High velocity readings, and case mouth problems.

[kirbymagnum]

I'm not sure whether my chronograph is lying to me or if this is standard velocities for the charge weight.

Information: Barrel 26" Pacnor 1:11 twist, 27.5 grains of H4895 40 grain V-max average velocity 3867 fps, ES 39.54, Sd 16.34 my group measured .440 for a five shot group.

My cases have been fired probably 4-5 times and the neck sizing die doesn't seem to be resizing them enough because the bullets don't seem to be as tight as they were the last firing (It takes a significant less amount of pressure to seat the bullet). I was testing loads with these seem to be less uniform/tight mouths which would cause 3-5 inches groups so I'm sure there is a problem. The bushing size is .226 all the equipment is Redding.

[BabaOriley]

I think the velocity sounds about right for that charge/bullet.

[Jim White]

Whats;

The temp, elevation, muzzle to chrony distance, lighting conditions?

I was just load testing the other day and with a slight overcast I was getting 3725 with a 39SBK from my Remington 700 (VLTHSS) with a 26" barrel. The temp was 80 deg, elevation is about 50' above sea level, distance between the muzzle and Chrony was 14 feet. When the sun came out from behind the clouds add about another 50 FPS to it.

As far as the case necks I don't know but i'm wondering if annealing would help.

Jim

[jo191145]

Seems a little fast according to Hodgen. No big deal. Book data is just that, book data.
Even Pac-Nors standard 204R reamer is probably tighter than a factory chamber. Both in case circumference and headspace. Less chamber volumne means higher velocity per charge weight.

Move the lands a little closer to the bullet(not vice versa) and a nice smooth uniform bore and its very easy to add 100fps.

As carbon builds in the neck it will act as a lubricant. Not nescessarily a bad thing but it will change the load requirement.
Bad thing = carbon in some and not in others. That will really mess things up.

Annealing will remove some carbon and roughen up the necks along with softening the brass. They'll seat more like new brass. Stiffer. I usually use a little Imperial dry graphite on a brush after annealing to relube the necks a little. This brings them back to the seating condition most encountered once the carbon begins to rebuild. I use no expander and assume your not either. I use a .225 bushing. Usually try a .224 with my loads to see if they improve. .225 usually wins.

You are correct to pay close attention to seating feel. It seems very important in the small bores to be consistent.
When I load my factory 204R (100rds)for a shoot I seat all the pills last. Anything that does'nt feel right gets left home.

[bigun]

i neck turn mine down to 12thou and end up useing a .224 redding neck bush ..it sounds to me you are useing wire wool on the necks .and takeing some of he brass of with out you knowing it ..go out and buy the next two bush sizes down .226 and .225

[kirbymagnum]

The temp was about 20-25 C, elevation is 1000 feet above sea level, it was cloudy but not overly dark out because it was around 2 pm, and the chrony was 10' away.

Thanks for all of the help and information.