Home Forums Reloading Big Game Rifles Good 6mm AR / 6mm Grendel / .243 LBC loads

My 6Gs have 20-inch barrels. I have not chrongraphed the Lever loads, I only clocked the initial loads with Re15, H4895, Varget, and AR-Comp. I will say that the 29.5 Lever loads did seem to fire with more enthusiasm, if you know what I mean. I'll make it a point to load up at least a few more of that load and chronograph it...I mean to chrono more of them since I am not confident in the numbers I got the first time around.




IIRC, I set up my die to bump about 0.002 inch. To be honest, I don't recall checking that with brass fired from BOTH rifles. Maybe I should revisit that...I may end up with another die because I use a Co-Ax and I detest fiddling with sizing die adjustments. I like "set-and-forget" for sizing dies (and I prefer that for my scopes too...a whole nuther can of worms!).



It has been eight months since I assembled the rifles, but as I recall the barrel fit to receiver was nice. I was able to slide them together but with a bit of resistance. I did not think LocTite would help in any way.



I think I used K2s on these rifles as well. They're Magpul, for sure. I'll try altering my grip as per your suggestion next time I shoot. I might take a look at getting set up with a better rear bag, too.

I appreciate your comments, thanks!

Yeah, Lever definitely has more flash and blast than some of the stick powders like 4895. That doesn't really translate to an indication of pressure, it's just a trait of that powder. I was thinking you had 22" barrels rather than 20", but still think you should be able to get better velocity than reported. Most of the advantage of this cartridge over the 6.5 Grendel is the ability to push velocities higher than the Grendel range for better trajectory at distance, so IMO it's worth getting the full capabilities out of it, within reason.

On the upper/barrel fit - if you can slide them together by hand, it can definitely benefit from Loctite and/or shimming. The point of the Loctite is to stiffen that joint; if it's not a press fit (or thermo fit, same thing) then the upper is only capturing the barrel at the extension flange, and can flex around the extension. With a tight or bonded fit, the upper/barrel connection is solid all the way back to the feed ramps. It's not a huge difference, but is one of the small incremental improvements that can help.

Today I was able to shoot the Leverevolution load again. I selected a different shooting position to make sure the chronograph screens were elevated to a reasonable height. My last three groups with the load averaged right at 3/4" while the first two were a little over an inch...and I am sure it was my fault as I was trying to get the hang of using a new squeezebag...never used one before today. Velocity was right at 2640 fps, a full 90 fps faster than what I measured several weeks ago.

Yeah you have to learn how to squeeze your bag. It takes a gentle touch...





I hope to have my 20" 243 LBC barrel ready to test fire in a few weeks, probably during the holidays. I'm interested to try the same loads in it and compare velocity to my 24". They are both BHW barrels and both chambered by BHW, I just have to profile and finish the 20". My 24" was a complete barrel from them (~$350 IIRC, and worth it IMO.) I'll report back here with some numbers.

RR - as promised, I did a brief velocity comparison of my 24" and 20" BHW 243 LBC barrels.

105gr Hdy BTHP
2.240" OAL
Varget 28.3gr

24" - 2794 fps avg
20" - 2709 fps avg
That's 85 fps difference.

I also tried a fireform load (for cheap x39 brass) with the Sierra 105gr SP and 4064, didn't write down the exact numbers but it ran about 2675 fps in the 20" and 2700 fps in the 24".

I need to load up more of the 105 BTHP bullet with Lever and compare those as well. I'll also be shortening this 20" barrel to 19", and will compare again. I'd be interested to hear what that same load of 28.3gr of Varget does in your barrel?

Hope that helps.

Thanks for posting this, Yondering. It's good to compare notes.

I still have not tried Lapua brass, sticking with Starline for now. I don't know how case capacity between Lapua and Starline would compare, but I suspect the Lapua brass will hold more powder. I get some ejector marks at 28.0 grains of Varget and ended up dropping back to 27.8 grains. I was getting about 2680 fps (@15 ft from muzzle) when the charge was 28.0 grains, so I'd say we're fairly close on velocity with Varget. I'm not real comfortable with the idea of running Varget at 28.3 grains in Starline brass---at least, not this batch. I think I tend to be a bit more timid when loading for an AR than a bolt gun...

I did shoot my 6G again this last Saturday, and I got results that make me happy enough. I shot five groups of the Lever load, and the average was well under an inch. With the two most errant shots taken out of the 25 shots total, the average was under 3/4 inch. I modified my bench technique a bit and it seemed to have made for more consistent results.

I also shot five 5-shot groups powered by 27.8 grains of Varget with the 105, and they shot nearly as well as the Leverevolution loads did. I'm thinking that Varget may be just as good as Lever in this application, but I'll cast a vote for Lever based on the fact that it meters so beautifully...and Lever DID beat it out to some extent.

I am going to shoot the 29.5 of Lever load a bit more just to see if I can refine my bench technique a bit more, then go back to playing a bit more with 90-grain Accubonds. I got pretty encouraging results with them early on and I think I may be able to wring a little more out of them with a little more AR practice-induced confidence. I'm really curious as to how they would like to collaborate with about 30.5 grains of Lever.

You can definitely push the velocity higher with Lever than Varget.

I set up my ARs with trued actions for full bolt lug contact, so I'm not as worried about breaking a Grendel bolt. As for pressure limits, the weak point is the Grendel case web and the primer pockets; you'll see loosening primer pockets first, and then expanding case heads on Grendel brass before you reach anything approaching dangerous pressure for the rifle; I would be using the same loads in a bolt action as in these ARs. It's pretty easy to work up until primer pockets just barely start to loosen a bit, and then back off. The first part of my load development with wildcats like this is to work up to max loads, seating fresh primers in each case after firing to test the pockets. When they get easier to seat than the first time, (using known new or once fired brass), that load or a little less is max. I've never run into any safety issues doing that, and generally try to settle on a load that gives at least a few loadings without loosening primer pockets, and that'd be a top end load.

I have not used Starline brass in this cartridge, but Lapua brass is generally accepted to be on the smaller side for case capacity. Anyway, the loads above were actually in Fiocchi x39 brass.
I can say the new barrel is showing signs of a little higher pressure (better fillout on those fireform loads) than my 24" barrel; the new barrel has less than 10 rounds through it while the 24" has been in use for a couple years. If your barrel is new, it may be more like my 20", and seem a little hotter for the same charge than my 24".