Damaged bullets and accuracy

[Ggmac]

Ggmac,

All the ballistic software I've used calculating bullet trajectories with typical rifling twists and muzzle velocities have the maximum ordnate in the upper 50's in percent of target range.

308 Win bullets typically have about 1.5 degree trajectory down angles at 1000 yards.

I don't think any bullets are fired fast enough in their highest velocity and typical fastest twists to keep their spin axis always parallel to the line of fire. However, bullets spinning well over 250,000 rpm has balance issues to deal with if they keep a given up angle. If their jacket doesn't split in a groove made by the lands. That happened with Sierra's first 28 caliber 168 grain HPMK bullets shot in 7 Rem Mag 28" 1:9 twist barrels with conventional rifling shapes.

Read Brian Litz books . The g7 data has changed all that I was taught .
Remember the leaking fuel from the blackbird ? How does this relate , well heat . Heat on the orig plastic tipped bullets , the bullet has a much greater speed than than the black bird and a much shorter time of flight . I forget the temp registered on the blackbird but it was tremendous, same for bullet tips . Deformed tips change the BC but not so much in accuracy .
Doesn't have much to do with what we're talking about but it was what started all of the modern fast twist research for me .
Brian litz's books are great insight into the over stabilized bullet staying positive up on its way down . I hope it was his books I read this in , getting old sucks , I've read many research papers and books concerning this fast twist trend . When I started , slide rules and a 1-10 twist was fast .
Time to take the shutters down , where do you live , if I find the information I'm talking about I'll copy it or possibly loan you the books .
Gary

 

[Bart B.]

I think there's a bigger problem with overstabilized bullets spinning way too fast. Any imbalance in them causes them to jump off the bore axis upon exiting the barrel.

The ballistic engineering folks at Frankfort Arsenal knew that and used a 1:12 twist for the new 30 caliber cartridge replacement for the 30-06. Its same bullets leaving 100 fps slower had better accuracy spinning slower. Lightest weight 147 grain bullets shot ~3000 fps from 30 inch fullbore match barrels were most accurate with 1:13 twists, often 1:14 in warm to hot weather

 

[Ggmac]

I think there's a bigger problem with overstabilized bullets spinning way too fast. Any imbalance in them causes them to jump off the bore axis upon exiting the barrel.

The ballistic engineering folks at Frankfort Arsenal knew that and used a 1:12 twist for the new 30 caliber cartridge replacement for the 30-06. Its same bullets leaving 100 fps slower had better accuracy spinning slower. Lightest weight 147 grain bullets shot ~3000 fps from 30 inch fullbore match barrels were most accurate with 1:13 twists, often 1:14 in warm to hot weather

Agreed but with today's bullet manufacturing and mono bullets it's gotten much better . It use to be spin it as slow as possible to stabilize just because of bad ammo . The British had a 1-14 tw 7.62-51 in the target Parker hale single shot m-84 or 82 can't remember, because the ammo was so bad .
Given good bullets , spun too fast , will still stay point up on its decent.
I know , it was new to me but proven . Look into Brian Litz's books , very good read for long range shooting and the reason for going to the G-7 formula .
I still have a half dozen or so of those Parker hale barrels , I started with 100 about 15 yrs ago ,they shot 155 real good .
Back to the deformed tips on early plastic tipped bullets , they found the problem and deduced the change in BC had to be from bullet tip melting .
A change that wasn't dramatic, but readily repeated , was resulting in more drop than should have been .
Anyway , more cleanup from the Dorian scare .
It's been a pleasure and informative talking to you .

 

[Bob Sebold]

Hatcher did a lot of testing on that. Its old stuff, but still meaningful. According to him, damaging the rear of the bullet had a lot more affect than the tip. And I re-chamfer my cases every time.

 

[Idaho-Lefty]

Old post I know BUT,.. I shoot, a 7.5 Pound, Tikka, T-3 in .270 WSM and it does, Recoil, a "bit",..
I am not worried about, a little bit of, Magazine, TIP "damage" on Accubonds or, Ballistic Tips,.. tip !
BUT, I am concerned that, a Berger Hollow Point, Classic Hunter, etc., "may" close up, the "Tip area" and NOT, Perform well, on Big Game ( AKA,.. "Pencil thru" ! ) Does ANYONE have, any Experience with, the .270 WSM or 7 MM Mag's and Berger's with, TIP, Damage, from recoil, in Magazine and subsequent, bad performance, on Game ??

 

[Bc'z]

Old post I know BUT,.. I shoot, a 7.5 Pound, Tikka, T-3 in .270 WSM and it does, Recoil, a "bit",..
I am not worried about, a little bit of, Magazine, TIP "damage" on Accubonds or, Ballistic Tips,.. tip !
BUT, I am concerned that, a Berger Hollow Point, Classic Hunter, etc., "may" close up, the "Tip area" and NOT, Perform well, on Big Game ( AKA,.. "Pencil thru" ! ) Does ANYONE have, any Experience with, the .270 WSM or 7 MM Mag's and Berger's with, TIP, Damage, from recoil, in Magazine and subsequent, bad performance, on Game ??

Hit high shoulder and sleep well.

 

[Idaho-Lefty]

You DIDN'T answer, my Question about, HP Berger, Tips CLOSING upon , Recoil ,..
And,. I have, NO plans to do, a shoulder Roast, Back strap Steak,.. ruining,.. shot !
As we eat, our,.. Elk / Moose.

 

[rwj]

You DIDN'T answer, my Question about, HP Berger, Tips CLOSING upon , Recoil ,..
And,. I have, NO plans to do, a shoulder Roast, Back strap Steak,.. ruining,.. shot !
As we eat, our,.. Elk / Moose.

If another member can’t provide the answer you’re seeking, a range trip surely can!

 

[Idaho-Lefty]

If another member can’t provide the answer you’re seeking, a range trip surely can!

YUP,.. the Wind is still blowing, so haven't been shooting for, a couple of Days.
I have loads loaded, ready to test for grouping .
Just thought that,.. somebody might know

 

[Dub]

Old post I know BUT,.. I shoot, a 7.5 Pound, Tikka, T-3 in .270 WSM and it does, Recoil, a "bit",..
I am not worried about, a little bit of, Magazine, TIP "damage" on Accubonds or, Ballistic Tips,.. tip !
BUT, I am concerned that, a Berger Hollow Point, Classic Hunter, etc., "may" close up, the "Tip area" and NOT, Perform well, on Big Game ( AKA,.. "Pencil thru" ! ) Does ANYONE have, any Experience with, the .270 WSM or 7 MM Mag's and Berger's with, TIP, Damage, from recoil, in Magazine and subsequent, bad performance, on Game ??

I really doubt this is an issue

 

[Idaho-Lefty]

How is your first shot WELL Placed round going to get damaged in the magazine. The Berger is not a HOLLOW POINT Bullet. It is a OPEN TIP Bullet. The bullet enters the animal and the balance is disrupted, NOT that the tip opened up, Its starts to tumble and breaks apart. This is in a matter of inches that this happens. Shredding bits and pieces of shrapnel inside the chest cavity. So, if using Berger Bullets careful to inspect your heart and liver if you are incline to eat them.

I do plan on making, the FIRST shot, count ( haven't needed, a 2nd shot in Years ! ).
I just thought that, the other 2 in the bottom of the magazine "might" close the "Tips" upon,.. recoil.
Just "in case" i needed, a "Follow up"
My Accubond tips are blunted, upon Recoil as, the .270 WSM does kick, a "Bit" with, 140's going 3,150 FPS in a 7.5 pound Rifle,.. "all up".

 

[Idaho-Lefty]

I really doubt this is an issue

I hope so !
I'm loading the 140 grain Classic Hunter's at, SAMMI length of, 2.860"
2.895- 2.900" is my Magazine length.
I'll KNOW for sure, in 2-3 Days

 

[Bc'z]

You DIDN'T answer, my Question about, HP Berger, Tips CLOSING upon , Recoil ,..
And,. I have, NO plans to do, a shoulder Roast, Back strap Steak,.. ruining,.. shot !
As we eat, our,.. Elk / Moose.

Not trying to argue with ya.
The amount of meat lost in respect to the size of the animal is minimal.
High shoulder shots have a tendency to drop them in thier tracks.
Around our house all trimmings and organ meat feeds our rottweiler, she is a very captive audience when I'm cutting game.
Sorry I cant answer the question of bullet deformation, maybe preforming a seating test pushing bullets deeper into the case keeping them off the front of magazine would help alleviate the problem.

 

[Idaho-Lefty]

I am hoping that, these Berger's, being a bit shorter ( at 2.860" COAL vs 2 .895" ) than, my Accubond Load, solves the issue,.. AKA, a "Non-issue" !
This is, my first time "playing with", the Berger's for, a Hunting Bullet.
I will "study up" on, those high shoulder shots !
Thanks for all the reply's, everyone !

 

[Fast14riot]

I am hoping that, these Berger's, being a bit shorter ( at 2.860" COAL vs 2 .895" ) than, my Accubond Load, solves the issue,.. AKA, a "Non-issue" !
This is, my first time "playing with", the Berger's for, a Hunting Bullet.
I will "study up" on, those high shoulder shots !
Thanks for all the reply's, everyone !

I don't have any helpful info, but something about the way you type, I can only read it in a Christopher Walkin vernacular, in my head, lol!

 

[Idaho-Lefty]

Yup, Me and Christopher Walken are, on a whole nother level, for sure ! LOL
He's one of, my all time, favorite, actors !
Its' a BAD habit, for sure and, I'll try to, work on it ( old habits, die hard, tho ! ).
I'll figure out, the answer, to this question, myself. It seems like nobody, knows the answer.

 

[grovey]

Wrong ! The test were conclusive. Tip damage shows virtually no difference at 100yds. Base damage shows significant loss of accuracy.

I've shot quite a few fowlers with pulled bullets @ 100 that had the same point of impact as my load, and I pull bullets with pliers.

 

[grovey]

I don't have any helpful info, but something about the way you type, I can only read it in a Christopher Walkin vernacular, in my head, lol!

Noowwwl.... I can't read it, any other wwaaaay.

 

[DRNewcomb]

Wrong ! The test were conclusive. Tip damage shows virtually no difference at 100yds. Base damage shows significant loss of accuracy.

I knew a couple of guys who were gifted a bucket full of Mexican Match pulls. The method of pulling the bullets was to put them in a press and grab the bullet with a pair of vice-grip plyers. Needless to say, they were all sorts of gnarly. They tested them in .308 & .30-06 loads and couldn't see a lot of difference at 100 yards. Now, they were only interested in SR-1 accuracy, not bencrhest, but it was still interesting to see nasty, beat up bullets hold a group at 100 yards.

 

[Webster]

Been reading ....... again!

I think we all agree that damage to the point of a bullet will effect accuracy. Just read where damage to the base may be even more dramatic.

So, I am now carefully chamfering my cases with a VDL tool to avoid a scratch especially with flat base bullets.

Has there been any serious testing using damaged bullets?

I am thinking of the testing done on damaged crowns.

Bill

It's been a long time I don't remember the details. I would have to redo it. I believe some bullets I pulled with a RCBS collet puller had scratches (more like scuffing) on the bearing surface from metal texture on the neck I.D. I am not a believer that mandrels push small high points to the case o.d. My rifle normally shoots groups in the .350-.400" range with most bullets in he price range of Hornady 58 gr VMax. I shot a 4 shot group about .400" and the 5th. shot with a pulled bullet was one inch out of the group. There was no visable damage to the bullet from the pulller collet but I had to tighten the collet pretty tight on the bearing surface. Getting pushed down the barrel didn't make it round again.

Several years ago I had a 58 gr VMax with a large part of the jacket missing near the tip. Once I considered taking a split wooden dowel with 800 or 1200 grit sandpaper and running it in each case neck with a drill to remove most of the high points. Never did it, the amount of metal removed would be to small to measure. You could just do it just once on each case. If I was still employed I could have measured and photographed the neck i.d. texture with an optical profilometer.