Low MV

[Gd33333]

Doing some load development for my RPR 6.5CM and am getting substantially lower velocities than data anywhere. For example, using 140 grain ELDM bullets over 41.5 grains H4350, I’m averaging 2645fps. The gun is factory with roughly 500 rounds on it. 24” barrel. At 41.9 grains I’m averaging 2677fps. I’m using new but sized Starline brass, small magnum primers. Wondering if I should keep going up as I haven’t seen pressure signs. Thought?

 

[Rio Precision Gunworks]

Hornady manual has 41.5gr of H4350 at 2700 and is their book max. So, you're not that much slower.

If you keep going, you're not going to get any amount of substantial performance increase from another 50fps or so.

 

[rustyinbend]

I'm getting 2678 with single-digit SD's, tight groups, and sub-MOA over 1,000 yards with 43.0g of StaBall. Let your rifle tell you what the right velocity is. Ignore what others "think" it should be.

 

[DeathBeforeDismount]

Some barrels are just slow.

 

[Gd33333]

Hornady manual has 41.5gr of H4350 at 2700 and is their book max. So, you're not that much slower.

If you keep going, you're not going to get any amount of substantial performance increase from another 50fps or so.

True. I keep hearing 41.5 gr H4350 is the sweet spot for the 140 grn bullets. I’m not seeing fantastic SD’s here so has me scratching my head.

 

[Gd33333]

Some barrels are just slow.

Getting higher velocities from factory ammo so just just making sure I’m not missing something. Thanks

 

[straightshooter1]

Doing some load development for my RPR 6.5CM and am getting substantially lower velocities than data anywhere. For example, using 140 grain ELDM bullets over 41.5 grains H4350, I’m averaging 2645fps. The gun is factory with roughly 500 rounds on it. 24” barrel. At 41.9 grains I’m averaging 2677fps. I’m using new but sized Starline brass, small magnum primers. Wondering if I should keep going up as I haven’t seen pressure signs. Thought?

That powder seems a bit slow, but some of that might because you're loading with a long COAL??? Another issue might be the humidity you're loading in where if it's somewhat high humidity, the powder might have higher moisture content slowing down the burn rate . . . ??? Just a couple of thoughts that came to my mind.

Note that you've filled the cases pretty full if you're loading to a COAL of 2.800. See chart below that you might find of some help.

 

[KnowNothing256]

Getting higher velocities from factory ammo so just just making sure I’m not missing something. Thanks

Factory ammo often has special powder blends that develop higher MV. Higher MV doesn't necessarily correlate to more consistent ammo though, and it takes a ton of MV increase to buy better wind performance.

Small groups and small SDs are what you want, don't worry about the final MV average.

 

[hafejd30]

When I loaded 6.5 CM I was hitting pressure around 2750 fps. Shot best around 41.5 of H4350 with a 142 smk. I wanted more so I went back to 260 rem.

Depending what you want to do. You’ll be fine for 1,000 yd + with that speed

 

[Gd33333]

I'm getting 2678 with single-digit SD's, tight groups, and sub-MOA over 1,000 yards with 43.0g of StaBall. Let your rifle tell you what the right velocity is. Ignore what others "think" it should be.

I bought some of that but haven’t tried it yet.

That powder seems a bit slow, but some of that might because you're loading with a long COAL??? Another issue might be the humidity you're loading in where if it's somewhat high humidity, the powder might have higher moisture content slowing down the burn rate . . . ??? Just a couple of thoughts that came to my mind.

Note that you've filled the cases pretty full if you're loading to a COAL of 2.800. See chart below that you might find of some help.

View attachment 8363252

i like that chart. Where did you get it?

 

[Gd33333]

Factory ammo often has special powder blends that develop higher MV. Higher MV doesn't necessarily correlate to more consistent ammo though, and it takes a ton of MV increase to buy better wind performance.

Small groups and small SDs are what you want, don't worry about the final MV average.

True. Thank you!

 

[Gd33333]

When I loaded 6.5 CM I was hitting pressure around 2750 fps. Shot best around 41.5 of H4350 with a 142 smk. I wanted more so I went back to 260 rem.

Depending what you want to do. You’ll be fine for 1,000 yd + with that speed

Shooting my first prs match this spring so trying to find my perfect pill. Thanks

 

[straightshooter1]

I bought some of that but haven’t tried it yet.

i like that chart. Where did you get it?

That chart is from the app called QuickLoad. It's a helpful tool for developing a load. Is something that helps reloaders get in the ballpark and can save time and components as one develops a load. There's a somewhat steep learning curve to get to using it correctly.

It's not free. You can look it up with a search.

 

[Gd33333]

That chart is from the app called QuickLoad. It's a helpful tool for developing a load. Is something that helps reloaders get in the ballpark and can save time and components as one develops a load. There's a somewhat steep learning curve to get to using it correctly.

It's not free. You can look it up with a search.

I’ll check it out. Thank you

 

[spife7980]

Shooting my first prs match this spring so trying to find my perfect pill. Thanks

There isn’t one. Buy a good bullet and develop its favorite powder and seating depth recipe. You can make just about any bullet these days shot well

 

[DeathBeforeDismount]

Shooting my first prs match this spring so trying to find my perfect pill. Thanks

Don't worry your bullet will be the least of your problems lol. Ammo will start to matter in year 2.

 

[Gd33333]

Don't worry your bullet will be the least of your problems lol. Ammo will start to matter in year 2.

I’m sure you’re 100% right. Should be fun