Have you been leaving it on the bow, or taking taking it down each time? If you are taking it down it's possible that you are untwisting the string upon removal (or, it could happen in the case if you aren't securing the ends somehow).

I shoot mostly b55 strings and have very little problem with stretch. I expect to gain about an inch after I build it, but after I stretch it, and serve it the strings are pretty stable. I may have to add a few twists over a week of the string settling, but not more than 1/2" of brace height loss after I start shooting it. It may be that it wasn't stretched enough before you got your hands on it.

 

Yes, it’s normal.

Dacron has both “stretch” and “creep”.

Stretch is the elastic type of lengthening - the string gets longer under tension, then contracts a bit when you take it off. You need to stretch it out a bit every time you string the bow. Easy way to do it is place the strung bow pointing down on a hard surface (chair works well) and push down on the limb ends to stretch the string out. You’ll feel some “give” and then the resistance will increase. Measure the BH, add twists if necessary, repeat. Each time you string it, you’ll find that the BH will start off too high but then will end up at the correct BH after you press down on the limbs. After several times stringing the bow, the string will settle in and you shouldn’t have to add many twists.

Creep is a permanent elongation while under tension. If you leave a bow strung for a long time, you’ll notice the BH slightly decrease after days, weeks, months. Again, just add twists.

Always keep the loops clipped together so you don’t lose any twists when it’s off the bow.

 

I have been taking my string off but leaving the string on the bottom limb and around the top so it can't untwist.

 

The thing you should be concerned with is the build quality of your string. It obviously wasn't pre-stretched by the builder. I pre-stretch all my B55 strings at 200# for several hours. This takes out most of the creep, and "sets" the Flemish twist

 

I take my bows apart for ease of transport. But I use a paper clip and twist the loops together, so I dont loose my brace height. This works for both dacron and B55 strings.

 

If I have to make a Dacron string I make it 1” shorter than desired string length then stretch it on stretcher at 100# or I put in bow then burnish with paper towel and push on string and limbs at the same time and within a day it stabilizes so I rarely have to adjust it and if I have to it’s between 1/8 to 3/16”

 

Don’t know yet about B-55 but the old B-50 would stretch a good 2“ Before it settles in. Even endless loop strings stretched at least an inch. I only have one bow that requires Dacron string thank goodness and it’s not shot very often.

 

M60 2 inches. Wow. That should not happen on any string. Most I'll ever get is 1/2 - 3/4 during the stretching
process.

 

Screw this I'm going fast flight. You can take these Dacron crap

 

Probably a good call. But be aware, a new Fastflight or other “no stretch” material Flemish string will also need a few shooting sessions to settle in as the ends compress, so you’ll still want to keep an eye on the BH and add a few twists as needed.

 

Yeah, I'm good with that. I have fast flight capable limbs so I want the extra speed anyways. I only use bow to shoot 3d so not concerned with noise.