Spine Question: Shaft Length vs point weight

[Zbearclaw]

In your experience have you found a consistent comparison between shaft length and point weight?

i.e. is a 25gr difference in point weight = to a 1/4" difference in shaft length?

I got bare shafts flying perfect with a 125gr head, but I want to hunt with a 200gr.

I am going to start cutting but would like to know if there is some established comparison to go on, or just cut it and see it.

thanks

[robtattoo]

I'd screw on your 200s, & then shorten from the nock end of the shaft, 1/8" at a time. Carbons seem to be a lot more critical of length, rather than point weight. You may well find that you won't need to do anything to your shaft at all 75gn really isn't a lot of weight.
I know with my setups (YMMV) I can switch from 125gn up to 300gn with no discernable difference in flight or impact point with a fletched shaft, out to 20yds.

[Richie Nell]

Zbear...Depending on the current location of your silencers, you may only need to slide them toward the middle just a hair to keep arrow tuned with 75 more grains.
Like Rob..said 75 ain't too much.  Just fine tuning may do the trick if you would rather not have to do any cutting.

[wapiti]

Raising point weight by 75 grains you shouldn't ned to cut more han 1/2" uness yo are on the lower end of your usable spine range. Cut no mor than 1/4 at a time.

[George D. Stout]

robtatoo,  you would see a difference if you put a sight pin on and held on the bull at 20 yards.  From 125 to 300 grain is a lot of weight (175 grains).  Your arrows may fly straight, but there will be a trajectory bump with that 175 extra grains out front....no way of getting around that.

If everyone held, pulled and released the same, then one could maybe put a number on how short or how long to cut.  Trouble is, it will vary from shooter to shooter.  If you want heavier points, then try them as they are first.  If they are too limber, than cut about a quarter inch at a time until they tune.

[Zbearclaw]

So 1/4" is a good number to work with?  I have read that but I also know from my compound days that carbons react very quickly to length changes.  I didn't want to cu 1/4" and findout that I went 1/8" too far.  

thanks,  the 200gr show a bit of nock left but the 125 is hitting as it should, just a smidge nock high.  

I can group broadheads, fieldpoints, and bareshafts pretty well out to 15 or so, but seeing the nock kick left makes me wonder what my broadheads will do after a thunderstorm above treeline.  

Once these 200's are flying well I will be good to go.

I will try the silencers right now.  I am guessing both sets toward the middle?  

FYI I am shooting a Blackwidow PSAII #55 @27, drawing about 27".  Shooting CE 250's @ 29" right now, with wraps and the CE insert.

Zeke

[GMMAT]

We've found (using cx 250's) that 1" shaft length = 50 gr.

EX.

I can shoot a 30" shaft with 225gr up front....or a 31" shaft with 175gr there.

[xtrema312]

I have some notes that say 3-5# spine for 25 gr. head weight change and about 5-6# per inch of arrow change. think it varies as the shaft gets shorter.  I don't know how accurate that is, but it works for me so for as a rough guide so I don’t cut ¼” eight times when I need to trim off at least an 1” to even get in the ball park.  I try to get within 1” and tune with different weight points and then do the fine cutting as I work down

I would personally stick those heads on and start shooting.  I don't know much about BW's, but I think they are cut past center, but not sure.  If you are shooting standard inserts and 125’s on a CE 250 that is only 29” you have a real short stiff arrow now.  You could be over spined, but I don’t know much about BW’s.  My cut to center 55# @ 28" pulling 28" with a 5575 takes 245 gr. with a 29.5" shaft length.

[bigbuckmalik]

I just cut 1/2" off to stiffen 225 up front to fly with 195 up front. 225 is what i want to hunt with so i nipped a few times till i felt it was perfect.