Velocity Question

[HuntPA]

Start super and back down slowly in 0.3 or 0.5 grain increments. Bullets don't go much slower than 800 fps depending on barrel length before they stop in your barrel. Eventually the bullet will stop in the barrel. CHECK between EVERY round that the barrel is clear. Eye opening to me how much force it takes to move a bullet through rifling.

I have had luck with A1680 for a sub load in a 22 inch barrel.

 

[dellet]

Start super and back down slowly in 0.3 or 0.5 grain increments. Bullets don't go much slower than 800 fps depending on barrel length before they stop in your barrel. Eventually the bullet will stop in the barrel. CHECK between EVERY round that the barrel is clear. Eye opening to me how much force it takes to move a bullet through rifling.

I have had luck with A1680 for a sub load in a 22 inch barrel.

This really is important, with the gain on popularity of subs. There really still isn’t t reliable load data for the many combinations of cartridges, bullets and barrel lengths out there.

I was given a handful of 250 grain ATip when they first came out to try as subs in 300 Blackout. An interesting combination, with an interesting set of problems. Because of the length and weight of the bullet the window of suitable velocity and over pressure was pretty small. I was confident in the load I chose as being safe, and probably higher than needed in a 16” barrel, but chose to try it first in a 8” barrel. Less chance of a stick bullet.

First round measured 250 fps according to Lab Radar. Checked all the settings, second round 300 fps. Set up a second chronograph that confirmed the low velocity. Bumped the charge weight, no real change in velocity.

I was using data that had got 1400 fps safely for a 265 grain cast bullet. Pretty sure it was the bullet. After careful measuring I was stumped. Started reading reviews looking for excessively low velocity problems.

What I eventually stumbled on was people talking about the nice little gift that Hornady included with the individually separated bullets, everyone needs a Hornady logo rag. Turns out the bullets weren’t cleaned after manufacturing and still had on oil coating. The rag was to wipe off the oil. Velocity problem solved. A good example of friction, pressure, velocity relationship. It’s just really magnified with subs

 

[Bowhunter41]

Charlie b

Thanks for the responses I was also thinking of raising the muzzle up to ensure most if not all powder was near the primer.

More experiments to come. I found on sniperhidw forum guys using faster burning powder. When one looks at the hodgdon manual the one page has burn rates of powder froM fastest to slowest while a lot of people say Trailboss that burns relatively slower than say titegroup or tite wad.