Perceived wisdom

We've all read the magazines and web sites where the experts tell us that every tiny last bit of brass preparation is critical for producing accurate ammunition. Also, only neck sized brass will do - we are told that full length sizing just doesn't cut it.
We generally just go along with this as the science behind their reasoning appears sound and these guys are often champion benchrest shooters. If they don't know what they are doing who does?!

However, have you tested before and after results yourself to see what works in your rifle? No? Thought not ;)
Most folk (including myself) just go along with the perceived wisdom.

The test

For this short article, I thought I'd test some common ways of preparing brass and see what works in the real world and in my rifle.
22 rounds were to be used for this test with four groups of 5rounds representing each of the four preparation types. A further 2 rounds would be used to foul the clean barrel.
All the brass was one fired Hornady brass which had no previous preparation.
The brass was to be split into four groups of 5 rounds each and treated as follows:

• Type 1:
  • Decapped
  • Ultrasonically cleaned
  • Full length sized using cleaned dies set to bump the shoulder one thou
• Type 2:
• Decapped
• Ultrasonically cleaned
• Neck sized using cleaned dies set to size 85% of the neck
• Type 3:
• Decapped
• Ultrasonically cleaned
• Full length sized using cleaned dies set to bump the shoulder one thou
• Trimmed to length
• Inside and outside neck deburred
• Primer pockets cut and uniformed
• Primer hole deburred inside and out
• Neck inside reamed
• Full length sized using cleaned dies set to bump the shoulder one thou. This is done a 2nd time to re-centre the neck after reaming and turning
• Type 4:
• Decapped
• Ultrasonically cleaned
• Neck sized using cleaned dies set to size 85% of the neck
• Trimmed to length
• Inside and outside neck deburred
• Primer pockets cut and uniformed
• Primer hole deburred inside and out
• Neck inside reamed
• Neck sized using cleaned dies set to size 85% of the neck. This is done a 2nd time to re-centre the neck after reaming and turning

Most of the brass preparation was done with the excellent Forster tools.

Forster case trimmer and "deburring base" in the background.
This can be fitted with an inside neck reamer, outside neck turner, primer pocket uniformer,
inside / outside deburring, etc, etc, etc...

Measurements

After initial preparation, the brass and loaded rounds were measureed on an RCBS CaseMaster tool

RCBS CaseMaster

The rounds were loaded with a known accurate load and after loading, bullet run-out was measured:

The test and results

So place your bets, which would you guess was the most accurate?

The day of testing was cold, but absolutely still with smoke rising vertically - great conditions for this sort of testing.
I fired the 2 foulers first and then fired one round of each type at a different target before allowing the barrel to cool. This was repeated - one bullet of each type and cooling - until all 20 rounds were fired.

Here are the results in glorious technicolor:

Type 1 - cleaned and full length sized only

Type 2 - cleaned and neck sized only

Type 3 - full prep and full length sized

Type 4 - full prep and neck sized

My guess is that virtually all knowledgeable reloaders would have guessed that the neck sized and fully prepared brass would be the most accurate. Surprisingly it performed the worst of the lot and by a huge margin!
Moral of the story - test everything :)
Kev.