AR-15 in .300BLK (300 Blackout)

[jd4320t]

That's what I am afraid off, I don't have the muscle or knowledge to take upper apart. Well, guess I have to wait until I save enough to get something nice to have but not needed.

Don't let it scare you. You can find an upper receiver to go with the barrel for a little more money.

 

[Slow Hand]

Mine broke down something like this:


CMMG barrel-$250
Del Ton Upper-$100
YHM free float rail-$125

Put those together, add sights or optics and slap it on your lower, using your existing BCG. I eventually picked up a Spike's BCG and built another lower so I had a full rifle, but it can be gotten into fairly reasonably. If you're nervous about assembling the upper, there are probably dozens of guys on here who would be more than happy to help out, myself included.

 

[dagibson1507]

Slow Hand, what do you think of the cmmg barrel? Im looking to get a short barrel and they are offering a 8.5 by the end of the month. I hear stories they are bad about thread to bore concentricity resulting in baffle strikes. Wondering if I would be better off getting a 16" cmmg and having adco cut it down and enlarge the port.

 

[Slow Hand]

Ive been happy with mine. I was thinking anout getting a shorty from them and biodiesel g a pistol while waiting for an SBR stamp but I think I'll just keep what I e got and cut it down when I get a stamp. I've got a pistol length gas system on it and it's worked fine for me with and without my .30 cal can.

 

[jblomenberg16]

So, the more I looked at my data from this past weekend, and the more I read on load development, the more I realized that 2500FPS from those 125gr. Noslers was probably bogus. I had loaded up 5 test rounds in each of 3 different powder chargest to reconfirm.

It was unseasonably warm here in Indiana today, so I couldn't resist going out to the range for a retest. This time we used 2 chornos. What we found was interesting...that the Chrony that I use is very sensitive to muzzle blast (no big surprise there). Once I moved it out 3-4 yards from the muzzle it began to be much more consistent (within +/-5 FPS) with the other control chrono we had placed at that distance for all of the shooting.

So, revised results for 5 shot test loads (do not use as official load data):

125gr Nosler BT, loaded to 2.120" OAL with Winchester SR primers.

17.0gr H110
2091
2175
2166
2082
2041

17.5gr H110
2087
2174
2133
2130
2106

18.0gr H110
2271
2225
2237
2255
2246

As you can see 18.0 grains was much more consistent, and gave low 2200FPS performance on a 50deg F day. Primers were flattened, but no signs of over pressure with bolt imprints, etc. I think I'll use the 18.0 load going forward and get a few more rounds with it to see how it does.

 

[rhino]

How did the recoil feel on those compared to 5.56mm?

 

[jblomenberg16]

How did the recoil feel on those compared to 5.56mm?

Honestly I didn't feel a big difference. With a nose to charging handle hold on both, I have noticed my nose gets a little more of a thump with the .300BLK than with the .223, but nothing painful or uncomfortable.

 

[rhino]

Honestly I didn't feel a big difference. With a nose to charging handle hold on both, I have noticed my nose gets a little more of a thump with the .300BLK than with the .223, but nothing painful or uncomfortable.

Thanks!

 

[mammynun]

Honestly I didn't feel a big difference. With a nose to charging handle hold on both, I have noticed my nose gets a little more of a thump with the .300BLK than with the .223, but nothing painful or uncomfortable.

Ditto with Gunn factory ammo... now that I think about it I didn't notice a difference between sub and super-sonic either.

 

[jblomenberg16]

Comming soon...comparison of the 7.62 intermediate rifle cartidges.

 

[esrice]

Comming soon...comparison of the 7.62 intermediate rifle cartidges.

Is it here yet?

 

[jblomenberg16]

Is it here yet?

Thought I'd just bump the post to tease you a bit...


Gonna hit the range tomorrow to compare them on a few parameters, so will probably be tomorrow night or Monday before I post it up. Any suggestions?

Was gonna do a pretty basic comparison of velocity, iron sight accuracy, and probably some barrier pennetration tests (time and weather permitting).

Ulimately would like to add a few more scientific tests as well. Maybe some gel testing, etc.

 

[esrice]

Any suggestions?

Oh so many possibilities!

Barrier tests are fun, but can get complicated, expensive, and messy.

You could chrono them but that number alone doesn't tell the whole story.

Accuracy is one facet that would be easier to document on a single range trip.

A visually appealing comparison would be to hit some soft fruit with each caliber.

Wonder if you could find a way to compare felt recoil??

 

[Slow Hand]

Did some shooting today. Tried three different cast bullet loads. First was a 180 with 9.5gr of Lil Gun. It wouldn't cycle for the most part and sounded supersonic (chrono battery was dead and guy next to me was shooting a PSL, so everything was loud!), though I did get a couple of rounds to cycle as the magazine emptied out. Still have some left for next range trip. Also tried 9.0 of Lil Gun and 11.2 of A1680 under my home cast 225gr round nosed gas checked bullet. they shot fairly well, and the A1680 load was definately quiet! Only loaded 30 rounds of each, but they cycled just fine. I"m thinking I"ll play with both a bit, maybe going up and down in powder, but they are shooting decently so far. I'm thinking that for my 100 yard and under plinking, the cast bullet is definately going to take over for the expensive SMK's! I"ll probably buy another box of SMK's and load them up to have around, but the bulk of shooting will be done with my cast bullets. They feed fine and bassically cost the price of the gas checks and my time. Four cents a bullet is my idea of fun shooting!

Did some close range 'drills' (and I use that term loosely) with 125gr Speer TNT loads and had a good time. Recoil is not bad at all, and shot to shot times seemed pretty good. Shot the same thing with my .223 upper, but it's an 18" heavy barrel with a comp on it, so recoil is non existant with it! hard to compare the two. I'd definately feel fine using the 125gr load as a defensive rifle.

 

[jblomenberg16]

Oh so many possibilities!

Barrier tests are fun, but can get complicated, expensive, and messy.

You could chrono them but that number alone doesn't tell the whole story.

Accuracy is one facet that would be easier to document on a single range trip.

A visually appealing comparison would be to hit some soft fruit with each caliber.

Wonder if you could find a way to compare felt recoil??

Good ideas...will add those to the testing.

Unfortunately plans changed this weekend and I didn't get as much range time as I had hopped to do the 7.62x39 vs. .300BLK comparison on velocity etc.

By the time I started doing chrono testing the sun was low enough on the horizon I wasn't getting reliable results.

I did find a good subsonic load with the 208A-max though!

 

[jblomenberg16]

In case anyone was wondering...Troy Battlemags look like they will feed .300BLK reloads reliably.

I ran a very fast string of 30 round through it last night without a hiccup. Rounds were some reloads with 147gr pulled bullets loaded to about 2.130" OAL (so I could crimp to the cannular).

Think that might be my strategy to avoid mixing mags. 5.56 in my PMAGs, and Troy Battle Mags for the .300BLK. Visually and tactily different.

 

[shooter521]

More cheap(er) factory ammo:

PNW Arms. 300 AAC Blackout Ammunition

 

[dagibson1507]

The lancers that wilsons sells for their 7.62x40wt should work good too. They come with the rib already removed.

 

[jblomenberg16]

Bump and a pic from the shoot this weekend up at lovemywoods' range.

Esrice must have super awesome ninja camera skills, as he caught the action cycling.


Oh, and for those wondering if the .300BLK has some punch to it, just ask the dueling tree and those that witnessed it.

 

[loki.fish]

I didn't read all the posts, so if I'm reposting something, well, you can never have enough :P

300BlkTalk • Index page

It's attached to the silencertalk forums, the lead guy behind the 300BLK posts quite frequently on here. The list of companies working on this caliber continue to grows.

I'll be putting together my first 300BLK rifle tomorrow and starting on the paperwork for a suppressor and sbr within the next couple of weeks.