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Will Lee · April 11, 2012, 10:52 PM

I don't know if you will ever be able to get 3000 fps out of a 18.5" barrel.
Twist rate has no affect on MV.

Most loading manual data is developed using a 24" barrel. As a ball park figure you can use 40 fps loss for every inch of barrel length. The only way you will ever know is to use a chronograph.

Most loading manuals are conservative with regards to max loads. If you are looking for the highest velocity with acceptable accuracy you can load above max but only in .3 grain steps watching very carefully for over pressure signs (primer crating, ejector pin marks on the case head) if you see any of these signs back off.

The rounds you load over book max need to be marked (with a red Sharpie) in some manner that you will know those rounds are over book max. (I color the necks)

I also use a red sharpie to write the powder weight on every case.

Here are some photos of 223 Rem load development I just completed. This group is at 100 yards and is .5 gr over book max.

April 11, 2012, 10:52 PM	#3
Will Lee Member Join Date: November 30, 2011 Location: North Texas Posts: 99	I don't know if you will ever be able to get 3000 fps out of a 18.5" barrel. Twist rate has no affect on MV. Most loading manual data is developed using a 24" barrel. As a ball park figure you can use 40 fps loss for every inch of barrel length. The only way you will ever know is to use a chronograph. Most loading manuals are conservative with regards to max loads. If you are looking for the highest velocity with acceptable accuracy you can load above max but only in .3 grain steps watching very carefully for over pressure signs (primer crating, ejector pin marks on the case head) if you see any of these signs back off. The rounds you load over book max need to be marked (with a red Sharpie) in some manner that you will know those rounds are over book max. (I color the necks) I also use a red sharpie to write the powder weight on every case. Here are some photos of 223 Rem load development I just completed. This group is at 100 yards and is .5 gr over book max. Last edited by Will Lee; April 11, 2012 at 11:12 PM.