Lapis 139 scenar vs Berger 140 BTLR @ 1K

[dskogman]

I have been shooting Lapua 139 scenars in a 260 with 40 gr of H4350. It's not a hot load @ 2700 fps but accurate enough. This last weekend I shot them in the first round at a local 1K match and then switched to the same load but with Berger 140 gr BTLR's in the second and third.

I expected some difference but the Bergers shot almost 2 MOA higher and also seemed more consistent vertically. The GC's are not that different and my ballistic app only showed about .3 MOA difference. They were loaded to to same ogive length so the COAL was longer on the Bergers. Did I get that much velocity difference by changing bullets?

 

[Berger.Fan222]

Hard to say without measuring the velocity.

 

[terryperkins]

The 140B BTLR has G7 of .304 and the 139Sc is .290. According to JBM at sea level, 59 degrees,50% humidity the difference is 1MOA at 1K. Looks like the Bergers start out faster...30 to 40 fps, maybe? Remember the bearing surfaces are different.

 

[Hengehold]

I have been shooting Lapua 139 scenars in a 260 with 40 gr of H4350. It's not a hot load @ 2700 fps but accurate enough. This last weekend I shot them in the first round at a local 1K match and then switched to the same load but with Berger 140 gr BTLR's in the second and third.

I expected some difference but the Bergers shot almost 2 MOA higher and also seemed more consistent vertically. The GC's are not that different and my ballistic app only showed about .3 MOA difference. They were loaded to to same ogive length so the COAL was longer on the Bergers. Did I get that much velocity difference by changing bullets?

is the bearing surface length longer on the Berger?

 

[Laurie]

is the bearing surface length longer on the Berger?

No, shorter at 0.378" v The Scenar's 0.456" (Bryan Litz measurements). The BT Long-Range's bearing surface is the shortest of the four Berger 140gn designs. It's a superb long-range performer if your barrel likes it.