Reloaded 9mm Velocity Way Too High

[Prowler53]

I'm fairly new to reloading and inherited a nice lot of gear and supplies, including a Dillon 550 press. I reloaded some 40 S&W without issue and decided to get setup on 9mm. After reloading maybe 50 rounds to take out and test I got some bizarre velocities. I'm using a Caldwell Chrono to measure the velocities (https://www.amazon.com/gp/product/B00HTN5DTE/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1).

The first string had a handful of shots ~860 - 980 fps. There was one or two that came in low around 550 fps. Then several shots in the order of 5000-6000 fps. A second string started with 5000-6000 fps again. I stopped wanting to investigate further to figure out if it was true reading or the chrono doing something funny. In between I shot a box of factory loads that all measured up fine. I don't see any signs on the brass of over-pressure and a close inspection of the firearm didn't show any signs of abnormal wear or damage. I'm at a loss of how this velocity is possible and frankly how I didn't blow metal into my hand.

I am using Tite-Group which I have read stories of being sensitive and I noticed more variation in the COL than I would like. All of the data is below with pictures. Please if anyone could give me any advice it would be much appreciated. I don't know if I'm pressing them too tight or if I should back down the powder significantly and test more?

Bullet: WB38MC130 (130 Gr. FMJ .356 diameter)
Powder: Hodgdon Tite-Group
Primer: Winchester Small Pistol
Target COL: 1.15
Powder Weight: 3.8 grs

I used the load data

 

[Prowler53]

Muzzle flash when too close to the chrono will cause erratic readings. Stand back 10-12 feet.

 

[H&R Glock]

Yup, read the destructions! Once you get far enough from the chrono, you will get accurate readings. My plated 115 grain bullets register about 1150 fps to reliably function my 9mm pistols.
Happy new year!

 

[MEHavey]

I was definitely bumping up as close as I could to the chrono

You're getting blast effect.
Back off to 10-ft+

 

[jmorris]

Then several shots in the order of 5000-6000 fps. A second string started with 5000-6000 fps again. I stopped wanting to investigate further to figure out if it was true reading or the chrono doing something funny.

If your 9mm was still in one piece after pushing a 130 to 5000 FPS, I wouldn’t trust your chronograph or you should be further away from it.

 

[Texas10mm]

You made too many ASSUMPTIONS. When you're working with something that can cause bodily injury or death ASSUMPTIONS are BAD...VERY BAD.

If in doubt ask questions BEFORE proceeding.

 

[booran1]

You made too many ASSUMPTIONS

I'm not sure what assumptions you thought I was operating on?

Yea, I'm not as experienced yet and working with a less forgiving powder, I get that. I worked up some numbers based on a handful of different data sets, picked a starting point, and tested it. I ran the press probably about 20 - 25 times, measuring each powder drop to see that it was consistent. Obviously where I screwed up right now is standing way to close to the chronograph.

Was there something I assumed that I'm missing?

 

[Texas10mm]

You assumed that two bullets of different construction would load the same. Biggest mistake many new reloaders make.

Bullet construction is important. Using jacketed data for plated or lead bullets is dangerous and can cause a pressure excursion.

Using plated or lead data with jacketed bullets can lead to a squib.

 

[fxvr5]

Using plated or lead data with jacketed bullets can lead to a squib.

Using the right load data can lead to a squib, too.

https://americanhandgunner.com/handguns/the-extreme-danger-of-squibs/

 

[Col. Harrumph]

My guess is, the 5000 fps reading was the speed of the venting gas.

 

[booran1]

You assumed that two bullets of different construction would load the same.

Well, I actually compared data from several different types, I just referenced one of the ones of a different construction :/. Still the effect of the construction is something I'm learning a lot more about as I go.