C6-5s acting like C6-7s?

On three recent launches, from two different packs bought at different places, I have gotten "bonus" delay from Estes C6-5 engines. These were used in larger rockets.

The first, my Semroc Centurion, ejected way past apogee and a line came off of the 'chute causing a slightly hard landing with minor fin damage.

The second was my Big Bertha with a baffle. I thought it was going to core sample when it finally ejected, ripping 3 lines from the 'chute! Luckily this rocket is really tough (I call it the "Beat Stick") and it landed with no damage.

The last was my Semroc Vega, also with a baffle. This rocket soars very high on a C so I did not see where the ejection took place. It came down a little faster than usual, with no damage, but it popped a line like the Centurion did.

On previous flights the coast did not seem to be that long. Am I just unlucky with engines? Are these rockets too heavy? (I do not have a proper scale to weigh them.) Should I try a C6-3 next time?

I had the same issue with C6-7's I launch a Patriot BT-60 and it came in ballistic under power and ejected the parachute about 25-30 feet before crashing into the lake bed. Surprising enough there was no damage to the rocket or chute. Previous I sent it up on a C6-7 and didn't have an issue. I then switched to the C6-3 and it worked out fine...it's pretty weird.

I had the same issue with C6-7's I launch a Patriot BT-60 and it came in ballistic under power then just without power the other half of the way and ejected the parachute about 25-30 feet before crashing into the lake bed. Surprising enough there was no damage to the rocket or chute. Previous I sent it up on a C6-7 and didn't have an issue. I then switched to the C6-3 and it worked out fine...it's pretty weird.

I've had the same problem with the C6-5 and my Centurion and Big Bertha. The Centurion has been about half-way to the ground at a right good clip when the charge(s) went off. Amazingly—no zippers. I was using two ten-inch 'chutes on it. The 'Bertha wasn't quite so bad, but then I built it a good bit lighter and used the stock eighteen inch 'cute with it. No damage to any of the two rocket's recovery gear—even though the Centurion's 'chutes have been fairly "ripped" open. I'm going with C6-3's from now on. That is until I get a case and reloads or some hi-buzz single use motors.