TS Customs .223AI + 300BLK Switch Barrel

[orkan]

I had been shooting this rifle with the 300BLK barrel on it for the last year or so. An absolute hammer in 300BLK configuration, but I had Travis provide the rifle with a .223AI barrel at the same time he did the build on the blackout. This is a pretty typical TS Customs story here, but I'll share it for those that might not know. This thread is a combination of posts I made on gunhive.com over the last year or so.

I first started on the 300BLK.

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I have gone through about a 8-10 different types of powder, trying to find a solid accuracy load for this rifle. Turns out there is a LOT of 300BLK data out there which is complete garbage. Apparently most people shooting 300BLK are using it for more of a toy than a precision rifle round. Finding a subsonic and accurate load was pretty difficult. It's been a very fun experiment though. Here's some preliminary data.

I started with 220smk, but the throat on this chamber places that bullet WAY down into the case. Well past the neck/shoulder junction. I measured the lands at 1.700 lands putting the BtO at 1.690 when seated. I have 2500 or so of these, and they are like a freight train, but couldn't get them to perform well with any of the early powders I tested. Trailboss was very quiet, as was N320, but the accuracy just wasn't there. I didn't even record a lot of the data because the velocity, case fill, or accuracy was so poor that it wasn't worth sharing.

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With a 175smk I measured the lands at 1.655, which put the 175SMK bearing surface well up into the neck. Here's some rough notes in no particular order.

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Trailboss - Very quiet, but not accurate enough. Also doesn't run out of the Prometheus due to it being a big flake powder.

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175SMK 1.640 to ogive - N320
7gr - 1125fps
6.5gr - 1035fps
6.4gr - 1000fps

**Velocities: **
962
1012
1013
1003
1010

954 half mil low
1018

964 half mil low
1018

949 half mil low
1012

974 .3 mils low
999

Noticing a trend there? First shot from each string was about 50fps slower than the rest of the shots in the string. Very odd behavior, but with this powder, it happened like clockwork. My guess is that this powder leaves a residue that drastically changes the bore condition shortly after the barrel cools a bit. It isn't as if the 300BLK gets very hot anyway. I didn't wait as long between strings on that last one, which is why you see a smaller fps swing. In any event, 1.5-2" groups was all it could manage.

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175SMK 1.640 to ogive - N110
10gr - 1250fps
8gr - 980fps

I didn't spend much time with this powder. It didn't like running out of the Prometheus very well. Seemed to shoot ok, with about 1.5" being average. I still wasn't blown away by it.

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After changing powders, it takes 10-15rnds for the barrel to stabilize. Interesting behavior that I've only ever seen before to this degree on a rimfire. No doubt subsonic rounds are a bit more finicky!

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175SMK 1.640 to ogive - N350
7.1gr
1080
1070
1066
1080
1069

Very stable, but pretty dirty. The accuracy was not very good however. 1.5" - 2" groups with lots of unexplained flyers.

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175SMK 1.640 to ogive - IMR 4227

10.5gr
1043
1036
1043
1054
1046

11gr
1108
1105
1126
1083
1121

11.2gr
1115
1126
1110
1126
1121

I started at 11.2gr, just shooting from the hip on powder volume. I got close, but it was a little fast. I worked my way down to 10.5gr and realized I had finally found something. Velocities were real good, and the accuracy was stellar. This will probably be where I stay. It will take a few hundred rounds to really get a lock on how it behaves over time and temperature swings, but I'm pretty excited. This load is accurate enough to show all of my errors. That was the main reason I put this Blackout together in the first place. There's enough recoil here to test your position extremely well, and due to the very slow velocity, you must drive the rifle flawlessly in order to have those bullets land where they are suppose to.

This load is not the quietest, but silence doesn't help me if I can't hit what I'm intending to. Also I learned that Thunderbeast Ultra cans have some NASTY first round pop when working with subs. Subsequent rounds are nice and quiet, but that first one is holy-shit loud.

100yd 5-shot group:
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300yd 5-shot group: Shots on bottom of plate. Bottom shot was first round, so I made an adjustment and fired 5 more. That's just on the plus side of 3" at 300yds. I'm pretty pleased with that considering it's subsonic 300BLK.
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Worked up a supersonic 175SMK load as well. Boy am I tickled with it!

https://www.gunhive.com/load-data/575620768ead0e2c5b8b4567/

175SMK Supersonic, 1.640 to ogive, 16gr IMR4227, Lapua brass, CCI-450 primer. This is about 15 thousandths off the lands in my chamber. Getting an average of about 1715fps. What a giggle machine to shoot!!!!

The case fill with IMR4227 is stellar. Right at the neck/shoulder junction.
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5 shots at 100yds. Just barely opened the hole up. I sure do enjoy when everything lands in the black.[IMG2=JSON]{"data-align":"none","data-size":"full","src":"http:\/\/i.imgur.com\/n6HKEzol.jpg"}[/IMG2]
5 shots at 300yds. Up 4 mils from my 100yd zero. Slightly sub-MOA at 300 in a 15mph wind with a cartridge this ballistically inferior? I'll take it.
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I've long held the opinion that a 308 is probably one of the very best training rounds out there as it pertains to working on the fundamentals of precision rifle technique. I'd have to say that heavy bullets in a 300BLK tests your form even more than the 308 does. The recoil is significant enough and the lack of appreciable velocity gives you an eternity of dwell time. This amplifies any deficiencies in your firing position and presents them to you with clarity. Yet it is not so severe as to cloud the "learning moment" behind a scary whuppin, and it is also extremely easy on the wallet due to inexpensive components and extreme barrel life. I suppose I'm about 5 years too late to the 300BLK bandwagon, but no one ever laid out it's value as a training tool for precision rifle technique before. My primary mission with this rifle was to discover if the 300BLK did have any potential there, and at this point I can confidently state that it absolutely does!

Moving forward in time about a year, I get the .223AI barrel out for some fun.

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24gr of Varget behind an 80gr berger in lapua brass with a CCI-450 turned out to be a great forming load. Shot pretty good, but the odd flyer that is typical of forming sometimes gets annoying fast.

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Got 100pcs formed and worked up a load today with the once fired newly formed set. Goodbye flyers, hello little knots. I shot the 5 on the left, then added a click and killed a couple dots. Well, I winged them good anyway. Gonna need to come a click right yet... but there's plenty of time for that.
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Proofed the load a bit and it's shooting real good.

Lapua brass
CCI-450 primer
80gr Berger target
25.5gr Varget
1.900 BTO (.010 off lands)
2.400 OAL
2750fps (16" 8-twist Benchmark 5R)

Pretty impressive for such a little pew pew cartridge!
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Fired these 5 @100yds first. Forgot to come a click right from the last session.
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Tacked that click on and then fired 10 shots @ 100yds.

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Then I moved to 300yds to confirm, and just HAD to let one get out the top. In my defense, I wasn't very sheltered in this position and there was a 12-22mph gusty wind getting a hold of me... so I'll take it I guess. My 5 shots are by my finger there. I was too lazy to go paint before I started shooting.
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This experience is typical of the rifles and barrels I get from TS Customs. Many of my customers can attest to the same. Just incredible shooting rifles and excellent customer service is really the only thing to come out of his shop. I have a little over 1000rnds through this rifle so far, and the way this barrel is shooting... I'll have this .223AI barrel toasted pretty quickly this summer.

https://www.gunhive.com/firearms/5727a0348ead0e51328b4567/

 

[bunsen27]

Thank you for sharing, that was an excellent read. I've recently myself discovered the fun shooting 73/75 gr bullets for .223Rem I have been toying with the idea of doing a .223rem & .300BLK switch barrel rifle. Very interesting .300BLK load data.

 

[spife7980]

Interesting, I had always thought that trailboss was the preferred powder for subsonic 308s but not 300 BOs as the BO doesnt have the problem of nearly as much volume to fill. I agree that most the load data out there being junk for precision goals but is instead focused on ARs where getting proper cycling seems to be the primary objective with accuracy being a distant second.


I only started my own load development for my 330 BO two weeks ago. My first loads were with IMR 4198 as its on every shelf and I had read of people having good success so I snagged some but at max book load of 10.9 gr I was only at a hair over 900 feet per second with a 220 sierra round nose and getting some concerning swipes on my brass.

Last weekend I went to CFE BLK and it gets me to ~1025 with the max book load of 12.1 grains under the same 220 round nose but the brass and primers have no marks so Im going to push it up a couple tenths and run a ladder on it this weekend.

Your rifle is much further ahead of potential accuracy then mine. Im curious how much accuracy you might be able to wring out of the 220 grain bullets with CFE BLK or AA1680 or any other blackout focused powder vs the pistol powder. (Not that your results arent great with the pistol powder and 175s)

 

[tansinator]

Try 26.2 grains of Varget with the 80's. Shoots 2830 fps in my 22 inch barrel. I/2 MOA vertical out to 1000.

 

[orkan]

Try 26.2 grains of Varget with the 80's. Shoots 2830 fps in my 22 inch barrel. I/2 MOA vertical out to 1000.

No thanks. I'm quite certain on my load development techniques and I'll leave it right where it is.

 

[orkan]

5 shots at 593yds. It was windy today, but I only dropped one.

Fired 8 shots at 1111yds. Once I found the plate with one, I was able to land them out there.

Nothing supernatural on my part... but the rifle shoots well and my firing solutions were spot on. Definitely not my first choice past 800yds when the conditions get tough.

 

[black5.3]

Thanks for sharing Orkan. Rifle sure is a shooter. My 300blk is an sbr thats more of a plinker and coyote gun than long range gun but it has impressed me out to 300 yards as well. The little 8" barrel doesn't help with velocity but for what i built it for, it exceeds my expectations. Im only shooting 110gr vmaxs with h110 for now. Haven't really messed with subs until i get a can.

 

[Geno C.]

What freebore are you at on the 223ai? I put together 2 223ai's this last year and I'm getting my best results with 80vlds and Varget also. Both of mine shoot best at 25.0 and top out at 25.7. I find it interesting because the barrels are 21" and 30".

 

[orkan]

It's a .060" freebore.

 

[RickyRodney]

I've been told that subsonic performance out of a 16" barrel in 300BO can be finicky because it is designed to run out of a 8-9" barrel? Anyone know if there is truth to that?

PS: Orkan, Not to go off topic, but how do you feel about going from the KMW to the DTA in terms of feel and ergonomics? Was considering just about the exact build you have done here, to go with my DTA.

 

[orkan]

The ergo's of the KMW are excellent. I would rate it as very similar. Really excellent platform.

 

[Geno C.]

It's a .060" freebore.

I went with a .100" freebore and fit in an accurate mag with 80vlds and a little file work.

 

[coldboremiracle]

I've been told that subsonic performance out of a 16" barrel in 300BO can be finicky because it is designed to run out of a 8-9" barrel? Anyone know if there is truth to that?

I have heard the same thing as well. That said I have a 16" 300BLK in my SRS, and have found it to be very consistent. The only variable I have found is actually quite consistent, my cold bore shot always hits about 1/2" above the next few. Not a big deal, as long as you remember it.

 

[Seandradamus]

Orkan
what twist is your 300 barrel and any idea on freebore length

 

[orkan]

Orkan
what twist is your 300 barrel and any idea on freebore length

.174 on the 300blk, and it's an 8 twist.

Any info you'd likely want is here on that rifles firearm profile page: https://www.gunhive.com/firearms/5727a0348ead0e51328b4567/

 

[ltfirehunter]

Orkan , what dies are you using with the the 300 blk? Right now I'm using the Forster MIcro seater set, but looking to get a Wilson bushing sizing die.

 

[orkan]

I'm using a forster FL sizer and ultra micrometer seater.

 

[softcock]

that Viht.N-320 powder, is probably the quietest load that I shoot out of the .30blk . and the quietest with i think,probably least amount of expanding gasses.
I always use the lightweight .30 bullets like 110 grn Speer soft point HP . with ( 4.4 grn. 320 ) . I was little hesitant to move into any heavier bullets with the 16" barrel with that fast burn powder .
.
edit add:
I always stuck it in the back of my mind that the N-320 would be the ticket with .30 Heavies and the Boltaction platform in a short barrel suppressed 12" and shorter barrel length .
.