6x45 AR-15

We just got back our 6x45 barrels (nine were made - seven @ AR-15 and two at Remington 700 (not shown)).



What is 6x45???

.223 brass (aka 5.56) that is necked out to .243 thus making it legal on deer in Virginia.

Accuracy and speed?



Will post our own pics once we get them built and tested.

All load data is from external sources. Use at OWN RISK. Work up all loads

Powder 8208XBR. COAL -2.260
75g Hornady VMax - load 25.2g Velocity - 2895
95g Nosler Ballistic Tip - Load 23.1g Velocity 2495
Use posted loads at you own risk

Had some cycle issues. Gas port too small most probably.

Speced as 0.080"

Measured at 0.078" with my crude tools.

Increased to 0.096" (44% increase in gas). Will test and report back.

Below is a Pi x Radius Sq. calculation

Given that everyting is the same as a .223/5.56 gun, what happens if you accidently run a .223 mag in your .243 and vice versa?

Nothing is idiot proof. And I'd probably look at someway to color code mine or something.

The 6X45 is a standard 223/5.56 necked out to a 6mm (.243). Uses same magazines but knowing how reliable all AR mags are we should definitely take a selection next time.

.223 will go bang safely, but will be terribly inaccurate.

6x45 in a .223 gun won't close battery. Pill will jam at the throat.

As for color coding... exactly right you are.

100% of my 6x45 brass is nickel to mitigate oops afield.

As for color coding other calibers... been doing that for a few years now... colored duct tape from Walmart.





FYI... the above color code chart is old and has since been updated as calibers exited my collection.



Guess this caliber?

Extra capacity and bullet length can be accommodated with a case change
Lots more case to play with

http://6mmar.com

Keep up the updates and let me know if you guys do another build, I might want 'in' on it.

Two of the guys built BOTH AR-15s and Remington 700s (those four are not pictured here).

The others are now done (Top one is Nick's (Addy Auction)), the next one is mine (Uber lightweight (should be under #5 as a complete 17" rifle... w/o glass and mag), #3 and #4 are other close friends.



#5 (not pictured) was picked from the Smith previously and is currently in use for load development (see targets above).

Try some 58gr v-max in the 6x45. Been loading for 6x45 for about 7 years now and the v-max with a charge of H4895 does very well in my 1-10 twist 16" BHW barrel. It's my go to predator load.

Thanks (please PM your load... I will ladder up)... we are using 1:9 twist barrels. Stoner barrel in pic is 1:8. You said yours is a 1:10.

I plan to play in the 70-80 range mostly to start. I have a 3,050 - 3,100 FPS load with Varmageddon 70s I am looking to try as soon as the pills get here.

This info was sent to me...

... and with FIFTEEN PAGES of data (over 1k recipes) it seems like there are plenty of 1/2 MOA loads to test.

http://www.predatormastersforums.com/forums/ubbthreads.php?ubb=showflat&Number=1455558

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ALSO... a few from my Lee book (2nd Edition)

Finally got my #5 rifle together... BUT SHE NEEDS TO GO ON AN 11 OUNCE DIET. Open to all suggestions. The BCG, Barrel Nut, Buffer and Buffer spring are the only immediate thoughts.

5#-11 Oz without glass

7#-5 Oz with Nikon IRT 2.5-10

Almost 2 lbs for the scope! Many options there. Go for a fixed 6-8-10X Or a basic variable batteryless optic.

Drill holes in the carrier or machine flutes. A nice side effect to this is you can use a lighter buffer.

Change the rail to a shorter one. Expose the gas block.

Many titanium parts out there. ie castle nut, gas block, muzzle brake, take down pins, V7 etc.

A company sells lightened lowers. Lowers with lightening holes and cutouts at the non-critical areas.

The Nikon IRT is a keeper (built in laser range finder is something I want on this one). 26 oz on scope and mount is comparable to most fixed (FX-3 6x Leupold with mount is around 20 oz).

Scope is not part of the weight reduction I am working on.

Lighten up BCG... great idea... Google Image has some nice pics.

Lighter buffer... great idea. Wonder about a lighter spring as well. Spring is kinda heavy. Some testing is needed.

Fore grips is uber light (lighter than CF). Gas block is alum. Ti castle nut, buffer tube, take down pins, grip screw might drop 2-3 oz.

Mag tactical lower, so that is covered. I could skeleton upper and lower for a few ounces. Barrel nut as well.

This weight reduction game is more of "let's see if we can" problem vs. a "real" problem.

So we are done with the 95gr development and H335, at 22.6gr we were getting consistent 1/2 inch groups. .1 up or down and they opened up. Started the 70gr Noslers and they like it fast, got 1/2 inch groups at 27.4gr, will try some super hots to see if it will come in some more (always watching for pressure signs). Also ran the75gr VMAX and we were very disappointed, consistently bad across the entire speed range, oh well.

Use posted loads at you own risk

Not sure what the HG was on it currently, but a suggestion is that may be where to lose weight. Alg handguards mod 0 or 1 are cheap and very light. Or Guntec mlok (or key I think) slimline handguards, even cheaper, maybe even lighter.

Love the builds. I don't even hunt and 6x45 still fascinated me.

Finally got my 6x45 to the range to run-in the barrel some... and function test. Gas port final was 0.092" on a carbine length DI system. Function was perfect.

Broke-in with a series of shots and through cleaning.

1 shot & clean, 2 shots & clean, 4 shots and clean etc.

Nothing to write home about (after all she is an ultra featherweight profile, and I never expected premium accuracy)... However, the groups did get better as the barrel wore-in some. Figure about 80 rounds and she will be a fully shootable/huntable rifle.

Load came straight out of the Lee Manual. 27.5 Gr of H335 over cheap 70 gr. Nosler Varmageddons. 2.226" COAL. Theoretical speed of 3,066 FPS (did not measure). Nothing fancy except nickel brass (visual demark that it is not .223 ammo). Total mix bag of brass (5.56, .223 and 4-5 different headstamps).

Can is a .30 cal ThunderBeast 5". Almost hearing safe, but not quite. Recoil is nil. Optic is a Nikon IRT (laser range finder) 2.5-10. Trigger is horrid... may edit/polish/change springs.



Forth (or fifth) set of break-in shots (6 rounds... looks like 5 in hind site... doesn't matter, just barrel run-in shots).



Last set of break-in shots (9 rounds, NOT 10 as noted)



Others may post their results (we expect 82-86 gr pills to be 1/4 MOA), but I am done posting on this build unless something weird happens down the road... the other 8 builds should be far more accurate than my featherweight.

Had my Smith make us some case gauges...



Cost $15 each... CHEAPEST (+1 Quality) Smith I have ever met.

85gr SMK 25.3gr H335. Using 4.5lb Rock River trigger. Still breaking in rifle. 5 rounds. Outside edge to outside edge .63 (dot is 7/8 inch)

Not my target, but one of the 9 barrels we had made.

3 shots a 100 yards. Not bad for cheap barrels and a frankenbuilt AR.

That was using a 87GR VMAX at 3175FPS(EST). we are getting .25 inch groups with 80gr and 85gr bullets also.

Super nice... Congratulations!

Went looking for Hornady 2440s (87GR VMAX)

These came up VERY VERY CHEAP (even cheaper at other sites)

http://www.centerfireguns.com/ammo-overstock-spec-buy-2440-bull-243-87-sp-bulk-3500-2440b.html

BUT this .243 87 gr VMAX bullet has a listed diameter of .327" (something weird going on here).

Found these instead... If anyone wants to split a 2k box

http://www.centerfireguns.com/ammo-overstock-spec-buy-6mm-243-80-psp-2000rd-22967.html

Photo-Suckit killed the pics...

Here are a few...

Bump

Bump

Forgot all about this one bump...

Gonna play around with 55 gr. bullets at 3,540 FPS...

JUST BECAUSE I CAN.

Published data on the Accurate Load Data site using A2200 powder.

SINCE THAT TIME...

I did witness a similar problem...

A good friend and very competent GunSmith/FFL DID ACTUALLY chamber and fire a .300 Blackout round in a 6x45 barrel... same scenario would be possible if the gun was a .223

How could this possibly happen???

The bullet set back into the cartridge case as the BCG closed battery. I assume insufficient crimp on the round.

No one got hurt and believe it or not... the .308 bullet DID leave the .243 barrel... however that barrel was irreparably damaged.

Lesson learned by me...

Check, crosscheck and recheck everything... every single time.

If you are ever in doubt... STOP!!!

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OR... if you do some of the really really weird monster stuff I do... wrap the gun in a moving blanket, ratchet strap it to an oak tree/bench and get yourself a long string. (i.e. back when I was learning to play with 730 gr. .458 bullets I did just this).

Data straight from the Accurate website.

3,460 FPS with a Nosler 55 SP FB (the ones I was selling for a dime each).

SDs suck and the BCs also... but to 200-250 yards... 3,500+/- makes for a nasty little RPG.

How much lead on a running coyote?

NONE

Changed the handguard and dropped about another 6 ounces...

Changed the scope and lost a pound.