Determining C.O.L.

[savageT]

Please bear with a novice here.  I have a 6.5x55mm Swedish Mauser M38 and I need to find out where the rifling is in relation to the bolt face.

#1  I've de-primed a once-fired,sized, and trimmed case and pressed a Hornady 140 gr. SP bullet in the case (on the long side@3.185") and checked it for bolt closing....It closes OK.  The over-all-length of this cartridge is longer than what the Lyman Handbook lists for C.O.L. (3.062" max).  I measured the distance from the neck opening to the center of crimp groove on the bullet @about.150".  Can you tell me if I can determine where the rifling starts using the bullet/cartridge as a spacer?  If so, how do I find where the Cannelure is on the bullet to measure that length?  Thanks for the helping hand.

#2  I tried using a new Bullet-Puller (the one that looks like a hammer), where the shell is held with a collet in the extractor groove and you bang the opposite face of the hammer on a bench block........didn't dislodge the bullet.  Any thoughts?  I didn't have any powder in the case??

Jim

Jim

[John Traveler]

Hi, SavageT!

The method you described is fine for determining bullet seating depth where the bullet just starts to engage the rifling.  HOWEVER, that is bullet seating depth, does not necessarily give you the COL you desire!  The COL is dependent on magazine length, bullet style, shape, ogive, weight, and a bunch of other things.  Yes, you can determine the origin or leede from your trial bullet seating.  Just use a Sharpie or Magic Marker pen to paint your bullet nose (ogive and bearing surface) and chamber that round.  The origin of rifling will show clearly as scrape marks on the jacket.  If your cartridge case is trimmed to maximum length, you can then measure to find the distance to origin of rifling.  COL should allow bullet nose to be just short of touching the leede.

As for your kinetic bullet puller not working, try rapping smartly on a harder surface.  a block of hard wood or a slab of Formica plywood.  Most military ammunition is made with asphaltum or a varnish-like waterproofing material that makes them a real bear to pull out.  Rap harder.

[savageT]

Hi, SavageT!

The method you described is fine for determining bullet seating depth where the bullet just starts to engage the rifling.  HOWEVER, that is bullet seating depth, does not necessarily give you the COL you desire!  The COL is dependent on magazine length, bullet style, shape, ogive, weight, and a bunch of other things.  Yes, you can determine the origin or leede from your trial bullet seating.  Just use a Sharpie or Magic Marker pen to paint your bullet nose (ogive and bearing surface) and chamber that round.  The origin of rifling will show clearly as scrape marks on the jacket.  If your cartridge case is trimmed to maximum length, you can then measure to find the distance to origin of rifling.  COL should allow bullet nose to be just short of touching the leede.

As for your kinetic bullet puller not working, try rapping smartly on a harder surface.  a block of hard wood or a slab of Formica plywood.  Most military ammunition is made with asphaltum or a varnish-like waterproofing material that makes them a real bear to pull out.  Rap harder.

John,
Ok, I will use a magic marker or some Prussian Blue I have to coat the bullet.  My cases have been trimmed to the Minimum (not Maximum length).  Should I be using Maximum length?  Thanks for the clarification on C.O.L. as opposed to bullet-seating depth.  Do I ignore the C.O.L. to determine bullet depth?...I know there should be .005 to .020" gap between the bullet face and rifling toprevent excess pressure problems.

As far as the kinetic bullet puller, I was using a dry two x four to beat on, but I guess you really need to whack it!  Is there another way to pull the bullet w/o ruining the bullet finish?  I ended up using vise-grips on the Rock Crusher to pull the bullet.  Thanks again John!

Jim

[John Traveler]

your Prussian blue marker works fine.  If you have some of that, you might be in the machinist/layout/stock inletting line of work?

Using case min or max is not important; the intent was to get you close to bullet seating depth, which of course is related to COL.

COL is given in the reloading manuals to get you in-the-ballpark for useable ammunition (factory magazine maximum).  It may not apply at all if you want to seat bullets WAY OUT for use in a single shot rifle with long leede, for example.
 
The collet-type bullet pullers work well with minimum damage to the bullet.  they are much faster than the universal inertia-type pullers.  With really hard to pull bullets, you may do some rim damage.  By the way, most visible damage to a bullet does not hurt accuracy for most purposes.  I used to squeeze .312 bullets down to .308, and had several thousand pulled bullets with prominent puller dents and dings and yet they shot just fine.

[savageT]

your Prussian blue marker works fine.  If you have some of that, you might be in the machinist/layout/stock inletting line of work?

Using case min or max is not important; the intent was to get you close to bullet seating depth, which of course is related to COL.

COL is given in the reloading manuals to get you in-the-ballpark for useable ammunition (factory magazine maximum).  It may not apply at all if you want to seat bullets WAY OUT for use in a single shot rifle with long leede, for example.
 
The collet-type bullet pullers work well with minimum damage to the bullet.  they are much faster than the universal inertia-type pullers.  With really hard to pull bullets, you may do some rim damage.  By the way, most visible damage to a bullet does not hurt accuracy for most purposes.  I used to squeeze .312 bullets down to .308, and had several thousand pulled bullets with prominent puller dents and dings and yet they shot just fine.

John,

Again, Thanks for all the help!  The Prussian Blue was something my Dad used all the time in tool-making layout in a can with brush applicator.  I purchased a tube of paste (like artists' paint) from Brownells to help out in stock bedding, as you pointed out.

After noting the bullet markings following insertion w/ the bolt, I measured the markings and came up with 2.520" from base of case to the markings on the bullet ogive, I believe it's called (where the bullet reaches its maximum diameter).  Now, ( Big Breath here) what do I do with this measurement?.....What is it, and what do I do with the information, since it isn't the C.O.L., or the bullet seating depth?  Do I subtract .005 to .020" from this test case C.O.L. length? Is that my correct cartridge over-all-length to seat the bullet to for best accuracy?  I realize I have to be able to magazine load and smoothly extract these rounds, but that is how to arrive at best bullet seating depth?

Jim