I bought a Weatherby Vanguard 1/10 twist that was chambered for .243 converted or reamed barrel out to 6mm Ackley Improved. Gun has a trigger job and nice suppressor installed...its a long action....I know the Mesquite gun show is this weekend and wondering if I can find regular 6mm Rem. ammo there at a decent price...Checked with most retailers around the DFW area and the ammo is pricey...I would even consider some regular re loads for sighting in the gun; has no scope, rings or bases on it as yet...I don't reload so shooting the 6mm AI bullets are out of the question, till I can find a retailer that sells them...
Was actually looking for an old 22.250 for my varmint hunting at our farm, but got a good deal on this gun, so it is what it is...lol...Anyone ever notice the Gun Shows selling the 6mm remmy rds...?

I'd contact chad (custom reloads of dallas) on here he could hook you up with much better ammo than you can buy.

How did you get a wby vanguard in 243 in a long action? You buy it used/previously modified?

Gun shows are not going to be any better as far as pricing. In fact, if you factor your time getting there and back plus admission, it's going to cost you more. Now for clarity, it is chambered in 6mm AI but you want to shoot 6mm Rem, is that right?

If it is the 6mm Remington AI then you can shoot factory 6mm Remington in it without issues, velocity will be a little lower since it will be expanding the case out to a larger combustion chamber but it will work. AI rounds use the same headspace datum as the parent cartridge

If it is an AI chamber and you shoot standard 6 Rem, I would save all the brass and have someone load it for you. Performance will be better.

Left 7mm-08

Right after being fired in a 7mm-08 A.I. chamber.

The left one still shot extremely tight, and consistent.

Do you often get the ring on the bullet from seating?

Yes, and I have learned to look away. Or, I may see of I can get the seating stem out, and open it up in the lathe.

JG - I’m by far not the handloading expert here, but by the looks of that picture the one on the left looks like virgin Lapua brass, and my 6.5 Creed Lapua virgin brass had really tight necks when I seated the bullet (plus no carbon in the neck). I got those same rings.

I bet that once you size that brass after fireforming with your desired neck tension, that the ring mostly goes away.

At Chad’s suggestion, I ran the rest of my virgin Lapua brass over an expander mandrel to ease up the neck tension and then loaded them for fireforming. That ring pretty much disappeared.

It doesn't go away, even with .002" of a neck tension. Thousands of rounds have looked like this, since every rifle is loaded with as high a BC bullet I can run in it. Their shape makes this happen.

Interesting! That’s about what I had after the mandrel - .0015-.002” neck tension. Sounds like your solution of opening up the seating stem is the right one then...

I too look the other way cause mine have it too and there's nothing I can do about it. I have not noticed that it has an effect on flight cause I continue hearing the impact against the steel. I usually live by the motto if it ain't broke don't fix it but please let me know the results if you modify your seating stem, this idea has caught my attention.