Mixed brass effects oal?

[Axis II]

Loading 124gr extreme 9mm with mixed brass and I have the die set to 1.140 but I'm getting from 1.140-1.145 being the highest. Put it back in die and don't budge so checked previous one and it was 1.142.

Any clue? I measured several pieces of brass and all the same oal so could it be the bullets are off?

 

[Ironicaintit]

It's most likely variations within the bullets causing that. A .005 swing in COAL is well within "normal" I'd think.
At least, I hope so...because even with spotlessly cleaned dies, mine do that, too.

case length variations are a net zero effect on OAL of the cartridge

 

[Lokichoki]

Without a bullet comparitor your measurements will be varied with measuring the tip, also if your using a well used press with those damn breech lock inserts the play havic on c.o.l

 

[cfullgraf]

There are lots of factors that can affect the seating overall length. Particularly with mixed heat stamped cases, neck tension can be one of them.

A variation of .005" is not outside the realm of "normal" in my opinion.

Another example of the variation in length, if you are trying to dial in your desired overall length by making small adjustments. If you then seat the next bullet/case, the overall length will be different than the cartridge used to "dial" in the length.

 

[9mmepiphany]

If you're loading on a progressive press, having the shell plate full will make a difference in OAL than having only a single case being loaded

 

[SASS#23149]

the length of the brass has nothing to do with coal. Look at a loaded round in your hand,and mentally shorten that brass case mouth a quarter inch. ...did the bullet tip move because the brass is shorter ? nope.

bullet fit into the seater stem,and your hand pressure on the press handle can easily cause the variance.

 

[Klint Beastwood]

Case volume maybe? maybe it has less volume and the powder is stacked higher in the case..

 

[LoonWulf]

I agree that its likely just a difference in individual bullets, and or slight variation in press operation.

Measure a few bullets see if theres much difference.
You can also make a jury rigged bullet comperator by running a case thru the sizer but not expanding, then using that to check the difference between loaded rounds at a point other than the bullet tip.

When using a none cam over press ive found that final pressure can change coal of the same round that much. With a press that cams changing the speed you operate the handle significantly can as well.

 

[Axis II]

I'm using a 2yo lee classic turret. I put the ones that measured long in the die again with the ram all the way up/bottomed out and still no change. I didn't think 5k would make much difference my mind just says i have to know why.

I also noticed that some cases wouldn't flare a lot to hold the bullet in the mouth and i would have to guide them up with my finger.

 

[Ironicaintit]

I also noticed that some cases wouldn't flare a lot to hold the bullet in the mouth and i would have to guide them up with my finger.

now that, is probably because of different case lengths. long ones flare slightly more, shorter ones may not get flared at all

 

[higgite]

Are you using a combo seating/crimp die? If so, varying case length will have an effect on COL due to crimping starting sooner in the seating cycle with longer cases. For plinking and close range target practice, I haven't found it to be a problem.

What shape seating stem are you using? A flat stem will flatten the noses of round nosed bullets, giving you inconsistent COLs. (Don't ask me how I know that.)

 

[Walkalong]

I have the die set to 1.140 but I'm getting from 1.140-1.145 being the highest.

A .005 spread is pretty normal. Doesn't matter if the brass is all matching or mixed.

I load most RN to fall between 1.130 and 1.135 OAL.

 

[Walkalong]

A .005 swing in COAL is well within "normal" I'd think.

Yep.

 

[Axis II]

Are you using a combo seating/crimp die? If so, varying case length will have an effect on COL due to crimping starting sooner in the seating cycle with longer cases. For plinking and close range target practice, I haven't found it to be a problem.

What shape seating stem are you using? A flat stem will flatten the noses of round nosed bullets, giving you inconsistent COLs. (Don't ask me how I know that.)

you guys will get mad but im using a lee factory crimp die and lee dies. im not sure what stem is in it.

 

[scythefwd]

why would we get mad?
FCD is a collet crimping die unless the round is roll crimped. Good news, its not inconsistent start of crimping causing your 5 thousandths of an inch difference. I am currently setup to use a fcd on my 308 setup...

 

[Walkalong]

FCD is a collet crimping die

Not in 9MM. It crimps like any other taper crimp die.

Explained here:
https://www.thehighroad.org/index.php?threads/rcbs-38-spl-die-question.822005/#post-10563470

 

[cfullgraf]

I put the ones that measured long in the die again with the ram all the way up/bottomed out and still no change.

Once you have seated a bullet in a case and as long as you have not made any adjustments/changes in your seating die, you can keep putting that cartridge back in your seating dies until the cows come home and the OAL will not change.

If you lower the position of the seating stem, then you will shorten the OAL the next time you put that cartridge in the die.

Of course, then other cartridges will now be shorter than they would have been with the seating stem at the original position.

On the other hand, raising the seating stem to make cartridges' OAL longer will not magically make a cartridge with the bullet already seated longer.

 

[Axis II]

Once you have seated a bullet in a case and as long as you have not made any adjustments/changes in your seating die, you can keep putting that cartridge back in your seating dies until the cows come home and the OAL will not change.

If you lower the position of the seating stem, then you will shorten the OAL the next time you put that cartridge in the die.

Of course, then other cartridges will now be shorter than they would have been with the seating stem at the original position.

On the other hand, raising the seating stem to make cartridges' OAL longer will not magically make a cartridge with the bullet already seated longer.

ya don't say! LOL.

I said that because someone mentioned not putting the ram all the way up. my comment was about me trying it again thinking I didn't send it all the way in and it still not moving.

 

[Hooda Thunkit]

When I first started reloading, back in the 1980's, I got all twisted up about those .005" variations.
Then I opened a box of factory Winchester and started measuring.
After measuring a dozen or so factory rounds, I stopped being concerned about it.

 

[Ironicaintit]

The only time I ever fuss over length variations, is if I'm building them to a maximum length for a magazine.
I'll run out a batch, then set my calipers to my spec, and run the rounds through it, like a go, no-go gauge.
The too long offenders get another pass through the readjusted seating die

 

[LiveLife]

Loading 124gr extreme 9mm with mixed brass and I have the die set to 1.140 but I'm getting from 1.140-1.145 being the highest. Put it back in die and don't budge so checked previous one and it was 1.142.

Any clue? I measured several pieces of brass and all the same oal so could it be the bullets are off?

For single stage/LCT press reloading, when the ram reaches the top, OAL variation comes from bullet nose variation as typical RN bullet seating stem does not push on the tip of nose rather further down on the nose/ogive. Variation in case length or headstamp have no input on the OAL as you can use 380 or 9x18 brass and end up with same OAL as 9x19/9mm brass using the same 115/124 gr bullet.

For progressive press reloading, shellplate flex/deflection is added to reloading variables and can significantly contribute to OAL variance. To minimize shellplate flex/deflection, you can use resized brass.

I also noticed that some cases wouldn't flare a lot to hold the bullet in the mouth and i would have to guide them up with my finger.

Case length variation directly affects amount of flare. Measure some of your mixed brass resized lengths and use the shortest cases to set the case mouth flare amount.

FCD is a collet crimping die unless the round is roll crimped. Good news, its not inconsistent start of crimping causing your 5 thousandths of an inch difference. I am currently setup to use a fcd on my 308 setup...

OP is loading 9mm and FCD for semi-auto pistol calibers is different than FCD for revolver calibers and FCD for rifle is further different.

FCD for 9mm is essentially a taper crimp die with tapered carbide sizer at the mouth (unlike other calibers like 380Auto, 40S&W, 45ACP, etc.) and thus cases cannot be push-through resized.

 

[scythefwd]

yes bds, that was pointed out earlier.. at least for 9mm

 

[mdi]

I had a recent struggle with 9mm seating depths (which kinda bothered me since I've been reloading for 30+ years and as a lifelong machinist/mechanic I can normally figger out problems easily). I had some new RMR 124 gr. JHP that I was loading for my "in case" stash. I was having difficulty holding .005"-.006" OAL which for me at least and my past experience is too much. I measures the bullets length, not more than .0015"-.002 variation in length. I measured diameter, not more than .0005" difference in diameter. I sorted cases by headstamp (I did find some WCC brass that had "distorted" rims). I disassembled my seating die and cleaned it (Lee, which has preformed flawlessly in the past). I re-formed the seating stem to give the bullet a better seat. Still an occasional OAL .004"-.006" longer. I even tried different methods (place bullet in case, raise into die just enough to start the bullet .010", lower the ram, turn the case 1/4 turn, seat about half way, lower, turn another 1/4 turn seat all the way). Then I tried some Nosler 124 gr, JHP. I was able to hold .002" OAL. The RMR bullets, while otherwise are pretty good must have had some variation in the ogive/profile of the bullet and accounted for the variation (my normal variation of .002"-.003" plus perhaps a .002" variation in profile).

I only tried 1,000 or so plated bullets and I'm not overly impressed with either the quality or performance, so I would say your variations come from the bullet...

 

[ponchh]

I put a dead stop on my press and cured most of that. On pistol loads .005 wouldn't worry me because I can't shoot em that good any way, but
.005 on my rifle loads sends me into orbit.
I stop the linkage from breaking over center. When you raise the ram up, then let off and it feels like there is a spring pushing back that can't be good. Anyway this is what it looks like.

 

[Walkalong]

I had some new RMR 124 gr. JHP that I was loading for my "in case" stash. I was having difficulty holding .005"-.006" OAL which for me at least and my past experience is too much.

You could always seat them with a flat stem. Did you test how they shot with an over .006 spread in OAL? Did it matter. If so, try a flat stem and retest. Just thinking out loud.........