Need Help. Huge Fps Spread.

[Flight]

Just loaded with my bnew 650 XL and was able to chrono the various loads I made. I noticed huge spreads on my reloads, something like 90 fps from the lowest to the highest.

Borrowed 6 rounds from my buddy which he loads himself and got only 13 fps spread.

Just FYI, I'm a noob at reloading. My platform is not bolted to the flooring, it moves a little on the down and up stroke. Another problem that may cause my spread is that I only use the fail safe rod, I have not installed a spring that attaches to the powder bar.

Hope you guys can help me troubleshoot the problem. Thanks in advance

[HSMITH]

What is the load, powder, primer, bullet, dies, etc?

The press DEFINATELY needs a solid sturdy mount.

[38superman]

There are quite a few things that could cause a wide velocity spread.

Make sure the powder charges are consistent.

Take 10 rounds from a loaded batch, pull the bullets and weigh the charges.

If they vary more than +/- .1 grain, that may be part of your problem.

Second, with a dial caliper check your O.A.L.

In my experience, it will naturally float about +/- .003

This is normal and will not make much difference in the ballistics.

I have never noticed any meaningful difference in velocity until the length changes by at least .010"

Take a loaded round and check the length. Press the nose of the bullet hard against a rigid surface and recheck the length.

If the bullet has moved you do not have enough case tension to secure the bullet.

This can cause a round to move deeper into the case when it hits the feed ramp.

Check the length of your brass.

If you're using range brass the length can vary quite a bit.

This can cause the crimp to have more or less bite on the bullet causing a variance in bullet tension.

That can translate into a corresponding change in the internal pressures when the round is fired.

There are a number of other things you can look at but these would be what I would check first.

You might also try experimenting with different powders.

Some powders are just inherently more consistent than others.

Good luck with it.

Tls

Edited August 4, 2006 by tlshores

[tightloop]

Not trying to be contenscious, but bolt the maching to a good platform and use it like it was intended....weigh the first 20 charges you throw to see if there is a big variance...that should fix it.

[vluc]

Just FYI, I'm a noob at reloading. My platform is not bolted to the flooring, it moves a little on the down and up stroke. Another problem that may cause my spread is that I only use the fail safe rod, I have not installed a spring that attaches to the powder bar.

Hope you guys can help me troubleshoot the problem. Thanks in advance

Bolt it down, use the spring...those parts are there for a reason. ANd then what the rest said....

[JFD]

You definitely have to have a solidly mounted press.

What spring are you not using? The only powder bar spring I can think of is on the old powder measures.

If it's the spring on the failsafe rod, then that's a bad thing and could cause quite a bit of variation.

[vluc]

RTM....

650?

[Flight]

I havent used the spring (not the fail safe spring) for the powder bar since the reloader didnt have one when I bought it. But Ive seen a couple of buddys reloaders with powder bar spring.

Since Im using the new powder bar/measure, do I still need it?

[JFD]

The springs are for the old style powder measures. You don't need them anymore.

I'm guessing the bench is your problem unless you're not smooth and consistent operating the handle.

[Flight]

I'll bolt the platform to the flooring which I think is the cause of my problems. Also like JFD mentioned a smoother stroke from the operator is one more thing that I should work on.

Thanks again to all of you.

I'll bolt the platform to the flooring which I think is the cause of my problems. Also like JFD mentioned a smoother stroke from the operator is one more thing that I should work on.

Thanks again to all of you.