What's the story with the 6x45mm?

6mms aren't to popular other then the shooters that know the perks to using 6mm. Lack of rifles to chamber it. Even an ar-15 I think it's to long or it won't be to its full potential. Made for lighter bullets to, heavy 6mms are popular know. There's really a bunch of reasons it's not popular, but I don't care I've always like the small 6mms.

Makes for a nice combo varmint/deer round be perfect in a sako l461 action for a nice light rifle.
Or a cz 527.

Contender rifle in that would be a pretty cool yote/deer rig I reckon.

I know for me, there needs to be significant performance boost relative to the original cartridge.

6x45 isn't a big enough of a jump to warrant leaving such a popular, cheap, and known entity in 5.56.

Same for 25-45 sharps. Or a few other wildcats.

But.... Grendel was a big enough jump and common/cheap enough to make the change as well.

At least that's me

Shot one owned by a range regular.
Agree with the above of, very similar to 5.56/223.

It is a bit of a jump up, but not enough to knock the 223 off its pedestal.

I'm more interested in the 6ARC, which is just a 6mm Grendel. It's got more case volume, and is designed to work better with the heavier bullets.

I think that'd be a better yote/short range deer cartridge.

I bought a used upper in 6 x 45 and have never shot it. I got a good deal and I believe it’s high quality as the company that made it has a great reputation. Brass has been difficult to form no matter how I try and do it. The problem is I end up with lots of deformed cases. It’s the neck one time and the shoulder next. I’ve formed wildcat cartridges in the past and once I got it figured out I had minimal problems. I’ve probably got 300 to 400 cases formed and at some point I’ll take it out, but right now I’ve got too many other things going on.

I contacted the original owner and he admitted he sold it because he got tired of messing with the brass.

.455_Hunter said:

Why isn't the 6x45mm more popular?

It seems to check many of the boxes for an improved 5.56x45mm, plus is interchangeable with just a barrel swap.

Click to expand...

This question come up periodically. To offer some insight, an article by the late Greg Rodriguez in Shooting Times:
https://www.shootingtimes.com/editorial/ammunition_st_proposal_200808/100271

The "Why isn't ___ more popular" question is almost always answered by lack of demand.

I think I would turn the question around.

What is the use case for a 6x45? What does the extra 0.019" do that 223/556 doesn't.

It was an incremental change from 223 when it was wildcatted in 1965.
It doesn't have enough powder capacity to handle the heavier .243" bullets that have the best BC's for caliber now.
Wildcat brass and forming.
No major factory ammo support. Black hills used to make it, but not currently.
It is able to be used in jurisdictions where the minimum hunting diameter is more than .224"

To get to the "ideal" place where you have enough powder capacity to push the bullets with the best BC, we are talking about calibers that are too long for an AR-15 action, like the 6BR family, 6 Dasher, 6x47, etc.

The 6x45 is simply another wildcat that falls through the cracks. It doesn't have enough performance upgrade to differentiate from the standard caliber for AR-15's, but there are better options if a bolt action is chosen.