how to bump cases that aren't all the same????

Beeron

Beeron

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Greetings,
I am looking for some advice from some experienced reloaders......

I have been loading for a while and generally have good success developing accurate and consistent loads using the .002 bump.

I recently decided, I think for the third time now, to again load for precision in a 223.
I started with virgin brass (Starline) and load data I had had good success with in the past (good, not amazing).

For those who aren't Starline fans, I have excellent success with this brass in 6.5 Creedmoor, 308, 243, 300blk, and 6.5 Grendel.
And of course I am also trying a few other brands (hornady, PMC, Federal). No Lapua or Alpha or the like yet.

After firing about 200 rounds, I figured I was ready to start doing some "bumping" and I have always done the .002 bump.
I am finding that I dont have a lot of consistency in the shoulder length in the fired cases. I have tried a few different collets in the comparator to hit different parts of the shoulder.

I am shooting 77gr compressed loads so I expected to have maximal stretch but I am a bit confused by this.

Accuracy is decent and under MOA but it just feels like I should be able to get tighter brass tolerances if I was doing something different maybe??


Interested to hear thoughts and advice.

Thanks
 
Beeron said:
...After firing about 200 rounds, I figured I was ready to start doing some "bumping" and I have always done the .002 bump.
I am finding that I dont have a lot of consistency in the shoulder length in the fired cases. I have tried a few different collets in the comparator to hit different parts of the shoulder.

Interested to hear thoughts and advice.

Thanks
Click to expand...
I have experienced the same thing. I found this link from accurate shooter to be helpful. https://forum.accurateshooter.com/threads/proper-new-brass-initial-firing.3989737/
 
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My question is how is the accuracy of the different brass you are bumping without changing g anything?
That is the acid test, because even if your cases do not measure out the same, if the groups do not show any inconsistencies, then I would not worry about it.
Cat
 
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OP, many here will disagree with this, but when I fireform brass these days, I use a load which is very close to the load I would use in the field.

For decades, I went through all of the steps included in using mild loads to fireform new cases for the chamber of whichever rifle I was loading for at the time. It could be a new rifle, a new chamber, or one I had tossed the cases for because they were past their best before date, or not enough cases remaining in the batch to be useful.

A shooting acquaintance had been promoting the full load method for years, and I had been reluctant to try fixing something that didn't seem to be broken.

Switching to a new batch of brass, even if it's from the same manufacturer, is always going to involve changes.

Sometimes it's only a couple of adjustments on the scope, but most often it requires a slight change to charge loads.

When fireforming for a chamber you already have a bullet/primer combination set up for, it's much easier.

When fireforming for a new chamber, with new cases/powder/bullets, it's a bit more difficult.

I'm not going to go into a lot more detail, because lots of books have already covered the subject and many have different theories.

One thing to consider, brass cartridge cases can differ greatly between batches, due to metalurgic mixtures, such as zinc or another compound ratio.

People will cry foul, but if I have a load that will fit in the case, and I intend to use it for whatever purpose, I start with that load and work from there, from the very first shot.
 
mmattockx said:
Set your die and size a few, then measure them after sizing. Are they consistent then?


Mark
Click to expand...
Short answer. Yes.
As long as I set my “bump” short enough.

What I want of course is to set them at .002 from the longest measured case after firing.

What im observing is that the same brand of brass, fired once, AFTER FL resizing with no expander ball and then using a mandrel for .002 tension.

Some of the cases have not stretched enough for the die to even bump at all.
This is firing 100 cases of virgin brass with identical charges, primer, and pill.

This is with what I assume is high pressure loads of compressed charge with a heavy for caliber pill.

O loaded them that way deliberately to ensure i got full expansion.

What im seeing with my measures is that not all of the cases have expanded to the same length.

I am used to seeing very consistent expansion n my other rifles which allows me to very effectively and consistently set my dies for a .002 bump.

I might just have to shoot these another round I guess.
 
iron cat said:
My question is how is the accuracy of tge different brass you are bumping without changing g anything?
That is the acid test, because even if your cases do not measure out tge same, if the groups do not show any inconsistencies, then I wpulx not worry about it.
Cat
Click to expand...
Thanks.

Ya. Early days still.

I am on my second batch of loads with this rifle now.

Here’s an addendum,

Is it just to be expected for smaller cases such as 223 to have higher SD’s than say 308, or 6.5 cdm??

I did always have trouble getting single digit SD’s in my 300blk.
 
bearhunter said:
OP, many here will disagree with this, but when I fireform brass these days, I use a load which is very close to the load I would use in the field.

For decades, I went through all of the steps included in using mild loads to fireform new cases for the chamber of whichever rifle I was loading for at the time. It could be a new rifle, a new chamber, or one I had tossed the cases for because they were past their best before date, or not enough cases remaining in the batch to be useful.

A shooting acquaintance had been promoting the full load method for years, and I had been reluctant to try fixing something that didn't seem to be broken.

Switching to a new batch of brass, even if it's from the same manufacturer, is always going to involve changes.

Sometimes it's only a couple of adjustments on the scope, but most often it requires a slight change to charge loads.

When fireforming for a chamber you already have a bullet/primer combination set up for, it's much easier.

When fireforming for a new chamber, with new cases/powder/bullets, it's a bit more difficult.

I'm not going to go into a lot more detail, because lots of books have already covered the subject and many have different theories.

One thing to consider, brass cartridge cases can differ greatly between batches, due to metalurgic mixtures, such as zinc or another compound ratio.

People will cry foul, but if I have a load that will fit in the case, and I intend to use it for whatever purpose, I start with that load and work from there, from the very first shot.
Click to expand...
Well,
If im being honest, thats what I am doing.

I am starting with a load that is meant to nearly optimize the 77gr bullet for long range shooting.

I have a few 69gr loads in my notes that are outasight but i was hoping for a bit more wind bucking.

And as i said, i am getting pretty good accuracy at 100 and pretty good out to 600 with what i have now.

I am hoping to tickle the steel at 1000 with this build so maybe i just have to gwt used to 223 and wind.

Thanks for the thoughts
 
It’s likely to take at least a couple firings for the brass to fully form to your chamber and not all will expand at the same rate. For the first couple firings I typically measure a few pieces to sort out one that is longer, then set my die to just “kiss” the shoulder when sizing that piece. I’ll then test that case in my chamber to see if there is any resistance at all. If none then I go ahead and size the rest without adjusting my die. The shorter pieces will just continue to stretch next firing.

By around the third firing I again find a longer piece (by now they are pretty consistent) then set 2 thou bump, test in my chamber, if no resistance then size the rest. This works for me, in my 300 PRC using ADG brass I just got 12 firings, I did anneal after every firing using a torch and drill.
 
ruby76 said:
It’s likely to take at least a couple firings for the brass to fully form to your chamber and not all will expand at the same rate. For the first couple firings I typically measure a few pieces to sort out one that is longer, then set my die to just “kiss” the shoulder when sizing that piece. I’ll then test that case in my chamber to see if there is any resistance at all. If none then I go ahead and size the rest without adjusting my die. The shorter pieces will just continue to stretch next firing.

By around the third firing I again find a longer piece (by now they are pretty consistent) then set 2 thou bump, test in my chamber, if no resistance then size the rest. This works for me, in my 300 PRC using ADG brass I just got 12 firings, I did anneal after every firing using a torch and drill.
Click to expand...
Thats pretty close to what I settled on.

I measured 30 fired cases and averaged the longest 5.
Set my die to bump that .002 and now we go into round 2.

Im excited to see.
I was ringing moa steel at 700 with no issues with virgin brass.
 
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