Has anyone actually coronographed a .308 win. in a 20" bbl.

[Country Boy]

 What do plain ole factory loads like from Wally's choronogrape in a 20" bbl. I'm talking 150 grn or any handloads would be nice. I habe a blr in .308

[jd45]

Country, the term is chronograph, & even if you don't have one, you can get a pretty good idea. Go to any gun shop & pick a catalogue from whatever ammo maker you choose. Look up the load you're interested in, in .308, & check what barrel length they used for the data. Then subtract about 50fps for every inch your barrel is shorter than theirs. I think you'll be in the ballpark, as they say. jd45

[hunt127588]

168 gr SMK
44.7gr Varget
WW Brass
CCI BR2


This setup yields me 2550 fps in my Remington LTR.

[Casull]

jd45, I think you're right about the 50 fps per inch, but you also need to subtract 100 to 200 fps from that for the difference in advertised pressure barrel velocities and real world, rifle barrel velocities. 

[jd45]

Casull, thanx, I was not aware of that additional negative factor. jd45

[MikeP]

With my 18.5-inch Remington Model 600 barrel, my .308 with 50 grains of IMR4350 and 165-grain Speer spitzer, I have recorded 2502 fps. Today's Speer manual shows this load to be one grain over max, but the older manual I used when developing this load showed it not to be over.

[Old 180]

Remington 742 with 150g Hornady SST, WLR, 2.800" O.A.L. & 47.0g Win 748 = 2830 ft/s