Long range rifles

I agree, DOD giving it the thumbs up will breath some serious life into the round. Only issue I see is the longevity of the bolt faces, that Russian rim doesn’t leave much meat.

But quoting over 2600mv out of an 18” barrel is very promising.

 

Yeah, I'm hoping industry has figured out that you can't stick to C158 on grendel bolts. I guess 9310 is pretty much required if you want serious bolt life.

 

Trying to get my rifle figured out.

I found a fantastic node running 136 Scenar-L, 42.2gn H4350, rem primers, Lapua brass, .002” neck tension, once fired and annealed brass. Everything was great till I shot across a chrono...2980fps with an ever so slight ejector mark. Fast forward to my last match, ammo was wet, and i started to collect primers only my action.

I then dropped down to load development to find the 27xx node for 6.5’s, and loaded up some test loads at 39.5-40.5gn, and found a decent enough node at 40.5 but only had five rounds, so I couldn’t chrono that loss. I ran across what I had left, 5ea with 39.7, 39.9, 40.1, 40.3, with the 40.3 chronoInf at 2827!

In the past I was running some fantastic Berger match loads that were quoted at 2847fps. I did a little analysis on my load work up and decided to go with 40.6gn of powder. Buddy had his Labradar at the match today and I found I was running avg 2840fps with a 6.1 SD. Perfect.


So here’s the deal, any load I can find published, including my buddy who has the same rifle (sequential serial number even) is running 2760 with 40.2gn on the same day. That load in my rifle is cooking along at 2827. The inter webs say 42-43 gn is a good load for 2800s in a 24” .260.

How am I running the same speeds with one to two, even three full grains less?

Shit doesn’t make sense.

 

Sounds like internal/tolerance problem.
Have you scoped your bore to check for a carbon ring? Also do you log a round count through the bore?

 

Have not scoped the bore, I’ve had 576rds to date down the bore including the proofs at factory.

 

Verify your load is actually the mass that it's at, but I could see having a super tight chamber and getting velocities that high because of it. What rifle/barrel/chamber is it? Magnum Primers?

 

Every load is dropped short on an RCBS comp powder measure, and trickled to 0.1gn on a RCBS 10-10 beam scale, that is zeroed every session. I’ll verify with a check weight. Large rifle primers.

Factory savage 12lrp, 26” fluted heavy target (1” at crown) 1:8, .260rem with COAL to ogive of 2.159.

Loads are Lapua brass, annealed, full length sized via Redding type-S, .002” neck tension, no need for trimming yet, Remington large rifle primers, 40.6gn H4350, Seated to a COAL at ogive of 2.139 with Redding comp micrometer, and checked every 10 for proper COAL. Velocity yesterday was 2840, 6.1 SD over 15rds, with no pressure signs and a .46” group at 100.

I’ll be checking the bore for obstruction or carbon ring, but there was no excessive pressure signs or wild variance in accuracy or velocities seen.

 

Sounds like you might have a mythical tight but pressure relieving chamber. Or they're doing some weirdo squeezebore goofiness over at Savage now.

I'd just take it and run. You found the free lunch lol.

 

Got my trust finalized today.

 

Anyone else as enamored by the 6ARC as I am?

 

I'm really 50/50 on it. 223 does everything I need it to do with aplomb. Maybe once Magpul brings a pmag to market and I can get a pencil/gunner profile 18-20" barrel for it I'll put one together. It has definitely supplanted 6.5 Grendel for me.

 

That’s what peaked my interest. I have an 18” grendel that I like, but why shoot a 105gn 6.5 at 2400fps, when I can push a 136gn at 2800? With the limited long range of the Grendel, I am always grabbing for something else.

But since I have the Grendel, they means I have everything I need, minus the barrel. I would LOVE for magpul to produce a polymer mag, but the Andersen mags are good enough, and all three of mine feed without issue.

I might grab a 20-22” in 6arc and see how it goes. Seems to fill the gap in performance I wanted out of the AR platform.

 

I want one.

I shoot a 6x47L in my bolt gun so I have a lot of 6mm bullets.
Would love a good gas gun setup w/o having to build an an AR-10 platform.

 

I think that's what is really bringing things to the fore on this round. It's a perfect round for a guy who has 6mm stuff, wants to build an AR15, and doesn't want the headache an AR10 can bring.

 

What AR-10 headaches?
Just curious not looking to into a full out internet nuclear exchange

 

They have a high prevalence of needing lots of tweaking to get to run right.

 

Mine wasn’t all that finicky

 

Primarily the multitudes of standards. I'm of the belief that just about any setup should have a lightish buffer and standard spring, and be gassed to match with an adjustable gas block, but receiver height vs handguard height, barrel extension geometry, these things all make it just that much harder to have a cohesive build work full time. It's getting better, but it's still way more accessible to go AR15, because things are built around mil-spec.

Mind you, you can bypass 99% of this by buying most of the rifle parts from places like Aero/Faxon to put a solid base together but it's still "another thing" to worry about.

 

I’ll take my m14 over the ar10 for problem free. And I’m likely basing my statements on 10yrs ago AR10s.

 

Yep, AR-10s especially homebuilds are a demonstrated exercise in "tolerance stack"