COAL possible range?

[dpete]

I was at the range this past Thursday doing the round robin OCW ladder loads and came up with what I think is the load to go with for my rifle.  I'm using CFE223 which Hodgdon lists 49gr as the top load for 168  HPBT bullets.  I'm using Hornady #30501 HPBT 168gr bullets.  I started with their 49gr load and went down in .3gr increments, then did the round robin ladder upward through 49.3gr.  No serious pressure signs were seen, even on the 49.3gr fired cases.  They were almost identical to the midrange loads.  The 48.7 and 49gr loads were almost identical in target placement and pattern so I think I'll load a small batch of 48.8gr to stay under max but still stay within the good zone.

 

Now my question.  With 2.80" listed as COAL for these bullets, what kind of length range do I dare test to see if I can further reduce the pattern?

 

I have seen where others have found sweet spots slightly above 2.80" and some below.  How deep can I seat these bullets before I start running into excess pressures due to bullet depth?  I will be doing the round robin ladder method once again for these 48.8gr bullets at different depths and checking for pressure signs on each case as its fired.

 

The barrel is a Criterion 18.5" lightweight profile sold by Fulton Armory, and the upper/lower/BCG is all Aero Precision.

 

[Dane Armory]

I haven't used CFE223 for 308 but there are two member who have extensive posts on that powder in the reloading section.

As a general statement ; if you keep the COAL between 2.795" thru 2.805" and use less than max loads there should be no excessive pressures or loading problems. The steel and plastic mags should except all of those cartridges.

[AngelDeVille]

The biggest limiting factor in length is the magazine. IIRC, both my lancer and magpuls max at about 2.82.

Seat too short and your accuracy degrades because the bullet has to jump to the lands of the rifle.

Also too short can reduce feeding reliability AND increase chamber pressure.

Too long and not having enough jump to the rifle lands will increase pressure.

Edited April 4, 2015 by AngelDeVille

[98Z5V]

i think that "too short" and the increased chamber pressure comes from compressed loads - check your depth from case neck down to the powder level, and determine how far you can seat your projectile before you have a compressed load.  Anytime you seat deeper than that, successively, you're compressing more, and increasing chamber pressure more. 

 

Also, seat a projectile in an empty case - and seat it long - much longer than magazine length.  Don't crimp the case, at all.  Fully chamber that round by hand.  This will tell you how long you can seat it, and just hit the lands.  Seat shorter than that.

 

Your ultimate restriction is magazine length.

[dpete]

Hmmm, for some reason I never thought of physically measuring down to the powder surface inside the case mouth to figure out how deep the bullet can go before starting to compress things.  Thats a great idea!  It will at least get me in the ballpark of knowing how deep is too deep, which with bullet seating can be bad as oppossed to some things which way deep is GOOD.    <thumbsup>

[planeflyer21]

RE: Compressed (powder) loads, make sure the powder manufacturer doesn't have any warnings against compressing the powder you are using.  There are a few which expressly advise against compression.

[dpete]

Compressed loads are something I want to avoid.  That is why I'm concerned about getting the COAL too short and increasing the pressure too much.  

[98Z5V]

In some powders, to get what you want, you'll have compressed loads.  It just works out that way - never "just decide" to make your own compressed loads - if you don't find a reference for a compressed load that comes from a published load data book, then don't even play with it.  Always be cautious with compressed loads, and always use a published source for information - multiple published sources if you can.