Home Forums Hunting & Shooting Ask The Gunwriters Losing velocity, it's not the chrono...any ideas???

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.