I tried to science today

[Stefan A]

Yes, in my own amateurish way. My goal has been to lower the point of impact with my Uberti 45 Colt. It was suggested that I try lighter cast bullets, so that's what I did. I was shooting from about 15 yards and used a table for aiming support. Velocities given are from the manual because I don't have a chronograph. 1, 2, and 3 the aim point is the center red dot. #4 was bottom left red dot just to keep shots separated. On the target below, here's the key:

1 = 10.9 of N340 with 200g cast bullet - 1119 FPS
2 = 6.1 of Titegroup with 250g xtp - 815 FPS
3 = 5.9 of 231 with 200g cast bullet - 761 FPS. - A very powderpuff load - probably too much so
4 = 7 of 231 with 200g cast bullet - 881 FPS - very light as well

My conclusion - Lighter bullets do hit lower. But not sure how velocity plays into it. Do I need to keep going to a lighter bullet? Higher or lower velocity?

 

[reddog81]

Once the primer goes off the gun starts to recoil. As the gun recoils the barrel raises higher/tilts upward.
Lighter bullets will typically be faster and exit the barrel quicker.
Heavier bullets will be slower and stay in the barrel longer. Being in the barrel longer means the gun recoils more while the bullet is in the barrel and this results in higher POI (point of Impact).

At least, that's how it's supposed to work with handguns at normal handgun ranges... Depending on the bullet used, loads used, how tight you grip the gun, what sort of rest you are using, etc can also make a difference. For rifles you'd have to get an answer from someone else...

 

[__steve__]

Yep, they say heavier loads shoot higher because the muzzle is pointing higher by the time bullet exits it.

Using 3.5” revolver I’ve been shooting hefty 400 gr loads accurately with, If I sight to a target about 15 yards away with a muzzle magnet on, the laser point is about 1 ft lower than where I am visually aiming through the sights. Likewise, if I were to load lighter weight bullets traveling about same velocity (they should drop at the same rate) they would theoretically be expected to shoot lower than the others.

 

[Bill M.]

With the same bullet weight faster loads should shoot lower at 15 yards.

 

[Englishmn]

Speed up load 3 and see what happens.

 

[Stefan A]

Speed up load 3 and see what happens.

Actually, load 4 is a speeded up load 3 . Not much difference there, but there's still room to grow.

 

[gwpercle]

Split the difference of Load #3 and Load #4 ...say 6.5 grs of 231 , my book says that should be in 820 - 830 fps velocity , not a bad velocity for a target / tin can load .

The starting load in the RCBS Cast Bullet Manual ,
45 Colt / 200 gr. 45-200-SWC and 45-201-SWC
Start : 6.9 grs 231 @ 832 fps

Max. Load : 7.9 grs 231 @ 943 fps

So a load of 6.5 grs. 231 @ 820 - 830 fps isn't exactly a powder puff ... if things go acording to plan ... this load should be right between them ... a little more fiddling with exact charge weight should have you on the target . I like a 6 o:clock hold myself ... good if the POI is a tad high !
Gary

 

[243winxb]

1. Didnt shoot lowest, with highest velocity.

4 shot 1" lower then 3. As it should.

1. N340 is slower burn rate. Peak pressure is later then 231. N340 burns farther down the barrels length.

Not only does velocity affect bullet inpack, so does timing of peak pressure on firing.

The early peak pressure lowers bullet impact? Or does it?

 

[Bfh_auto]

Yes, in my own amateurish way. My goal has been to lower the point of impact with my Uberti 45 Colt. It was suggested that I try lighter cast bullets, so that's what I did. I was shooting from about 15 yards and used a table for aiming support. Velocities given are from the manual because I don't have a chronograph. 1, 2, and 3 the aim point is the center red dot. #4 was bottom left red dot just to keep shots separated. On the target below, here's the key:

1 = 10.9 of N340 with 200g cast bullet - 1119 FPS
2 = 6.1 of Titegroup with 250g xtp - 815 FPS
3 = 5.9 of 231 with 200g cast bullet - 761 FPS. - A very powderpuff load - probably too much so
4 = 7 of 231 with 200g cast bullet - 881 FPS - very light as well

My conclusion - Lighter bullets do hit lower. But not sure how velocity plays into it. Do I need to keep going to a lighter bullet? Higher or lower velocity?

View attachment 1115777

That did help you. Get closer to poa.
I'm going ask a question that's more related to your shooting.
Do you line the top of your sights up the same as with a semi auto? If so try holding a half bead. It's a method used for iron sight hunting so it's easier to hold elevation on game.

 

[wcwhitey]

15 yards is close, have you tried 50? Bullet should be high at those ranges to hit POA/POI at 100. You might be just where you need to be with #4

 

[Stefan A]

Do you line the top of your sights up the same as with a semi auto? If so try holding a half bead. It's a method used for iron sight hunting so it's easier to hold elevation on game.

Yes I do. Sights are quite small. It's either line up the front and rear, or you don't see it at all. Basically, you're saying hold lower? Of course, that's what I do.

15 yards is close, have you tried 50? Bullet should be high at those ranges to hit POA/POI at 100

My furthest target is about 70 yards, but most are 10-25 away. When I try to hit my 70 yard target, I still have to hold low to hit. But, I figured I'd do this test at the ranges I usually shoot.

 

[Stefan A]

You might be just where you need to be with #4

Yeah, that seems to be the closest. The problem with that (and 3) was the extreme amount of unburnt powder and that they were very much powderpuff loads. Not very fun at all and not what I think of when shooting a 45C. I have other threads about my efforts to eliminate unburnt powder primarily because I tend to get splatter in my face. BTW, I don't want to revisit that whole topic here - it's been hashed to death in my other thread. I like 1 the best because that load uses about twice as much powder and there is nothing unburned and no hot splatter to the face. So, this continues to be a work in progress. Too many variables.

 

[Tall]

You will find that unburned powder is the result of poor ignition from too light a load. WW 231 is ideal in my opinion for 45 Colt but it does not like to be loaded light. I use it with 255 grain powder coated Keith semi wadcutters and it is fabulous.

 

[Stefan A]

You will find that unburned powder is the result of poor ignition from too light a load. WW 231 is ideal in my opinion for 45 Colt but it does not like to be loaded light. I use it with 255 grain powder coated Keith semi wadcutters and it is fabulous.

Yes, I know this - but thanks. For me, it seems 231 is not the powder - at least for 200g coated cast bullets. See below how my experimentation is proving this powder to be getting worse

 

[Stefan A]

I loaded up 5 rounds with 7.5g or 231. The shots are on the right and I was aiming for the bottom right dot. Comparing shots 3, 4, and these new unmarked ones it looks like more velocity has made POI even higher. So, 231 is definitely not the powder for this particular bullet. At least in my gun.

 

[Tall]

You might need a taller front sight blade.