Small primer or Large for 6.5CM

You did not state your main purpose, hunting, target, max distance. The SR primers will give you more reloads before the pockets loosen up. LR will preform better in extreme cold temps, though. Lapua brass will more than likely give you better overall accuracy as is, without all of the brass prep work. Starline brass will last longer than Hornady brass. Hornady brass has a history of loose primer pockets after 3 firings. I use Starline brass for my main general use, Lapua brass for my high precision target loads. Be aware that Lapua uses a smaller than std flash hole, 0.058" instead of the std 0.062". They say it promotes better overall consistency. I could not see any differences between the 0.058" and the 0.062. So I let my universal depriming die enlarge the flash hole. My powder of choice is H4350 behind the 140gr ELD Match. Imr 4451 is second choice. You will give up velocity with the IMR 4451. but it's a good powder for the 6.5 CM.

I have read several articles on this and they claim the brass with LRP performs better. I have no first hand knowledge though.

Sorry, autocorrect on my tablet changed a few words and I didn't catch it.

Blue68f100 said:

Hornady brass has a history of loose primer pockets after 3 firings.

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I have three batches of Hornady 6 creed which are 6, 7, and 12 firings. My current batch this season is on its 4th firing.

For the OP: Don’t wring your hands over it too much. Small primers have advantages for target shooting, but large primers aren’t incapable. I’ve stuck with large primer Hornady brass for one of my rifles and Lapua in another to keep my batches separated. I’d be lying if I said I can shoot the difference between the two onto paper, and even shooting custom barreled Ruger’s myself, I’d be hard pressed to believe an M77 will show you the difference between the two.

Bushings with small primers are nice, but there are lots of Ruger’s out there with large pins and sloppy pin bores firing small groups with small primed cartridges.

I cannot point to the article, but from what I recall, they found the small primer brass to be more accurate. Lapua the most accurate, but starline doing a darn good job.

Bat Rastard said:

You lost me with "grass". Please clarify.

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I fixed the post, sorry.

You might find some useful info in the following "What the Pros Use" article. It covers both 6mm CM and 6.5 CM, so you need to scroll toward the bottom for the 6.5.

But to cut to the chase for the primer question you originally asked, by far the favorite primer for the 6.5 is the CCI 450 small rifle magnum primer. But as others above have mentioned, for your stated purpose of punching paper at 100 yards, you would be hard pressed to really see a major difference, I'm guessing.

https://precisionrifleblog.com/2019/09/06/6mm-6-5-creedmoor-load-data/

I hadn’t read the PRB article on 6 and 6.5 load data which @climbnjump referenced, as I don’t read PRB for anything except the finals load out articles, but the trend he noted for the 6.5 creed is reversed for the 6 creed.

I can’t say why the bias is so distinctly reversed, but despite both Hornady and Lapua brass being available for both, it looks like the 6.5 shooters predominantly used Lapua small primed brass, and 6 creed shooters predominantly used Hornady large primed brass. Lapua brass for 6 creed was available, and many of us were necking down Lapua 6.5 brass even before that - but the fact these two are reversed and have such extreme biases within their respective categories says more about the data set than about the products.

Varminterror said:

but the fact these two are reversed and have such extreme biases within their respective categories says more about the data set than about the products.

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Well, sure. All you have to do is look at the number of respondents for each to see that. But the OP wasn't asking for a comparison between the 6 and 6.5, he was asking about the 6.5.

(There were only about 33 respondents to the 6mm survey and of those, 6 were using FACTORY loaded ammo from Hornady. Since the Hornady brass is LRP, that is going to skew results from that small data set.)

Seems like he was asking about the difference in small primers and large primers.

Can you elaborate as to why the 6 creed might favor large primers and 6.5 would favor small?