315 micro brace height

[billnconnie]

Hi everyone,
I received a 315 micro for Christmas, I put the bumpers from Wyvern on it and a Hawke 1.5x5 scope. I had problem from the start with the arrows changing point of impact after letting the bow rest over night. Notice the string was stretching some over night and the brace height getting closer to the bumpers. Finally located a pdf file that showed the newer micro with a brace height of 1.5 to 2 inches. This put the string at 3/8 to 1/2 inch away from the bumpers. I marked the side of the rail and the arrow movement has mostly vanished if I keep it there. Has anyone noticed poi changing on the micro on lower brace height? like 2 to 3 inches up and down and left and right at 30 yds when the brace height was at 1.25 to 1 inch. Could the bumpers cause the point of impact to change when the string is to close?
Thanks Bill

[vixenmaster]

I try to keep my Brace ht. 3/16-1/4" behind the bumpers. String will stretch some, jus keep twistin. POI i would use jus one a rrow n mark my down vane n shoot it. Then once you have that arrow sighted try the next. If'en it don't hit like the 1st try anudder vane down til it either hits right or won't group wid the 1st n set it to the side n try the next n so on

[janesy]

Good advice from VM there.
Now would be a good time to go throught the bow and make sure that all the acrews are tight. Loose screws can really play havock on the POI.
Specifically, remove the stock, and make sure the screws into the bottom of the trigger are tight, and the screws for the scope base/ADF. Many choose to locktight them, but ill leave you to search and decide for yourself if thats the route for you

[Carnivorous]

Brace height should only affect elevation and is very minimal on most bows. If your shooting off to the left or right it's not the brace height.

Check fasteners.
Use the same cock vane on one arrow to dial in.
Get better arrows if your not getting good groups.

[billnconnie]

I've done all the screw thing and shooting just one arrow. The bow doesn't have a brace mark on the rail. After finding the spec sheet on line I found that the brace height had been raised to 1.5 to 2 inches on the new bows. I set it at 1.75 and put a mark on the rail and kept the string at that mark. So far I've had no problem with the poi. I'm shooting Zombie slayers at 16 inches with a 110 gr. insert and 125 gr. field points. accuracy is good with this combo and the brace height at the height mentioned. Crony said I'm at 305 fps with brace at 1.75, it was at 298 when I set the string at 1/4 inch from the bumpers.
Thanks, Bill

[robertyb]

I put a small dab of white out on the side of my rail to mark the brace height point.

[robertyb]

I put a small dab of white out on the side of my rail to mark the brace height point. I use 1/4" off bumpers.

[longbow joe]

If you're shooting from a rest and impact is changing ,using the same arrow . You have to have something loose brace height is not that critical by 1/4 inch . Take off the stock and check trigger unit screws and all scope mounts.

[janesy]

I found my 315 cared the most about brace height, as far as speed goes 3/8 above the pads was fastest. The rest really didnt seem to matter much if at all.

[billnconnie]

Have gone through the entire cross bow and found one screw only slightly lose, tighten it and shot an arrow and there was no change of impact. I did give the scope a good wack and it was then shooting 4 inches low at 30 yds. I think I found the problem. Thinking about a nikon bolt.
Thanks Bill

[Ferguson Outfitters]

There are two crossbow scopes, the Nikon Bolt and Trijicon ACOG.

[billnconnie]

Put the Nikon bolt on the bow and there was no change to the problem. Talk with Mr. Miller this afternoon and gave him all the information about what was going on. He came to the conclusion that the left limb was weaker than the right. He going to check it out for me. Like the Nikon Bolt by the way.
Thanks, Bill

[billnconnie]

Wanted to post a update,
Danny worked on the riser and limbs for me, after getting the bow back and reassembled I shot the bow several times and then moved the brace height higher There was no change in point of impact at 30 yards. I have moved the brace height several times with no change in point of impact. Thank you Mr Miller! Now for the strange part of the story: The bow before service was shooting 305 fps with a 405gr. arrow. Now after the work that Danny did its shooting 321 fps with the same arrow. I know, I checked the chronograph with my target rifle and it was within a few feet of where it's always at.
What could change that much?
Thanks, Bill

[janesy]

If all you changed was the limbs, it only leave the defection of the limb itself.

Thats a stout little sucker, mine at 400 is shooting 311 iirc.

[billnconnie]

Limbs and riser both were changed, I couldn't tell any difference in the look of the riser. Don't know if there is any difference in the micro risers.
Thanks, Bill