Excal string stretch
 

I'm really bummed as I write this. Took the Excal out for a late season hunt yesterday and really screwed up.
Had a buck come in and offer a 15 yard shot. Long story short I barely drew blood and we had some snow on the ground yesterday. Left him overnite and went back this morning and trailed him until there was nothing to follow. I think I just barely grazed him as there was hair and just a little blood on the bolt.
Came back home and shot the bow just to make sure it was human error. I was shocked as 2 bolts hit 8 inches low and 6 inches right. Had just shot the bow 4 weeks ago and it was dead on.
Checked my marks on the rail and my string was almost ½ inch off of the mark, it was fine 4 weeks ago.
I know, I probably should have checked this before hunting with it BUT IT HAD ONLY BEEN 4 WEEKS SINCE I SHOT IT. My string is old but in great shape. Guess it’s time for my new "Boo" string.
My questions for you Excal guys are…
Is it common for a string to stretch this much in 4 weeks with no shooting involved?
Was I wrong for not checking my string with my rail mark?
Sick to my stomach,
xbowbarry

Yes it is, that is why I make a point in my website to say that when you have found your preferred brace height then mark the side of the rail with a paint dot so you can see in an instant where you are. BTW, not that it matters but the correct term is creep. Which is the permanent elongation of the string. The factory string is made from Dacron and creeps and stretches a lot. That string will continue to creep but at a decelerated degree as time goes on. However it sounds like you have another problem. A brace height change of that much should not cause that reaction or at least that much.

Here's a picture of what I mean.

Don nailed it pretty much. I have a buddy I set up w/ an Ecet. A year later, his string was down on the riser it had stretched/crept that much, I just happened to catch it as he was going hunting.

Since you are no doubt replaying the shot in your mind, I'd offer the suggestion did you spin test those bheads?

What bheight are you using? Some of the Excal crowd claim there's a 'sweet spot' at 1 1/8" which is w/ serving just touching the inside of high mark, I tend to agree. The bows seem to really like it and it gives one a little more leeway w/ a stretched string.

The main problem w/ too low a brace height is the string slapping the riser and trashing the serving and/or string.

New strings are infamous for stretching, although they have been getting better. Until I started using 'Boo's', I used to set the bheight on FFF's about 3/8" above high mark and leave the bow c0cked overnight a time or two. Eliminates a few adjustments.

Sorry about the deer, that's rough!

Sound like too much of a POI change to be affected by creep. Shoot the bow some more to make sure it's wasn't THAT arrow or some other factor, like loose scope mounts or even scope going bad.
When mine changed that much it was a bad scope at fault.

To answer a few of you guys questions.

I'd offer the suggestion did you spin test those bheads?
I’m using Goldtips with Slick Tricks and they spin fine.

What bheight are you using? Some of the Excal crowd claim there's a 'sweet spot' at 1 1/8" which is w/ serving just touching the inside of high mark, I tend to agree.
Brace height is marked at 1 1/8"
Shoot the bow some more to make sure it's wasn't THAT arrow or some other factor, like loose scope mounts or even scope going bad.
Shot the bow, consistantly hits low and right. I use a Nikon rifle scope on my Excal, have been for years, what do you guys think about rifle scopes on crossbows?

xbowbarry

One thing I did not mention was the fletching. If you do not have enough off-set to your fletching it will become unstable at distance, especially with a broadhead. Number your arrows and see if it is two arrows in particular that are going stupid on you.
BTW, get a G5 ASD and square all front inserts. If it does not fix your problem it will give you finer accuracy. I rarely see a broadhead not wobble with out being squared.

http://g5outdoors.com/#sec_asdtool

I use Gt's and Slicks also. When I first tried them, I screwed a few on, spun them, and thought all ok was the nature of the beast[s]. Bad move, found out later I needed to spin each one.

Parallax is not your problem and has nothing to do w/ clarity of sight picture. The latter is a focus concern of the ocular lens, parallax is an optical allusion and is dealt w/ by either pre-set ranges from factory [xbow vs rifle scope] or dialed out via adjustable objective lens [AO].

While parallax can come into play a tad using a rifle scope on an xbow, it's not going to account for the shift you are experiencing

Parallax can also be defeated on two different range devices like xbows and rifles by mounting the cheek weld the same every time...........

Sorry Cossack, we gotta agree to disagree on this one.

Sorry Boris, I`m with Dan on this one. I only use rifle scopes on all of my bows. I don`t run into parallax issues because I center my eye in the scope consistently. If I was shooting dots at 50 yards then it may be an issue. They are also a better scope (the ones I use) in every practical way other than cost. I do have the new Hawke crossbow scope on order and who knows, it may change my mind. I presently own a MAP and although it is a good scope the only things that bug me is the anti-reflective coating of the ocular lens is not to my liking and it`s light management is not as good as my Vari XIIIs. It is however an awesome scope for the money.

Fletching is offset but I also have wraps on my bolts, I've had them for years and never had any trouble. I limit my shots to 25 yards and under while hunting.

Will this ASD work on brass inserts?

I'm in a wheelchair, paralyzed from the chest down with no use of my fingers so I have to get someone to check all this stuff that you guys are telling me.
Thanks so much for the help and advice.
Barry

The ASD works on brass, aluminum, carbon fiber, etc.
I was yapping about the plastic under the limbs extending towards the center and numbering the arrows(to see if it is arrow or bow related erratic flight) earlier. These two things are an important precurser to finding out why the POI changed so drastically.