So after a shooting session with my 260 rem, I thought I had a chrono problem because velocities on known loads were suddently coming back 60-80 fps slower, and many folks here, and especially the folks at Oehler, were super helpful. Without rehashing all the details, it's not the chrono.

After Oehler worked over my 35p, I went out and shot again today and I probably have MORE problems than less, but not because of the Chrono.

I shot probably 50-75 rounds of 22 over it in strings of 5, 10 and 15, and it seems to match what I would expect according to the box. CCI minimags, going mid 1200's. There was considerable variation in a few of the velocities, but I'd expect that from 22's and the average was probably 1250, IIRC.

In addition, I shot the 260 again. And again, it was about 80 fps slower than previous shooting sessions had established, just as it was at the beginning of this week.

But this time, I had found an additional box of loads that I had loaded up last summer when I established load data. It was from the same batch I had chrono'd before and set my expected velocities. I brought those along and shot those along side the more recent loads. Lo and behold, right where they usto be. Perfect velocities from the stuff from last summer. So two, supposedly, identical loads, consistently 60-80fps off, shot at the same time, same gun, back and forth over the same chrono.

So I reserved some of both batches and took them home and pulled the bullets and weighed the powders against each other. The weights were the same. Some were dead on, some a little low, which I probably lost a little or something in the pulling, but the distribution/average was identical between both batches. So it's not a powder measure mistake or problem.

Checked overall lengths. Check.

The only things I could find are the following:
1) The faster (older) stuff was a LOT harder to pull the bullets. I actually cracked my front door threshold hammering them out. Neck tension must be higher, a lot higher. How this is possible, I don't know as the same seat die was used (Forster Ultra), and no adjustment was made. But maybe neck tension comes from the sizing die...I can't remember...but that's important because...
2) All the brass is Lapua from the same box, but the faster stuff was previously fired in my rifle and barely partially resized to just push the shoulder back 15 thousandths on a forster benchrest FL die.
The slower stuff, I had not used previously. I did not size it, as it came sized and chambered just fine, I just primed, powdered and seated.
3) It is possible that maybe I used a different lot of powder. I thought that both sets came from the same can, but maybe I ran out earlier than I remember. But there is no way I can verify this and is speculative.

So now I am on to a new problem. Next step will be to load up the cases that I pulled the bullets from and see if the new 'sized by lapua' stuff vs the old 'sized by forster' stuff ends up being the answer.

I wonder if I need to resize them? Or should I just powder them seat them and send them?

Any other thoughts on what could cause this problem?

Thanks!

Fired brass chronographs faster.

The first time you fire it some of the energy is absorbed ironing the crinkles out of it.

That's true, but the difference wouldn't be 80 fps.

I suspect neck tension is the main problem. Even if new brass will hold bullets, I run the necks over an expander ball of the correct diameter to even out neck tension.

That variation could be caused by:

- Cold weld between the bullet and case neck increases pressure/velocity slightly
- Formed brass
- Different lots of powder

Pretty serious STRESS goin' down here ( particularly fro the Oheler outfit, it would seem).

Did the POI shift appreciably ?

Custom barrel / match chamber ?

....or Rems notoriously capacious hole in front of the bolt for this particular cartridge ?



...no way THAT might affect anything,....

Okay, so looks like neck tension/new brass is the likely culprit. I can test that, no problem.

So what is the best way to do that. Can I just take the cases I just pulled the bullets from and repowder and reseat? Or will the seating, pulling and reseating have screwed up the neck tension so that I need to resize entirely?

I'd like to just powder and reseat so that very little is changed from cases that I know worked in the past, but if neck tension is the issue, I don't know if pulling the bullets ruins that.

Neck tension is set by the sizing die, not the seater. Neck tension was way higher on the old loads because of a cold weld forming between the bullet and case neck.

Neck tension isn't "set" by the seater. It depends on how much the neck is sized, and how soft/hard the neck is.

What about outside temp? Extreme variances in weather temps when you shot over your chrono may cause this. Just a thought. Some powders are more temp sensitive than others.

Thanks for all the advice! Responses are coming in faster than I can read them, so I had to go back and edit.

So 1, what is a cold weld?

2, John, how would you go about testing this to get to the bottom of it quickly?

Thanks!

They were tested on the same day, time, going back and forth, so temp etc. is all the same.

If you are losing powder when you pull bullets, you are doing something wrong right there.

I had not planned to speculate in this thread since WE already discussed the O 35 and Cold Weld in the "Sticky Bullet" thread.

However this statement from crossfire tells me a lot.



Sorry crossfire - but lot/lot variation CERTAINLY can produce 60-80 fps variation. Sometimes even MORE.

I see your 'whistle' icon so maybe you're being sarcastic in a friendly way ?

Yes - IF you changed lots of powder that 'could'be the cause. Over the yrs I've seen a whole lot of variation from Lot to Lot. Some is almost insignificant, some extreme.

Others have already mentioned neck tension AND/OR cold weld. Both are worth checking.

catorres1 - I know you have been occupied and so IF you haven't read the "Sticky Bullet" thread in this forum, it might be worth your time.

Jerry

We NEED a "friendly Sarcasm" icon / smiley,...whatever ya' call them.

I'm more than hip to lot to lot variations, Sir, and was joshing for sure.

GTC

Since I didn't know for sure, I thot you were AND

I was hoping you were.

Jerry

You are right, I have not read the sticky bullet thread. I'll check that out, thanks for the tip!

John,

would something similar to the Lee Factory Crimp Die help to even out the release of the bullet from the neck on firing?

Just a thought, as those already seated bullets of both batches could be run through a FC die, no?

Geno

As a point of reference I have some 223 brass. Nickle plated Remington brass. Once fired I get 3050fps, using everything the same in New brass I get 2950fps.

The fact that the older ammo clocks the same now as it did last summer sort of eliminates seasonal variations.

I don't think we;d see a cold weld situation in just a few months,given normal ammo storage would we?

My first hunch is different powder lot, but the OP has not told us unless I missed it.....Are the new and old loads from the same powder lot, or not?

It would be no trick at all to see that much velocity loss from one lot to another,depending on the powder.

Are you really pushing the shoulders back 15 thousandths?

I mentioned the same thing in my 'Temperature Insensitivity' thread. A 'known' load suddenly ~50fps slower. In my case I was using a different lot of powder. One other possibility, maybe my scale was set differently. I find I have to adjust the balance scale a little with each use. Perhaps I was actually putting in a bit less powder. I doubt that would explain it all, but maybe in combination with a slow lot of powder it explains it. Only plausible explanation I can think of. While neck tension can be different, I can't imagine it mattering much in the scale of 0 to 60k psi.

Just a few thots for consideration.

1. You're using an 'inertia' (hammer style) puller. MAYBE ? something changed in the tension (grip) of the puller and it was not HOLDING the shell AS TIGHT ? Just a possibility.
...
Neck tension is 'affected' by the sizing die PLUS the expander ball BUT that shouldn't have changed.

2. Also neck 'thickness' (consistency) also varies EVEN in the same lot of brass.***I noticed you said "all brass came from the same box". That ELIMINATES the possibility of lot-lot variation in brass--be glad.

3. At THIS POINT, as in so far, I think a change in lot of powder is VERY likely....

BECAUSE you also said that you ONLY loaded the faster stuff LAST Summer AND they graphed the same as they DID. IMO you didn't get 'cold weld' when you loaded them, that takes some time to happen.

Maybe NOT much help, but trying to eliminate possibilities.


Jerry

You are comparing apples to oranges. Previously fired brass vs new brass. Different hardness in the neck gives different neck tension. ie, different pressure.The more neck tension,the higher the pressure then the higher velocity.

My 2 cents worth,but you probably owe me some change

saddlesore -

you are right about previously fired vs new brass. I went back and re read the OP and he said he had not used the 'slower stuff' BUT he did not say how many Xs the previously fired brass had been shot.

First - I 'assumed' the faster loads had NOT been shot much. I give you that.

Second - In all my years of loading and graphing - I never saw the same USED brass to yield 80 fps more speed than UNfired brass of the same lot.

Yes as brass is fired multiple times it hardness, thus the need/practice of annealing.

I think we need to ask 'how many Xs' the previously fired (faster) brass has been shot. If it hasn't been shot many Xs, I don't ?think? it would create that much hardness and pressure.


Ok - if you send me a STAMPED envelope, I'll send you a penny! <grin>

Jerry

You are probably right.I think it doesn't matter as much as how many times,but how hot it was. Other than the OP using a different lot of powder or maybe different primers,this is the only answer I could think of.

No, sorry, meant ten thousandths. My bad!

Sounds very familiar! I bet this is it.

Bob, I thought they were from the same lot. But I loaded them so long ago, so I am now questioning whether I am remembering correctly. Unfortunately, I did not write down the lot number from that can, so I can't verify it.

Now, I write down the lot numbers on the cans I have, but I did not do that then.

But I must admit, I did not know the lot would make THAT much of a difference. I am using H4350 and understood it varied very little, at least in terms of what I need (not a target shooter etc.). But going forward, I am keeping track. And when I have FINALLY finished with all this dickering and have my loads set, I'll purchase a bunch of the same lot all at once so I don't have to mess with this anymore.

Honestly, I don't like doing this, I like shooting and getting better. For me, all this testing is just something I have to get through for the good stuff, so the sooner I am done, the better.

I am actually trying to use just one powder for our 3 rifles for this reason, so I can buy a whole bunch at once, and not have to think about it any more.

God speed that day!

Guys,

Thanks for all the replies and help! I'll try and answer all the questions I have gleaned from reading all the posts this morning.

The old stuff is on it's 4th loading.

The new stuff is brand new. Never seen a sizing die. Just straight out of the box, primed, powdered, seated, shot.

I was using an inertial. I have pulled bullets with this before using various stuff loaded with forster dies, and it has always been very tough.

But when I did it with the 'new' stuff, I was pleasantly surprised, as it came out relatively easy. Three bangs or so and each one came loose, no problem. I had been dreading pulling all the bullets I planned because my experience in the past suggested it was a pain.

But when I started pulling the bullets from the 'old' stuff that had been sized, back to expectation. I had to bang the hell out of them to get those bullets out. Every one of them were a lot more difficult to get out, that's why I noticed it. The difference was unmistakable, so I noted it my notes.

As to the powder lot, I thought they were the same, but considering the velocity drop, I am questioning that. Unfortunately, I cannot answer that definitively, so I'll just have to assume it is the same and check the other things that I can check.

My plan is as follows:

Take the 'new' brass that I had pulled the bullets from and repowder and reseat these as is.

Take the 'old' brass that I had pulled bullets from and repowder and reseat these as is.

Take some fired 'old' brass and resize, powder and shoot

Take some once-fired 'new' brass and resize, powder and shoot

Hopefully, that will give me enough data to know if it has to do with using new unre-sized brass/neck tension vs...maybe a different powder lot.

Fingers crossed, hopefully lesson learned!

From what you have stated concerning the extra pressure it took to unseat the bullets of the 4x fired brass,vs new brass,I'm still guessing it is the old brass that has been hardened, causing higher neck tension and needs annealing.

60 to 80FPS slower means about exactly nothing in bullet drop.As long as I was getting good groups I would not even think about it.

catorres1 -

Based on your last post and the 4 steps you listed:

My MONEY is on a Diff Lot Powder.




Now just for Your Future Reference---It CAN happen:

Sometime before 1995 is as close as I can get time wise.
I bought two 20 count boxes of NAME brand brass. It was NOT Win/Rem. It was higher valued and considered top of the line. I'll not mention the brand name.

I was loading/shooting a 270 W with a long standing record and KNOWN velocity.

So 1 day I was graphing and JUST FOR THE HECK of it I shot some of my loads in the NEW BRASS.

Catorres - here I hit a stump like you have.

These KNOWN loads in that BRAND brass LOST-LOST 200 FPS!!!
Long story/short. I did similar to Catorres. I checked/double checked EVERYTHING. I spent a week or two chasing every thing possible.

Conclusion - I proved this to be SO.

For whatever reason THAT batch of brass was LOSING 200 FPS.

NO - I could NOT add more powder-- I was shooting a 'compressed' load. There was NO room for more. Guys I have not listed EVERY component but I CHANGED & CHECKED every component.

Just store this away in YOUR own memory- it can happen.

Jerry

I've seen powder lots make over 200 fps difference, that could never safely be gained back... AA 2520 many moons ago.

They changed something from one to another. Sad day as we had run out and had bought almost 100 pounds in 8 pounders and had to dump it on the market again...

I"ve not seen the same since, but I have seen lot to lot, in 223 cases, make you change your load a few tenths of powder, but that happens too as the barrel wears you have to keep adding if you are smart enough to try to keep the velocity the same so you are in the in the same node as the barrel wears.

catorres,

The following may seem over the top, but I've learned in the long run that it saves time:

1) I normally use only one lot of brass for each load in a certain rifle. If that can't be done, then I check a new lot to make sure it's basically the same weight and neck thickness of the older lot.

1) As noted earlier, with new brass I run it over the expander ball in my sizing die--or if I'm using a collet or bushing die, I check the neck thickness to make sure it's basically the same as older lots of brass, and run it into the die. Either is done to make sure the INSIDE of the case necks are the same diameter. Otherwise neck tension varies from shot to shot.

2) After brass is fired, I keep it in zip-lock bags marked with how many times it's fired. I learned the hard way that mixing up brass that's new with brass that's been fired several times just doesn't work when loading for consistent accuracy. I then anneal each batch regularly. In a couple of rifles I anneal after every firing, but usually it's after every 4th firing.

3) I record lot numbers of powder, and when I buy a new lot I test-fire it to make sure it's close to the old lot. I do this on the same day at the range, with brass that's the same for both lots of powder.

Primers don't seem to matter as much, but have encountered primers that changed enough from lot to lot to require tweaking a load. But the BIG problems in primers usually come when a company makes significant changes in primers without any announcement. I know for a fact, due to talking to one of the long-time employees of a major company, that their magnum primers went through three significant chamges in either the amount or type of priming compound in the years I've been handloading.

Fantastic, thank you!

I have not been running the new brass over the expander, from now on, I certainly will.

As for the brass, I usto shoot lots of 375, so was afraid of short life and case separation, so have always kept each 'batch' in different cartridge boxes with the number of loadings written on the label. In this particular case, I only have one lot of brass, all from the same box of Lapua. And each batch has been kept separated.

On the powder. Fail. I have not been keeping track until yesterday. Lesson learned. I have now written down the lots on both the cans I have currently (they are the same). Unfortunately, I need to hunt up some more, so looks like I'll have to drag that Chrono out again in the future. This time when I buy, however, I will know it's the powder I want, and will buy in quantity. I did not this time, because I did that in the past, and then was left with a quantity of powder I cannot use. Anybody need a 5lb keg of RL15?

On the annealing, never done it before. Guess it's time to learn.

I'll report back hopefully next week when I shoot all those loads. Hopefully, it's conclusive and simple and I can move on a little wiser!

I remember that too, Jeff.

The Israeli AA2520 was damned good powder.
Their plant blew up, and subsequent batches were out of the Czech Republic, IIRC,....velocities were all over the map, and the stuff STANK when it burned.

GTC

Mule Deer -

Regarding your last post for record keeping and separating components, I don't feel those things are excessive OCD for many/most loaders with only a few guns-rifles/handguns.

I can understand it becoming more complicated having many rifles-handguns and ALL the components required as in your situation. At the same time, all the record keeping simplifies matters in the long run.

I appreciate the importance of 'consistency' in reaching valid results.

I basically do the things you listed but not exactly the same way. IMO the handloader will find out that the extra time and details come in handy when trying to solve a problem or finding 'comparative' or consistent results.

I guess I'm recommending fellow handloaders to apply your list as it fills their needs.

I'm also saying THANKS !!

Jerry

Really NOT rushing ya, but am curious. Sometimes LIFE gets in the way of important bizzness. <grin>

Just a reminder OR interested in your results.

Jerry

Hey Jerry!

Yeah, you nailed it...life in the way at the moment. I like to think I'll be able to get this done this week, but in reality, it will almost certainly be mid-march at least. Too much going on, so my window of opportunity has closed for a few weeks.

But I'll get back to you when it's done.

Something that may help, when I change lots of powder, I've had more consistent results by loading to volume rather than weight.

With modern 'smokeless' powder AND lot to lot variation...

I don't trust 'volume' measurements.

Yep, it works with Black Powder, etc.

YMMV


Jerry

catorres1 -

Yes, I call it "shooting interruptus"..

Thanks for the reply.

Jerry

Wore out, wearing out barrels slow a lot. Really a lot.

Why don't you trust 'volume'? Try it with a micrometer measure and two different powder lots and see which one is more consistent in velocity with your original load. I think you'll be surprised.

Because in the past I've had 'several' less than desirable results with KNOWN loads in modern powder SIMPLY by getting a new lot of powder.

1 example - I have had TWO blown primers at DIFF times and DIFF lots of a popular powder--now OFF PRODUCTION line.

2nd example - I still have most of a pound of a diff powder altogether with LOT # recorded. It gave OVER pressure loads AND 100+ fps. I can use it but MUST reduce the charge by @ 3 grs. (volume IS diff)

3rd example - Others who participate here had BLOWN primers by changing lots of ANOTHER diff powder. It too has been taken off production.

TOO many experienced problems personally PLUS others reporting the same problems with diff powders.

Go right ahead, it's not my fingers, nose, or eyes.

Jerry

Yes indeed. As the bore wears it increases inside dia. and less pressure and less velocity are the results.

In this case, I don't remember if/not the OP told us how much this barrel has been shot.

Jerry

Guys,

The barrel is brand new. 50 rounds through it total so far.

Edit: Sorry, that was for the 300. For the 260, probably 100 rounds through it. Maybe 150. Still, basically new.

Don't you just hate it when you have to "pull out before you get thru "


Jerry

In our previous discussions per Losing Vel and Chronographs:

I had to REplace my O 33 skyscreen IIs. I've had the IIIs a while but was not satisfied with them mounted on the board that I've been using.
Pic 1 is of Skyscreen II


That has worked virtually flawlessly since 1981 but a couple of yrs ago I was getting funky numbers and inconsistency. I called Oehler and they sold me the Skyscreen IIIs that work with the Model 33.

In the past week or so I got a 'larger' board to mount the IIIs on that gives much better protection. This board is a rough cut FULL 2"X6" and the IIIs sit in and on better.

Also the screens are mounted LEVEL with each other and EXACTLY 5' Center-Center.

These PICs are for 'demonstration' only. I don't shoot from my yard toward a road or neighbors house; just so U know.



I made a taller and narrower target holder so that bullet flight is HIGHER than the screens. Also the holder will fold down and clear the STOP screen.

The III system can be used WITH or WITHOUT the diffusers.



Since the 33 -- II screens were not designed for the diffusers, I've never used them and haven't had any problems. In the coming days I'm going to run a few testS using a couple of 22 LR, 1 handgun and 1 rifle. I want to see if there is any diff between using and NOT using the diffusers.

I have a pile of dirt in my pasture that I use for a backstop and I can shoot from very close or back out around 200 or so yards. I'm looking forward to giving the Skyscreen IIIs a workout.


Jerry

You've blown exactly two more primers than I have, but I've only been doing it for 45 years or so. Anyway, my post was that as a rule, I've found that lots vary less by volume than weight, not whether hot loads and powder variations can cause problems. We already know this.

jstevens-

you are 4 yrs my senior at handloading.

I guess it's

to each...his own


Jerry

Hey Cator-

Have you found out anything in particular?
Still interested in your results.

Jerry

Ahh! Work and life has been too hectic. I got the ammo loaded and sitting on my bench, but time to get to the range has been non-existent. But I have not forgotten to update, I will PM you when I get it done, hopefully soon!

Thnx but I am not rushing ya.

Sometimes life gets in the way of 'important' stuff.<grin>

I have some load development and graphing to do as well but we've had a WHOLE lotta rain. Hopefully the WX will cooperate so I can get it done soon.

If you'll update us here is sufficient.

Hope you find good answers.


Jerry

Hello Mr. Factory Ammo, it's been awhile.....

16bore -
The following quote of mine is from P 4, 2-19-16



That WAS the problem/result. Don't ask me how I know, but I do.


Jerry

No quite sure I'm following you or if you read between the lines of my post.