estimated bullet velocity of this 168 amax load?

[uracowman]

hey guys,

I just got done with my first set of reload and I was curious to see what you guys though the estimated velocity of my loads would be. I don't have a chronometer, so some input would be appreciated before I go out to fire them off tomorrow.

I loaded some 168G amax bullets into some once fired federal brass from GMM ammo and once fired winchester brass. The loads are as follows:

1)

168g amax
federal FC marked brass
43g IMR 4064
2.800 OAL

2)

168g amax
winchester marked brass
43g IMR 4064
2.850 OAL

Both rounds will be fired out of a 26 inch barrel.

According to the reloading manual I have, 42 grains of IMR 4064 while firing a 168g BTHP will yield a velocity of 2479 while a 46g load will yield a velocity of 2721. I am assuming this was shot out of a 20 inch barrel. With a 43 grain load, would it be safe to assume a 2650 muzzle velocity when calculating my elevation?

 

[Deadshot2]

Re: estimated bullet velocity of this 168 amax load?

Based on my experience with this load, you will see two different velocities. I have measured case capacities and the FC is a smaller volume case. I'd look for around 2600-2650 for this case and just under 2600 with the Winchester.

To "nail it down", zero your rifle with one of these loads at 100 yards. Then shoot at a target out at 200 yards without adjusting your scope. Measure the drop. Then use one of the free online external ballistic's programs to determine the speed. Keep varying the muzzle velocity on the program until it shows the same drop that you measured at 200 yards. Repeat for the other case load.

Not as easy as using a chronograph but you're just solving the problem from a different direction.

 

[louboyd]

Re: estimated bullet velocity of this 168 amax load?

I'm assuming you're talking about a 308 Win cartridge, though your post doesn't say so. You didn't state case capacity of Federal or Win brass, Quickload assumes 56 grains H20 for both. It's easy to measure with a fired cartridge. It also assumes the bullet is seated a little off the lands, which can affect pressure. Seating on the lands will raise pressure.

Here are the results of Quickload computer simulations.

#1 load, 168 Amax, 2.800" COAL, 43 grains IMR 4064: Is 104.3% compressed load and will give a pressure of 56273 psi and a velocity of 2713 fps from a 26" barrel.

#2 load, 168 Amax, 2.850" COAL, 43 grains IMR 4064: is a 102.3%
compressed load and will give a pressure of 54005 psi and a velocity of 2692 fps from a 26" barrel.

There are three things I consider indispensable for handloading. Those are a chronograph, a target range to watch bullet point of impact, preferably at maximum effective range, and Quickload to predict the effect of load changes.

 

[roggom]

Re: estimated bullet velocity of this 168 amax load?

I usually gather my info from Hodgdons and they use a 24" 1:12 bbl. With your load, you should add between 20-40 fps for the extra 2" of bbl.

Now, velocity is a very important variable, but I have found the POI to be just as valuable.

I use G7 online software, http://www.gseven.com/films/sunjectthree/g7-free-online-ballistics-calculator---overview-(1

You can register for free and use the G7 website, or the LRBC over at Vortex, the Vortex would be perfect for those with Vortex scopes, as you can print out a reticle drop chart.

Either way, you only need a close estimate of velocity, and you can look up your bullet to create a drop chart. Then you go to the field and validate your numbers, make adjustments, and the software will automatically change the velocity, or the BC. This allows you to make drop charts for different temps, altitudes etc.

Here is a vid tutorial

http://www.vortexoptics.com/video/range_day_trajectory_validation_part1



Anyway, to answer your first question, I would agree to about 2650-2700 fps.