brace height & point of impact?????

wabi · Post by **wabi** » Wed Sep 29, 2004 9:06 pm

Took the Exocet out and sighted it in with a new string and slightly heavier arrows a few days ago. Shot it the next day and it was still right on. Got it out this evening and the string had stretched a little, so I twisted it up a couple of turns bringing it to about 1/4" above the 1" scribe mark on the rail. I shot it at 40 yards and was about 4" high. Moved in to 20 yards and was about 1 1/2" high. 2 clicks down put me right on target, but I couldn't come up with a good reason for it to change in 2 days of storage. Would changing the brace height less than 1/4" have that big of effect on the accuracy?
BTW - checked all screws & fasteners and all were tight!

GaryL · Post by **GaryL** » Wed Sep 29, 2004 9:41 pm

Well If'n I had too guess I would be thinking lower as a heavier bolt should drop not rise.

Change in brace height of 1/8" higher may make for less noise but should not have changed impact by more than 1/4" at 40 yds then it also would have been lower not high...

The heavier bolt SHOULD have lowered FPS giving a drop not rise....

Sooooooowhat were ya

Seriously wabi it sounds as if something is kicking your bolt up

wabi, · Post by **wabi,** » Wed Sep 29, 2004 9:52 pm

Gary L.,
The Exocet was sighted in with the heavier bolt. The only change today was brace height! I'm starting to wonder about my scope now. I'll check it tomorrow, and if it changes any I may put the fiber optic front & rear peep on it. Sure hate to open the deer season with doubt in my mind. The only other possibility is the change from sand bags to just resting it with my hands on the bench. I guess the change in manner of resting it could make a difference.
wabi

GaryL · Post by **GaryL** » Wed Sep 29, 2004 10:01 pm

Quote in part "the change in manner of resting it could make a difference."

Possible if you were snap/jerking the trigger which I doubt as you been shooting to long, inless of course it is opening day jitters

Slap another scope on and try it, be a little quicker then putting the peep sights on.

Woodsman · Post by **Woodsman** » Thu Sep 30, 2004 7:29 am

Wabi, if you want to be sure try putting the brace height back to where it was and retest. I've heard it repeated several times that an increased brace height slows down the arrow somewhat so it should drop as GaryL has mentionned, but have never really tested this theory. I'm not so sure it works out this way all the time.

You also have to consider that a shorter string increases the poundage of the limbs by stretching them further. I understand the idea that a longer string gives a longer travel and therefore a longer push to the arrow. However, there is an ideal length of string for any bow. Take for example a simple long bow or recurve bow. If we go to both extremes of having a very long string or a very short one(and keeping the same draw length), both are inefficient at maximizing power to the arrow. We find that somewhere in the middle is the ideal string length. While not every bow is exactly the same, some may find an increased speed above or below the marked brace height.

I'm betting that your change of impact has nothing to do with your scope and everything to do with the change in brace height. But that's just my theory!

wabi · Post by **wabi** » Thu Sep 30, 2004 10:18 am

Thought about it last night, and I'm thinking the sandbags vs hands rested on the bench may be the problem. I usually just shoot it kneeling with my hand holding the forearm resting on the bench. I was right on and shooting well, then put the new string and went from 350 to 380 grain bolts. I then put it on sandbags without even shooting it the other way, and it was way low (3 clicks), so I raised it. It shot good, and I thought I was in good shape. Last night I shot the old way (kneeling and one hand firm on the bench) and it was high (2 clicks). I got to thinking the 3 click adjustment was more than it should have been. Usualy 1 or 2 will compensate for minor bolt weight, or serving thickness changes! The Exocet recoils more than the Vixen I used to shoot, so it's very possible the recoil with being solidly benched could make it shoot to a different point of impact. I'm going back tonight or tomorrow and try it with both shooting forms to be sure.
I guess my shooting form would be more likely the cause of problems than Excaliburs quality