbage brass first to get the rhythm. I know some people insist on case annealing; but that might not happen right away. I think a tight neck in chamber might help to protect against cracks.

You don'tneed to worry about annealing if you're converting LC 5.56 brass.  That stuff is already annealed so deep, initially, that you're covered on the first several 300BLK loadings from it.

Check it:

 

[Lane]

12 hours ago, 98Z5V said:

You don'tneed to worry about annealing if you're converting LC 5.56 brass.

Thanks; and also for the refresher on the 300 Blackout process. I had read that before when you mentioned it a while back, and it was good to go over it again.

I made up a few test cases and a dummy to measure. The spec on the neck diameter is .334", and this measured .333". I think that's pretty good considering the factory round I have is only .325". I don't think I'm going to need to worry about customizing my chamber on the barrel fabrications. I should be able to regulate with brass thickness and neck turning as needed.

For some reason though; the bullet seating die I have will not stop anywhere near max length. I'm not sure how I'm going to resolve that (it wants to make much shorter overall length if the adjustment is at max). The only way I got even close was not moving the ram all the way up. Of course this too may not matter in the end; but it was surprising to me.

I have not even tried the Lake City brass yet; this was all junk .223 I had laying around. Honestly I used a tubing cutter to trim these cases; while I wouldn't recommend it to anyone, it worked fine for these few after a bit of practice. Sure do need a lot of lube with the initial neck forming.

[Lane]

Stopped by the local gun shop to look for more ammo. Found one box of 300 AAC Blackout in 110 grain; expensive, but worthwhile for initial testing. I asked about the SBR issue and was told it was totally illegal if you aren't LE. I believe that to be the position of most every FFL in the state of NY, on any issue involving loopholes or grey areas. Unfortunately the state police still refuse to provide any clarification of those specifics, in regards to the SAFE act especially. That lack of clarification is why the fixed magazine issue is different here than in California as well. 

I still have plenty of time to send off dummy rounds to the barrel fabricator for chambering. I simply have not decided if that is a better choice than trying to examine what I receive and build off that on my own. Presumably they will cut a barrel that is tight to specification, and I should be able to tune my cartridges to make that work well. I am also aware that it is common practice to go the other way; and have a barrel made to the rounds for accuracy sake. My current feeling on the matter is that I don't have enough starting data, like desired overall length, or an idea what this barrel will prefer. Earlier I looked at getting these made one at a time; but the shipping cost would have been 1/3 of the cost of barrel blanks if I had done that.

Pretty well ready to set this project aside for a while. I have a few lowers to make up over the next few week in preparation; but there isn't too much else I can do in the short term. Almost ready to shift into that .260 Rem build while I wait this out...

[98Z5V]

You can always buy a chamber reamer, and chamber them yourself.   Are they already threaded for the barrel extension?  How "blank" are the blanks?...    Rifled blanks, only, or finished blanks, just unchambered?

[Lane]

18 minutes ago, 98Z5V said:

You can always buy a chamber reamer, and chamber them yourself.   Are they already threaded for the barrel extension?  How "blank" are the blanks?

I'm not sure I trust myself to chamber new blanks yet; I would prefer to practice that on an old useless barrel first. 

These blanks are Green Mountain raw rifled tubes; 1.25" x 25" with a 1:7 twist for 300 Blackout. Strangely Green Mountain sells a 21.5" gunsmith blank (with the barrel extension mounted, and chambered) in a 1:8 twist. That twist isn't available in a raw rifled blank tube though. 

The fabricator does everything else for me in this case; and throws in the barrel extension for free (or will mount one provided for the same price). I sent the blanks to Compass Lake Engineering in Florida for that part of the job. I would have preferred Green Mountain do all the work; but didn't push the issue after they told me they had a 100 barrel minimum on custom work.

[98Z5V]

Compass Lake Engineering has been making accurate ARs for a very, very long time.  National Match rifles, that win.  Their barrels are out of this world.  Fear that work not a bit, man - it will be pure quality.   

[Lane]

14 minutes ago, 98Z5V said:

Compass Lake Engineering has been making accurate ARs

Didn't see a bad word written about them anywhere. The price was right; and they didn't bat an eye at my specifications. So many other custom shops didn't even have 300 AAC Blackout as an option; much less offer length. I've been curious to know what the broader shooting community thinks about modern CNC made barrels vs. what couldn't have been made that way back when the Houston Warehouse was in operation. This would be something like a CD vs. vinyl quality argument in my mind; and I really have no opinion either way.

If none of you figured this out yet; the 21.750" is going to be my long term holding (and with great pride). No idea where the rest of the experiments are going to go in the end. If I can't go below 16" by law; one can only guess.

Measured the new ammo I picked up today once my desk was cleared of contamination sensitive materials. It's much closer to what my reloading dies are putting out; so much so, I'm not sure I'll try to fire that tiny neck 125 grain garbage I had bought a while back. Unless I need to fire form that part of the chamber; it's not worth thinking about.

Pretty well set on the Hornady GMX in 110 grain for starting loads. It gives me length to play with, and seems to have a good BC at 0.305. I have a few other options in mind; but all that depends on future measurements of course. Absolutely considering a custom .260 barrel if this stuff meets expectations.

[98Z5V]

43 minutes ago, Lane said:

Pretty well set on the Hornady GMX in 110 grain for starting loads.

That's a straight game load, an not an accuracy projectile be any means.  That doesn't mean, in the least, that it's not an accuracy projectile - but it was designed for killing game animals first, with accuracy second.  GMX, SST, ELD-X - those are hunting loads, not accuracy loads.  Hornady HPBT, ELD-M, older A-MAX projectiles (that are being phased out) - those are accuracy projectiles.  Compare BCs on what you're looking at - but select the right tool for the job that you're primarily going for, as the first option, man...  

https://www.hornady.com/bullets/rifle/#!/

Not to be deterred by what I've said, though, in a testament to hunting projectiles, the most accurate projectile I found for my 25/45 Sharps loads was the Sierra .25 cal GameKing, in 90gr.  It smoked everything else out there, in my accuracy testing - the bonus was that thing was built as a coyote gun in the first place, and it was a hunting projectile that did the best - that cartridge is just different, as a whole.  I'm happy with it.  

Consider your goals, first, go outside the box during testing with different projectiles - but certainly don't develop a barrel profile around a specific projectile - that specific projectile might suck for you...  then it's all down the drain, all the labor, work, testing - and you'l think the caliber sucks, based on all the math beforehand...  300BLK is a SAAMI-spec chamber  - don't develop some specific chamber for it, based on some prpjectile you want to use.  Just have the chamber cut at the SAAMI-spec for the chamber, and run testing from there. 1:7" twist is crazy for a BLK load - that's for the heavies, the sub's, the suppressed loads primarily. 1:8" twist is what you'd be looking for, for something that you want to launch fast, as accurate.  1:8" twist will do much better than 1:7" twist, for supersonic loads. BLK is weird - and you're getting into weird here, but you do what you want.  You're looking for results, though, so in the long run, you need to really look at what you're trying to do.  You certainly picked the right caliber for the "max amount of options" to try this with...  Initial selections that you make right now, might disappoint you down the road.  Then you'll be arguing all the data here, saying none of the data is right - and I'll be that asshead pointing right back at you on your initial selections - and why it all happened.

Again, my go-to on BLK is the Hornady 150gr FMJ-BT, at around 1800fps loads.  It's in the middle of everything, and does quite well.  If I was only accuracy-testing, it would be my round.  Overall, it's badass.  Since I can't "hunt" FMJ rounds in AZ, it's not my go-to as a hunting projo in BLK, I'll take the Barnes 150gr .30 cal TSX for it - the BC is slightly lower, but it's an even match, so much that I don't have to change the powder charge.  

I find the same thing in the Hornady 75gr loads that I make for my 5.56 rifles - HPBT projos.  Accurate as all hell.  For hunting those guns, I only load Barnes 70gr TSX projectiles.  The lighter Barnes bullets are actually longer - and my powder charge is exactly the same, for the same accuracy, between those loads. 

There are some projectiles out there that are "freaks of nature."  You need to find the right projectile - but off the bat, don't rely on the hunting projectiles as the ones that are gonna give you what you're initially searching for here. 

You picked a winner of a cartridge here, man, to do this test on.  There are SO MANY variable with it, it's not even funny. 

Edited March 5, 2019 by 98Z5V

[Lane]

28 minutes ago, 98Z5V said:

Compare BCs on what you're looking at - but select the right tool for the job

This is why I mentioned some other options. That GMX is lead free, light; and has a good BC? I'm very much looking at accuracy loads; but I can shoot a pure copper projectile at almost anything, and not care about my water supply (that gives me distance testing at home). 

Been meaning to clarify some erratic questions I posed earlier. Am I looking for pure speed when launching these light projectiles given the small cartridge size? Am I in good shape to shoot for a fast 78 grain if I can find the right load data? Have tons of other calibers/cartridges I can test here now that I have a chrono; it just hasn't been nice enough weather when I have the time.

[98Z5V]

3 minutes ago, Lane said:

This is why I mentioned some other options. That GMX is lead free, light; and has a good BC? I'm very much looking at accuracy loads; but I can shoot a pure copper projectile at almost anything, and not care about my water supply (that gives me distance testing at home). 

Been meaning to clarify some erratic questions I posed earlier. Am I looking for pure speed when launching these light projectiles given the small cartridge size? Am I in good shape to shoot for a fast 78 grain if I can find the right load data? Have tons of other calibers/cartridges I can test here now that I have a chrono; it just hasn't been nice enough weather when I have the time.

You're not looking for pure speed, just an efficient projectile - the most efficient projectile you can find.   You will be much better served with a 1:8" twist over a 1:7" twist, if you end up with that 78gr projectile.  That's why I'm trying to head that 1:7" twist decision off now, before you do it.  That 1:7" twist will serve you WELL in the 180~220gr selections - but those aren't what you're looking for, in the stated purpose. 

[98Z5V]

If the 1:7" is already ordered, then up the weight on the projos, over the light-weights with muzzle velocity.  If the 1:7" is already on the way, then the game has already changed, right into mid-weight projectiles, at a minimum... 

Like I said - you picked a winner of a cartridge to do this test on...   TONS of variables!    

[Lane]

Ah poop. Yes. I wanted that 1:8 barrel made longer. Only Green Mountain wouldn't do that for me in a 21.750" or 24.000" in barrel. Live Free or Die is what they say; but actions speak louder than words. (I've got that live free or die in my blood); it's all good.

Just trying to virtually tune my load before I get the barrel.

[Lane]

Or am I wrong again in my calculations?

[ARTrooper]

8 hours ago, Lane said:

Stopped by the local gun shop to look for more ammo. Found one box of 300 AAC Blackout in 110 grain; expensive, but worthwhile for initial testing.

I always purchase ammo online. you can find a lot better deals on a larger variety. You can find a lot of decent 300 blk for pretty cheap

[98Z5V]

19 minutes ago, Lane said:

Or am I wrong again in my calculations?

Only the loads will tell...  

[Lane]

2 minutes ago, ARTrooper said:

I always purchase ammo online.

I want to; my local gun shop offered to take if for free (usually a $35 fee). Only now; the last few times I've visited, it wasn't a friendly environment. New people, and it's not going well in the back of the store. Again in NY, we can't quite buy online; has to be shipped to an FFL. I wish anyone would try to fix this garbage; but I just reload as a result. 

6 minutes ago, 98Z5V said:

Only the loads will tell...  

I really wanted to buy that 21.5" 1:8 twist GM barrel. I just couldn't justify the shipping when dealing with the rest of this. Is that a necessary accessory in this mix?

[Lane]

Tight butt holes; and nobody looks you in the eye. Everyone checks out your belt region though. They'll call the cops if the see a bulge. Welcome to NY state.

[ARTrooper]

seriously!? so glad I live in Wisconsin. only thing I have to send to an FFL is a lower. everything else comes straight to the house. I'm not sure, but I think we can probably order tanerite in the mail. lol.

[Lane]

17 minutes ago, ARTrooper said:

think we can probably order tanerite in the mail. lol.

So far as I can tell, that's still totally legal. These builds should all land above that 2,000 fps threshold. Might find some nice fossils if planted correctly.

 

[Lane]

I walked outside today and heard someone shooting full auto; dumping 10 round mag, after 10 round mag. What a tease...

Picked up some test projectiles for this project at the local shop. I know we discussed match vs. game projectiles last night; but I don't see a problem tuning my loads with game projectiles; and buying match grade when I find a good weight.

Also got a micrometer today so I can measure necks; and about to order a tube micrometer to check wall thickness.

17 hours ago, 98Z5V said:

If the 1:7" is already on the way, then the game has already changed, right into mid-weight projectiles, at a minimum... 

I ran all the numbers I have through a ballistic calculator, and checked against barrel twist calculators. I didn't see anything to be overly concerned about with this 1:7, but I may be missing something important. I realized that I can start collecting empirical data with my .308 Win which has a 1:10 twist, and supports the same range of projectile weights (about 1000 FPS faster of course). Heard the weather should be reasonably nice this weekend...

16 hours ago, ARTrooper said:

I'm not sure, but I think we can probably order tanerite in the mail. lol.

Sure enough; I saw a bunch of 1 pound exploding targets at the gun shop today. There wasn't a price on the shelf, but when I got home I looked it up. They aren't very expensive, I should have grabbed a handful. Next time for sure...