Sudden loss of accuracy conundrum

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Scopes are funny things. Something may be loose inside that may have rectified itself temporarily between the session before you bought factory ammo and using the factory ammo. It may be a pain, but have you tried swapping the scope for another instead of questioning every aspect of your reloading? All you need to do is be on the paper for your groups, not the bullseye. Shoot your handloads and then shoot the factory loads. If the handloads shoot as they once did, problem solved. If this doesn't work, I would suggest you change only one thing at a time. If otherwise, you are not going to know what the problem is/was.
 
I know you stated that there are no contact points along the barrel channel but have you checked the channel with a dollar bill after you have shot your groups and the barrel is hot? I had an issue with my rifle that all of a sudden started to spread the groups when I started doing some loads development. Cold bore shots were good but after 4 to 5 shots they would spread.
 
I’d go with a good barrel scrubbing. I shoot a lot of bench rifles and am a stickler for groups. I might pull a bore snake through every 100 rounds or so with a dry patch. When sub moa groups open up I do a thorough cleaning with Butchs Bore Shine. Then plan on wasting 10 bullets or so to get the barrel fouled back enough to tighten back up. Lot of gun ranges have gun smiths that will run a bore snake through for you for a $20 to verify for sure if you don’t have one. You could measure the neck tension on the annealed brass for good measure. Nothing else you’ve mentioned leads me to think any different.
 
If you know it's your hand loads, then check every component.

Brass is discussed above.

Are the bullets from a new batch? Are bullet weights consistent?

Is your scale calibrated? Do you have multiple scales to compare charge weights?

Are the primers from a new batch? Did you try a different batch to compare?

Double check your recipe to the inaccurate batch of hand loads. Check COAL.

Also, are the larger groups stringing vertically? If so, could be result of inconsistent charge weights.
 
Lots of good questions and ideas here. Im a stickler for a clean bore, Im certain there is no copper staying in the bore, its spotless. Overkill is underrated so I hogged out the barrel channel more than was necessary, barrel shouldnt be able to contact the stock under any conditions.
I always weigh sort my bullets to the 1/10 gr. For testing 165 gr SSTs, every bullet I use will be 165.2 or 165.3 I always choose to load ladder test with bullets it always the same or no more than 1/10 of a gain off from the others just to eliminate another variable. I wont run some that 164.9gr with those that weigh165.5, even though I imagine it won't make a bit of difference especially it only 100 yards, but I do it anyway because Im OCD and a perfectionist. I will never be able to load fast but it is what it is.
I've tried this with CCI 200s, Winchester large rifle primers, Winchester large rifle match, and S&B large rifle primers. Anytime I do a load work up, all the cases get primers from the same batch, I never mix different primers in a test.
I do have multiple scales that I check each other against as well as calibrate them frequently. I'm pretty sure I've got this issue nailed down to 2 problems. One is I may be slightly over annealing, resulting in inconsistent neck tension. 2nd issue I believe is thinning necks from having varying numbers of loads on any particular case.
 
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Just realized I didnt reply to fotheringill. I have not swapped out scopes and generally would have done just that at the beginning if I had another known good one to try. Ive broke 2 cheaper bushnells and loaned out another so not much to swap with. I do have 3 other known good scopes but 2 are on my kids 243s and are nuts on for eaches prefered load, and the other is on my muzzleloader. Having to re zero for the Muzzleloader sucks when the bore gets fouled and you have to clean it two or three times while zeroing, the other 2 because I hate to mess with a good thing with my kids rifles. They don't get the hunt with me as much as we would like so I try to make sure everything's tip top shape so when they do get to go we don't have any issues.
I hate to say it but I have a hard time even shooting my $200-300 scopes once I bought my Vortex PST 5-25. I got spoiled massive increase in magnification and better glass clarity than all my other Scopes as well. The loophole VX2 glass is decent but being able to aim really small has ruined me so Ive been hesitant to swap scopes because of that as well.
 
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Not that the brass isn't a good place to start, it is and would likely be the first thing I changed as well. A couple other things that come to mind.

-beam scale or electronic?
-Do you reload with LG pistol primers?
 
brasscollector said:
Not that the brass isn't a good place to start, it is and would likely be the first thing I changed as well. A couple other things that come to mind.

-beam scale or electronic?
-Do you reload with LG pistol primers?
Click to expand...
I use both. Most of my loading is done with an electronic scale but I check it against the Beam scale. I do not use large pistol primers as all my handgun loads use small pistol primers.
 
Have you carefully inspected your crown?
My Ruger LCRx3 .357 revolver was shooting very inconsistent from one shot to the next. Turned out to be a damaged crown that was causing all my woes.

Long story short...returned it to Ruger..they put a new barrel in it. It is spit on every shot now.
 
When I find my most accurate load, I always measure and record the overall length using a bullet comparator and also the measurement off the lands. I used to load 50-100 rounds once I found the most accurate load, but soon discovered that as the throat erodes the jump increases and the accuracy falls off. Now I prep all brass, but only load 20-40 rounds, depending on my shooting frequency for that particular rifle.

Possibly that might be your problem? Maybe you should adjust your seating depth a little at a time and see if accuracy comes back! Hope this helps. QM
 
Have you, by chance, opened a new container of powder with a different lot number?
Different lot of primers?
Different lot of bullets?

It sounds crazy, but I have had new lots turn my proven loads into run of the mill stuff.
 
Stevenvalleyky said:
Lots of good questions and ideas here. Im a stickler for a clean bore, Im certain there is no copper staying in the bore, its spotless. Overkill is underrated so I hogged out the barrel channel more than was necessary, barrel shouldnt be able to contact the stock under any conditions.
I always weigh sort my bullets to the 1/10 gr. For testing 165 gr SSTs, every bullet I use will be 165.2 or 165.3 I always choose to load ladder test with bullets it always the same or no more than 1/10 of a gain off from the others just to eliminate another variable. I wont run some that 164.9gr with those that weigh165.5, even though I imagine it won't make a bit of difference especially it only 100 yards, but I do it anyway because Im OCD and a perfectionist. I will never be able to load fast but it is what it is.
I've tried this with CCI 200s, Winchester large rifle primers, Winchester large rifle match, and S&B large rifle primers. Anytime I do a load work up, all the cases get primers from the same batch, I never mix different primers in a test.
I do have multiple scales that I check each other against as well as calibrate them frequently. I'm pretty sure I've got this issue nailed down to 2 problems. One is I may be slightly over annealing, resulting in inconsistent neck tension. 2nd issue I believe is thinning necks from having varying numbers of loads on any particular case.
Click to expand...
I believe you just found your issues, here’s my advice do with it as you see fit.
Actually three things
1- stop annealing, test with new brass
2- measure your bullets base to ogive loading only those within.001 each session - weight is written on the box...
3- only use one calibrated scale
 
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