Lot to lot bullet variation

COElkChaser

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Oct 8, 2019
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Hey all,
I got through most of a load development and went to go confirm my drop at 300 yards this weekend. I loaded 17 rounds, 7 with bullets from the lot I did my earlier testing with, and 10 with bullets from a new lot.

Results were terrible! This load shot .6" 5x shot groups repeatably. The first 5 from my latest batch went 3" at 100 yards. The second and third groups of 3 and 4 went around 2".

Finally, because I didn't know what else to do, I shot the last 5 at 300 yards, and they were all within 2.9".

A couple thoughts: the vertical spread is fairly tight on the 100 yard shots. So the large groups could be due to some level of shooter error, but I don't believe that explains the full issue. Also, I didn't keep track of which round had bullets from which lot, but my guess is that I shot 5 of 7 bullets during the 300 yard group.

Wondering what you all do when switching to a new lot? Start over on load development? Do you see this level of sensitivity? What do you measure on bullets to look for consistency?
 

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First, what are you shooting? Hand loading I take it? I’ve found over the years that bullet manufacturing has improved drastically, especially in premium bullets. I remember weighing Speer bullets 20 years ago and there was a range of 5 grains either direction. Garbage, and now would never go near them. Learned shooting aversion. Barnes and Nosler at the same time were within 1... collect data. Weigh your bullets? Weigh your powder charges? Check and eliminate everything.
 
Years ago when I started reloading, we didn't really have the tools to do all the things we can today. back then we settled for 1" group's though probably most could have done better by simply bedding their rifles! Today we have all the latest and greatest in tools and equipment and still can't shoot a .000" group! I think most of us are hunter's but when it come's to reloading we quit being hunter's and became scientist's without proper training! How in the world we ever got 1" group's in those days I have no idea! The opening up from .6" groups to 3" group's would suggest to me something a lot more drastic than bullet diameter though I know most will disagree with me. And then because you didn't know what else to do you fired the last 5 into 2.9" at three hundred yds? My though is it has little to do with the bullet's.
 
Possibly your barrel is really copper fouled? Good scrub and try again. Good luck.
 
Are you measuring with a comparator or off the bullet tip? I’ve seen some variations from lot to lot but normally if seating off the Ogive your load won’t change if your in the node.
 
I'm using the RCBS precision mic to measure seating depth.
Possibly your barrel is really copper fouled? Good scrub and try again. Good luck.
Thanks, I shot the 300 yard group last with good results, so I would assume fouling isn't too problematic, right?
 
Without having anything marked you are throwing darts guessing at problems . Load a new set and re shoot.
 
Just noticed you were loading Barnes. Barnes will sometimes change bullet designs or materials used without warning. I would suggest remeasuring your lands with the new bullets just to be sure and load a few more test rounds. Also how far off the lands is your load? How many times fires is the brass?
 
Just noticed you were loading Barnes. Barnes will sometimes change bullet designs or materials used without warning. I would suggest remeasuring your lands with the new bullets just to be sure and load a few more test rounds. Also how far off the lands is your load? How many times fires is the brass?
Everything has been with once fired Nosler brass, and bullets set 0.150" off the lands. Good point about remeasuring to lands
 
This new lot is pretty interesting. I tested one bullet 5x for distance to lands and got 0.081" on the RCBS mic (all measurements within .001"). I tested another bullet from the same box and got 0.058". Pretty surprised to see the variation, and it seems like a lot considering how much Barnes hammers on seating depth being important to accuracy.

How does Barnes compare to other manufacturers? Anyone else noticed this sort of thing?
 
0.150" from the lands?

Due to magazine restrictions?
Or just what you load?
Most mono bullet manufacturers reccomend 0.050" off the lands. Barnes included.

Are your action screws tight?
Along with your optics?
 
That's right, I started working on this load following Barnes COAL measurement of 3.240, which turned out to be .150" from the lands. After finding the best powder charge I did a seating depth test and found getting closer to the lands ended up with my groups opening up.

I checked scope and action screws at the range, but those were fine.
 
I only use Accubonds and do not reload anymore. I do not find variations in my shooting patterns that I can't blame on myself or the wind. My 300 yard groups shooting from bench without a bench rest are all within a 3 inch circle which is good enough for me. My 100 yard groups are around a quarter.
 
This new lot is pretty interesting. I tested one bullet 5x for distance to lands and got 0.081" on the RCBS mic (all measurements within .001"). I tested another bullet from the same box and got 0.058". Pretty surprised to see the variation, and it seems like a lot considering how much Barnes hammers on seating depth being important to accuracy.

How does Barnes compare to other manufacturers? Anyone else noticed this sort of thing?

Could be due to quite a number of factors but doesn’t surprise me with Barnes. You could measure and sort out the very bad ones if you wanted.
This is another reason why measuring off the Ogive(CBTO) is my preferred method vs measuring off the bullet tip(COAL).
 
Could be due to quite a number of factors but doesn’t surprise me with Barnes. You could measure and sort out the very bad ones if you wanted.
This is another reason why measuring off the Ogive(CBTO) is my preferred method vs measuring off the bullet tip(COAL).
That's what's so strange, this is from measuring off the Ogive, not the tip.

I measured another 3 bullets, and they're all coming in at 0.058" - 0.059" so looks like that first bullet I tested was the outlier.

I've been considering moving to the Nosler E-Tip, any experience with consistency in that bullet?
 
Are you measuring loaded rounds? If so how are they only .058 off when your load is supposed to be .0150?
 
I'm measuring dummy rounds - I half size the neck on a fired case to give the bullet some tension, seat the bullet long, load into the chamber and close the bolt, remove the dummy cartridge, measure the round on the RCBS mic.

The measurements on the mic are relative measurements, meaning if the bullet is touching the lands the mic does not read zero. In the latest measurements the mic reads 0.058" when the bullet touches the lands.

Then to get to 0.150" off the lands I would seat the bullet until the mic reads -0.092".

Problem is that I'm finding different bullets within the Lot have different measurements from base to Ogive when touching the lands. So if I load all my bullets to a seated depth of -0.092" (mic reading) it results in various distance to the lands.
 
Your COAL of 3.240 is irrelevant and just a very generic number in the loading book. COAL only matters IMO to determine if my rounds will fit the magazine box.
You stated your rifle shot best when loaded .150 off the lands. Take 3-5 of your new bullets and load them to .150 off the lands with your already determined powder charge. Then shoot them and let us know the results.
Also it’s not surprising the base to Ogive measurements of the Barnes is varying. I’ve seen much worse from other bullets also. What matters is setting your distance to lands with those bullets the same as the others in the box.
If you want to stay with mono bullets I’d suggest trying some Hammer bullets.
 
Ollin Magnetic Digiscoping Systems

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