Chrony with bp.

gutpile11 · 03-23-2006, 06:09 PM

I have a question about using a chrony with bp loads. I just got the master chrony beta. Ilooked atthe info with it and they said to cover thesensors with glass, plastic or clear tape.Has any onetry-ed this and if so how does it affect the accuracy of the unit? I what to test laods for 12ga and the 50 cal encore.

Roskoe · 03-23-2006, 06:41 PM

OK - I admit it . . . . I have blown away several chronographs . . . . three to be exact. But only one with black powder. And I think I know how to prevent the problem from re-occurring. Biggest issue is with sabot rounds. Even at 30 feet away, a plastic sabot packs enough punch to destroy expensive instruments. I now put a large brick in front of the display area. The steel rods and sunshades are somewhat expendable. You also need to be aware that sometimes the sabot goes through the skyscreens right behind the bullet and gives an odd reading. When shooting conicals there is really no big issue, other than being far enough away to prevent smoke and hot embers from hitting the instrument or giving a false reading.

lemoyne · 03-23-2006, 07:28 PM

I have the best results with mine by seting it up at 25yds since I don't have a brick I use a piece of 1/8 steel hinged to the bottom that swings up in front just to make sure the sabots don't hit the wrog thing. Lee

Underclocked · 03-23-2006, 07:35 PM

Fellow by the handle of Grouse makes this box for chronographs...
Tom Drechsler: hunttrky2@zoominternet.net

sabotloader · 03-23-2006, 09:14 PM

gutpile11

I am always afraid of hitting the chrono with a sabot - so I set mine really close to the muzzle, about 12 feet on a steady tri-pod (2 legs to the back one leg at the muzzle). The blast from the barrel will deposit some material on the chrono, the rods that hold the sky screens and the screens themselves...

I protect the chrono - it is totally wrapped in turkey basting tin foil - the thicker stuff. I then cut away the foil over the sensors and apply clear package tape across them. The face is protected with a heavier clear piece of plastic (like a thick zip lock bag) taped in place.

The problem: after shooting it is necessary to wipe the equipment down with a damp cloth + oil the sky screen rods.

So far I have been really lucky - I just betting the sabot can not come off in 10-12 yards....

skeeter 7MM · 03-23-2006, 11:41 PM

First off since you have the master model it has the remote display or face feature. Assuming your within cord reach of the chrony/bench the display should be out of harms way. As for the unit itself I believe chronymentions the tip: of marking the rods for the sky screens at 4 - 6" above the "eyes" or sensors as a aim reference point. 4" is for open sites and 6" is for scoped...if you use both then mark both reference points with coloured tape to allocate your aim point for the particular situation.

As to your question, clear scotch tape or packing tape placed over the "eye" or sensor will keep debris from this area. However if that isn't your style to go taping up your new toy or building something, Chrony does sell a plastic protective guard for this purpose for 10 bucks.

The tip about a tripod with 2 legs to the rear is a good one, seen more than few tip over at the range after a stiff muzzle blast.

I set my chrony up approx. 15 feet from the bench for CF and ML.

* Noteif your wanting to chrony a shot load from the 12 gauge,may want to bring that in tighter!!!

*

Enjoy

gutpile11 · 03-24-2006, 09:52 AM

Thanks for all the tips. After making a few calls to my buddy's to tell them about the toy. I now think that the ammunition manufactures invented the chronograph. I think between me and three of my bud's we bought all the ammo in the area.

Were all heading to the range tomorrow to do some testing.

Roskoe · 03-24-2006, 10:19 AM

That's what I thought too. The most recentChrony I ruined with a sabot was about 10 - 12 yards away. I'm thinking those sabots must flare out and drop back earlier than that - may only a foot or so from the muzzle. They tend to follow the bullet, I'm sure, for quite a distance. But not real consistently. It was surprising how much force they still had left. I'm not sure if 3/8" plywood would have stopped it.

sabotloader · 03-24-2006, 11:38 AM

Roskoe

The last sabot I chrono'edgoing across mine was traveling at 760 feet per second. at 12' feet that would bruise a guy or break the face plate of a chrono. Often I shoot across the chrono without the sky screens if there is enough clouds and often i do not get the bullet speed but I do get the sabot speed.

So far I have really been lucky as my sabot are getting across the chrono, but if the crown of the barrel happens to be dinged a bit or the wind is blowing right you might really get some strange acting sabots.