Trying to use the Redhead Carbon Supremes 250 given to me a few years back out of my 50# recurve.  Straight out of the box they bareshafted in a zigzag pattern all the way to the bale only to stick in to it sideways.  As I knew they would be, way too stiff.
Recently I purchased the 250 grain fieldtips from 3 Rivers to see how they would work.  Made a big difference in how they flew bare, only kicking up a little bit and no zigzag.  Fletched up a couple and instead of the feathers smoothing out the flight they are porposing to the target.  At least the side to side is clean but the up and down isn't, yet.  Got to say the extra weight quieted my bow down tremendously from my normal arrows.  Like that outcome.
I'm nocked about 5/8" above level normally and did try to lower the nocking point in incriments but it did not help in that regard.  Give me your feedback so I can put these arrows to use.
Thanks

Are you shooting split or under?

Maybe grind some off a 250 field point a little at a time and see if it flattens out.

split

How long are the shafts and is that 50# at your draw?

Depending on how your shelf is cut you may have to go a little higher nocking point. One of my bows likes a 3/4" nock point and I shoot split fingered.

Shafts are 29 1/4" long and, yes, 50# at my draw length of 28"

I'll give that a try, James, and see if it cleans up their flight.
I did lower the brace hight and it made it worse so it is back to about 8 1/4".  Interesting how much work is can be to acheive perfect arrow flight.

try nocking over your nock point instead of under and see if it gets better, unless you can see which way it's porpoising first it may be hard to tell which way the nock point needs to go, you may have to go higher instead of lower, just an idea that's easy to try

The easiest way I know how to tune is to use the bare shaft planing method. You tune according to where not how your bare shafts group along with fletched arrows.

I had the same problem with mine out of my buffalo. Mine were pretty much on the same line just kicking high. Fletched with feathers and they leveled out completely.

I was having the same problem with my grizzly which mine wouldn't flatten out until 3/4. Then I decided to try a raised rest. On my rest I use the soft side of velco. Took to peices of the velcro only this time used both the rough side and the soft side. I pealed the plastic off the adhesive side of both and stuck them together with adhesivesides stuck together. Then I cut a peice that I just together to about 1/4" x 3/4", then cut the Sharp corners off. I stuck it on my orignal peice of velcro with roughside side down. Which raise my rest about a 1/8"and noticed my arrows started to straighten out. Which lowered my noc point to 7/8 since I never moved my noc point from 3/4. I am merely stacking velcro on top of the other 1/8" at a time. After stacking to layers which ended up being 1/4". Then I thought I would set my noc point at 3/8 with my to peices still stackedand noticed it was still shooting flat. Come to find out my arrow was hitting my rest at orignal height. After raising it 1/4 I no longer showed nock high.