It's Alive! Franken-ARC born

[stagpanther]

My 6mm ARC Monster barrel arrived from sixfive this morning, so I was able to put the rifle together. Credit goes to Mel80 on this forum, I was inspired to try the barrel based on her spectacular results.

I was able to put the thing together with all parts that I had on hand, so it is a bit of a "mix and match" affair--no points for style. I've put quite a few Grendel/lbc's together over the years (still have some type 1 parts) so I had everything needed already. The one thing that was kinda interesting/disappointing is the the heavy-duty type 2 NB bolt I have for my 6mm predator will not engage with the feedramps/extension. Oh well, I still have several conventional thin-walled ones.

The biggest problem is that there is no 6mm ARC brass or ammo available anywhere--I'm lucky in that I have a pretty ample supply of left-over Grendel brass that I can convert.

[stagpanther]

I decided to ditch the off-color stuff having found black stuff. Here's my first go at reloads from Grendel brass sized down, using 90 gr vld's.

[9x19]

You using the dot sight just for reliability testing?

Upper looks good, but I'd want a little bit of magnification for accuracy testing.

[stagpanther]

We're in the middle of a raging rain/sleet/snow storm--what better time to go out and do a function test, right? Loaded the mag up and shot them all--everything worked perfectly. Love it when that happens on the first try.

In regards to the brass, I had a mix of different case lengths due to trial and error when first resizing the Grendel brass. I was (unnecessarily) worried about having too little space for the neck as a result of flowing metal up from the shoulder when resizing. As it turns out there was more than enough slack between the case neck OD and the chamber's wall--almost too much, I forgot that hornady generally makes their dies size towards minimum case measurements specs even if they don't call them small base. I noticed that the 3 cases under 1.49 tended to have signs of gas leaking. Other than that, I'm very happy--also noticed it's remarkably soft in recoil though the brake may have helped that. I can see for that reason alone this may become very popular, proving that maximum velocity attainable isn't always the most attractive feature of a cartridge, this cartridge joins a busy crowd, but it just might catch on as a soft-shooting high performance bullet cartridge. Them Hornady folks are pretty savvy bunch of rascals.

[stagpanther]

You using the dot sight just for reliability testing?

It's a Burris 3x RT3 prism sight--perfectly capable of precision shooting to at least 100 yds IMO. I was aiming at a quarry wall that is about 100 times as big as the broad side of a barn--I can report that every shot hit the target!

[Brian Pfleuger]

Originally Posted by stagpanther

I forgot that hornady generally makes their dies size towards minimum case measurements specs even if they don't call them small base.

Interesting tidbits I shall have to files away for future reference.
Other than that I am deeply offended that you have brass and I don't, congrats on a fine rifle.

Is the brake from the same company as the barrel?

[stagpanther]

Interesting tidbits I shall have to files away for future reference.
Other than that I am deeply offended that you have brass and I don't, congrats on a fine rifle.

Is the brake from the same company as the barrel?

I have some spare used Grendel brass and can send you a few if you can't find anything. I talked to Hornady today and they don't see the drought ending any time soon. Between the pandemic apocalypse crowd and the political all our guns will be taken away fears, it might be a long time before supply catches up with demand.

Is the brake from the same company as the barrel?

Nope--it's an Area 419 "leftover" from another project--it kept coming loose on a bigger rifle so I took it off. For something like the 6mm ARC I don't think a brake is really necessary.

[stagpanther]

BTW--Brownells has stock of Bart's 100 count 66 gr match flat base bullets in stock at a low price--I just snatched 3 boxes. I have no idea how well they work in the ARC, but Hodgdon has data all the way down to 58 grs, and the smallest bullets I have in 6mm are 90 grs. having bought most of my 6mm bullets intending on using them for 6mm Creedmoor.

[Brian Pfleuger]

Originally Posted by stagpanther

BTW--Brownells has stock of Bart's 100 count 66 gr match flat base bullets in stock at a low price--I just snatched 3 boxes. I have no idea how well they work in the ARC, but Hodgdon has data all the way down to 58 grs, and the smallest bullets I have in 6mm are 90 grs. having bought most of my 6mm bullets intending on using them for 6mm Creedmoor.

Ironically, what I have plenty of is bullets, powder and primers. I bought a bunch of 6mm when I built my .243AI and never got around to shooting it. Good thing, I guess.
I may grab some of those Bart's anyway though as I've seen a review or two that say they shoot great.

That is a pretty gnarly looking brake for an ARC but I bet she kicks like a .22
I would concur that it is almost certainly unnecessary, but sometimes "I think it looks cool" or even "I've got it, why not" is all the necessary we need.

I'll shoot you a PM on the brass, glad to pay a fair price if you've got spares.

[rickyrick]

As a former varmint hunter, these little-bullets-with-a-fat-cartridge type ARs are intriguing to me, but alas, I’m not adventurous enough.

I plan to move back to Texas in the next year or two. I’ve currently lived in Washington for 7 years now I’m ready to move back to freedom and varmint hunting lol.

[stagpanther]

I was actually a bit surprised it fed flawlessly, Grendel cartridges can be a bit finicky feeding in AR's with bullets "way out there."

You might find this interesting: http://bartsbullets.weebly.com/6mm-grinch.html

[mel80]

very nice i havent goten to try any of the arc specific bullets in mine yet , with myplans i plan on sticking with the lightwieght hunting and varmint stuff. im actually thinking about buyingsome ofthe leghih controlled chaos bullets to try in mine

[mel80]

forgot to add ive got a 12" 6 arc barrel from sixfive on the way

[mel80]

Originally Posted by rickyrick

As a former varmint hunter, these little-bullets-with-a-fat-cartridge type ARs are intriguing to me, but alas, I’m not adventurous enough.

I plan to move back to Texas in the next year or two. I’ve currently lived in Washington for 7 years now I’m ready to move back to freedom and varmint hunting lol.

ive done most of my varmint/predator hunting this last 2 years with a 6.5 grendel u wont be dispointed , ive got a 420y antelop kill with a 123g eld-m bullet , a 540y coyote kill with a 123g nosler hpbt , 430y racoon kill also with a nosler 123 , and hundreds of racoon/rochchuck and other varmint kills at ranges from 100-400y with 90g speer tnt and 90g nosler varmagedons

im really looking forward todoing some varminting at 300-600+ y with the arc and some light wieght bullets this year

and hopefully some even longer range stuff with my custom 28" mcgowen barreled6.5 grendel

430y racoon 6.5 gren supressed
https://www.youtube.com/watch?v=5jLtVYrPtDo

[stagpanther]

very nice i havent goten to try any of the arc specific bullets in mine yet , with myplans i plan on sticking with the lightwieght hunting and varmint stuff. im actually thinking about buyingsome ofthe leghih controlled chaos bullets to try in mine

Thanks. Lehigh makes good stuff--I have a buddy that uses Maker bullets--similar "petal" technology--in his Grendel to keep his freezer full of venison year after year.

[mel80]

Originally Posted by stagpanther

Thanks. Lehigh makes good stuff--I have a buddy that uses Maker bullets--similar "petal" technology--in his Grendel to keep his freezer full of venison year after year.

ive got a few boxes of the 80g tipped trex's on the way for the gren just picked up 4 lbs of 2000-mr for the arc for loading 70/75/ and 80g stuff

[stagpanther]

I've had great results with 2000MR in my 224 valk AR's using 95 gr SMKs--most powders cross pretty well from Grendel to 6.8 spc type cartridges in my experience.

[stagpanther]

I did a little more fudging around with the case lengths--for my particular chamber a length of 1.495 seems to be the sweet spot for easy load and extraction.

[stagpanther]

My first real "controlled" loads--95 gr ballistic silver tips.



The trigger group BTW is a PSA EPT trigger combined with jp reduced power springs for a smooth hunting trigger of 4 to 4.5 lbs pull. Nuthin fancy, a cheap but nice set-up.

[stagpanther]

Just got back--it's still rather stormy with rain and winds so my results probably could be much better, I only shoot a couple of groups at a time anyway as "seasoning" the bore is the most important thing to me right now. The rifle continues to operate flawlessly, not a single hiccup with loading, cycling or lock-back of bolt since the very first shot. This is my fifth Grendel/Grendel-based AR build and far and away the best reliably-operating one of the family. I rarely get such "positive vibes" from a new cartridge intro.

[mel80]

if u can find any give the nosler 6mm 70g balistic tip varmint bullets a try p/n 39532 , my barrel absolutely loves them it also apears to love the sierra #1515 80g spbt blitz bullets from my first round of testing

i was hoping to get back out with mine over this weekend but its been cold af and even snowed back into the mid 70's end of this week though

i now have 6 gren based builds only ones that ever gave me issues were the 10" barreled one thanks to the pistol lenght gas system , and my custom 28" inch barrel but that was to be expected since im well into uncharted territory with that beast of a rifle , now wih the low mass carrier and rp spring that thing runs like a champ across the entire bullet weight spectrum

[stagpanther]

Mel--if you get a cavity back PRI cut-out magazine--you can seat your bullets to 2.3+ assuming your chamber can take them and depending on the ogive of the bullet. It gives you "options." I've never used any small 6mm bullets--but I'll try a couple in the ARC.I have some 90/95 gr ballistic tips.

[mel80]

my grendel mags allow me to seat to 2.30 they work just fine in the arc as well

2.310 just starts to rub the bullet tip on the mag


i have yet to measure to lands on anything with the arc yet , with the 70 and 80's im using a really short coal of 2.150 on the 70's and 2.125 on the 80's