BC ?? on 53 & 55 V-Max

[Kevin R]

I have been shooting the 53 & 55gr V-Max out of my 223.
Same load for both bullet's, 26.0grs H4895 CCI BR primers is good accuracy. 2.250" groups at 300yrds.

The 55gr with a BC of .255 is 5.5" low at 300yrds.
The 53gr with a BC of .290 is 8.5" low at 300yrds.

Now stupid me forgot the Chrony yesterday so couldn't check the velocity for each, but my thought(witch may be out to lunch) would be that the lighter bullet to be faster??

Any thoughts on why this is???

Thanks



Kevin.

 

[Trickymissfit]

I have been shooting the 53 & 55gr V-Max out of my 223.
Same load for both bullet's, 26.0grs H4895 CCI BR primers is good accuracy. 2.250" groups at 300yrds.

The 55gr with a BC of .255 is 5.5" low at 300yrds.
The 53gr with a BC of .290 is 8.5" low at 300yrds.

Now stupid me forgot the Chrony yesterday so couldn't check the velocity for each, but my thought(witch may be out to lunch) would be that the lighter bullet to be faster??

Any thoughts on why this is???

Thanks



Kevin.

my charts don't do a .29B/C but here's what I got using a .30B/C

55 grain Vmax @ 3300 fps

200 yard zero (1.3" high @ 100 yards) = -6.8" @ 300 yards

53 grain Vmax with a .29 B/C (remember I used a .30) @ 3400fps

200 yard zero (1.1" high @ 100 yards) = -5.8" @ 300 yards
gary

 

[MT4XFore]

It sorta seems that way, doesn't it? Tricky's figures show you that the lighter bullet's higher BC does make it shoot a bit flatter than the heavier one. But I dont think that is what you are seeing. Almost anytime you change even one component in your load recipe it will most always result in a POI shift. That's because the bullet is leaving the barrel at a different point in the barrel's oscillation. In other words, you've changed the "harmonics" of the load/barrel combination. Because of that, heavier bullets may fly higher at a given distance than a lighter one, in spite of the velocity. The opposite can happen too. All it means is you need a different zero with each bullet. Sucks, huh? So goes reloading and shooting! Some rifles will shoot different loads to the same spot, but it is really rare. Good Luck.

 

[Kevin R]

Thanks for the replies guys.

Ok, here are my findings today which make way more sence IMO.


The 53gr V-Max with 26.3 H4895 (up 2 tenths) with a 5 shot avg of 3441 fps, a 200ryd zero, 6.5" low @ 300. 2.125" group (my best yet)


The 55gr V-Max with 26.1 H4895 with a 5 shot avg of 3365 fps, a 200yrd zero, 8" low @ 300. 2.750" group.

All just for hunting but just playing around to see how well a out of the box gun and standard scope will do. (and the old man behind the trigger)

Savage model 10 Predator 1-9 twist, Vortex 4-12


Kevin.

 

[Trickymissfit]

Thanks for the replies guys.

Ok, here are my findings today which make way more sence IMO.


The 53gr V-Max with 26.3 H4895 (up 2 tenths) with a 5 shot avg of 3441 fps, a 200ryd zero, 6.5" low @ 300. 2.125" group (my best yet)


The 55gr V-Max with 26.1 H4895 with a 5 shot avg of 3365 fps, a 200yrd zero, 8" low @ 300. 2.750" group.

All just for hunting but just playing around to see how well a out of the box gun and standard scope will do. (and the old man behind the trigger)

Savage model 10 Predator 1-9 twist, Vortex 4-12


Kevin.

first of all your in need of some powder. Beg borrow, or steal a can of H335, BLC2, and H322. This can be followed up with some 2015BR and 2230. Seat those bullets within .002" of the lands, if not just barely touching them. The Speer manual calls out 3031 with the 55 grain bullet, and 2015 are very similar burning rates. So where they come up with their data is odd to me. I'd be starting with something like H335. I shoot the 55 grain Vmax bullets out of a .223 all the time, but honestly with a 1:9 barrel I'd be moving into heavier stuff with a B/C around .35.

I'm sorta bothered with your velocity verses the trajectory figures. If you have access to another chronograph, it might be worth doing a compairison. According to the curve your velocities are lower, or else your 300 yard targets are further out (I'm better the latter). Anyway I have had good look with BLC2 and H335 as well as H322. I shoot thru a 20" barrel for 3274 fps, and group in the mid fours on a good day. From a 26" barrel to a 20" barrel I lost about 75fps Next question; are your groups stringing vertically? If so put the bullet about .0015" into the lands, and try again.
stay in touch!
gary