Rentedmule

Thanks for the replys. Was kinda worried as this is the first time I loaded towards the upper end of listed load data. The load shot well and I would like to keep it. I am kinda curious if the velocities listed in the manuals are as read from a chronograph or calculated back to true muzzle velocity, and how they compare.

Anyone know a quick rule of thumb or a resource to calculating muzzle velocity? Here's my problem: My velocity readings on my chronograph are 100 fps above the listed load. The load data was for a 4" barrel where I am shooting a 6". My chronograph is 10' from the muzzle. I know I will gain some velocity from a longer barrel. No pressure signs but I don't have much experience in looking for them. If my chronograph is accurate then my velocities are over the max listed in the manual. The load is actually for a 38 special but I am posting it here as there is more traffic here. If it helps my load of 5.6gr of unique for 125gr Hornady XTP HP is listed at 900fps and my chronograph is reading 1000fps. So how do you correlate the chronograph reading to actual muzzle velocity? Is the drop in velocity from the muzzle to the chronograph enough to worry about?

Thanks for the replys guys. I think I may have figured out some of the powder variance problem. I noticed some small amount of powder was sticking to the inside of the neck maybe due to some of the spray lube getting in there. Don't know if it will be that much but it cant help consistency. Will try a "dry" case tonight and see if it still sticks in there. I will probably wait until I can get some non magnum pistol primers but after building the bench, ordering the supplies, reading everything in sight, and setting up the machine, I am getting impatient. I am going to start with the minimum load anyway for the first group but I don't want to start off coloring outside the lines. Once again thanks, I'm sure I'll be bothering y'all again

First of all thanks to all who post and help us new guys here. I have learned a ton reading this and other forums. I have just got my 550B set up and loaded my first 223s. I am taking it very slow as I do not have a mentor locally to help. Three questions I have either not been able to find the answers to or have read conflicting information. 1) Do you need to or should you crimp rifle cases if they are to be used in bolt rifles only? The bullets do not have a cannelure. 2) When checking the powder charges I am getting a variance of 0.2gr between drops consistently with a 0.3gr difference every tenth round or so. I am using H335. Is this normal and acceptable? I am checking the charges on two separate scales and while a slight variance between scales is present, it seems that could be explained by both scales being accurate only to the 0.10gr. 3) How do I adjust my load if using a small pistol mag primer vs the small pistol primer called for on the 9mm load? I have the mag primers and cant find the small pistol. Will be using Tightgroup powder most likely if that matters. Thanks