New ProChronoDigital

[swampy308]

Ok I have never used a chronograph before today, and I know you can get erratic readings sometimes and this is what I got with my first string of shots.
1. 634
2. 651
3. 688
4. 652
5. 692
6. 627
7. 664
8. 1119
9. 674
10. 673
Shot from 4.25" colt commander extreme 230 gr hp over 5 gr win 231 oal 1.255, got a couple questions.

First the 8th shot didn't feel or sound different so I guess was just a bad reading for what ever reason, is this correct?
Second how much faster can I load this bullet?

 

[1stmar]

8th shot should be thrown out, all others look normal.

 

[swampy308]

I deleted the 8th shot and came up with an average of 661.6 FPS.
I started out at 4.6gr and worked up to 5.0gr.
Going to creep on up and see if I can find a more accurate load.

 

[Unclenick]

First, let me applaud you for starting low and working up instead of just assuming the middle of the range is OK. From both Hodgdon's data and QuickLOAD, it appears to me your velocity should be higher—about 760 to 790 fps—than you have.

So my first question is, how far from you was the chronograph? If it was less than 10 feet with a pistol, the readings may be suspect. Shorter ranges than that work sometimes but not other times. The issue is muzzle blast and powder particles cause the first screen to trigger before the bullet actually arrives, causing a false low velocity reading. In the extreme, I am aware of one .338 Lapua Magnum rifle that would not stop false triggering until it was set 18 feet in front of the muzzle. I never use less than the SAAMI standard 15 feet with an optical chronograph (though I went over to the Lab Radar unit, so my two optical units don't see much service now).

If you have a friend with a chronograph, ask to set theirs up in series with yours to see how close the readings are. This will give you a cross-check on light conditions, too.

 

[Nick_C_S]

Along the lines of Unclenick's post: I chrono at 4 yards - seems to be far enough out for what I'm doing (pistol {many calibers}; and the occasional .223 AR.)

 

[swampy308]

Ok first thing I did was read the directions, and it said 5-15 feet, 5-10 for pistol, and 10-15 for rifle.
Unclenick to answer your question, I shot the first 5 shots from 7 feet, and the second 5 from 9 feet.
I'll try backing up next time, I also checked 5 different manuals and saw that my velocities were lower and new something wasn't right.
Also comparing these to win white box they feel lighter, the reason for wanting to go higher in powder charge is to find better groups.

 

[Unclenick]

The CED company used to have a good write up for their chronograph that had some tips usable with all chronographs. Now they've shortened it and lost some good info.

One thing that can be an issue is inadequately diffuse lighting. Some guys take some plastic milk jugs and make bigger diffusers. You can also try shooting on an overcast day to see if that changes your numbers.

Another factor on the old CED list was ground glint. Placing the unit over light colored ground or concrete or gravel can cause a reflection off the bullet to trigger its front screen early. Lay a black plastic garbage bag on the ground under it or spray paint some cardboard black and drill a hole for the tripod screw and sandwich it between the chronograph and tripod with the black side up and extending beyond the front screen by a foot.

You can check the chronograph for accuracy by shooting a round of .22 LR rifle match ammo over it from a rifle. .22 LR's burn out their powder in the first 16 to 20 inches of barrel, after which the bullet starts to slow again, but not very quickly. As a result, almost any rife will give the stated box velocity of match ammunition within about 50 fps. This makes a quick check to see if the lighting conditions are good enough and to make sure it isn't just off for some reason.

 

[ShootistPRS]

The maximum load for a cup and core jacketed 230 grain bullet in 45ACP with 231 ranges from 5.3 to 6.2 in my different manuals. The standard military rounds give 800 to 850fps with a 5" barrel. I would think that 231 will be capable of at least 800fps BUT I would be very careful going to a higher loading than 5.8 grains. Your gun has a short barrel so velocities are going to be lower. Use the manuals to decide on your load and then use your chronograph to see how fast the bullets are going. You can't use the chronograph to determine the pressures that a load develops.

 

[Unclenick]

His barrel should only lose about 30 fps with that bullet and powder. His numbers just seem low as a percent of the expected number, unless we are missing something we haven't identified. A 2.5" barrel would be expected to be down there.

 

[swampy308]

Ok folks I finally got time to try again.
Heres the results.
From 14 feet.

1- 659
2 - 654
3 - 699
4 - 659
5 - 661
Avg. 666
ES 45
SD 18
From 16 feet.

1 - 678
2 - 660
3 - 682
4 - 689
5 - 668
Avg. 675
ES. 29
SD. 11
I also shot 5 of the WWB and only got 2 readings, 794, and 762. I believe I was holding to high on the other 3.