sooty deposits around case of mouth from low pressure?

[mattinPA]

hello
I  have alot of sooty deposits around my 308 case and was told it was from to low of pressure. My load was 42GN IMR 4064 pushing a 168 A-max that is just touching the lands.
I was happy with the groups with that load at 100 meters .
I started my test loads at 42.5 and seen less soot around the mouth of the case but there still seem to be quite a bit .I then try ed 43 /43.5/44GN and still had soot around the case with no differences
The case were trimmed down to 2.07 OAL before shooting
I have not gotten any high pressure signs yet. I guess I will try 44.5 next and see what happens but would like to have some input before I go on.

thanks for any help

matt

[Castaway]

Per the IMR site, you are operating on the low side of powder to bullet weight.  The most common cause of the powder on the neck is low pressure.  as you increase the charge, the neck will seal the bore and the carbon deposits around the neck will reduce and may stop entirely.

[goodconcretecolor]

You might try using a thinner walled(lighter weight) brand of case. Military cases are usually the heaviest and Remington or Winchester the lightest. If you are pleased with the accuracy, have no pressure signs and sooty necks, you wuld be envied by many.

[LaOtto222]

Sooty deposits mean nothing if you are shooting to good velocities and getting accuracy to your liking. I have 224 caliber guns and get the soot on all of them. One of my 223's is pushing the upper limit of pressure and I still get some soot around the neck. I could help this by turning the necks and making them thinner. Thinner necks does not take as much pressure to seal against the neck wall of the chamber. I tumble all of my cases before reloading, so the soot really does not bother me. If it bothers you a whole lot, you can shine them up with fine steel wool before reloading. I other words soot does not hurt a thing if you are getting the results you want. If the soot starts running the length of the cartridge then you are way under pressure, necks do not mean anything.

[mattinPA]

thanks for all the replies
I have no load data for the v-max so I am working up my loads and with the bullet on the lands I just don't want to over do it
I am getting some awesome groups at 100 meters but not that good at 200 and 300 .
I was hoping that the soot and the poor performance at 200,300 meters were connected
 I will find out this weekend to see if some of the hotter loads work better at 200,300
For one of the test I did not re size the neck the hole way    just 0.235 .I have read  that some people get better accuracy doing this .

Well  that's  have the fun finding the right loads
thanks matt

[Chuck White]

mattinPA
I know that many times you'll get conflicting information.

BUT, According to the Hornady reloading manual, 42.2 grains of IMR 4064 is the max powder charge for a 168 grain BTHP.

I know that this is a different style bullet than you're using, but the weight is the same.

Be careful!

[quickdtoo]

On the other hand, Hodgdon's 2007 Annual shows 45.9gr compressed IMR4064 as the max load for the 168gr Sierra HPBT, the Lyman 48th shows 45gr compressed and the Speer #13 shows 46gr compressed with the same bullet. The Hornady 6th doesn't list IMR4064 for the 168gr A-Max.

Tim