Hornady CX 270 Win load development

[Obi Wan Reloadi]

Good evening, all.

I am working up a load for Hornady CX 270 Win 130gr, using RL19. Rifle has a 1:10 twist.

Q1: I cannot find any load data for that particular bullet with RL19. So I am planning to use the 130gr GMX data from my Hornady Manual (9th Edn. - I can't lay my hands on the latest one) as a reference starting point - I read somewhere that the load data for the CX and GMX were interchangeable, but now for the life of me I can't find that reference. Can anyone confirm that?

Q2: What is the lowest fps you have found that the CX will reliably expand at? I need it to work at 250 yds max for deer, and I read that Hornady recommend a minimum 2000fps for reliable expansion, but that seems awfully slow?

Many thanks.

 

[JmacD]

#11 (via app) lists RL 19 with a min of 50.6 and a max of 59.4. The bullet guide in the front of the manual gives use range of 2400-3600. Hope that helps.
Edit: I believe the eld-x has a lower expansion velocity.

 

[Obi Wan Reloadi]

#11 (via app) lists RL 19 with a min of 50.6 and a max of 59.4. The bullet guide gives use range of 2400-3600. Hope that helps.
Edit: I believe the eld-x has a lower expansion velocity.

Thank you - that's useful and interesting. Seems similar then. 50.6 gr gives 2600 FPS and 59.4 gives 3100 fps for the GMX

 

[JmacD]

Thank you - that's useful and interesting. Seems similar then. 50.6 gr gives 2600 FPS and 59.4 gives 3100 fps for the GMX

That jives with the velocities listed in the loading section

 

[horsemen61]

I’ve heard you need at least 2,000 fps for the CX to Open and that’s at the Low End you really Need All the Speed you can get for a Mono Cooper bullet

 

[JmacD]

I’ve heard you need at least 2,000 fps for the CX to Open and that’s at the Low End you really Need All the Speed you can get for a Mono Cooper bullet

I got to say, that alloy that they made that bullet out of is pretty impressive. I saw one that was taken out of a Whitetail shot at a pretty significant distance. It was a mushroom that I would have never associated with a monolithic bullet..

 

[Obi Wan Reloadi]

The charge spread from 50.6 to 59.4 is pretty wide.

That's a lot of rounds to test if I start at the bottom and work up in half grain increments and 3 shots per load, which is how I normally approach it. Given the shortage of primers here in the UK (I'm down to my last 200) I may run some numbers through a ballistic calculator, see what a decent fps looks like @ 250yds then load to that - it may mean starting further up the charge weight list - even 2900 fps over 55.9gr will drop off a fair bit at 250yds I would imagine.

I have found that with my 243 using Barnes TSX 80gr that speed is king.