[Citadel99]

Need a little help here... I don't have a chrono...I'm reloading 42 gr of imr in lake city brass shooting Sierra 165 gr SBT. 20" barrel FN PBR.

Any idea on ballistics/bullet drop at 100, 200, 300 yards?

Mark

[interlock]

imr? which powder?

[Citadel99]

ooops. IMR 4895

[Remo-99]

The velocity would be around 2500fps-2600fps(guessing as I don't have data specific to your barrel length and brass, in front of me now.)
I only have tables of Speer bullets in front of me too. Which show 165gr BTSP has a BC of .48

The table shows;
2500, 2320, 2147, 1982fps@300yrds.
-1.5, 0.0, -5.0, -17.5 using a 100yrd zero.

2600, 2416, 2239, 2070fps@300yrds.
-1.5, 0.0, -4.5, -15.9 using a 100yrd zero.

I'd say your somewhere between those, not precise I know, but hope it helps you some.

[USSR]

Lake City brass has a reduced capacity, and the same load in my 26" FN SPR would clock at about 2750fps. So, subtract whatever you want for the 6" shorter barrel, and plug it into an exterior ballistics program for your drops.

Don

[JimKirk]

Using BC of .419/Sierra web site and Velocity of 2500 fps/ Hodgdon Data allowing for 20"
barrel

Range Drop
(yd) (in)
0 -1.5
25 -0.6
50 0.0
75 0.2
100 0.0
125 -0.6
150 -1.7
175 -3.2
200 -5.1
225 -7.6
250 -10.6
275 -14.1
300 -18.2

Your velocity will be unknown unless shot over chronograph, only estimated.

Jimmy K

[Citadel99]

Thanks. I'll have to see if I can "borrow" chrony time from somebody at the range.

Mark

[dubbleA]

There are so many variables in this equation. Even if you had the exact velocity of that load in your barrel I would encourage you to actually go out and shoot at the intended ranges and dont rely on paper ballistic charts. Sure they can be guide lines but are not written in stone. Your results are going to vary.