Going all the way back to the OP's first post, may I suggest another way to think about the recovery system? Separate the "attach point" of the system from the "shock cords" of the system.
Essentially, when I build a rocket, the "attach point" is securely (and, for smaller rockets, permanently) attached to the motor mount. I like to ensure it comes away from the motor mount tube in a "Y" configuration (as opposed to being attached to one point at, or near, the centering ring) so the end loop of your attach point is centered in the middle of your booster tube.
Here is a photo from a 54mm MMT to illustrate:
This is also an older photo and I now terminate the end loop (where the purple heat shrink tube is) with a properly sized swivel. If you use a heavy Kevlar cord for this attach point (that is appropriate for the rocket size), it will last darn near forever. Note in the picture above, the thick Kevlar used is way, way overkill in terms of the rocket size/weight, but, since it will be the permanent attach point for the recovery system, I did not see a reason to skimp
. This should allow the attach point to weather almost endless deployment charges.
I size the length of the attach point to end so the swivel generally is touching the edge of the body tube:
Ideally, the middle of the swivel ends up on the edge of the body tube, which helps to prevent zippering:
I use this method even with small LPRs. For really big rockets, the attach point is usually removeable and attached to large U-bolts. Here is a photo of a recovery system I made for a 100 pound 8" diameter rocket. Part number 47 is the attach point, which is formed from two pieces of 5000# rated sewn Kevlar and a 5000# rated swivel (all the Kevlar cords and the attach point in this picture are from Onebadhawk):
By separating out the attach point, you can ensure you get a very secure mounting in your rocket that will not fail, you know it is centered and has a built in swivel and then you can easily attach any shock cord you want in the future by quick-linking it to the swivel (for small rockets, you can even use a small zip-tie to secure the shock cord to the swivel since a quick link may be heavier than the whole rocket or use a small fishing swivel with an openable clip), which is up near the top of the body tube, instead of messing around with eye-bolts and quick links way down by the motor mount centering ring.
I am not suggesting this is the "right" way to do it, just an alternative method of engineering your booster recovery attachments that I have found to work well and is scalable to virtually any size rocket you may build. I recently built an LPR with my daughter and we used that method and I am also in the process of building a 12" diameter rocket that will end up being around 500 pounds on the pad and the same method works just fine.
Also, a simple way to protect cords that will be exposed to deployment charges is to wrap them in masking tape. A single layer of green painters tape lasts multiple flights and is easily replaced when it gets beat up from the deployment charges.