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CED ProChrono erratic readings with reloads but not factory ammo


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I just bought a new CED ProChrono....yesterday I tried it for the first time...

I started with factory ammo to test the accuracy of the unit...it was spot-on accurate

Then I started running my reloads through and the readings were fluctuating by 10 PF....I tried different loads on both 180gr and 200gr CMJ FP's and it still fluctuated a lot..

I load with a Dillon 550B....is there a reason my reloads are that far apart??

HELP!!

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How many rounds did you measure? What was the average and the standard deviation?

FWIW - I usually run 10 rounds at a minimum and that is after at least a couple of rounds have been shot through the barrel.

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I would think that 50 fps is a lot of deviation..isn't it?...I am new to chronographs, so maybe it isn't bad.....after I shot a few rounds of factory ammo, it was within 1 fps, and I know that reloading won't get me that close, but a variation of 50 fps I would not think it is acceptable...maybe it is....you experienced guys can tell me, please

Thank you

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It was like 825-875 fps deviation

I don't think you mean there was a 825-875 fps deviation, I think what you mean is you saw a range of 825-875 fps (a difference of 50 fps from min to max) with your reloads.

That isn't abnormal. You didn't provide all your specifics (load, gun, etc.) but you can probably tighten that up with more consistent powder charges and improving your reloading skills. But, your subject is probably off base and gives a reader the impression that your chrono was erratic when more than likely it was your loads that were "erratic" (in your words).

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It was like 825-875 fps deviation

Glock, if all your rounds were in the 825 - 875 fps range, there is nothing

wrong with your loads or the chrono.

That's normal distribution - at least in my experience.

We all hope the range will be smaller, but usually isn't.

How's the accuracy?

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I am running an STI Edge with a 6" barrel, Fusion barrel..

My load was..

5.0 grains of HP-38

200gr Precision Delta FMJ FP

OAL is 1.198....my gun likes longer OAL's

My FPS were..

Low of 907 and High of 960 and a 10-round average is 924.6 FPS

This might be a normal deviation...I don't know for sure..

I am a newbie to a chrono, but I am not new to reloading...2 years under my belt there..

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Are you using the same brand of brass for your test? I will get that deviation from mixed head stamps. When I tested my 9mm load with Winchester brass my extreme deviation will be 7. Using mixed brass I can double or triple that.

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Yep. Same head stamp and use lube. Those two steps will tighten things up considerably. Then you can get down to the nitty gritty by pulling the first few rounds off the press and putting them in the practice bucket. Same with the last few as well. Keep the press moving fluidly during a run. Don't stop and start except to reload primers.

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I separated my brass this morning on my 40 S&W brass...I have a question..

On the Winchester brass, I have both the name "Winchester" stamped on some of the brass and I have an equal amount of brass stamped "WIN"

Should I further separate these, or is it OK to mix them together, because they are both Winchester brand?

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I separated my brass this morning on my 40 S&W brass...I have a question..

On the Winchester brass, I have both the name "Winchester" stamped on some of the brass and I have an equal amount of brass stamped "WIN"

Should I further separate these, or is it OK to mix them together, because they are both Winchester brand?

Those two are most likely interchangeable. Look out for WCC and WIN NT. WCC is Winchester military with crimped primer pockets. NT is not toxic and in my experience the primers don't seat as well unless I ream the pockets. You can ream pockets on WCC as well but from what I understand the inner dimensions are different so the pressures will be different. Not to unsafe levels but certainly enough to throw off your chrono testing.

Edited by Sarge
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I hear you about the NT brass....learned that from loading 9mm with FC and FC NT...NT's would not allow a primer in the pocket at all !

Hmmmmmmmmmmmmm............I just finished loading a batch using only FC and FC NT range pick up brass. No problems and all brass had no problems seating primers on my 650. All was well.

PS.........they all go bang too as and added bonus.

Edited by mjohn
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I hear you about the NT brass....learned that from loading 9mm with FC and FC NT...NT's would not allow a primer in the pocket at all !

Hmmmmmmmmmmmmm............I just finished loading a batch using only FC and FC NT range pick up brass. No problems and all brass had no problems seating primers on my 650. All was well.

PS.........they all go bang too as and added bonus.

You might have picked up brass that has already been swaged.
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