Quote from: Graybeard on January 09 2022 01:39:46 PM MST
I?ve noticed that Bluedot has a very distinctive and somewhat nasty smell at lower pressures, too. You can tell you?re getting closer to the sweet spot in a work up when that goes away.

I hadn't noticed that but will try to check it out. My smeller isn't always the best LOL.

Doug

Quote from: The_Shadow on January 09 2022 11:46:54 AM MST
With Blue Dot I set my Chrony at 12 feet as some unburned flakes can trip a sensor.

That being said heavier loads tend to burn cleaners with Blue Dot.  Measure your crimp on the very edge of the case mouth, should be 0.4215" or 0.4220".

Thanks for that info, mine are measuring right at .422

Doug

Quote from: Graybeard on January 09 2022 08:37:04 AM MST
flbed gives some valid reasons for errors from optical chronographs. I've had errors for those reasons from the Chrony brand. They usually weren't consistent, like your 9 shot string.

One thing is for sure, you definitely weren't pushing a 155gr XTP at 3000+fps with 10.2gr of Bluedot. My top speed for that bullet was 1530fps out of a 5" 1911 using 800X. Recoil and muzzle blast were pretty stout. Your load should have felt fairly mild.

Yup, I agree on not pushing that at 3k+ for sure which is why I was really confused. I'm shooting these out of a RIA 1911 5". Iv'e since upped my powder charge to 12gns aiming to get 1300+ out of it.

Doug

Quote from: fltbed on January 09 2022 07:51:10 AM MST
Chronographs like your Caldwell, use light sensors to see the bullet pass by in order to figure velocity.  Things like, amount and angle of sunlight, powder ejecta and even muzzle blast can and do effect readings.

I suspect in your case, either the angle of the sun or powder ejecta giving you erroneous readings.  Or, like Greybeard suggested, you accidentally had it measuring in MPS.

Jeff

Thanks Jeff, you could be correct, it was 3PM here when I was out testing, the chrono does have lights but I didn't use them thinking it was bright enough out mostly sunny. I was about 10 feet away when firing which is what they recommend.

Doug

Quote from: Graybeard on January 09 2022 06:02:41 AM MST
313.2 meters per second is 1028 feet per second. Any chance the units were the issue?

That could be, I'll have to check that the next time I go out and test these loads again. I had a feeding problem and I think I didn't crimp enough. Thanks for the feedback.

so, being new to 10mm reloading, I had some blue dot and Hornady 155gn XTP bullets. I loaded up 10.2 gns and went to the range with my Caldwell Chronograph. The Hornady reloading guide indicates for a load of 10.2 gn Blue Dot and 155 gn XTP that the FPS would be 1150 fps, however my Caldwell Chrono recored an average of 3132 fps over 9 shots (I forgot to hit start on the first shot of 10). I don't understand the huge difference. I was approximately 10 feet away from the chrono firing at approximately 15yds. I believe the load is safe but I want to understand the discrepancy in FPS from my chrono. I can't find anything on the web regarding my chrono. Any ideas? I trust the load data but suspect my chrono.

Hi all, new to the 10mm, been shooting 40S&W forever. Reloading both. Real name here is Doug