Bullet seat depth change after storage????

[reynolds357]

I have a particular hunting load for my 6.5x 284 Norma that I have used for years. Long story short, a particular load of IMR 4350 shot great last season. Stored the ammo In an ammo can in my climate controlled shop(never under 60 never over 80 Deg F) after last deer season. Grab the ammo and head to the range to shoot. Rifle is clean. First round I chamber feels tight. Pull bolt back, bullet stays in rifling, powder everywhere. Clean mess up, shoot 3 and it happens again. Go in shop and run all cartridges through seating die. About 1/3, of them I could feel move. Shot over 200 of this batch last year and never had so much as a sign of a problem. Never had this happen in anything else I have ever loaded or in factory ammo I have stored forever. IMR 4350 was about the only powder I used for my first 15 years of reloading. I have 257 Wby IMR 4350 handloads over 30 years old stored beside this ammo and they are fine. I still have the 8 Lb jugs the 6.5x284 was loaded out of, stored in same shop that by visual and smell test is still fine.
???????

[jetinteriorguy]

Possibly a heavily compressed load that slowly pushed the bullets out over time. Also sounds like your neck tension is weak since it pulled the bullets out of the case when extracted. If it were me I’d use a Lee collet neck sizing die and possibly use an undersized mandrel for better neck tension. But doing so may raise pressure so I would also drop my load by a few increments and work back up watching for pressure signs.

[reynolds357]

Originally Posted by jetinteriorguy

Possibly a heavily compressed load that slowly pushed the bullets out over time. Also sounds like your neck tension is weak since it pulled the bullets out of the case when extracted. If it were me I’d use a Lee collet neck sizing die and possibly use an undersized mandrel for better neck tension. But doing so may raise pressure so I would also drop my load by a few increments and work back up watching for pressure signs.

Thanks. It is not a compressed load. 48.0 in Norma brass and a 130 Berger VLD. That is actually a 6.5x284 Winchester load. This being a 6.5x284 Norma, you can still hear powder shake after seating.
Cases are not crimped.

[jetinteriorguy]

My next guess would be the neck tension is loose enough that the bullets were possibly sticking in the seating die and being pulled back out a bit. Pretty easy not to notice this before putting them in the can.

[reynolds357]

Originally Posted by jetinteriorguy

My next guess would be the neck tension is loose enough that the bullets were possibly sticking in the seating die and being pulled back out a bit. Pretty easy not to notice this before putting them in the can.

Can't say for sure, but they all worked last year. 70% of the batch was shot last year building the dope sheet.

[jetinteriorguy]

Perhaps you missed resizing some of the brass and the bullets are just too loose in the neck. I’d check the shell cases with a good calipers/micrometer to see if there are discrepancies.

[big al hunter]

My next guess would be the neck tension is loose enough that the bullets were possibly sticking in the seating die and being pulled back out a bit.

I think if this were the case the bullet would have moved easily enough during clambering to not notice a hard close. My thought is that the original seating was short stroked a bit for some reason.

[reynolds357]

Originally Posted by big al hunter

I think if this were the case the bullet would have moved easily enough during clambering to not notice a hard close. My thought is that the original seating was short stroked a bit for some reason.

But they all worked last year. They are 33% failure this year. Statistically it's impossible.

[Metal god]

But they all worked last year.

My question would be , were all rounds loaded including the 200 last year loaded at same time during same reloading session with all components coming from same sources ? Maybe if not compressed I could see them getting just a tad shorter but longer is very odd . To the point of sticking in the lands hard enough to pull the bullets seems even more odd since "they" all worked before . Which makes me think they are not all actually the same .

[Nathan]

First, I question your failure rate. I’m guessing many of them were just pushed in and fired last year. This year, you are more careful.

I’m guessing case necks have hardened over several firings leaving neck tension too low. Did you measure and oak’s? Did they change from your notes?

[reynolds357]

Originally Posted by Nathan

First, I question your failure rate. I’m guessing many of them were just pushed in and fired last year. This year, you are more careful.

I’m guessing case necks have hardened over several firings leaving neck tension too low. Did you measure and oak’s? Did they change from your notes?

New Norma brass. Straight out of the box, F.L. sized.
They were all seated the same depth. You can feel the ones that are going to stick.
I have a batch that I loaded with Staball 6.5 at the same time. Dug them out and they are all fine. They are not as accurate as the 4350, but they are still uniform length.

[Unclenick]

Well, this is odd. The first thing I would do is take a comparator and measure all the ammo. If it turns out all the long rounds are equally long, then I would assume the seating die adjustment changed for the last third of the batch and the resulting rounds were mixed together, but not uniformly, so you didn't get any of them last year.

I have seen lubricated lead bullets that were waiting for crimping that were pushed up gradually out of their cases by the air compressed in the case from seating the bullets. A jacketed bullet should have too much friction to have that happened, and I have yet to hear of it occurring. But a worst case thought was deterioration of powder, which begins randomly in some cases and not others, had pressurized the cases and pushed the bullet's out if they weren't fitting tightly. But this seems very unlikely.

One thing I didn't see mentioned was what bullet jump you were trying for. I have seen bullet's off different tooling with repeating variation in bullet shoulder to ogive seating stem contact location length due to that tooling difference. But if the change is greater than a few thousandths, and unless you were trying for a really short jump, this should not explain it.

[reynolds357]

Originally Posted by Unclenick

Well, this is odd. The first thing I would do is take a comparator and measure all the ammo. If it turns out all the long rounds are equally long, then I would assume the seating die adjustment changed for the last third of the batch and the resulting rounds were mixed together, but not uniformly, so you didn't get any of them last year.

I have seen lubricated lead bullets that were waiting for crimping that were pushed up gradually out of their cases by the air compressed in the case from seating the bullets. A jacketed bullet should have too much friction to have that happened, and I have yet to hear of it occurring. But a worst case thought was deterioration of powder, which begins randomly in some cases and not others, had pressurized the cases and pushed the bullet's out if they weren't fitting tightly. But this seems very unlikely.

One thing I didn't see mentioned was what bullet jump you were trying for. I have seen bullet's off different tooling with repeating variation in bullet shoulder to ogive seating stem contact location length due to that tooling difference. But if the change is greater than a few thousandths, and unless you were trying for a really short jump, this should not explain it.

These are definitely NOT crimped. I seated them with my Redding Bench Rest die. I sized them with my standard Hornady FL sizing die. My Redding sizing die is for my tight neck 1000 yd rifle, and it's turn necks before sizing. I rarely crimp anything not loaded for a semi auto or revolver. I always check COAL on last cartridge loaded. If I am running a batch of 100, usually check s couple in the middle of the run as well. There is not much jump on these bullets. I do not remember the measurements, but it was loaded close. In load development, it shot the tightest group with no jump. But the bullets in testing that were lightly pushed into the lands would extract without dropping powder.

[Nathan]

Originally Posted by reynolds357

New Norma brass. Straight out of the box, F.L. sized.

Thanks for the answer. I have never been more wrong!

[Unclenick]

Originally Posted by reynolds357

I always check COAL on last cartridge loaded.

That was sort of the point of my last paragraph. The seating stem pushes on the bullet ogive rather than the tip (except the Lee Dead Length Seating Dies push the tip or very close to it). I have measured Sierra MatchKings, where the length from the bullet base to the tip varies by nearly 0.015", but the base to the ogive measurement had half that spread. So it is conceivable individual bullet tooling could give you several thousandths or even a hundredth of variation in the actual point at which your bullet meets the lands. If you decide to pull any of these, it would be interesting to hear how well the bullet dimensions matched.

[reynolds357]

Originally Posted by Unclenick

That was sort of the point of my last paragraph. The seating stem pushes on the bullet ogive rather than the tip (except the Lee Dead Length Seating Dies push the tip or very close to it). I have measured Sierra MatchKings, where the length from the bullet base to the tip varies by nearly 0.015", but the base to the ogive measurement had half that spread. So it is conceivable individual bullet tooling could give you several thousandths or even a hundredth of variation in the actual point at which your bullet meets the lands. If you decide to pull any of these, it would be interesting to hear how well the bullet dimensions matched.

I might go back and measure at ogive just for fun.
This is where I am.
1. They ran fine last year.
2. They sticking this year
3. Ran them through seater again, still set up same from last year. Felt some move. After running through seater again, they are all fine. Have chambered every one of them.

(Seat depth changed on about 33% of them in storage)

[Unclenick]

For 1and 2 to prove a change occurred in storage, you have to know your loads were a homogeneous mixture of your production output. I know mine typically are not. Unless I am loading for a careful test or a match, my tendency with run-of-the-mill loads is to seat bullet's from a box until it's empty, then move on to the next box without necessarily checking production lot numbers. Even if I did match lot numbers, I can't know if one box was filled at the start of a run or at the back end or somewhere in the middle, which may favor production off one set of tooling over another. So, I can't really prove homogenaity of my general production unless I measured everything before loading. This is why measuring bullets might have revealed a pattern if you kept track of which ones were high. But, that said, this problem is odd, and I would not have expected it to happen to jacketed bullets at all.