At the risk of showing my ignorance I have couple questions.
270-300 win mag (cloward custom) 1-10" twist?
150 gr Hornady SST at 3000 fps too fast?
76 gr of XMR 3100+150grSST= what fps?
Using FED 215 primers (all i could get)

Im trying to design an accurate (500yard) round for this rifle. I am over seas, the gun is at the house.

no clue as if to "too fast" .. though a 150 in my 300 win will go 3100 .. and a 180 will go 3000 NFT

I've got a 270WSM that will get 3100fps with 150gr bullets using 60gr/R-17. Might want to do a search on the 270 Allen Mag they post
http://www.longrangehunting.com/

let me clarify: how fast is too fast for a 150 gr down a 1-10 twist, 26" barrel?

Too fast for what? paper punching or killing (what)? 3000fps w/ a 150g is certainly easy to achieve w/ a 270/300WM. You should be able to use 270 WBY starting loads and work from there since the 300 WM case holds more powder. You might compare the 270 WSM starting loads also. Do the research! Look at several load manuels and you can get info online from Hodgdon, IMR, Alliant and Accurate. ALL the normal precautions apply. Work up slowly and pay attention!

was asking for load suggestions, i am over seas, the gun is obviously not with me, nor my reloading equipment.

Remington 150gr CoreLikts would do 3480 fps out of my 26" barrelled 300 Win mag. Cannot offer more.

quote:

Originally posted by towedjumper2:
let me clarify: how fast is too fast for a 150 gr down a 1-10 twist, 26" barrel?

Some bullets might blow up at high velocity. This depends on their construction, so there is no blanket statement that can be made about a .277", 150-grain bullet. More information would be needed. The 150-grain Hornady will be OK at 3000 FPS.

As far as the bullet is concerned, I've driven 150gr SSTs in 270 cal upwards of 3600fps (270-300 RUM w/30" barrel) with no ill effect on the projectile.

Now from experience, I can say that XMR 3100 is really to fast to reach the full potential of the cartridge, but if it's all you have, it will work.

(I really need more info. COAL, your exact case capacity, is your bullet jammed into the lands.)

Useing the info you gave and making a few assumptions, I ran the numbers in Quickload and came up with a velocity of 3160fps and max pressure of 66,500psi. I would suggest going to a powder like Magpro. Using Magpro and pushing pressure to 65kpsi the simulation gave you a velocity of 3287fps.

Re 25 gave 3250fps @ 64,708 psi
H1000 3250fps @ 64,500 psi
Retumbo 3230fps @ 60,360 psi
IMR 7828 3270fps @ 64,740 psi
RS Magnum 3275fps @ 64,900 psi

These are just a few examples of the increase in velocity you could achieve running @ maximum or close to a maximum pressure of 65Kpsi.

Now, like I said I need more info and these simulations are based upon a few assumtions, but they should show you approximately what your cartridge is capable of.