New bullet 260 rem help with powder please

[Trigger puller UK]

Hi guys
I have a new bullet to try in my 260 rem, It Is a solid bullet turned on a CNC lathe. The material of the bullet is a brass/bronze. The bullet's weight is 118gns. As you can see in the photo the bullet on the left is a Amax 140gn, the bullet on the right is the new solid 118gn bullet. I haven't got a BC for the new bullet but as it is very similar in physical size would it be fair to say it would be very close to the BC of the Amax which is 0.585 G1?

The manufacturer of these bullets have told me that they need to be pushed at around 3100 fps to gain the advantage of the ballistics as they weigh less!

I have tried using H3450 powder with the max Avg fps gained was 3026 with a charge weight of 45.9gns but the accuracy was bad, getting alot of flyers. can any one recommend a powder to get these bullet's to the 3100 fps with good accuracy?

My rifle specs
Accuracy International AX260
26" Border barrel 1-8.5

Lapua 260 Brass
CCIBR2 primers.

Thanks Ady

 

[WRM]

Re: New bullet 260 rem help with powder please

I'm going to guess that the BC will be 118/140 X .585 = .493 G1 due to the difference in weight and assuming IDENTICAL form, as weight is a big part of BC.

If your case is full of 4350 (you can't add anymore powder to increase velocity), I'd look for a powder with slightly faster burn rate, maybe 4895 or 414, but that is a total guess on my part....

Good luck,

Bill

 

[bohem]

Re: New bullet 260 rem help with powder please

You will likely need to look at a powder burn rate at least 1-2 steps FASTER than what you'd shoot a120gr bullet from a 260 with.

So, if you'd look at H4350, then Varget would be an obvious next choice.

But, since Varget works well for 120's in the 260 and my experience with turned solids si that they're very slippery in the bore you will need to go to 4895 or something like BLC2 or maybe even H335

I made some 180gr bullets for 30c out of copper, I never hit pressure signs at 3100+fps from a 26" barrel 30-06 and I was shooting 58.0gr of H335 underneath it.

In terms of BC, WRM's advice is going to be a conservative estimate. You will see a lower BC but that's a realistic starting point without knowing anything more on the bullet's shape.

 

[Trigger puller UK]

Re: New bullet 260 rem help with powder please

I do have some Varget in stock, what would be a sensible starting charge weight?

I friend of mine suggested using Vihtavuori N560/ N550, which powder out of these three would be the first choice with this bullet?

Thanks Ady

 

[bohem]

Re: New bullet 260 rem help with powder please

I would start with what the Hodgdon site lists for a 260 shooting 120gr bullets with Varget. Then work up in 0.5gr increments looking for proessure signs.

 

[Cmonroe]

Re: New bullet 260 rem help with powder please

You would be much better off trying to hook them up with a slower twist. Good look with that 8.5 twist and a 118g bullet at 3100. Just so you know I have seen several guys on here push 130-142 g bullets between 2900 and 3000 fps!!!! and you can get those BC's in the 600's at that velocity. If your set on trying this I would work up a 4895 load after thinking about it a little further this would be better than RL_17 or 4350.