what's your calculated pointed bullet's BC numbers

[bsumoba]

I'll start....

Cartridge: 284 Shehane
Bullet: 7mm 180gr hybrids
Velocity: 2890fps from a 30" barrel
Pointing Die: Whidden
Meplat Trimming (Y/N/Model): None
Mfg G1/G7 BC: Berger G7 0.345
Adjusted BC: 0.375 G7 at 1000 yards and confirmed at 800 and 900 yards. 8% BC increase!

 

[Keith Glasscock]

I'll start....

Cartridge: 284 Shehane
Bullet: 7mm 180gr hybrids
Velocity: 2890fps from a 30" barrel
Pointing Die: Whidden
Meplat Trimming (Y/N/Model): None
Mfg G1/G7 BC: Berger G7 0.345
Adjusted BC: 0.375 G7 at 1000 yards and confirmed at 800 and 900 yards. 8% BC increase!

Silly question: What are you observing that gives you the BC number? Are you comparing pointed and unpointed or something else?

 

[seymour fish]

Simple: alternate pointed and unpointed at 1K. Note if groups demonstrate a vertical spread. Measure the spread and reverse engineer BC via some ballistic program. What part of this meets any criteria for "silly" ? Seymour

 

[Steve Blair]

I use a Hoover meplat trimmer and Whidden pointing die.The three I trim and point are: [br]
Berger 6mm 105 Hybrid
Published G7 B.C.: .278
T&P estimated G7 B.C.: .297
Improvement: ~6.8% [br]
Berger 7mm 180 Hybrid
Published G7 B.C.: .345
T&P estimated G7 B.C.: .377
Improvement: ~9.3% [br]
Berger .30 230 Hybrid
Published G7 B.C.: .380
T&P estimated G7 B.C.: .410
Improvement: ~7.9% [br]
Additionally, trimming and pointing cut my vertical spread by up to ~1/3.

 

[Keith Glasscock]

Simple: alternate pointed and unpointed at 1K. Note if groups demonstrate a vertical spread. Measure the spread and reverse engineer BC via some ballistic program. What part of this meets any criteria for "silly" ? Seymour

The question is the silly part... Anyway, so, the two groups are ~10" apart at 1K in the first example? That makes sense to me and is how I've tested in the past.

What doesn't make sense is the use of come-ups to determine what the BC is. None of my scopes (Nightforce included) are able to make measurements that precise.

 

[Keith Glasscock]

The only testing I've done on the subject:

Berger 30 cal 200 Hybrid:
Pointed W/ Whidden die
Alternately shot @ 1k
MV: 2650
Difference in impact: 5"
Delta G7: .009
Estimated G7: .329

Berger 6mm 105 Hunting VLD:
T&P Whidden
Alternately shot @ 600 yards
MV: 3020
Difference in impact: zero

 

[Joe Salt]

What is the matter don't all of you believe pointing changes point of impact? Ask dkHunter14 he told me it doesn't work, now for me to show the world record holder that it did, I even let him mix the rounds up in the Sure-Feed so there wasn't any cheating! (IT WORKS) And they were both 5 shot groups and the pointed ones were 12" higher and tighter in there group.

30 cal.210 burger VLD's
300 WSM
Shot @1K
MV 2855
Difference in impact 12"
NO B.S.

 

[bsumoba]

Simple: alternate pointed and unpointed at 1K. Note if groups demonstrate a vertical spread. Measure the spread and reverse engineer BC via some ballistic program. What part of this meets any criteria for "silly" ? Seymour

The question is the silly part... Anyway, so, the two groups are ~10" apart at 1K in the first example? That makes sense to me and is how I've tested in the past.

What doesn't make sense is the use of come-ups to determine what the BC is. None of my scopes (Nightforce included) are able to make measurements that precise.

What I did was shoot groups at 1K with non-pointed bullets and it was very close to the calculated 25.25 MOA drop at 1K in my calculator (it was off by maybe 1 click (1/8 MOA adjustment needed on scope and I was on the waterline consistently). I made the corrections in the calculator for that day and then shot the pointed ones and noticed that they were shooting X inches higher. I made the scope corrections to get it to the waterline and noted what I dialed in for elevation, which was now at 24.375 MOA. In my ballistic program, I can give the program a scope dope correction (24.375 MOA) at a given range and assuming my MV is for the most part correct, it can calculate the new bullet BC.

 

[Blaster-37]

You guys might consider there are a lot of variables in pointing tools and methods. I know I am going too deep for some but it seems every shooter I talk to about this does it differently including the sortings. Barrel fine tuning seems to vary between pointed and not pointed for me. Variable winds are also a huge factor in verticals at 1K. Whatever gives you a warm and fuzzy, just keep shootin' smaller groups.
ps, I believe the best groups come from the loading bench and barrel tuning. I have never seen pointing do worse than factory except when I was first learning how to point without consistancy... OK, bad G7, bad G7.
greg

 

[Hollywood1009]

+ 1

No way can you measure bc difference at that distance much less the factors even with wind and temp or how fast you shoot each group to variables of the shooter themselves 😁

You guys might consider there are a lot of variables in pointing tools and methods. I know I am going too deep for some but it seems every shooter I talk to about this does it differently including the sortings. Barrel fine tuning seems to vary between pointed and not pointed for me. Variable winds are also a huge factor in verticals at 1K. Whatever gives you a warm and fuzzy, just keep shootin' smaller groups.
ps, I believe the best groups come from the loading bench and barrel tuning. I have never seen pointing do worse than factory except when I was first learning how to point without consistancy... OK, bad G7, bad G7.
greg

 

[Keith Glasscock]

I fired pointed and unpointed Berger 105 VLD's (orange box) today at Phoenix.

6 Dasher - Velocity 3020 fps.
Range: 1000 yards
Temp: 75 deg F
Difference in impact: Nothing! All of them hit in one solid waterline.

Looks like I'm not pointing these any more...

 

[bsumoba]

I fired pointed and unpointed Berger 105 VLD's (orange box) today at Phoenix.

6 Dasher - Velocity 3020 fps.
Range: 1000 yards
Temp: 75 deg F
Difference in impact: Nothing! All of them hit in one solid waterline.

Looks like I'm not pointing these any more...

I don't point anything that I am going to shoot out to 600 yards. 800+ is where I see a POI difference with 180gr hybrids. I think part of it too is certain bullets have larger "hollow" points like the 7mm 180gr hybrid, so these will benefit more from pointing. Maybe the 105gr VLD point is already pretty small which is why you saw no significant POI shift.

 

[Keith Glasscock]

I agree. These meplats measure .052" out of the box and I close them to .044"

The 180 Hybrid I've never tested because others have and pointing takes some of the vertical out.

 

[Laurie]

In addition to Busdriver's point (no pun intended) about scope click accuracy, one has to be sure that conditions remain absolutely constant throughout the test along the entire length of the bullet's flight as so many things can affect elevations at long ranges.

I've had mixed views on pointing and come to the conclusion that some bullets don't seem to get as much benefit as expected or may even see a performance deterioration. It's only after I started shooting 284 / 7mm Shehane that I finally found bullets that really seem to appreciate the process, the 180gn Sierra MK and the new 180gn Scenar L. Scenars generally seem to have increased meplat diameters in recent batches and some models are very big indeed compared to Bergers. All the L models irrespective of calibre and weight are big - this seems to be linked to the manufacturer seeking to improve product consistency and a large meplat makes it easier to eject the bullet from the nose forming die without distorting anything.

 

[essexboy]

I must admit that i thought that the idea of pointing bullets was to increase consistency and the by product was a slight gain in bc, i also thought that the pointing of small calibre bullets would have a greater effect bc wise than large calibre as the meplat diameter of a small calibre constitutes a larger frontal area percentage wise?
But this is what i love about shooting, you're never to old to learn.

essexboy