Spine weight for my longbow?????

[rwarrich]

Well, while I am at it, might as well get the 'experts' opinions as to what spine weight my arrows should be.  I keep getting conflicting information from online and personal sources.  I get information telling to use anywhere from 50 lb spine up to 70 lb spine.  

I am shooting a 72" longbow with a shelf(that makes it a centershot bow?), 50 lb draw weight at 29 inches.  My current target arrows use a 125 grain glue-on field tip but what to make up a set of  6 hunting arrows using wood screw adaptors so that I can switch between screw-in broadheads, field tips and blunts.  I plan on using Sitka Spruce shafts.  Any and all help/suggestions will be appreciated.  I am on a rather tight budget, using my income tax return to feed my archery addition.  lol

[Jeff Strubberg]

I would start with a 55-60 spine and leave them a little long. Understand though, you will be a lucky man if you hit the right arrow first time out of the gate.

[SpankyNeal]

I'm with Jeff - should put you close.

[Hartlines]

I agree with Jeff,if you stay with 125g. heads 55to65 is a great place to start.
Good Luck

[Apex Predator]

Just because it has a shelf doesn't make it center shot.  This one is 1/8" from being center shot.

 

[Shawn Leonard]

30"s to the back of the aluminum adapapter than those adapters are almost 2"s long and the point,. That actually gives ya an arrow that is 32"s to the back of point. Alos as said above ya may not be center shot. either way and 1/8" out from center or centershot that long of an arrow weakens spine quite a bit. I would say 65-70# spine would get ya right in the ballpark. Ya can always add a bit of point weight or go to a little lighter head to fine tune. Shawn

[Fletcher]

I'm gonna have to agree with Shawn regarding the adapters.  They are long and heavy and will definitely increase you spine needs by 10-15 lbs.  The same shafts won't work for both the adapters with screw points and just glue on field points.  Search up the dynamic spine calculator on here and let it help you.

A 72" longbow is likely a Hill style and probably cut 1/8" or more out from center.

[rwarrich]

Well, I ran a straightedge down the centerline of my bow and the side of the shelf is off by maybe 1/8 of an inch past center. Mine isn't angled like the one in the picture above.  Also I plan on making my arrow length 29 inches to the back of the adaptor and the adaptor is less than 1 3/4 inches long, so that makes in under 31 inches to the back of the point.  I am going to use screw-in broadheads, screw-in field tips and maybe screw-in blunts, so the arrow length won't change just the overall length will vary.  It says on the package that the adaptors weigh 60 grains but I haven't weighed them personally yet and I think I can shave off a 5-7 grain just by emmerying off the shoulder and smoothing off the roughness on the front where it was turned down.  I was also thinking of dropping down to a 100 grain broadhead but haven't found a 3-bladed one like the Snuffer that I like.

[dave_570]

The best way i've found is to get 1 shaft for each
spine weight,@...40-45, 45-50,50-55,55-60 lbs. put a tip and nock on each,....no feathers..tape a piece of plain white paper flat on ur target. stand
back 10-15 ft and shoot into the paper. the shaft
that cuts a CLEAN hole in the paper without tearing
it is ur spine. works every time. some people will
say this is bs but this is the way trad archery
is supposed to be....u do this stuff on ur own to learn.

[rwarrich]

I do have test shafts in 45-50, 50-55 and 55-60 range now, just have to put nock and tips on yet.  Is this like paper-tuning where the paper is a couple of feet in front of the target and you shoot through it?