I went shooting with Gary back at the beginning of November with my "new" bench rifle. We wanted to get sighted in and start learning about which slugs the rifle liked the best. Some of you may remember this rifle from Standing Stone 3. We're still putting it thru its paces here. Here are some initial results:



Barnes Delta 45 Custom
Sight-in / Chrono Session
November 1, 2008
New Windsor, MD
Temperature: 77 degrees F
Elevation: 500 feet above sea level

Up Range (11 yards)

224 grain Barnes Shrike (pointed – sized to .4515”)

Fill Pressure     Â	Velocity (fps)Â	Energy (fpe)
2800 psi         Â	802.3, 804.7	321.2
2900 psi	824.2, 815.6, 820.5	334.6
3000 psi	818.4, 822.6	334.9
3100 psi	831.3, 837.0	346.17
3200 psi	833.3, 838.8	347.8
3300 psi	839.2, 841.0	351.1
3400 psi	846.6, 841.7	354.22

422 grain Barnes Avalanche (pointed – sized to .449”)

Fill Pressure	Velocity (fps)	Energy (fpe)
3150 psi	682.2	436.2
3400 psi	684.4	439.0

140 grain Hornady .454 Roundball

Fill Pressure	Velocity (fps)	Energy (fpe)
3100 psi	946.8	278.7
3400 psi	963.7	288.8

Down Range (149 feet – chrony in front of 50 yard backer. I shot the group shown below at the same time.)

224 grain Barnes Shrike (pointed – sized to ..4515”)

Fill Pressure	Velocity (fps)	Energy (fpe)
3100 psi	742.6, 748.1, 736.5	274.2

Calculated Ballistic Coefficient for Barnes Shrike: 0.0415
BC adjusted for elevation and temperature: 0.0394



I found that we need to get some more height under the rear scope mount in order to take full advantage of the range of elevation of the scope's adjustments. The Shrikes, while pinpoint-accurate at 50 yards, don't group too well at 100 -- neither Gary or I could get a really solid grouping. The Bishops may be the ticket out there, and we still haven't done any accuracy or velocity measurements on the bigger slugs (Peppergrinders and Avalanches). So, there's still a lot of work to do.

-- Jim

Now that's some serious data collection right there! If you find a favorite slug, you can use similar data to make a scope knob tape so you can click to any range.

Jerry Wrote:
-------------------------------------------------------
> Now that's some serious data collection right
> there! If you find a favorite slug, you can use
> similar data to make a scope knob tape so you can
> click to any range.

You got it Jerry . . . I still have to calculate the BCs for all of the other slugs as well as roundball. The good news is that, once this is done, other folks using the same slugs can use the BC in their own applications. We especially need to calculate the BC of the Barnes Raptors for sale through Surefire Casting!

I was especially surprised that the Avalanches are making almost 440 fpe. Gary originally designed the Delta 45 as a "310ish" fpe rifle (scroll down to 6-09-03), so it's shooting a tad over spec.

-- Jim



Edited 2 time(s). Last edit at 12/09/2008 06:53PM by Jim.

A tad over spec indeed!

A good customer in New Zealand actually did some BC calculations on the Raptor. It will be interesting to compare results.

Jim,

We can also run some tests with Shrikes at slightly different diameters. I recall the slug being more accurate at long range. At the Standing Stone 3 shoot off, both guys using the gun were pounding steel groundhogs out at 130+ yards with the Shrikes. Now, there's also a difference between pounding steel and shooting groups. But, there still might be more there. Sometimes a tiny slug diameter will make a big difference.

Gary

It just occured to me that we have built a pretty solid stockpile of entertaining and useful content on this site. The main forum is 24 pages deep!

This post goes all the way back to before the war wagon was remodeled into the high zoot mobile lab it is now. Jim was clearly cranking out some great data.

Jim looked so young way back then

No doubt . . . what happened?

BTW, *that* is my favorite airgun.

-- Jim