Primer Pocket Size???

[Hoekight]

Necking down is the way to go I have found after working with this cartridge for more than 10 years, if you neck up from 243 you will always end up with very short necks after fire forming, not good. I think it is a great cartridge even though I have only worked with 10 twist barrels so lighter bullets.

Thank you for that bit of information. Hands-on experience is greatly appreciated. I am excited about getting it built and testing it out. I am using a 7.5 twist Brux that’ll finish at 30”. I am excited to see what kind of accuracy it will give and although it’s not what I’m seeking I’m very curious where the velocity settles with a couple of different powders. Planning on using 135 grain Berger LRHT bullets. And thanks to you I’ve about decided to get some 260 Remington brass to use. Peterson has some in SRP and I think that’s the route I’m choosing first.

 

[Hoekight]

I've been spiballing a similar project for a couple of years. Maybe just a 25 Souper. Why not use 260 Rem. brass? It's only a .007" reduction. Lapua & other premium manufacturers make it, maybe even in both small & large primer size. Just a thought.

As always YMMV

To be honest I had forgotten about the 260 being the same case but you and others have pointed that out. That’s the way I’m going to go and in srp Peterson brass. Thanks for the heads-up. This is why I’m not scared to post questions I’m not sure about.

 

[Steve Donlon]

I use both and it depends on the powder and the fact that you may need to use a little more powder with SRP's to get the same velocity as LRP's. The SRP does have the advantage of using hotter loads. They both work good if you spend the time to figure out what you need. I do use 450 primers though. These are all for a 6.5 Creedmoor.

 

[209jones]

Using a small magnum primer shud keep you out of ignition issues with most powders. It would seem to be colder weather that causes issues with std SRP's, which are hangfire issues for the most part, as far as I've seen. Just how cold it has to get, all I can say is maybe closer to freezing temps is where issues seem to be.

 

[Fast14riot]

I use Peterson SRP 260 brass exclusively in both of my 260AI. Rem 7-1/2 work great for me under 45gr of N555.

 

[Hoekight]

I use Peterson SRP 260 brass exclusively in both of my 260AI. Rem 7-1/2 work great for me under 45gr of N555.

I have some questions if you don’t mind me asking. What kind of velocity are you getting from the 260ai with 555 and with what bullet? And have you tried n160?

 

[Fast14riot]

I have some questions if you don’t mind me asking. What kind of velocity are you getting from the 260ai with 555 and with what bullet? And have you tried n160?

For 260AI info, check here: https://forum.accurateshooter.com/threads/260ai-roll-call.4105592/

I shoot the low node in both of my guns, newest gun has 680 rounds on it, 2805fps with the Berger 153.5. Old gun has about 1800 rounds on it, 2750fps with same bullet.