Velocity Increases With Five Grain Powder Increases
 

In addition to doing Underclocked's work for him last week end with the Great Plains experiment ;), I added three more data pointsto my earlier experiment of shooting the same bullet & sabot combination over a chronograph,starting at 65 grains weight of T-7 FFFGand working my way up in five grain increments.

In the first experiment I shotfour sets of weighed charges at65,70,75 &80 grain weight.

Last Saturday I shot85,90 & 95 grain weight charges.

Allcharges were loadedunder300 grain Speer Gold Dot Hollow Points and Harvester Crush Rib sabotsand setoff with CCI small rifle primers in a 25 ACP breech plug.

Here are the average velocities for each load.

Grains Of Powder Average FPS
Weight= VolumeFive-Shot Groups Group Size

6574.7 1635 3 1/8"
7080.51624 (-11 fps)4 3/8"
7586.21660(+36 fps)2 7/8"
80 92.01698(+38 fps) 3 1/4"
8597.81775 (+77 fps)4 1/2"
90 103.5 1822 (+47fps)3"
95 109.31829(+7 fps)3 3/4"

As said earlier, I really can't explain why 65 grains had a higher velocity than 70 grains.

RE: Velocity Increases With Five Grain Powder Increases
 

That is some excellent information there. It really makes me wonder what those big conicals I shoot are doing.

RE: Velocity Increases With Five Grain Powder Increases
 

That's the trouble with this kind of info - it gets you to wondering about other stuff.

The crush ribs load easily in the Mustang. In my "Same Load / Six Different Sabot" experiment I found that regular Harvester long sabotsshot better out of the Mustang than the crush ribs. Igot a four-shot average velocity of 1667 fps with 75 grains weight T-7 FFFG and the 300 grain Gold Dot - almost the same velocity as the crush ribs with that load - with a 1 7/8" group.

RE: Velocity Increases With Five Grain Powder Increases
 

Semi, I may be workin' you too hard ;)but you are doing some very interesting experimenting. I hope you are recording all this somewhere - I think a book might be in your future.

Or, you might just get away with it. ;)

RE: Velocity Increases With Five Grain Powder Increases
 

Semi - Now you have me curious. Did you record each velocity? I see you listed the average but it would be interesting to see what the velocity variation was for each load.
Keep up the good work.

RE: Velocity Increases With Five Grain Powder Increases
 

Semisane - interesting work.

From your previous posts I gather those are 3 shot groups @ 100 with a scope? What is the twist rate of the Lyman Mustang? How did you get such precise numbers on the "volumn" measurements? One thing your tests make me wonder is whether there are multiple performance points for a given combination. For instance, maybe a gun dislikes 70,75 grains, likes 80 grains, dislikes 85,90,95,100 then likes 105. Interesting stuff. Thanks.

RE: Velocity Increases With Five Grain Powder Increases
 

Hey bronco. Yes, I do record shot by shot velocities. They are generally pretty consistent. See the readings on the Harvester long sabot target below. That was a four-shot group because I had only 4 of those sabots on hand.

I usually shoot five-shot groups at 100 yardsyeoman. Sometimes I shoot at 50 yards when it's hot and I don't feel like doing a lot of walking.

I have a 3X9 Leupold on the Mustang (which I use for most of my experiments) and a 2X Simmons pistol scope on the New Englander, which was my "go to" ML before I got the Mustang last year. Lyman twist is 1 in 28".

The "volume equivalent" is derived mathmatically. A while ago, using my brass powder measure, I threw a bunch of 100 grain charges with each kind of powder I had and weighed them out.100 grains of T-7FFFG weighed 87.0 grains. So1 GV=0.87 GW and 1 GW = 1.15 GV.Therefore, when I'm working with weighed charges I just multiply it out to get anidea of the volume equivalent - i.e. 75 GW x 1.15 = 86.2 GV.

RE: Velocity Increases With Five Grain Powder Increases
 

Yeoman,
Your question about multiple performance points is not unusual to see. In reloading for CF's I have noticed similar grouping at different powder levels with a spread between. It can to some degree be related to barrel harmonics. Every barrel vibrates when shot in a circular fashion. The point at which the bullet exits the barrel during that vibration determines to a great extent where the group will end up and how tight that group is. If you find two loads that exit at the same point in the vibration cycle you will have a good chance that they both perform well compared to other loads in that gun.

RE: Velocity Increases With Five Grain Powder Increases
 

Semi
how do you protect your chronogragh from the sabot and powder blast? I have been going to do some of my loads but was not sure how to protect unit.

RE: Velocity Increases With Five Grain Powder Increases
 

Hey JM, I have a$99 Pro-Chronograph that I really like. I killed it last year with a sabot to the face that shattered the LCD screen. After I got it repaired I made a plexiglass shield. Took a 5" x 16" piece of 1/4" thick plexiglass and drilled a hole about 1" from one end, and (using a torch to heat it a little) bent about 5" of the other end up at about a 45 degree angle. The mounting bolt from a camera tripod goes through the hole in the plexiglass into the bottom of the chrono, and the bent up part protects the face. After I did that I found out that Pro-Chronograph makes a shield thats pretty much the same as mine, except it sits on top of the unit instead of under it.

RE: Velocity Increases With Five Grain Powder Increases
 

Grouse (Tom Drechsler at ModernMuzzleloader) makes this protective box. Works well by all accounts.

RE: Velocity Increases With Five Grain Powder Increases
 

Chronographs, shields, tripods.. more stuff for me to carry out to the range and then back to the house. I have it worked out now to one big load, but two small loads would work as well. :D:D

Now how far do you put that thing in front of the rifle stand? Also you have to shoot through the ears or the V of that thing.. right? All of this is battery operated of course?

That box looks easy enough to make. I have a camera tri pod some where in one of the gear closets... But then I would actually have to compare all the numbers, and I hated statistics classin college.. :D

RE: Velocity Increases With Five Grain Powder Increases
 

Awe come on Dave, you generate so much data already whats one more data point going to cost you. You know you really need one to make your setup complete and so many of us would benifit from it. Just go ahead and get one, I did and it is nice to be able to confirm what a load is doing.

RE: Velocity Increases With Five Grain Powder Increases
 

Just DO IT, Cayugad. With your set-up you could make a weather proof storage box out on yourrange and just leave it there.

I usually put mine 15 ft. from the muzzle with MLs and 10 ft with cartridge guns.

RE: Velocity Increases With Five Grain Powder Increases
 

Glad to get that info. I was worried about using my Chrony with my MLs. Guess I'll have to get busy and make a box now.

RE: Velocity Increases With Five Grain Powder Increases
 

You do want some kind of protection for your chrono. I was shooting some 200 shockwaves once before figuring that out and even at 15 feet from the muzzle one of the sabots dropped into the open top of my F1 master with enough force to put a hole in the plastic housing of the rear detector. The detector still works but the broken plastic had to be removed because it was blocking the eye. After that I decided to put some protection over it.

RE: Velocity Increases With Five Grain Powder Increases
 

You should email Grouse to see what he uses so far as the "glass" part. I don't believe it is standard plexiglass but cannot recall what he finally wound up using - nor the reason why.

I've never felt any need to own a chrono, I just time those big conicals. ;) Do enjoy reading the data that others post though - more of that vicarious testing! Aint the internet wonderful!? :D

RE: Velocity Increases With Five Grain Powder Increases
 

I agree with you, Dmurphy317,Dave has the most time, most expertise, most guns, best shooting range, most postsand is the resident expert on this board.Plushis way is kind and gentle, withregard to his knowledge, a true teacher/mentor in the BP way. We can all learn from him and his willingness to share hishard won knowledge of a sport we love so dearly.If you want to buy him a chrony as a gift of service to the board, I certainly am willing to contribute. I can't take the leadership on getting him one, since I don't have a chronyand I don't know what to look for in a good one.

I was glad to see the little experiment done by Semisane, it showed me that it takes a lot of powder to get a 200 or 300 fps increase, and many not be worth the recoil. This would be excellent info for any shooter. I am going to print it to PDF and place it on my web site. Chap Gleason

RE: Velocity Increases With Five Grain Powder Increases
 

"If you want to buy him a chrony as a gift of service to the board, I certainly am willing to contribute."

Right now I don't think I could coordinate this project, I'm having to do some traveling and may be changing jobs soon and having to move. There are probably enough posters here that may want to contribute to a "Chrono for Cayugad" fund that he could get one. I would suggest he be the one to pick out his own chronogragh since he is the one who will be using it. Maybe someone could arrange for a gift certificate to Cabella's or Midway or Bass Pro or where ever and send it to him with our compliments. Any volunteers?