Obviously new to this forum, and wanting to say hello.

Been watching people with the ARC for a couple years, and finally pulled the trigger (yes, pun intended) and built one.  Will be digging through the reloading info people have posted, as I'm curious what everyone has come up with.

For reference, here's my build and intention, sage rats (think gopher or small prairie dog) in eastern Oregon.

American Rifle Company (yes, an ARC for an ARC) Coup De Gras action
Preferred Barrel Blanks prefit in M24 contour, 26" 1:7 twist
Triggertech Diamond Single Stage
MDT Timber Chassis
Vortex HS-T 6-24x50 scope.

Since I only have 2 weekends from build to use, and only 1 weekend to actually do anything, not able to do much for load development, so am going with a within spec ammo recipe:
Starline brass
Sierra HPBT 107gn
Varget 26.7 gr
CCI 400 (what I had available)

Did a quick break-in/test the other weekend with factory Hornady Black 105 HPBT, and while it wasn't the most stable sitting on a bag at center of gravity, and twitching like an addict, once zeroed, was able to punch about a 1" group at 100 yards with 10 rounds, so I'm happy at this point.  Now to test the generic load this weekend.

Last bit of info, the MDT loves AICS mags, and I didn't realize that the Coup De Gras is an AIAW cut, so I'm looking at having to trim the mag a tiny bit so that it can catch on the mag release, it feeds just fine, but I should hand hold it to make sure it doesn't fall out of the chassis.

Anyway, thanks for making it this far, have a great day, and it's time to head to the range.

This is a good read from the folks at Berger.

VLD – Making it Shoot



Getting the Best Precision and Accuracy from VLD bullets in Your Rifle.
Background
VLD bullets are designed with a secant ogive. This ogive shape allows bullets to be more efficient in flight (retain more velocity = less drop and wind deflection). While this result is desirable for many rifle shooters the secant ogive on the VLD bullets produces another result in many rifles. It can be difficult to get the VLD to group well (poor accuracy).
For years we encouraged shooters to use the cartridge case base to ogive (CBTO) measurement to the lands which allows the VLD bullet to touch the rifling or be jammed in the rifling. This provided excellent results for many shooters but there were others who did not achieve top performance with the VLD jammed in their rifling. These shooters were left with the belief that the VLD bullets just won’t shoot in their rifle.
Other groups of shooters were discouraged by our recommendation to touch the rifling. Some of these shooters knew that at some point during a target competition they will be asked to remove a live round. With the bullet jammed in the rifling there was a good chance the bullet will stick in the barrel which could result in an action full of powder. This is hard on a shooter during a match.
Yet another group of shooters who were discouraged by our recommendation to touch the rifling are those who feed through magazines or have long throats. Magazine length rounds loaded with VLDs could not touch the lands in most rifles (this is the specific reason that for years we said VLD bullets do not work well in a magazine). When a rifle could be single fed but was chambered with a long throat a loaded round that was as long as possible still would not touch the rifling.
Until recently, shooters who suffered from these realities were believed to be unable to achieve success with VLD bullets. Admittedly, we would receive the occasional report that a rifle shot very well when jumping the VLD bullets but we discounted these reports as anomalies. It was not until the VLD became very popular as a game hunting bullet that we were then able to learn the truth about getting the VLD bullets to shoot well in a large majority of rifles.
After we proved that the Berger VLD bullets are consistently and exceptionally capable of putting game down quickly we started promoting the VLD to hunters. We were nervous at first as we believe the VLD needed to be in the rifling to shoot well and we also knew that most hunters use a magazine and SAMMI chambers. Our ears were wide open as the feedback was received. It was surprising to hear that most shooters described precision results by saying “this is the best my rifle has ever shot.”
We scratched our heads about this for awhile until we started getting feedback from hunters who were competition shooters as well. Many were the same guys who were telling us for years that the VLDs shoot great when jumped. Since a much larger number of shooters were using the VLD bullets with a jump we started comparing all the feedback and have discovered the common characteristics in successful reports which gave us the information needed to get VLD working in your rifle. We were able to relay these characteristics to several shooters who were struggling with VLD bullets. Each shooter reported success after applying our recommendation.
Solution
The following has been verified by numerous shooters in many rifles using bullets of different calibers and weights. It is consistent for all VLD bullets. What has been discovered is that VLD bullets shoot best when loaded to a CBTO that puts the bullet in a “sweet spot”. This sweet spot is a band .030 to .040 wide and is located anywhere between jamming the bullets into the lands and .150 jump off the lands.
Note: When discussing jam and jump I am referring to the distance from the area of the bearing surface that engages the rifling and the rifling itself. There are many products that allow you to measure these critical dimensions. Some are better than others. I won’t be going into the methods of measuring jam and jump. If you are not familiar with this aspect of reloading it is critically important that you understand this concept before you attempt this test.
Many reloaders feel (and I tend to agree) that meaningful CBTO adjustments are .002 to .005. Every once in a while I might adjust the CBTO by .010 but this seems like I am moving the bullet the length of a football field. The only way a shooter will be able to benefit from this situation is to let go of this opinion that more than .010 change is too much (me included).
Trying to find the CBTO that puts you in the sweet spot by moving .002 to .010 will take so long the barrel may be worn out by the time you sort it out if you don’t give up first. Since the sweet spot is .030 to .040 wide we recommend that you conduct the following test to find your rifles VLD sweet spot.
Load 24 rounds at the following CBTO if you are a target competition shooter who does not worry about jamming a bullet:

1. .010 into (touching) the lands (jam) 6 rounds
   
2. .040 off the lands (jump) 6 rounds
   
3. .080 off the lands (jump) 6 rounds
   
4. .120 off the lands (jump) 6 rounds
   

1. .010 off the lands (jump) 6 rounds
   
2. .050 off the lands (jump) 6 rounds
   
3. .090 off the lands (jump) 6 rounds
   
4. .130 off the lands (jump) 6 rounds
   

First test loads were shot this morning, Savage 110T with Burris XTRII 3-15x.  New Starline cases, F205MAR primers, 29.5, 30.0, 30.5, and 31.0gr WW748.  90gr TGKs were seated in the Forster mictometer die to 2.300", so put the shank of the bullet 2/3 down the neck.  31.gr pushed the bullets out to 2.310" so obviously compressed.  I tried bullets out as long as 2.34", but didn't think there was enough bullet in the case for strength, and they still didn't touch the rifling.

I was shooting @12x at steel plates at 300 yards.  Wind was variable and gusty, so not the best day for real groups.  90gr TGKs were shooting 3MOA higher @300 than Hornady Black factory ammo.  Once I realized that all I needed to do was aim center and watch the wind flags, I shot 5 shot groups.  ALL of the groups were wider than tall, and usually had 3 or more shots inside 2".  30.0 and 30.5gr were shot again, and both were sub 2.5" with the 30.5gr looking closer to 2".

edit: those 1x cases have 1.0gr more capacity 748 than the new cases had

Finally got things together to start work ups with these bullets. Starting with LVR just because. The Berger’s and SMK’s ogive length to lands are very close to each other right at 1.170. The 87 vmax’s are ridiculously short at 1.155. So much so that the load is pretty heavily compressed at the top end.

I am also seeing what people are talking about with the Hornady case volume. Noticeably different even case to case. We will see what the data shows.

My new Garmin Xero landed today. I shot over one last weekend and will never go back. What a fantastic tool!

Results to follow.

Hi, I'm building my first AR with 6 ARC. I was wandering what buffer length to use. My plan was to use a carbine but I have seen several guys using rifle length but not sure of the reasons. Any advice on this would be appreciated.

I see these Ruger Gan II are just starting to be released in 6mm ARC. What are your thoughts on this offering hitting the market?

Howdy all, 

This is the first forum i have been on in almost 20 years. Built my 6arc about 2 years ago with about a 2 year build time. 

I have always loved the MK12 platform but got bored with 5.56. I have a legit AMU SDMR from the early days of Iraq, full armalite rifle, with all original parts so i decided to build a more modern MK12 to give my SDMR a break.

Build specs are as follows

receiver set is an FDE Aero
BCM QRF12 in FDE
Magpul fixed stock (waiting on an a2 in FDE to swap)
BCM grip and trigger guard
Geissele airborne charging handle
Basic grendal BCG thinking i will have to swap to chrome when my can gets out of NFA jail (almost 1 year in jail)
Ballistic Advantage 18 inch SPR profile barrel
Dead air Muzzle break 
Geissele Tricon trigger
Kynshot Hydrolic buffer
Contessa 30mm mount
Element optics Helix 6-24x50 FFP scope (might swap for a 1-8 or 1-10). 

If you are close by drop a line, it would be cool to meet the one leaving me the brass at the local range hahaha.

the images are a mix, the black rifle is the SDMR from the AMU, id loved to get all the documents for it and make a showcase for it. the other 3 are different stages of the build to current date.

Better by $5 per hundred than anything I have found on ammoseek.  I bought 500 90 ELDX at 33.14 per hundred AND free shipping.  I'll probably regret not buying 1000 when the price crosses $40 but...

https://www.scheels.com/p/hornady-eld-x-...ll#start=8

Just saying Hello! I am a long time competitive shooter and reloader, but new to the 6MM ARC. I went back and forth between the 6.5 Grendel and the 6MM ARC looking for higher BCs than my .223 can provide and the ARC won, largely due to the availability of Craddock's RTR barrels.   Parts are on the way for the build!

6 ARC in a Lead Star chassis w/ 17” hg. 20” Ballistic Advantage barrel, JP recoil eliminator brake. Heavy buffer and standard BCG w/ bolt. Hiperfire 2 stage trigger. Atabal Stealth 5x30x56 FFP scope w/Leupold mount. Does not include rifle weights. asking 2200