Cfshooter
Silver $$ Contributor
From most of all the podcasts and YouTube vids lately, nothing matters, but we are still going to try all kinds of things, it gives us something to do lol.
Tuning and Bullet holes
- Thread starter Tim Singleton
- Start date
Larry Koch
Silver $$ Contributor
Need more powder. Seems to help more often than not. When the neck is full and some spills over. Your getting close.
JEFFPPC
Gold $$ Contributor
Larry Koch
Silver $$ Contributor
Jeff Im with you on Lt30. When it’s on it’s on. Plus it works well in 30 br. One powder two calibers. Now I’m shooting the current supply on the market. I haven’t any of the original batches.
Tim Singleton
Gold $$ Contributor
Jeff
I was making the statement turning a tuner can’t help a bad seating depth
I was making the statement turning a tuner can’t help a bad seating depth
You’re watching the wrong videos and podcasts. Tim is actually trying to demonstrate/teach something that’s actually fairly advanced in the Benchrest world.
Bart
AlNyhus
Silver $$ Contributor
Amen. -Al
Tim Singleton
Gold $$ Contributor
Thanks, Bart
The main point is when your normal stuff looks like the top two rows of this test
Don’t settle. There was a couple nice low .1 groups but they look awful plain awful. If I smoothed out the paper the groups aren’t that bad. But they are waiting to blow up
change seating depth change powder do something
jxb
Gold $$ Contributor
@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 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.
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Old Navy
Gold $$ Contributor
Right on! If you turn the target over, push the peddles down and scotch tape them you will see some really nice rounds holes when you turn it over. Also makes for a more accurate measurement.
Cfshooter
Silver $$ Contributor
That’s some serious worm hole diving, way more advanced than I am capable of. But I will be looking at my holes closer now lol. I’m not sure how much data I can get from mine though, my backers have more holes in them than the Mexican border.
Good target paper helps. The practice targets I use are made from the same paper the NBRSA (use to use) for their targets.
Shooters like Jeff Peinhardt will veto a load based on one shot. If the bullet hole looks big on the sighter he will move to the next load.
Tim is right about not settling. I’m certainly guilty of it. I get comfortable with what powder I’m shooting (133) and tend to ride it no matter what, instead of trying some LT32 or LT30. But NOT today! I’m going to break out some LT and see how it compares.
Bart
Cfshooter
Silver $$ Contributor
lol, yep, Tim F’d us all up with this post. Now we are all scratching our heads. Have to love this sport!
R.Morehouse
Gold $$ Contributor
I do load development on these. They are thick and strong and I mount them on cardboard. I take a straight edge and go through the bulls in both directions making a very precise point of aim. This is a very good set-up for reading groups and single-hole shapes. They are called RBA Rimfire Targets........This thread has some great input......
Regards
Rick
AlNyhus
Silver $$ Contributor
Jim, you bring up a good point. Since we don't know exactly how much in-bore yaw is present in a particular barrel (the math types assign a standard amount when figuring the Sg stuff), it's possible that some of what's seen on target as tune up issues may in fact be stability issues other than what the drag/twist formulas figure. In other words, can a tune up that that gives decent group sizes but ratty bullet holes actually be a stability issue before more obvious signs of instability show up? Some recent work with twist rates/jacket lengths in the 6's seem to point that way.
Good shootin' -Al
Jerry Wick
Silver $$ Contributor
Al, this may be what is happening. The PPC has been around a long time and there are some standards that almost everyone follows regarding bullet weight/length and twist. When you run those Sg calculators, it shows we should be on the very edge of instability with the usual 13.5 or 14 twist.
If you compare the PPC Sg with a 13.5 twist to your 30BR with a 17 twist, there's quite a difference.
I've had this discussion in the past with Randy @RGRobinett and tried a couple of 13 twist and even a 12 twist one season, but I keep going back to the 13.5. I didn't see anything magical and the herd mentality is strong. Not to mention, I don't have unlimited funds for new barrels.
DaveTooley
Gold $$ Contributor
I have never liked using the slowest powder for a given cartridge bullet combo. I think we limit the option of getting higher pressure without getting velocities too high. Funny how 100 FPS turns a rifle into a beast to shoot.
Ever tired N130?
Ever tired N130?
Interesting to note.....I like the UBR target paper we use for a clean hole.
I just don't like the bright white when things get fuzzy. I picked up some
100 yard IBS Hunter targets to practice on, and impressed how clean the
holes can be when backed up......It's also a great TD practice target being
much smaller.
jimmymac
Jim McGregor
Interesting. I’m working with a 12 twist PPC barrel right now that is a hammer. Bullet yaw need not apply.
I’m always aware of the shape of my bullet holes in paper. That’s why I use good paper and a new cardboard backer every time out. I need to know what my bullet holes look like because it matters to me.
Ok I get the ragged holes and bigger holes is some kind of stability issue, even I can see that. So the first thing that comes to my mind is the bullet is disrupted as it leaves the muzzle. I was told that is way the BR cartridges are all small, because the powder needs to burn completely before the bullet exits the muzzle. So it would seem to me that less powder or a faster burning powder would make the bullet more stable. But all of you are saying more powder makes it better. So, is it not the powder disrupting the bullet flight, and if so what is it???
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