Your pointy bullets and their flight

[Bryan Litz Ballistics]

Not sure I understand what you're asking.

The INTENT of pointing is to close the open tip, thereby reducing the meplat diameter. This means the front ~10% or less of the ogive configuration is now 'different'.

However, it is possible that when you point some bullets, it can affect more of the ogive by essentially 'crushing' the bullet. This can be measured as a difference in BTO measurement. However, this is a sign of 'overpointing'. In other words, the intent is not to re-shape the entire ogive in this way.

Does this answer your question?

-Bryan

 

[JRS]

It certainly does

Quite clearly, actually

 

[johara1]

Not sure I understand what you're asking.

The INTENT of pointing is to close the open tip, thereby reducing the meplat diameter. This means the front ~10% or less of the ogive configuration is now 'different'.

However, it is possible that when you point some bullets, it can affect more of the ogive by essentially 'crushing' the bullet. This can be measured as a difference in BTO measurement. However, this is a sign of 'overpointing'. In other words, the intent is not to re-shape the entire ogive in this way.

Does this answer your question?

-Bryan

If you trim and point you make the nose more uniform in length and the first sign of over pointing is a gain in the shank and pressure ring area. You also stated it's ok that a high BC bullet can't group better than a 1/4 minute at 100 yds. but will group in a 1/2 a minute at 1000 yds. That is some what miss leading, when i can shoot 6 groups in a row out of two different guns with the smallest being .043 and the largest .090 and take them to a 1000 yd. match and agg. 2.83" for 4 matches. You are right about the jackets now you will find .0001 minus now so groups should even get smaller ……… James O'Hara

 

[Bryan Litz Ballistics]

You also stated it's ok that a high BC bullet can't group better than a 1/4 minute at 100 yds. but will group in a 1/2 a minute at 1000 yds. That is some what miss leading, when i can shoot 6 groups in a row out of two different guns with the smallest being .043 and the largest .090 and take them to a 1000 yd. match and agg. 2.83" for 4 matches. You are right about the jackets now you will find .0001 minus now so groups should even get smaller ……… James O'Hara

James,
I was generalizing, of course, the reality that high BC bullets will maintain their MOA groups better at long range than low BC bullets. Your specific data supports this generalization.

Tom,
The column bullet is a very specific design which is intended to mitigate dispersion elements. The aerodynamic and mass properties necessary to mitigate dispersion, unfortunately, necessitate low BC profiles.

-Bryan

 

[johara1]

Bryan, I have one question….. I set a record with your 6mm 105H about 3+ years ago and the length of the bullet was well over 1.270 after the lot was depleted, lots after that were a lot shorter and did not approach the uniformity of the lot i had first. Did you implement a change to the design at that time ?….jim

 

[Bryan Litz Ballistics]

Bryan, I have one question….. I set a record with your 6mm 105H about 3+ years ago and the length of the bullet was well over 1.270 after the lot was depleted, lots after that were a lot shorter and did not approach the uniformity of the lot i had first. Did you implement a change to the design at that time ?….jim

Jim,

No, the design was not changed.

There are many reasons for bullets (or any manufactured item) to vary lot-to-lot. Some things include raw material supply and dies wearing and being replaced. With open tipped match bullets, these lot variations are typically most visible/measurable in the bullet length, and BTO measurements. Typically, the ogive shape, and the BT shape are very consistent unless a die was changed. In other words, the bullet dimension which typically varies most lot-to-lot is bearing surface length.

I'm curious; when you say that more recent lots are 'less consistent', do you mean there's measurably more variation in the bullets, or that they don't shoot as well in your rifle? or both?

-Bryan

 

[Bryan Litz Ballistics]

Maybe column isn't the right word I suppose. Still trying to figure out what I was seeing when testing the bib 104 in one of my previous posts. I only know the height of the lead line made a difference for THAT barrel and THAT lot of jackets and cores.

Tom

Tom,

There are different ways that the height of the lead line can affect the precision of bullets.

One way is thru the deliberate balancing of dispersion elements by design. This is the Berger Column.

The other is related to how well the bullet is formed with a taller or shorter core. In other words, due to combinations of core height and core seating punches, and how that relates to jacket taper, etc, you may get a more precise bullet at a given core height just because the equipment is better suited for that configuration. In this case, you could see precision affected by core height on any bullet.

-Bryan

 

[johara1]

Tom, I can only get them to grow .006-7…….. lol… jim

 

[johara1]

Bryan, I have one question….. I set a record with your 6mm 105H about 3+ years ago and the length of the bullet was well over 1.270 after the lot was depleted, lots after that were a lot shorter and did not approach the uniformity of the lot i had first. Did you implement a change to the design at that time ?….jim

Jim,

No, the design was not changed.

There are many reasons for bullets (or any manufactured item) to vary lot-to-lot. Some things include raw material supply and dies wearing and being replaced. With open tipped match bullets, these lot variations are typically most visible/measurable in the bullet length, and BTO measurements. Typically, the ogive shape, and the BT shape are very consistent unless a die was changed. In other words, the bullet dimension which typically varies most lot-to-lot is bearing surface length.

I'm curious; when you say that more recent lots are 'less consistent', do you mean there's measurably more variation in the bullets, or that they don't shoot as well in your rifle? or both?

-Bryan

Bryan, I measure everything and i also spin them on a Juenke. The lot i had all the success with was a max. of 3 divisions and the latter ones were every where to running the needle clear off the meter. I put a lot of wear on a lot of barrels trying to get the105 Hybrid to shoot. I have had lots with a shank size of . 2429 and some as high as .244and some with the pressure ring smaller than the shank size. I really liked the first lot but the ones after really turned me away but the VLD seems to stay very consistent, that is the part i don't understand……. jim

 

[expiper]

"pointy discussion" ,,,,Im wayy behind the times,,,,is Sierra producing two kinds of "tipped" bullets now,,,I just got an e-mail taliking about plastic tips on MK's ,,,,,are these something brand new !!!!...Roger

 

[johara1]

Roger, yep a plastic tip on some but the 6mm 107 is just pointed and have a BC. of .547……… jim

 

[expiper]

Thank YOU ,Jim,,,,,Merry Christmas ,,,,

 

[johara1]

Roger, same to you and i was trying to find the BC i posted but now i can only find the old 107 at .527. Boy it's hell to get old…….. jim

 

[dmoran]

Bryan -

Thanks for getting involved with the thread, for the input, and replies.....
While a couple posters have wanted to discuss what to do with current bullets, with great information to those scenario's. Jerry's intent of the thread is how to make bullets better, in design and/or process of the way they are made.
And is what is intriguing to me as well.....

You wrote to Tom the fallowing on column bullets:

Tom,
The column bullet is a very specific design which is intended to mitigate dispersion elements. The aerodynamic and mass properties necessary to mitigate dispersion, unfortunately, necessitate low BC profiles.

Probably my own dumbness here, but I don't get your reply.
- Why only a lower BC profile bullet?
- Doesn't core height effect center of mass, hence balance? And shouldn't it hold true for any bullet model?

Several years back (2005) I was using 107-SMK's, and ran into some Lot accuracy variation, that when dissecting, pointed to the core height being the suspected issue.
As best as I could from my limited resources, when trying to figure out "why", when dissecting the bullets, the jackets appeared fairly consistent to thickness', and the shape to diameters and lengths where very close as well. The only standout thing that appeared different was the core-height it self, which told me the density of the lead cores were different. Where the one Lot's had large "voids" tip to core, and the others had smaller void area's. The end results on the targets between the Lot's were very obvious in all my testing and use.

With that said, the "column bullet" philosophy has always appealed to me. When you guys (Berger) were first testing and moving forth with the light match column bullets, and marketing them to that clientele, I was very excited.... hoping that the day would come when Berger might give the philosophy a whirl in the low drag model bullets and the LR Competition clientele as well.
And still am.... because I strongly feel there would be relevance with high BC designs as well.

Regards
Donovan

 

[Bryan Litz Ballistics]

Donovan,

I apologize for not going into more detail on this subject. The dispersion mitigation design (Column bullet) is not something I'm allowed to describe in detail because of it's proprietary nature.

Suffice it to say that dispersion mitigation (as implemented in the Column bullet) doesn't work for high BC bullets.

-Bryan

 

[Jason Boersma]

Bryan,
What do you think would be better to sort bullets, by their weight or by their bearing surface?

 

[Bryan Litz Ballistics]

Bearing surface.

 

[Jason Boersma]

Thank you

 

[spclark]

Bearing surface.

Yep, what I've found most worthwhile.

Take a batch of the same lot # & sort 'em accordingly. The biggest pile (under the bell curve) gets segregated for rounds for score. The rest maybe for short-line, or foulers.

 

[jerrysharrett]

Bearing surface.

Bryan, 'nuther question. I can see where it is very important for the bullet to have dynamic balance (spinning) but what is a simple reason the bullet (stationary) must have static balance (front to rear??) to be an accurate projectile.

BTW, thanks for joining in.