6mm creedmoor AR308

[Moarguy]

I was contemplating the idea of the 6.5CM.. then I stumbled onto some information for the 6mm variant.

Many people here doing the 6mm with AR308?

It looks like h4350, RL16, RL17 and to an extent RL26 may all be good powders. I saw some people using H1000 but that seems awful compressed. RL26 has a reputation of being temperature touchy but also seems very dense, allowing a full charge to easily fill the case.

I see a DTAC 115gr projectile in .243 which looks very promising. At first, was considering the 110 Sierra. Though, being a significant reduction in cost for the 115 along side claimed better BC's.

Thinking a 22" barrel is about right.

What barrel length and powders are you all running for this new-age 243 winchester?

I was looking into starline brass, RL powders and the DTAC 115gr.

[Wilson1911]

4831sc for powder.

[gman47564]

I been shooting the 6mm creedmoor for a few months now. Not a ar but a bolt gun. Probably the most accurate gun I have.. I shoot the 107 gr. Sierra match king around 3050 mv with h4350. In hornady cases. I got a little better speed and accuracy with the 4350 than I could with 4831. Ranger188 also shoots a 6 creedmoor with reloader 16 and the 107 smk with great results. He worked with the 115 dtac's for quiet awhile i think but got better results with the 107's. He also tried the 110 smk and found them pretty finicky to get to shoot well. Im not sure what your best option would be in the ar platform with the shorter barrel. Were both running 26 inch pipes..great round in my book.

[Moarguy]

Really, why better results with the 107smk?

What makes those 110smk so picky?

I was wondering about rl16/rl17 and potentially rl26. H1000 was said to perform well, however not too keen on packing it in with a kabob skewer. Was looking for something dense and meters well with volume drop. So I may sort and prep brass then run it gently by hand on a xl650 progressive.

Rl16 is supposed to match h4350 well enough. The rl26 I was told will make good velocity but can be temperature sensitive.

Will 24" barrel squeeze 2900fps with the 115dtac? Just using a .295 g7 BC on hornady's basic ballistic calculator.. 1&1/2" sight height and 200yd zero was giving nice report card.

600lbs energy at 1000yds with good speed. Very flat and not much drift.

I cannot see much difference between the 6xc and 6 creedmoor. Other than, the creedmoor brass is more available. Starline makes quality. However, word was David Tubbs is supposed to be offering Peterson small rifle primer 6xc casings soon.

The spec on either brass was .020 to .030" of difference in OAL. With the shoulder being slightly longer on the 6 creedmoor. Some people claimed creedmoor brass would net a faster muzzle velocity of 50-100fps however.. *shrug* will 1-2gr case volume do that?

Either way, I want to make a nice reaching semi-auto. The ballistic chart implies it will hit steel more hard than a 308 beyond 400-500yards. So, it should be easy enough to see impact while being gentle on my shoulder after 100-200 rounds during a full day of barrel burning.

I am open to all input. You all have experience. I have a dream. Please help?

Thank you!

[flyer]

The 6.5 works well in an AR, I'm not sure about the 6mm.

The 6br variants and Dasher are more interesting to me but not really AR friendly.

I would play it safe with a 6.5 but that's just me.

[gman47564]

As far as the smk 110 goes I think they have a seacant ogive which makes them more sensitive  to seating depth where the 107 has a tangent ogive and more forgiving when it comes to seating depth. Course I could be wrong. Just know my gun likes the 107 smk.

[Moarguy]

Flyer, the 243 win functions well enough. Also a few places are offering the 6mm creedmoor in dpms/sr25 rifles now.

I believe David Tubbs used the 6xc in his large frame ar's but i dunno. It may be that special t2k rifle that costs $6000 plus barrel, trigger, mags, etcetera.

Just looking at a possibility.

Gman, thank you for the insight. I do not understand the differences. I am very green to all this stuff.

I need to make phonecalls and emails. Get more feedback.

Appreciated. The 6mm seems far more promising to me than the 6.5mm; i cannot tell a (significant)recoil difference between the 6.5 and 308. The 243 vs 308 is rather large. Nearly half the kick. If a more modern casing which offers use of high BC 6mm will function in the large AR platform, it should be pretty fun for unknown distance shooting on plates.

That said, I would be happy with hitting 10" gongs at 800yards. Though slapping 6" would tickle me greatly.

It seems the 6mm is much more flat shooting than the 6.5, according to all these internet claims. Though i have no experience. Just reading.

Thank you again!

[gman47564]

the 6 creedmoor doesn't have much advantage over its big brother the 6.5.. with a good brake either are a pleasure to shoot.. the six shoots a little flatter if you push it... the 6.5 does a little better in the wind with a 140 grain bullet.. to be honest its 6 of one and half a dozen of the other... both will do well in a ar platform the way I understand it...I just prefer bolt guns...

[Moarguy]

I appreciate you gman.

I think the 6mm would be better. If, the 115 dtac proves reliable in a semi-auto for accuracy. However, I am beginning to agree it may be more suited for manually opperated bolt guns.

The horizontal drifts were within 0.1-0.2mils of each other... being 6.5creed versus the 6mm. Comparing 107's to 140's. Someone had made up a chart and did rather large comparison.

Also, it is only about 100lbs less energy than big brother. For the trade of noticably less drop. Which seems to be more appealing to me.

If anyone has input from experience or other views I am very receptive.

Thank you