Interesting (non-scientific) study (45acp)

[CruelHalo]

Very few posts but a long-time lurker of these forums.  I’ve been reloading long enough to know what I know and know that I don’t know it all. 

 

Background:

 

• Lee Classic 4-hole turret press

• Lee Auto Powder Measure

• Lee dies

• x-Treme 230gr RN (0.452”)

• Bullseye 4.6gr

• OAL 1.245” (+/- .005”)

• Winchester Large Primer

• Random range brass tumbled with Lyman stainless media

   

  I was reloading 45acp last week and as I was placing the finished rounds into the holder, something seemed off with a few of the rounds. I decided to weigh all of the components separately and then weigh 50 of the finished rounds and noticed that there were a few that were heavier by about 5gr. This was a concern based simply on the basis of my charge weight and the possibility of a double charge was evident.

   

  I then charged 50 cases separately to see if the powder measure was off.  It wasn’t.

   

  I then weighed 50 random bullets and they were all within an acceptable range. Nothing extraordinary in terms of weight variance.

   

  I knew the primers were not going to be the cause but I weighed a handful and their weights were insignificant.  This led me to the brass and my initial thought was the possibility of stainless media being stuck inside the cases.  I checked about 500 recently cleaned cases and that was not the issue.

   

  I then randomly pulled the following cases (40) separated by the case’s headstamp and measured their weights (in grains); large primer pocket without a primer:

   

  Federal (6)

  83.2, 83.3, 83.9, 83.8, 83.3, 83.4

   

  Winchester (6)

  84.4, 84.4, 84.2, 82.4, 83.0, 83.3

   

  PMC (6)

  87.2, 89.1, 87.7, 88.8, 89.0, 89.9

   

  Speer (6)

  89.9, 90.0, 90.2, 90.5, 90.0, 90.4

   

  RP (6)

  83.8, 83.4, 84.0, 83.0, 84.0, 83.5

   

  PPU (4)

  80.1, 81.4, 80.1, 80.1

   

  SIG (4)

  86.0, 87.1, 87.4, 87.3

   

  Perfecta (1)

  85.3

   

  HRTRS (1)

  84.9

   

  I then reloaded the 40 cases and then weighed the finished round.  As I expected, the Speer cases were heavier by about 5 grains, whereas the other re-loads were within a similar weight range.  I felt much better in that I didn’t have to pull the bullets but it also made me think about the fact that Federal manufactures Speer brass.  Different specs? Different machining?  Oh well, my OCD stopped at that point.

[Hi-Power Jack]

I'm glad YOU"RE OCD - that took some time.

 

Appreciate you sharing it with us.     

 

I'm surprised the weight difference among brasses are 12% - that's a real eye opener.     

[Steve RA]

Shows why it pays to use only one brand of brass if you are going for best possible accuracy.

[mont1120]

Very typical of the .45 brass I have used. You will also find you get more failures on case gauging with the heavier brass, like the SIG. The absolute worst case is the A-MERC stuff, its only use is for recycled door knobs.

[jripper]

I've noticed a pretty wide range of variation in case weight on .45 brass myself.  I didn't go to the depths that you went to, but it is surprising.  I think it's differences in the rim and thickness.  I'm sure the larger the case (ie 45) the greater the variance.

 

[DougM]

I'll echo Mont1120's comments on the A-MERC brass.  Good only for weighing down the trash bucket.  Caused me a lot of grief until I figured that out.  Now I pre-sort brass just to find and dispose of that stuff.

[jripper]

2 hours ago, DougM said:

I'll echo Mont1120's comments on the A-MERC brass.  Good only for weighing down the trash bucket.  Caused me a lot of grief until I figured that out.  Now I pre-sort brass just to find and dispose of that stuff.

It's pretty horrible.  What brand ammo uses this?  I find it in my brass I buy from the indoor range.

 

[noylj]

Yet, accuracy at short distances (under 50 yards) is not effected much by velocity variations and Bullseye shooters have been firing very small groups for decades without any issues.

Back in my youth, I tried shooting handguns (.45 Auto, 9x19, and .44 Rem Mag) using mixed cases, identical head stamp cases, and identical weight cases and found that even at 50 yards, it just didn't matter and, for all three calibers, my average group size was smallest with the mixed cases (I had no idea what group I was firing until I finished the group).

Even my 1 MOA 7mm T/CU didn't change average group size at 100 yards with case changes.

When you start shooting 0.5 MOA or less, then start to worry about such issues.

[Jakobi]

I've noticed the same variation with .45 range brass but accuracy with my reloads is acceptable so I didn't see a reason to explore it further. I'm not surprised at all really.

Edited November 15, 2018 by Jakobi
Spelling!

[124gr9mm]

Thanks for sharing this.

like the others I've never been so concerned that I took the time to weigh cases, but I'm glad someone did!!

[ChuckS]

On 11/6/2018 at 4:44 PM, Steve RA said:

Shows why it pays to use only one brand of brass if you are going for best possible accuracy.

Not necessarily. I got this data was I was looking at various parameters while trying to reduce SD. This was back in 2012 so I am not sure of the origin of the brass. This sample was PMC.

[anachronism]

Well, you have done an excellent job of demonstrating that mixed brass gives mixed results. Thank you for all the work!

 

And it should be "CDO", not "OCD". That way everything is in alphabetical order, like it's supposed to be .

[rustybayonet]

I was taught, a long time ago:

Unless your doing precision reloading, never use finished round weights for any calculations.