Weight sorting cast bullets?

[wquiles]

I don't want to get into a religious experience regarding cast bullets, but, given this forum is about the "art" and "science" of bullet casting, so I figured it would be good to get opinions and advice.

I have been searching on prior posts here in the forum regarding "weight sorting" vs (or in addition) to "visual sorting", which is more on the "art" of bullet casting. I have also seen a few posts where doing weight sorting has some merit, which is more of the "science" part of bullet casting.

I personally don't do weight sorting for pistol shooting, but of course do the visual sorting, as in the distances involved with my pistol shooting are often under 25 yards, and the gun is probably more accurate than I can hold and align with iron sights or even a red dot.

That being said, for my shooting at 100yards, I am finally getting a little better, a little more consistent in my technique, and I am beguining to wonder if some of those "fliers" I get are potentially a too light or too heavy bullet at 100yards.

Now, I suspect that as I improve my bullet casting ability (I can only hope, right?) that I will have less deviation, but to test whether weight has any effect (or not) on my 100yard groups, I started with some recently cast Lee 165gr 308 cal bullets. I did my normal visual sorting, sized them, PC coated them, GC-ed them & size again (same operation), and then weight sorted finished bullets, and I got them into 3x groups:
- "light" - 168.9gr +/- 0.3gr
- "medium" - 169.6gr +/- 0.3gr
- "heavy" - 170.3gr +/- 0.3gr

I loaded them exactly the same, on my Mega single stage press. I plan to go shoot them in the next week or so. Something fun to do outdoors, right?

Advice/opinions/suggestions on the idea/concept of weight sorting vs fliers in a target?

Will

 

[Spindrift]

Very interesting subject! Personally, I have avoided weight sorting because it takes time. And nowadays, if I spend more time in my reloading room, I would probably have to spend less on the range.... But I have asked myself the same question, does it have any significant merit?
While I can’t answer you question, I can try to contribute some observational data to add to yours.
Happy shooting, good project!

 

[popper]

+/-0.3gr and you can't tell the difference between your light, med. and heavy. I don't bother. I did the experiment once just for fun, sorted into rows of weight, then did it again and the rows changed. Same batch of bullets. So I don't bother. I do visually inspect and cull into plinker and 'target'. Still can't see any difference on the target @ 100. Concentrate on pouring good ones. I don't trickle powder either.

 

[Rick]

I weight sorted for a time for long range handgun competition, 200 meter shooting. When I stopped doing that I couldn't tell any difference in the scores so never went back to it. The secret to minimal weight variation is a very consistent mold temperature. Work on that along with perfect bases and I think you'll find weight sorting pretty much a waste of time. Another way to look at is with my 200 gr revolver match bullets a one grain or less weight variation is a very small percentage of the whole and would at best make a very small difference.

 

[waco]

I try and be a stickler when it comes to sorting my bullets by weight when doing long range shooting. For high velocity 500 yard loads I try and keep the lubed and gas checked bullets to within .2gr weight of each other. Might not be as big of deal at 100 yards but I figure everything matters more at longer distances.
Taking casting advice and tips from Rick, Fiver, Brad, and Ian have helped a lot too. Maintaining a consistent mold temp and casting at a consistent cadence did wonders for me.
I can't shoot a handgun well enough to bother sorting buy weight for any distance. I look for nice flat bases first and foremost and look for nice sharp driving bands.

 

[Brad]

Notice a stress on MOULD temp. Keep the mould temp consistent and the bullets will be consistent.
I would use weigh sorting a sample as a way to judge variations in casting technique. See what happens when you change the cadence, use a fan for cooling, etc. You will eventually find what works best for you.

Weight sorting handgun bullets? For shooting at 25 yards max I will shoot some sorry looking bullets at times.

 

[fiver]

for 100yd. 1900 fps shooting I probably wouldn't bother too much.
what I would use the weight sorting for.
for my information.
so I could tighten up a 2gr weight variance in a 2 cavity mold.
decide if one cavity is dropping heavier than the other.
if my mold temp is wandering.

on a custom cut high velocity bullet.
I'd sort to help me catch little things I can't see or missed in the visual.

for random flyers I'd have to also suspect lube flyers, buildup at the relax point, or purging.
powder fouling purging is also something I'd track.

 

[Rick H]

Try shooting a group from loads with all three (light medium and heavy) in one group Vs. groups from the each sorted weight. I will be shocked if you can tell the difference with a total possible variation of less than +/-1/2 gr. with a nominal 170 gr. bullet.
My eyes were opened when I knocked a box of carefully weighed and sorted loads off the bench with the top opened. They were loaded in groups of 5. They spilled all over the place. I was disgusted with myself and shot them up there was no way of knowing what was what. There was no difference between the mixed up rounds and the carefully fired 5 shot groups before the mixmaster incident.

If you find a difference more power to you, go for it.

 

[Ian]

I only sorted all of the rifle bullets from two casting sessions, ever, and the only reason was to scrutinize my casting technique. I had less than .2 grain +/- each time at about 180 grains. Note that I toss the first 10-15 pours on a precision run and and don't stop for love or money until I've run the pot down enough that the pour volume is beginning to change (about 1/3 pot). Nice thing about ladles is the pour volume variable doesn't occur, but I still don't ladle very often. Why not? Not trying to brag, but most of the time I manage to cast good enough bullets from a bottom-pour furnace for what I need that sorting by weight is unnecessary, and you all have seen my 230,000 rpm groups from visually-sorted bullets. That doesn't mean I nail every pour, because I don't, but I can usually tell by how the pour looks and sounds if it got flubbed or not. I cull a lot of bullets straight from the mould and about 2-3% visually after the session. If I'm loading a couple of boxes for a hunt, I do usually go ahead and weigh/measure just those bullets just to put my mind at ease because it only takes a couple minutes and game animals deserve the extra QC.

I'll also say this about weight sorting: You're wasting your time if you are not also sorting by dimension, meaning checking the driving band dimensions in two places a quarter-turn away from each other. A fat bullet from loose hand pressure that also has a giant hidden void can weigh the same as dimensionally correct bullet with no void.

 

[wquiles]

Wow, great feedback. Thanks much. I can tell already that my casting technique is what needs more practice/attention, as you guys are having less than .5gr variation for the whole casting session on a bullet in the 170gr range, where I got well over a 2 full grain variation on that last casting session from the lightest to the heaviest bullet after visual sorting. So clearly LOTS of room for improvement on my part.

I still have the a question though: I use my RCBS to measure every powder charge automatically down to 0.1gr, and with my Mega press I get within .001" on overall length - but if I have two grains of bullet weight difference, would that matter at 100yards? Would a light or heavy (in my case say 1.5gr to 2gr change worst case) weight difference at 100yards be enough to give me fliers? Or would I have to shoot at 200-300 yards before I see a trajectory difference due to the weight difference?

Will

 

[Ian]

Whether or not the weight difference will cause a flyer depends on what your definition of a "flyer" is (1/4" outside of a half inch group, half inch out of a 3/4" group, or 3" out of a 2" group?), or if the weight difference is due to a void and if so where that void is located. A void near the surface of the bullet skin can theoretically cause the flyer to have a greater deviation than a void in the center, though I don't know of any way to actually test this without x-raying bullets. Testing deliberately damaged bullets via drilling a hole in the side to remove a small amount of metal can have a 1-2 MOA deviation, and has been proven through testing.

If your powder charge falls at the middle of a "node" of barrel vibration as determined by a ladder test of some sort, thrown charges are plenty good enough. I don't weigh powder, and neither do the benchrest guys. A BR competitor knows his system well enough that he will make slight volume adjustments to stay in the happy node as temperature changes a few degrees throughout the day, but still is just going to throw a volume and not worry too much if there's a few tenths variation charge to charge because it doesn't matter enough to worry about. This is from people who win with group dispersion measured to three decimal places. If you're on the edge of a node, a few tenths of a grain might throw you over and you may see it on target, but a load tuned to a node certainly will not.

 

[wquiles]

Thanks much Ian for the great follow-up. I ask about fliers since I often get two shots, or 3 shots making a nice MOA group at 100 yards, but when looking at the 5 shot group, it opens up into a 2-3 MOA group. So as I develop and improve my shooting skills I wonder how much that group opening up was me or a combination of me "and" poor casted bullets that only had visual sorting.

I "know" my casting needs lots of improvement based on this thread alone. In fact, doing the weight sorting "exposed" how much more work I have ahead of me. I found an image of when I sorted this batch of 30-cal bullets, sorted by 0.1gr increments. These were cast from the Lee 6 CAV CTL312-160-2R mold. This photo shows the very large variance in weight I got:




Will

 

[Ian]

That may be your technique, or the mould. Lee six-bangers have never been especially well known for throwing equal weights for all cavities. I have and RCBS 277-150 that varies four grains between the two holes, and many other examples. Next time you cast with that mould, shake the bullets out in order of cavity for about 3-4 pours and set them aside to compare.

 

[JWFilips]

My rifle bullets are sorted in +/- 0.1 grain increments for target shooting. I really don't mind the extra work because it tells me how I was running the particular mould so it is always a learning experience. I probably do not have to be so precise with 50 yard "low node" shooting ...it is just nice to know how accurate I was at casting them

 

[wquiles]

That may be your technique, or the mould. Lee six-bangers have never been especially well known for throwing equal weights for all cavities. I have and RCBS 277-150 that varies four grains between the two holes, and many other examples. Next time you cast with that mould, shake the bullets out in order of cavity for about 3-4 pours and set them aside to compare.

Wow, I never thought about it. I was assuming that cavity to cavity was not going to be that dramatic given the CNC equipment used now-a-days. I will definitely try that out next time to see if I can identify how much variability the mold alone has. Most all other molds are either NOE or from Tom (Accurate) and they are 4x cavity molds - probably less variation than on the Lee, but worth checking at least once so that I "know" what to expect.

I really don't mind the extra work because it tells me how I was running the particular mould so it is always a learning experience.

I know I have lots to improve technique-wise, but also think that this extra work will help me become more consistent, and then I can stop doing the weight sorting.


Man, I love this forum. Thank you guys

 

[Brad]

A mould by Tom hits a level of precision that Lee may not be away of.
I would gladly assume each cavity of a mould by Tom or MP is essentially the same, not so with Lee.

 

[Rick]

Don't think I would worry much over cavity variation with any of custom makers. I suppose anything is possible but . . . LEE may or may not be aware of what's possible but if they are it doesn't seem to hold much importance for them. The other makers take pride in what they produce. Yep, there are still people like that.

 

[S Mac]

I've never done powder coating, just wondered if that could contribute to weight variation, unequal coating.

 

[462]

My rifles and I need all the accuracy help we can get, so I do weigh my bullets, and though it's conceivable that it doesn't make any difference -- especially considering my vision and iron sights -- I have the time to do so.

I've had the thought to do a weighed versus non-weighed comparison, as well as one comparing weighed versus thrown powder charges, but it's just another roundtoit.

 

[JWFilips]

I've never done powder coating, just wondered if that could contribute to weight variation, unequal coating.

Yes it does....that add's another bullet weighing session ( if so inclined).
However I recently just started coating unweighed bullets then only weighing once after coating. It does mean however you are coating bullets that will be culls so it is extra work one way or another