6mm AR loads

[Zeus]

Ok folks....I have read every single thing I can on the WWW about loading for the 6mm AR, 6mm Predator or the 243 LBC. They all appear to be close enough in design to be able to cross-reference the data. I've deduced several loads from the vague (reliably sourced) data that's out there using some of the powders I have on hand.....H4895 and RL15. I'd like to compile more data for those powders plus a few more that are on the shelf.

If you have experience with these cartridges could you please provide me (us) with some safe loads that you've worked up? Looking for H335 (which I have a lot of), H4895, RL15, 8208XBR (and maybe IMR4064 and Varget if they are appropriate powders) data for any bullet........87 and 105 grain bullets are what I have on hand at the moment. I can load as long as 2.290 or maybe a little longer in the ASC mags that I have.

Apparently this is one of the more popular wildcats based on the 6.5 Grendel case so it would be cool to get enough info to make a sticky under this topic....There are a lot of requests floating around on the web for data with few useful replies. Having a thread on this topic could help a bunch of folks and maybe drive some traffic to the site.

I'll post my test loads as soon as I make sure that they are going to be safe....which they probably will be since I followed the instructions on 6mmAR.com to a Tee.

Thanks for sharing your knowledge!

[Zeus]

Just got back from the range with the 6mmAR. Since I was shooting at 25 yards just to get the scope lined up, test for functionality and signs of pressure I didn't give any credence to the groups....of course, as you would expect at such a short distance all six of the tested loads went into the same hole within their respective 3 shot groups.

Here are the loads that I tested with 105 grain Hornady BTHP Match bullets seated to 2.280"....from left to right as pictured:

H4895: 26.0g 26.5g 27.0g





RL15: 27.0g 27.5g 28.0g



Much of the research I've done has said that Grendel based cartridges do not exhibit the typical signs of pressure that might be seen in a bolt action rifle. The primers look to be in good shape for what it's worth. I do see some slight ejector marks on some of the brass but it's not consistent and nothing I'd call serious. What other things should I be looking at? I've seen web expansion mentioned........but really nothing else about what to look for.

All these loads were below what the 6mmAR site calls max. But they were using Lapua brass and I'm using Starline.....which is rumored to have slightly less case capacity.

What do you folks think? Heck, maybe I'm forging new trails here. Hopefully this leads to some meaningful discussion.

[StoneHendge]

Who made the barrel, how long and what type of gas system (length and agb)? Any ejector marks are a sign of over pressure unless you can attribute it to gas timing. Based on Whitley's data, those loads are pretty conservative. Do they drop out of the chamber freely? With my barrel, those would likely really be getting jammed into the lands at 2.28.

[Zeus]

It's a Whitley/Sabreco Inc complete upper with a 24" Hart barrel...The gas system is rifle length.

I loaded the rounds slightly under mag length (2.280") and checked if the bullets were into the lands.....they were not.......loaded and chambered rounds come out just fine.

Nothing about my test loads made me think that they were anywhere near over pressure. Having little experience with these cartridges I'm just erring on the side of caution. Hence the query looking for input as to what the ammo might be telling me that I'm unaccustomed to seeing in my bolt and single shot rifles.

[StoneHendge]

Ejector marks are definitely not something you want to see in an AR. If it's a 26" barrel with a rifle length system, it could be timing causing ejector marks. The bullet has 14" to go once it hits the gas port, so if the gas hits the bolt while the bullet is still in the barrel, the chamber is still under pressure and the brass is gripping the chamber walls hard. The bolt starts trying to unlock and the brass doesn't want to move - hence the marks. It could also be that your overgassed. The easiest way to rule out that timing is causing the marks is to turn the gas off completely. I actually ended up doing load development in my 6.5 CM (which is notorious for timing issues) with the gas off to rule that factor out.

[204 AR]

I have both a bhw 243lbc and an arp 6mm predator. The bhw I've had for over 2 years now and somewhere around 1600 rounds+. It's load is an 87 gr vmax over 28.6 gr 8208 for right at 3000 fps.

The arp is new, just got it last month but it seems to like the 87 gr vmax also but I'm at 28.2 gr 8208 with it. Drops at 500 yds suggest it runs very close to the bhw in speed, needing 1/4 moa more. But that is very preliminary with only a couple of groups shot. My crony crapped out but I'll go out on a limb and say it runs very close to 3k fps also.

So far the bhw is a hair more accurate with 200 yd groups as small as 3/4" but mostly around 1" or 1.25". The arp is running 1.5" groups at 200 but haven't had near the time to fine tune it yet. I can keep it sub-moa off of shooting sticks out to 500 yards so I'm happy with it to this point.

I have some 103 gr eldx but haven't tried them yet.

[454bore]

I shot some 108 eld's over 30.5 grains cfe and got 5 shot groups around 2/3 inch at 100 yards.
Chronograph velocity 2764fps.SD 15fps.22 inch krieger.
H-4895 shot the same but a lot slower.
Going to try 2000mr next.
I'm liking the Hornady 108eld.

[Zeus]

I shot some 108 eld's over 30.5 grains cfe and got 5 shot groups around 2/3 inch at 100 yards.
Chronograph velocity 2764fps.SD 15fps.22 inch krieger.
H-4895 shot the same but a lot slower.
Going to try 2000mr next.
I'm liking the Hornady 108eld.

Thanks for sharing 454