Tuning and Bullet holes

[ebb]

YES
I couldn't get 133 to do anything good. I switched to Lt32 and the bottom row began to look like something

Hotter than usual for our area today

VV133 is #89 on the 2024 burn rate chart, and LT32 is #78 on the chart. So you did go to a faster powder than you started with. Is the faster powder why it got better?

 

[6BRA]

Does a bullet traveling at 3000 fps cut a different hole than when say slowed to 2000 fps? 1500 fps?
Even if everything were dead perfect/ perfect load/ perfect backer? The comparison 100 yds to say 600 yds.
My guess is the 100 yard target will have a cleaner hole. Input?

 

[L.Sherm]

Isn't a perfect yaw on a bullet the same at 3,000 vrs 2,000?

 

[ebb]

Does a flat base bullet center in the bore better than a boat tail or is it all about bearing length. Or is it some thing I don't know about??? I imagine a boat tail like a foot ball but they do have a straight area that should center them as well and any bullet with the same bearing length or do they??

 

[6BRA]

Isn't a perfect yaw on a bullet the same at 3,000 vrs 2,000?

my thoughts were No yaw and speed cutting paper....

 

[gpoldblue]

What do you notice from the bullet holes in these groups?
This is something turning a tuner can’t help

When the bullet is in the barrel,it rotates around the center of mass....when the bullet exits the barrel,it rotates around the center of gravity........HOPEFULLY they're the same!!! If the bullet is not entered into the barrel straight,it won't come out straight due to pressures and acceleration forces causing distortion. Misalignment errors due to sizing errors,jumping the bullet,etc can cause this misalignment and the barrel will not straighten these errors so the bullet exits out of balance....unstable.
Good luck and stay safe.

 

[BoydAllen]

When the bullet is in the barrel,it rotates around the center of mass....when the bullet exits the barrel,it rotates around the center of gravity........HOPEFULLY they're the same!!!
Good luck and stay safe.

When it is in the barrel, it rotates around the center of its shape (geometric longitudinal axis?). Center of mass and center of gravity are (I think) the same thing.

 

[gunsandgunsmithing]

Good thread Tim. I've always struggled tuning bullet holes to be small...way before I went to tuners. I want the small holes BEFORE I touch the tuner...or not.
So, you went hotter to clean the holes up? A different powder? Different seating depth? All of the above? Can you clarify your process for the slower ones, like me?

 

[Tim Singleton]

Good thread Tim. I've always struggled tuning bullet holes to be small...way before I went to tuners. I want the small holes BEFORE I touch the tuner...or not.
So, you went hotter to clean the holes up? A different powder? Different seating depth? All of the above? Can you clarify your process for the slower ones, like me?

That particular day it took a powder change
I jad tried multiple charges of 133 and seating depths. Last resort pulled out another powder and it made a big difference

 

[Tim Singleton]

@Tim Singleton ok, so if I understand correctly, rows above bottom one weren't working (ragged holes) so you changed powder on the bottom row which cleaned up the holes and with that powder then increased charge right to left to pull in the group until bottom left also removed most of the vertical. Correct?

I also see you switched to a faster powder, if you have chrono data how did the fps compare? I know you said you were speeding up the LT32 right to left bottom row, but I mean N133 vs the LT32. I get changing powders, but I'm trying to understand why so much faster powder and also if or how much fps played into it. Also you said it was hotter, what was the temp differences between when you shot N133 top and LT32 bottom row. I did notice the last 3 groups are all same position on paper.

I was shooting both powders at the same velocities
3330 up to 3400

 

[6BRA]

I was shooting both powders at the same velocities
3330 up to 3400

100 yds?

 

[Tim Singleton]

100 yds?

Yes

 

[6BRA]

Yes

So, the bullet was still moving 2900? Faster than most 6brs or 308s at the muzzle. Are we looking for clean cut paper or clean round holes? For example as I posted earlier and then deleted. I shot this target at 600 3 weeks ago. This load has worked fairly well for 2 years. There is no yawing. I am curious with the knowledge of upper end shooters on this thread, what your thoughts are of these bullet holes? Again this is 600. Do you expect clean cuts at 600 at decreased velocity? I dont see any apparent yawing out of any of these holes. But they are not clean cuts on the paper. The holes themselves, not carbon rings appear to be 22 cal size. As in this past weekend I bore sighted a new gun at 100,. 3300 fps on this one. Clean cuts at 100 yes. I guess my question is....speed has to play a role in this. Right or wrong?

 

[RGRobinett]

6BRA, note that the holes are indicating a L-R air movement. As should be, for "stable" bullets, the me'plats all punched high-left "holes" - at about the probable equivalent of constant perpendicular vector, and roughly 2MPH velocity variation between the widest shots. As paper goes, those are pretty decent captures - I'd rate that as "good" paper. RG

 

[6BRA]

6BRA, note that the holes are indicating a L-R air movement. As should be, for "stable" bullets, the me'plats are all punched high-left "holes" - at about the probable equivalent of constant perpendicular vector, and roughly 2MPH velocity variation between the widest shots. As paper goes, those are pretty decent captures - I'd rate that as "good" paper. RG

It was pushing an inch L to R that day. Thanks! Interestingly I never observed the meplat being very slight out of center. Appreciate input! I'm going to have to get the +2.5 readers out.

 

[CharlieNC]

I'm not a BR shooter but found this interesting when I saw the vids a while back. Then when lot testing 22lr I observed the same phenomenon for the better ammo. The truth is out there Skully!

 

[gunsandgunsmithing]

It was pushing an inch L to R that day. Thanks! Interestingly I never observed the meplat being very slight out of center. Appreciate input! I'm going to have to get the +2.5 readers out.

Ol Randy's a pretty sharp cookie. To make it make sense, I believe the bullet will always point INTO the wind. If wrong, I hope Randy will correct me but pretty sure that's how it works and why he was able to read that from the bullet holes

 

[6BRA]

Ol Randy's a pretty sharp cookie. To make it make sense, I believe the bullet will always point INTO the wind. If wrong, I hope Randy will correct me but pretty sure tyhat's how it works and why he was able to read that from the bullet holes

Impressive..I've been watching bullet holes for about 2 years. For him to determine that was pretty eye opening. Taking to the next level. They aren't much off center. But he was spot on!

 

[Ccrider]

Great post. I will add that even with bad paper with poor backers, or wet paper, if you know what to look for, you can see the changes in the holes as tune changes.

When tuning, I normally see changes in the bullet holes as the gun goes in and out of tune. Of course, there are other things that I see as well, down to a change in the recoil/sound and feel of the ignition. Sort of hard to describe but they all go hand in hand.

 

[Tim Singleton]

Great post. I will add that even with bad paper with poor backers, or wet paper, if you know what to look for, you can see the changes in the holes as tune changes.

When tuning, I normally see changes in the bullet holes as the gun goes in and out of tune. Of course, there are other things that I see as well, down to a change in the recoil/sound and feel of the ignition. Sort of hard to describe but they all go hand in hand.

Yep they sound different and feel different