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Need Help. Huge Fps Spread.


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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

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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

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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....

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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.

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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?

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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.

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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.

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