Sooted and Booted Part III

Have I Found A Solution To My Dirty Cases?

You may recall two articles that I wrote in June 201o called Sooted and Booted Part I followed by Sooted and Booted Part II where I had encountered problems of carbon fouling covering the entire body of my once fired Full Length Sized Lapua Cases for my 6.5×55 Calibre.

I had a number of suggestions, from a number of different sources put to me with reasons as to why this could be happening.  Therefore I compiled a short list and decided to give each suggestion a trial to see if any of those suggestions did in fact solve my Sooted Cases problem.

Due to one thing or another I was not able to complete these tests last year.  Now more than 1 year on I have finally been able to get back to address this sooty dilhema.

During the past weekend I loaded up 10 fresh cases from two seperate batches that had been case prep’d, ‘this included those cases that I had trimmed to below recommended length with my Wilson Case Trimmer to bring about case uniformity in my quest to find the ultimate handload for my shooting stick.’

Day 1 Test Subjects:

  • The non uniformed trimmed cases were charged with a below maximum load of Vhitavouri N160 which I have used many times in the past and the bullet seated to a safe minimum that I have also used many times in the past.
  • The uniformed trimmed cases were charged with a hotter load of Vhitavouri N160 which I had not yet used in the past and the bullet seated to the same depth as above.

Other than the case length dimensions, I was testing a standard charge and a higher charge to see if either load would allow the case neck, shoulder and body to expand quickly enough when fired to seal the chamber from carbon blowing back towards the bolt face as the bullet is released.

Test Results:

  • In test subject 1 that had the non uniformed trimmed cases and below maximum charge the results where what I had expected.  The cases were completely covered in sooty burnt carbon once fired.
  • In test subject 2 that had the uniformed trimmed cases and contained the hotter load the results where somewhat of an improvement but did not meet my high expectations.  The first case fired from this batch ejected a clean case which raised my hopes that I was moving in the right direction until the second and third cases were fired and returned a sooted case.  Carbon had covered patches of the case body and stretched to the case head and bolt face, but not to the same extend of sooting as Test Subject 1 above

So it was back to my list from June 2010 and the next item to consider was bullet seating depth.

Back at my reloading bench I cleaned, prep’d, Neck Sized only with my new RCBS Die and charged the same cases with identical charges that I used in my first test.  The bullet a Lapua Scenar 139g was then seated to the depth stated in my reloading manual that had now left my Case Overall Length ‘COL’ at 80mm from case head to bullet tip.

Day 2 On The Firing Line

  • Test Subject 1 the 5 non uniformed trimmed cases with the below maximum powder charge were fired and the results were positive.  The cases were ejected and they were clean.  There was only a few marks of soot on the neck of the cases which is normal.  Although early days, it is quite possible the deeper seated bullets are allowing for that additional pressure to build up inside the case before the bullet is released.  So that the case neck, shoulder and body can expand to seal the chamber.  This then allows all the pressure to flow in the one direction down the bore pushing the bullet along.  Without testing it over a Chronograph I may even be getting a faster travelling bullet!
  • Test Subject 2 the 5 uniformed trimmed cases with the hotter powder charge were also fired and the results were positive.  All 5 cases came back clean of soot and carbon except for a little soot around the case neck as above, leaving me with positive thoughts on my results.

Accuracy And Bullet Seating Depth

Now we all want our shooting sticks to be as accurate as possible and I had thought perhaps this deeper bullet seating will bring my group size to tears at 100 yards.  On the contrary, my groups look to be holding together at 100 yards which is a great sign.

As I have stated above this is only a small preliminary test and I hope to test more of the same loads in a few weeks when back at the range.  I would like to have a longer distance to shoot out too, but for now 100 yards is what I have available and is sufficient for now.

Inset is a video of me shooting my Steyr 6.5×55 of a bench rest and producing those unforgiving sooted cases as mentioned above.

Your email address will not be published. Required fields are marked *