Determining velocity

[HEAD0001]

If you load a 30-06 with a 180 grain RCBS bullet at 1800 and 2000 and 2200 fps. How do you guys determine the velocity at 100 and 200 yards. I know how to use a ballistic calculator. But how would that apply to a bullet like the RCBS 180 in 30 caliber. I am trying to determine a target velocity for this bullet in a 30-06. I am not real concerned about bullet drop. I have enough confidence in my shooting capability to adjust for that.

From reading a few posts it seems like I would want the velocity to be at or above 1200 fps at my max distance-which I would consider as 200 yards. So how would I determine a muzzle velocity to attain that goal??

I am having a lot of fun trying to get this 30-06 bullet figured out, and you guys have helped me a bunch. So bear with me. Thanks, Tom.

[Doc Highwall]

That would be by using the ballistic coefficient for the bullet at the muzzle velocity. RCBS gives a BC of .293 for the 180 gr SP and .255 for the 180 gr FN.

[Larry Gibson]

Doc is spot on as usual:-)

Larry Gibson

[Harter66]

I have a calulator on my phone called shooter by sean kendy , there is a free version and a pay version . It'll give you drop ,drift,velocity,ft lbs,and let you do it in mil,us std,and metric . I've set my copy up for 10yd increments 10-300 for my rilfes , 10-100 for my pistols. The only bullet I've really tested it with has proved out tobe very acurate within my capiblities anyway.

Or there are BC charts in many of the loading manuals , speer has a decent 1.

I believe the Shooter app will run on your computer as well.

[Von Gruff]

This is a very good one.

http://biggameinfo.com/index.aspx?page=/balcalc.ascx

I just ran your data and a 30 cal with .293 Bc will be down to 1200fps

from 1800fps start 300yds 1205fps
from 2000fps start 375yds 1213fps
from 2200fps start 450yds 1214fps

Von Gruff.

[stephen perry]

Basic Physics equations will allow a shooter calculate velocity at any distance after knowing muzzle velocity and the distance before the bullet crashes into the ground.

Stephen Perry
Angeles BR

[Harter66]

Thanks for the link.
I ran my boolit in that calculater, TIF and drop were very close to my shooter numbers but the energy numbers showed my boolit to be different by a substantual amount. So I checked it against my Speer tables , which seem to be a happy medium between the 2.

Dang it now I have to find another 75fps to meet Nevada's minimum energy standard of 1000ftlbs @ 100yds. By the shooter app I have my 1k out to 150yrds yet the linked calulator says only 80 as does the Speer table,that I never thought to use untill just about 5 minutes ago.

Could the differing numbers come from the Shooter app using GPS/weather station data vs fixed location and fixed condition numbers?

[Mk42gunner]

Another simple, but possibly more expensiveway to do would be to put your chronograph at the desired distance. I would definately want the rifle on sandbags on a sturdy bench; this has the potentialto get real expensive, real quick. But at least you would know the exact velocity.


Robert

[HEAD0001]

This is a very good one.

http://biggameinfo.com/index.aspx?page=/balcalc.ascx

I just ran your data and a 30 cal with .293 Bc will be down to 1200fps

from 1800fps start 300yds 1205fps
from 2000fps start 375yds 1213fps
from 2200fps start 450yds 1214fps

Von Gruff.

That makes it look like there is not much reason to use the hotter load. It should be easy to get a good 1800 fps load. Then I could use a little softer lead for better mushroooming?? Looks good, thanks.

Where did you find the BC on the RCBS bullet?? I must have looked in the wrong place. That was the problem I was having with the ballistic calculator. Thanks Again, Tom.

[Alex Hamilton]

If you load a 30-06 with a 180 grain RCBS bullet at 1800 and 2000 and 2200 fps. How do you guys determine the velocity at 100 and 200 yards. I know how to use a ballistic calculator. But how would that apply to a bullet like the RCBS 180 in 30 caliber. I am trying to determine a target velocity for this bullet in a 30-06. I am not real concerned about bullet drop. I have enough confidence in my shooting capability to adjust for that.
The only way would be to place a chronograph just in front of the target. All ballistic calculators give estimates, which may be close but not exact. You should have no difficulty shooting though the target area of the chronograph without hitting it at 100yds.


From reading a few posts it seems like I would want the velocity to be at or above 1200 fps at my max distance-which I would consider as 200 yards. So how would I determine a muzzle velocity to attain that goal??
Tom.
It is important to stay above the transonic stage to avoid the buffeting that the bullet will be subjected to as it goes subsonic. As you intend to shoot over quite a close range of 200yds even relatively mild loads will stay supersonic at that distance, say anything above 1500ft/sec.
Alex

[Doc Highwall]

The ballistic coefficients that I posted for the RCBS bullets came from their cast bullet book.

[HEAD0001]

The ballistic coefficients that I posted for the RCBS bullets came from their cast bullet book.

Thank You for the information. Tom.