I recently put my R700 .308 in a new Bell and Carlson stock. Today I took it to the range to re-zero it. I brought 80 rounds that were reloaded at two different times. "Batch A" (40 rounds) was loaded on a progressive press, where I got the powder throw where I wanted it and went to town cranking those 40 rounds out in about 30 minutes. Done with batch A. "Batch B" was done on the same progressive press, but in single stage mode. Meaning I meticulously measured the powder thrown into each case, before seating the bullet. Also different about batch B, I adjusted the sizing die to bump the shoulder back since I previously had trouble chambering some rounds from another day. Now, I don't have a bump gauge so I just kept "bumping" the shoulder back until the case would chamber nice and easily. Anyways, so off to the range I went. I was expecting the rounds from batch B to much more consistent than the rounds from batch A, since I hand measured the amount of powder in each one. Batch A shot way better than batch B. The rounds that (I thought) should have shot great, were terrible, while the ones that I didn't put too much time and effort into (batch A) shot much better. Other than the powder measurement the only big difference between the two batches is that I bumped the shoulder back on B and not on A. I'm kind of a boot when it comes to reloading. Can bumping the shoulder back affect accuracy at all? if so what should I do with the 50+ rounds I still have from batch B?......Thanks in advance
- Thread starter Rockstar2f5
- Start date
I don't know how far back I bumped it. I don't have a bump gauge so I just kept tightening the sizing die down until I could easily chamber the empty brass casing.
The first set "batch A"; Some of them would not chamber, but 90% of them did, with no problem, and shot great.
I'm using a Dillon RL550b. The first set (A) I adjusted the powder throw once and loaded them. Then next set (B) I was constantly adjusting the powder throw for almost each round until the scale would read 41.5 gr. Now, the scale I'm using is not the best top quality. But I can't imagine that it could be that far off, to cause such in consistency. But I could be wrong. This is the scale I'm using.
Amazon.com: 1 New DigiWeigh DIGITAL POCKET SCALE-Gram/Ounce/Carat/Grain-PERFECT FOR Gold/Silver Coin/Jewelry, Diamonds/Gemstones & More!! LIFETIME WARRANTY + Free 5gram Gold Replica Weight Checking Bar: Everything Else
The first set "batch A"; Some of them would not chamber, but 90% of them did, with no problem, and shot great.
I'm using a Dillon RL550b. The first set (A) I adjusted the powder throw once and loaded them. Then next set (B) I was constantly adjusting the powder throw for almost each round until the scale would read 41.5 gr. Now, the scale I'm using is not the best top quality. But I can't imagine that it could be that far off, to cause such in consistency. But I could be wrong. This is the scale I'm using.
Amazon.com: 1 New DigiWeigh DIGITAL POCKET SCALE-Gram/Ounce/Carat/Grain-PERFECT FOR Gold/Silver Coin/Jewelry, Diamonds/Gemstones & More!! LIFETIME WARRANTY + Free 5gram Gold Replica Weight Checking Bar: Everything Else
If you are loading for general utility and range shooting, there is nothing wrong with this. you did not "over bump it", you sized the case properly. No need to make the process any harder than it has to be. I like to leave the shoulder where there is just a little resistance as I close the bolt. Keep experimenting, you'll figure out what works.
This is what the inconsistency looks like. Batch B had more time and detail put into it than batch A. Could this much inconsistency be from too much neck bump or is it something else? I would like to think that I'm the problem but I had a second shooter experience the same thing. The .242 MOA group and the "not acceptable MOA" group were both shot by the same shooter. The only difference was the ammo batch The other groups were shot by my self.
Attachments
Last edited:
Ok, so I will be ordering a better scale shortly.
What would cause more in inconsistency? A low quality scale or too much shoulder bump? Would it be wise to assume that the fluctuations I am experiencing are more so from the scale quality or the excessive shoulder bump?
What would cause more in inconsistency? A low quality scale or too much shoulder bump? Would it be wise to assume that the fluctuations I am experiencing are more so from the scale quality or the excessive shoulder bump?
I bought a cheap scale "to get by" when I first set up, supposed to be for reloading too. My loads were inconsistant as hell. I loaded up a few one day, but didnt seat a bullet. Weighed powder/brass/primer combo after charging the brass, loaded a few more, and went back and re weighed, all were different weights, by up to 2 grains. Still needed to stay on the cheap at the time, so I bought a Lee for $25 @ Cabelas with a gift card, with just that change, my consistency went way up.
If you go that route, I recommend re-zeroing your scale every time you load, or every so many rounds just to stay a little more consistent, especially since its a balance scale and moving it changes the balance.
If you go that route, I recommend re-zeroing your scale every time you load, or every so many rounds just to stay a little more consistent, especially since its a balance scale and moving it changes the balance.
Could be 1 could be both, without an accurate idea of how much you are really bumping the shoulder there's no way to answer that. Grab up a set of Hornady headspace gauges for your calipers and then redo the experiment with a solid number for how far you're bumping the shoulder. Then re-run the test with only 1 variable at a time. IE. bump the shoulders and use the same throw from the powder measure, then bump the shoulder and weigh every load, and run each of these test loads against your original batch A and see where exactly your deviations are coming from. It's the only way to answer your question accurately.
The cases from batch B were bumped back .004"........Is this enough to affect accuracy?
The cases from batch A were not bumped back much if any when resized, but didn't chamber well.
The cases from batch A were not bumped back much if any when resized, but didn't chamber well.
.004 should not effect your accuracy much if at all unless something is misaligned in your press/die setup, I normally only bump about .002-.003 but .004 is definitely not excessive.
Do you have a way to check the run-out on Batch A vs Batch B? That would tell you if something is wonky with your die/case alignment. I've noticed on my 650 that sometimes I have to pay close attention to make sure the cases get all the way in the shell plate. But honestly, I'd think the ones you pumped out rapidly (batch A) would exhibit this more than the others you were taking your time with.
Right now I'd say your digi-scale is suspect #1.
Sorry, I should have said concentricity, meaning basically the same thing only in a slightly different context.
A .004" bump shouldn't hurt anything at all. I agree that there's something else going on with the ammo. That something could be too much runout or a myriad of other things. I highly doubt it has anything to do with how much you bumped the shoulder.
Stop shooting 3 round groups.
Full stop, period, end of story.
You have to provide yourself with meaningful data so that you can make meaningful conclusions. I know, it's nice to see that 3-round group touching - but the longer you don't accept the fact that it's just a coincidence, the longer you will hold yourself from becoming a better shooter.
Shoot some 5-10 round groups, make a small change shoot some more - see if the groups change. Don't get caught-up in "waste of time" or "waste of ammo" BS - trigger time is never waste of time as long as you pay attention to your fundamentals.
Right now you have a 2MOA gun/ammo/shooter combination. Work from there.
P.S. At 100 yards you'll be surprised how little powder charge matters....
Full stop, period, end of story.
You have to provide yourself with meaningful data so that you can make meaningful conclusions. I know, it's nice to see that 3-round group touching - but the longer you don't accept the fact that it's just a coincidence, the longer you will hold yourself from becoming a better shooter.
Shoot some 5-10 round groups, make a small change shoot some more - see if the groups change. Don't get caught-up in "waste of time" or "waste of ammo" BS - trigger time is never waste of time as long as you pay attention to your fundamentals.
Right now you have a 2MOA gun/ammo/shooter combination. Work from there.
P.S. At 100 yards you'll be surprised how little powder charge matters....
I pulled one of the rounds from batch B and weighed the powder. It weighed 41.5 gr according to my scale. Now, I know my scale is a garbage can but there has to be some level of consistency with this batch if the scale reads the same thing every time. ( I could be wrong though, and please feel free to correct me.) I'm gonna get one of those bench rest cradles and lock the rifle down and see if anything changes with the rounds I have remaining from the same batch. I'm beginning to think that I just lack discipline and the "inconsistencies" are results of my disgusting application of the basic fundamentals of marksmanship. I am still getting a better scale btw.
IF you have enough loaded rounds run groups of at a bare minimum 5 rounds, 10 if you have enough, to really test the loads to see for sure if the previous results were anomalies or if it was actually the deviations you saw with 3 round groups.
Also, let your barrel cool fully between the groups.
Also just noticed the new stock part of your first post. Make sure that the barrel isn't touching the stock and that the action screws are torqued properly.
I have the action screws torqued to 55 in lbs. The stock came with no torque data so I looked it up on line and it said 50 to 60. If I can move a piece of paper between the barrel and the stock all the way back to where the barrel begins to taper into the action, is that good enough?
If you own a dillon progressive and are loading with a powder that meters well just adjust your powder charge on the first few rounds and load away.
If you're going to load by weighing every charge then invest in a scale that's capable of showing the small variations. A $20 MTM (or any of the thousand or so cheap chinese "dope dealer" scales on the market) are so erratic you're better off just keeping your powder reservoir filled and loading.
Unless you're trying for absolute accuracy (single hole groups) or shooting at 1k, small powder weight variations are not going to bother you as much as other factors.
Biggest single accuracy issues for me are neck tension and seating depth. Hit those on the money and your ammo will not waste much target space. Just nice small groups.
Excess shoulder bump can cause problems with failure to fire, false pressure signs, and case head separation, depending on the rifle itself and it's tolerances. That said, most unmodified factory dies won't bump a shoulder back beyond SAAMI minimums.
If you're going to load by weighing every charge then invest in a scale that's capable of showing the small variations. A $20 MTM (or any of the thousand or so cheap chinese "dope dealer" scales on the market) are so erratic you're better off just keeping your powder reservoir filled and loading.
Unless you're trying for absolute accuracy (single hole groups) or shooting at 1k, small powder weight variations are not going to bother you as much as other factors.
Biggest single accuracy issues for me are neck tension and seating depth. Hit those on the money and your ammo will not waste much target space. Just nice small groups.
Excess shoulder bump can cause problems with failure to fire, false pressure signs, and case head separation, depending on the rifle itself and it's tolerances. That said, most unmodified factory dies won't bump a shoulder back beyond SAAMI minimums.
