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Weighing the Bullets. - Printable Version

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Weighing the Bullets. - guitarhillbilly - 02-19-2020

I have made it clear in this thread that I find as much as a .8 grain difference in a box of 100. And its not just one bullet but as many as 20- 30 will have MORE than a .3 grains difference and some as much as .8 grains.If all the bullets in a box were .2 grains or less difference I would never WEIGH another bullet. I cull the bullets into .2 grains or LESS groups for loading.
Basic physics: If I load 2 rounds and one is 103.3 grains and one is 102.5 grains they are going to impact the target at different locations if every thing else is the same. This difference is compounded the longer the distance.
In fact if I were shooting BR competition I would make sure every bullet weighs exactly the SAME. Also would do a run out check on each load. Eliminate every possible variation in each load.

I wish all the bullets in a box were within .2 grains tolerance but that is not the reality.
If I'm going to take the time to trim every piece of brass to the same length-weigh each piece of brass [same brand]- weigh each powder drop-Use a Micrometer Seating Die and measure each OAL with a Hornady Comparator- then I'm sure going to take the extra 20 minutes to weigh the bullets.

Weighing the Bullets. - LRRPF52 - 02-19-2020

Kswhitetails Wrote:The experienced loaders and shooters locally say that the arbor press and wilson seating die are the right fix for this, and that after testing the double seating method they say while it does work, it still introduces far too much variation in finished runout. I will say that the 2" groups at 950 are pretty good proof that these seating steps work well. By far the best ROI in getting good results in precision is low SD. And the best ROI in obtaining low SDs IMHO is neck tension. Consistent neck tension is the quickest way to reliable grouping and precision.

If I weigh the first 10 bullets and find less than .2 grain of a swing, I don't weigh any of the batch. I can't shoot good enough to tell the difference at distance anyway. And I stay blissfully happy that way... Big Grin

The Forster Co-Ax with its floating die approach should also reduce runout similar to how the Arbor press does.

I can't argue with the consistent neck tension statement.

Theoretically, we'd all love to have consistent bullet weights that don't deviate at all, but manufacturing processes will always have some degree of variation and the short distance BR shooters typically will buy custom bullets from small shops that specialize in over-bore and very uniform flat-based bullets. The LR Benchrest crowd will uniform their meplats and do their best to get consistent base-to-ogive measurements with VLDs, SMKs, or use Vapor Trail bullets.

My take on bullet weight is that there is a mathematical ratio of stability factor / bullet mass variation, with the stab factor being such a huge component of that equation, that it renders the resolution at which we should see measurable group sizes so small, that in practical terms, it wouldn't show up until significant distance.

Is it something that will manifest itself with an AR15 at 600yds? Maybe, but how much?

For the NRA Service Rifle-type matches, maybe there is merit in your x ring count at 600.

For me shooting steel out to 1200yds, is it going to influence my hit probability enough that it's worth my time to add the step? Maybe, maybe not.

I've found that my ability to read the wind is far more important than my load procedures, and even if I pick up an additional .x MOA improvement, that would be x" at 1000yds.

I then ask myself is it worth it to spend the time weighing bullets and cases and shrink my group sizes by that amount?

If I was shooting a Bench Rest rifle for 600 or 1000yd competition, you bet I would be running a segregated lot of uniform brass and bullets weighed on a Sartorious lab-grade scale, with charges weighed on it after NASA-level load development. We've excluded the AR15 and shooting steel at this point, so I'm out of that space personally.

I'm a gas gun guy through-and-through, even though I learned to shoot LR with bolt guns and have burned through untold amounts of ammo through bolt guns chasing this discipline.

I used to segregate and align my cases by weight, and I think I even did a bullet weight line-up once just for the OCD nature of it.

Reading the wind is such a larger factor in what I do, that those steps were basically a waste of time for me, but if someone finds merit in them and is measurably shrinking their groups with bullet weighing, I say have at it and enjoy.

I don't want my passion for impacting steel to get in the way of someone's passion for cutting paper scores and group sizes.

Even with my lightweight Lilja 17.6" Wasp profile Grendel and a ball propellant (CFE223) load under the 123gr A-MAX, I was really surprised to see my rapid-fired 6 round group at 1000yds be well under 1 MOA vertical, and well under .5 MOA horizontal, especially shooting bipod-supported off a cement bench on-the-fly just to see what would happen.

This was my very first input elevation dial for 1000yds that day as well, not a group I shot after walking it in at 1000yds, which is crazy:

[Image: 3bf6ee00-ad92-4600-a7bb-e77b0832f99f_zpsfe8pbfh3.jpg]

I then transitioned to a 2/3 IPSC and center-punched it in the forehead. Keep in mind I'm aiming 2 mils into the wind with these targets, so my crosshairs are nowhere near being on the target. The small impacts on this target are from my 123gr A-MAXs. The larger ones are from a 24" 6.5 Creedmoor shooting 140gr or 143gr Hornady ammo.

[Image: d807b367-cd38-405e-9c04-61cd0684f23c_zps4xrper5f.jpg]

Weighing the Bullets. - guitarhillbilly - 02-19-2020

Thank You for this excellent posting.