Sudden loss of accuracy conundrum

[Stevenvalleyky]

I have been loading for and shooting a 308 Ruger American for 3 or 4 years now. It's always been wonderfully accurate with my handloads and has been very easy to develop several good accurate loads using 150gr & 165 gr SSTs,150 gr Sierra Pro Hunters, and 150 grain Speer grand slams. Most of these were capable of Cloverleaf or at least less than an inch groups as long as I did my part. Recently, during the 4 range trips I've made in the last 2 weeks, my groups with even known good loads turned into 4-5inch groups. I made sure all the scope mounts and Rings were tight, the action screws or tight and that the barrel channel was not contacting the Barrel in any way. I also made absolutely sure that the barrel wasn't copper fouled. No matter what I've tried the accuracy is just gone. Even though it has around 2000 rounds down the barrel oh, I figured being a thin pencil Barrel that it may just be shot out.
So today out of frustration , I bought a cheap box of Remington core locts and it shot less than an inch groups, so it's obviously my handloads. I shoot most of my loads over a chrono in my extreme spread and standard deviation numbers are very low. I hand weigh every powder charge for this rifle but just couldn't figure out what was going on till today. Now I know it's my handloads but I have no idea why.
Could having too much Lube built up in my dies possibly cause this? How about over annealing? I've been annealing for a couple years now with very good results but that's the only 2 things I could think of. Any ideas of what could be causing this?

 

[bob97]

I’m not some reloading genius but start with the obvious. Visual inspection of everything. Failing that, undid the last thing you did.

 

[Blue68f100]

Loads worked up during warmer weather being shot in colder environment? Any change in lots? Primers, powder, bullets? Different brass? All can have a influence.

 

[sequins]

Do you measure runout?

 

[murf]

how old are your cases?

murf

 

[LaneP]

I like where @murf is going with this. How about dropping the same loads into new or once fired brass to see if that makes any difference?

 

[murf]

also, do you check case length?

murf

 

[Stevenvalleyky]

Ok, gonna try to address each reply here. I visually inspected everything on the rifle as well as checking the scope bases and rings as well as action screws to make sure everything was tight and everything was tight. Using all the same components and the two powders that I have the most loads worked up with are Varget and IMR 4166, which are both very temperature insensitive. Also these loads were very accurate last winter as well as this summer with no discernible change in the point of impact. I changed absolutely nothing as far as brass, primers, powder and cases. I did try the same loads in different brass that has a little bit bigger capacity as well as the same brass that was shooting well before. Didn't make a difference. I did not check run out since I don't have the tools to do that at my house. I have checked before at a buddies house but he lives 2 hours away. When I did check run out, it was when my loads were shooting terrific, but have not been able to check since this problem started. The factory loads shot pretty good so I'm certain it's in my hand loads. I'm thinking it's one of two possible scenarios. I did slightly change the way I anneal my brass. I use to use a templistick on every piece of brass but I noticed while doing a big batch of mixed headstamp brass that because of the different composition of different brass, some head stamps took longer to anneal than others. To make it easier on me, I started annealing in the dark and drop them from the heat when they got the slightest hint of glow which was about the temperature that my 800 Degrees templistick would change colors. I'm thinking either I'm over annealing which is causing very inconsistent neck tension with some being much tighter than others, or there is a problem with one of my dies. I don't clean them like I should and they could have lube buildup I suppose. Would over annealing some necks cause inconsistent neck tension? I anneal after each firing specifically to try to get neck tension as consistent as possible but maybe I'm screwing it up.
Appreciate all the replies, I knew I could count on the Brain Trust

 

[Stevenvalleyky]

also, do you check case length?

murf

Yes. Cases get annealed every time before sizing then trimmed. If they arent long enough for my Lee trim length guage and cutter to trim any brass off, they just get chamfered and deburred.

 

[JFrank]

I would probably get a new batch of brass and not anneal them as a comparison. I know some Benchrest heavy hitters that never anneal.
Another thing I would consider is that IF you use a die with an expander ball you could be thinning the brass at the necks too much over time. I call it the pie dough effect. This definitely effects neck tension
J

 

[Stevenvalleyky]

I would probably get a new batch of brass and not anneal them as a comparison. I know some Benchrest heavy hitters that never anneal.
Another thing I would consider is that IF you use a die with an expander ball you could be thinning the brass at the necks too much over time. I call it the pie dough effect. This definitely effects neck tension
J

Thank you, I never considered the pie dough like thinning of the necks since I always think about brass flowing forward. I generally pick up brass anytime I see it at the little range I go to. I'll take it home clean it size it and integrated into the rotation. I keep stuff separated by head stamps and even separate cases by length and weight but never pay attention how many firings that any piece has on it until I get a definite Groove inside the case or partial case head separation we're brass it's been fired many times ends up with a crack most of the way around the case. When that happens obviously it gets discarded but I've not had any total case head separation Since I checked for grooves fairly often. But I will say in any particular headstamp other than my 19 pieces of Starline brass that have been fired twice, all other hand stamp has ranges from once fired to eight or nine times fired in the same bag. And so long as a cases proper length and not too thin in the web it might get used for the next load I try to develop.
I do believe you may have solved my problem. I will get some brass that all have the same number of firings, ideally new or once fired and hopefully that solves my problem.

 

[Dibbs]

The annealing thing sounds like the heart of the matter, I was going to ask how many times have you used the brass. There is a limit to how
much one shell can take before it gets "stretched out" (?)i.e. worn past the point of use, for accurate shooting. It sounds like you need to shoot up
a couple boxes of new brass.

 

[Stevenvalleyky]

The annealing thing sounds like the heart of the matter, I was going to ask how many times have you used the brass. There is a limit to how
much one shell can take before it gets "stretched out" (?)i.e. worn past the point of use, for accurate shooting. It sounds like you need to shoot up
a couple boxes of new brass.

I do believe and hope you are right. On that note, any of you tried atlas development group brass yet? Ive been told by a couple people now that its as good as lapua or better. Thats coming secondhand so take it with a grain of salt. Atlas factory is 20-25 miles from my house, are a little cheaper than lapua or norma and Im told picking them up instead of having them shipped is allowed.

 

[CptnAwesome]

You said you don't clean them like you should and they could have lube buildup.

If you're not cleaning them well they could have carbon buildup inside the case, which could in affect lower case volume. That would cause an increase in pressure.

That alone could turn a sub moa load into a 3-4" load.... Just a thought

 

[murf]

you might also try 750 degree templaq. and take spj's advise.

luck,

murf

 

[frankmako]

check your brass. clean the brass and mic the brass.

 

[Blue68f100]

If you have any left that shoot bad tear one down and confirm the powder charge.

 

[Stevenvalleyky]

You said you don't clean them like you should and they could have lube buildup.

If you're not cleaning them well they could have carbon buildup inside the case, which could in affect lower case volume. That would cause an increase in pressure.

That alone could turn a sub moa load into a 3-4" load.... Just a thought

The cases do get cleaned well, its the dies I was worried may have lube build up.

 

[Stevenvalleyky]

If you have any left that shoot bad tear one down and confirm the powder charge.

Ive done that multiple times, powder charge is always on. I hand weigh every charge for rifles

 

[Blue68f100]

Do you have any crony data to reference too. When I see a loss in accuracy I look at the crony number and compare against my original load. In most all cases I have found the velocity to be running low. Some times to different of powder, or primers.

 

[JFrank]

The cases do get cleaned well, its the dies I was worried may have lube build up.

I use a spray brake parts cleaner ,

 

[murf]

here is, hopefully, an explanation of why I suggested the 750 templac: http://www.csun.edu/~bavarian/Courses/MSE 227/Labs/5-Cold_Working_Brass.pdf

I think your annealing temp is too high, therefore your brass is too soft, therefore your neck tension is all over the place.

luck,

murf

 

[kelbro]

How sure are you of no copper buildup or perhaps a carbon ring in your barrel?

Have you borescoped it?

 

[JFrank]

How sure are you of no copper buildup or perhaps a carbon ring in your barrel?

Have you borescoped it?

That was my first thought but as posted he ran some store bought with a return of accuracy as per post number 1
J

 

[Riomouse911]

Is the bore spotlessly clean or is there a buildup of jacket materials, lead, crud etc. causing a drop off in accuracy?

You sound like a diligent reloader, so let’s try the bore first.

A dedicated copper cleaner followed by a lead-fouling cleaner until all is pristine may be in order. Then check bedding, action and scope screws, etc.

Just a thought...

Stay safe.