Winchester 748 - for Cast 270

[dsh1106]

Has anyone out there tried Winchester 748 for the 270 on anything heavier than 136 grain?

I have a 150 grain cast bullet I want to try, but 748 is a no go at this weight in the 270 ??? I did find 748 data for 150 grain for the 7 mm Mauser as well as a few in the 30 cal range.

Thanks
Scott

[Scharfschuetze]

I've never used 748 in my 270, but my experience with most ball or spherical powders is that they are not an optimum powder for cast bullets given their heavy flame inhibiting coatings. They are at their best at higher pressures. Of course every rule is made to be broken, but I think that you'd be much better off with SR 4759 if you can find it and if not, then 4198 or a stick powder with that general burning speed. Lighter loads can be propelled by the mid to slow pistol powders with good success.

[dbosman]

What velocity are you seeking?

[jsn]

I have a couple of the older Winchester reloading data pamphlets (pre-Hodgon marketing Winchester powders) and they have no W748 loads for a variety of Mauser, 308, and 30-06 based cartridges with jacketed bullets until you get into the 30 caliber and larger diameters.

However, RCBS Cast Bullet Manual #1 shows 29 to 31gr W748 for 135gr bullets, and 28 to 30gr for 150gr bullets. Both loads used CCI #250 Magnum primers, and started with about 1870fps to 2000fps.

The other recommended powders include IMR 3031, IMR 4198, Re7, SR4759, 700X and Red Dot.

[Hick]

I'd avoid 748 in this situation. A load of 28-30 grains in a 270 case is barely 50% full. Running with that low percentage of case fill with w748 is asking for trouble.

[lotech]

Unless you're looking for a near maximum load, 748 is not a good pick. Check some load manuals with cast data.

[EDG]

For the most part ball powders are never specified for reduced pressure loads. The powder is very position sensitive in less than case full loads. It also produces very large bright muzzle blast fireballs and very heavy concussion with the muzzle blast. You really need some kind of extruded powder.

I've never used 748 in my 270, but my experience with most ball or spherical powders is that they are not an optimum powder for cast bullets given their heavy flame inhibiting coatings. They are at their best at higher pressures. Of course every rule is made to be broken, but I think that you'd be much better off with SR 4759 if you can find it and if not, then 4198 or a stick powder with that general burning speed. Lighter loads can be propelled by the mid to slow pistol powders with good success.