velocity variations

dnepr · Post by **dnepr** » Sun Aug 12, 2007 12:23 pm

I went out to get my Exomax ready for hunting season . I have been practicing with 2219 eastons and the strings that come with the bow since spring . I switched to a FFF string and the carbon arrows that came with the right stuff package. I readjusted the scope and and they shot great with the target points. I had to readjust the string a couple time then it seemed to stop stretching but then the velocities started dropping fron the around 344 fps down to 321 fps and it seemed to be a progressive loss . I then switched to a broad head to see where it hit compared to the target point and the velocity jumped right back up and was even better I was right up to 352 355 I even had one go 360 . I weighed the target points and the broad head and the targets points run the target points are 98-99 grains and the broadheads are 102 . I am wondering if this is the fff string settling in or does my chronograph read the 2 different tips differently . The chronograph I am using is a Shooting Chrony . I noticed that an arrow is long enough to be over both photo eyes at once and I am wondering if this could give me incorrect readings. Anyone have similar experiences or can shed some light on what is going on it would save me scratching a bald spot on the side of my head.

Boo · Post by **Boo** » Sun Aug 12, 2007 3:31 pm

Fast Flight likes to stretch, albeit not as much as Dacron. I notice the lack of mention of your brace height. That will be one of your variables that is causing an affect on your arrow speed. As your string stretches the brace height becomes lower so your speeds come up some.
The Chrony will give you accurate readings on full length arrows shot from vert bows so I doubt that the length has any play on what you are seeing.
A string dampener and maintaining a consistent brace height will aid you in achieving more constant arrow speeds.

dnepr · Post by **dnepr** » Sun Aug 12, 2007 5:01 pm

Thanks for the info. I was trying to keep the brace hieght right on the one inch line but it did vary a little . I do want to try a string dampener . I had read that they quiet the bow down with no loss of velocity. If they make velocities more consistant that is just another reason to try them.

Shakky · Post by **Shakky** » Sun Aug 12, 2007 8:04 pm

Could be a wax build up slowing down the bow. You get wax and dirt on the rail and it will slow you down a little.

Bill T · Post by **Bill T** » Mon Aug 13, 2007 9:23 am

My guess is that there are variations in the light intensity causing variable readings. My chronograph will go down in velocity if a cloud goes over the sun, so I only chrony indoors any more under artificial light.

Normous · Post by **Normous** » Mon Aug 13, 2007 10:42 am

Right, consistant light will give better consistant chrono readings. I only use mine on sunny days.

Norm

Boo · Post by **Boo** » Mon Aug 13, 2007 12:17 pm

Diffusers should be used on sunny days as well as a more blunt tipped arrow.
Copied from the users manual.
F. ARCHERY: Bow to Chrony distance should be at least an Arrow’s length. Blunt-tipped or flat-tipped arrows give more Accurate velocity measurements.
Funny and sad that this is the first time I've read the manual since I bought mine 13 years ago.

dnepr · Post by **dnepr** » Mon Aug 13, 2007 6:21 pm

Thanks for all the info . I think that different light angles might have been the culprit I started shooting early and the sun was just poking above the trees and it was close to 11:00 am when I stopped. I was useing diffusers so as the sun got higher It was going more through them than sneeking past the side . The velocities I was getting at first were right where I would have expected them to be. my arrow weigh 370 gr so 342 , 344 fps was right where I expected them to be. I will have to search the bowels of the basement and find my indoor kit for my chrony.