Over the years I've noticed that if I load up a large batch of a certain load they don't seem to shoot the same as they did when I worked up the load.

I'm not talking about decades, but rather 3 to 5 years.

An experienced bench rest competitor friend of mine says he's had that problem and blames it on changing neck tension over time.

I'm talking about hunting accuracy (ex. 3/4" group opening to 2+") so I don't know if just neck tension would account for that large of a change.

These same guns will still shoot great groups with "fresh" loads so it's not the barrel, etc.

For ammunition stored in plastic or cardboard containers in a "cool dry place" I wouldn't think the powder could break down that quickly either.

I'm getting a little shy to load up large batches.

Does anyone else experience this problem? What are your theories?

Kyler

When I notice a given load losing accuracy, it means I've got excessive copper fouling, which I haven't completely remove. COPPER FOULING is a bigger problem than most people realize. My advice - get some WIPEOUT with Accelerator and clean your barrel until no "blue" remains. Then try that "old" load and see if doesn't shoot anymore. If accuracy doesn't return, your barrel may be gone.

I think your benchrester guy is right.

I once experienced a similar problem with an accurate .22-250. When fresh, the reloads shot great, 8 years later they were more than 2.5 MOA.

I had a LOT of this ammo loaded, so I experimented to try to save it.

It turns out that some (but not all) of the bullets seemed to be slightly sticking in the necks. I set my seating die on one of the loaded rounds so I could reseat the bullets to the original (accurate) seating depth. Next, I used a collet bullet puller to pull the bullets then just reseated them back to the same depth that they had been. No other changes.

Result: regular 1/2 to 5/8 inch groups just like before.

I had not cleaned my cases before loading, and I think some case necks were cleaner than others, resulting in about half of the loads exhibiting bullets slightly sticking whereas others did not.

Perhaps I could have saved the loads by just seating the bullets a hair deeper. I have done so with some old military surplus ammo, and it certainly did improve its accuracy. In this case, I could even feel that some bullets were harder to seat deeper than others -- very unusual I think

Checking for copper fouling is never a bad idea though...

John

what you have isn't uncommon at all. its an easy fix too. the benchrester is right, the bullet sort of glues itself into the neck after a period of time. all you have to do is to "bump" it a bit in the seating die, that will break the tension.

Yes, neck tension does change. The problem is that it does not change the same on all the brass but will vary from case to case. This will open groups. I have even had unloaded cases split the necks from sitting around and they had been annealed.
I doubt if copper fouling is the problem because he stated new loads shoot great.
Another problem is that the metals of the case and bullet start to stick together sort of like being soldered and this will be different in each case depending on how much fouling was left in the neck. This can be evened out by polishing the inside of the brass before loading. The proof of this are 50 year old military rounds, loaded in new brass, that still are extremely accurate.
I have never found a change in accuracy when new brass was used, only with fired and reloaded stuff. And it depends a lot on how many times the brass was loaded and if some cases had a lot more shots then others. The brass is the weak link.

I'm with Butchloc on his idea. For some reason the bullets seem to bond to the case. What I believe was happening to me was I wasn't getting all the lube out of the case mouth when seating. I felt a couple years later the lube became a bonding agent somehow. I too put them in the seating die and sometimes it takes alot of pressure to "crack" them loose. From here on out I get all the lube out of the case mouth.

How do you account for accurate militay ammunition than that was processed in LC 74 ? roger

quote:

Originally posted by bartsche:
How do you account for accurate militay ammunition than that was processed in LC 74 ? roger

Well...here is what I think for what it is worth.

Those are not reloads so every neck was equally clean.

Equally clean --> equal "sticking" of every bullet to the neck --> consistent bullet pull --> good accuracy.

The military loads that I improved the accuracy of by simply bumping them down were sealed with something that looked like asphalt and some had dried out more than others (judging from the bit visible outside the case neck).

Just my opinion... worth twice what you paid for it!

John

Well, maybe it is a neck tension issue. I guess consistent tumbling after sizing may help remedy that.

It sure makes sense that I could have left inconsistent amounts of fouling and/or lube in the case necks.

As stated above I don't see how it could be excess barrel fouling if the same components or others in a "fresh" load group well.

Now that you guys mention it, I don't remember having that trouble with loads in new brass. I've got a couple batches loaded for a few rifles in new brass, I'll have to do some testing.

Thanks for the great advice,

Kyler

Maybe this thread should be "Old Reloaders Losing Accuracy?"