less then 5 grains per pound
12-31-2005, 06:18 AM
#1
Thread Starter
Join Date: Jul 2005
Location: lehigh valley, pa
Posts: 128
less then 5 grains per pound
If I understand the ibo rules in the hunter class the arrows must be at least 5 grains per pound of draw weight, unless the speed is less then 280 fps. Is shooting an arrow under 5gr/per pound safe for the bow/the archer? If it is safe how light is too light?
thanks
Mike
thanks
Mike
12-31-2005, 09:30 AM
#3
Nontypical Buck
Join Date: Dec 2003
Location: Idaho
Posts: 2,072
RE: less then 5 grains per pound
In the hunter class the arrows need to have 4 inch vanes, unless you shoot feathers, you will have to drop tip weight to possibly get under that making your FOC pretty low. I would not want to shoot any bow under5 grains per poundanyway. The shots are not over 35 yards in the hc, so flat shooting bows are not necessarily needed. I would think that a higher foc and a more heavy controlled arrow would win as the shots are in close and it turns into more of a shooting game and not a yardage and shooting game as the other classes. You are correct on the 280 rule though.
12-31-2005, 11:34 AM
#4
Join Date: Feb 2003
Location: Blissfield MI USA
Posts: 5,293
RE: less then 5 grains per pound
I don't know what the rules are, but as far as safety goes it depends on the set up of the bow. The 5 grns/lb rule is for an IBO set up. Which means 30 inches of draw and 70 lbs of draw weight with a 350 grn arrow. If you decrease draw weight you can decrease arrow weight accordingly. However this is still assuming you have a 30 draw length.
If you shoot a lighter set up like a bow with lower energy cams or a shorter draw length you can safely go below 5 grns/lb, or if you have a lot of stuff on your string.
Here is a link to the minimum AMO arrow weight you can use. Remember this is AMO weight which is heavier than IBO.
http://home.att.net/~sajackson/amochart.html
Lets take my darton for example. It has 50 lbs of draw weight at 26 inches of draw. I have the older CPS cams with an IBO of around 298 fps. I think for this chart that would be a speed cam. So I can safely shoot 195 grn arrows according to AMO standards. This is considerably less than the 5 grns/lb standard. Now my Bowtech would be a slightly different set up. I shoot 55 lbs with it at the same draw length, however it has a much faster cam on it. It has an IBO speed of 324. I might want to take that into consideration and err on the high side, say go to the next block in draw weight choices or something. That would put me at 259 grn of arrow weight, which is still less than the IBO standard.
Basically if you shorten your draw length or go to the lower end of your weight range you are decreasing the amount of power your bow can develope. A 60-70 lb medium cam bow set at 60 lbs with a 27 inch draw length will simply not produce any where near the energy a 70 lb bow at 30 inches with a speed cam will. So why would you need the same weight or spine arrows? You don't.
Technically you should be able to shoot what ever weight arrows will let you achieve the advertised speed of the bow and it should be able to take it, since it is producing the same amount of energy either way. The shock and vibration should be equal with either set up. I don't know if I would suggest it though, but on paper it is sound.
Personally my opinion is that the only reason you should shoot light arrows is if you are competing in 3-D and the extra speed will actually gain points. I would make sure that the reduced weight actually gave you enough speed to make your trajectory better though, you might be surprised in some cases. It takes quite a bit of speed to actually make a difference sometimes.
Other wise I would shoot heavier arrows. They seem to fly better for me, are quieter and much better on your bow. Where the above says I can shoot a 259 grn arrow, and I would probably get above 280 fps with it I choose to shoot 450 grn arrows, especially for hunting. I don't shoot 3-d though or worry about range estimation. I practice the way I hunt, and when I hunt I don't guess at yardarge so speed and arrow weight is not a concern for me.
Good luck,
Paul
If you shoot a lighter set up like a bow with lower energy cams or a shorter draw length you can safely go below 5 grns/lb, or if you have a lot of stuff on your string.
Here is a link to the minimum AMO arrow weight you can use. Remember this is AMO weight which is heavier than IBO.
http://home.att.net/~sajackson/amochart.html
Lets take my darton for example. It has 50 lbs of draw weight at 26 inches of draw. I have the older CPS cams with an IBO of around 298 fps. I think for this chart that would be a speed cam. So I can safely shoot 195 grn arrows according to AMO standards. This is considerably less than the 5 grns/lb standard. Now my Bowtech would be a slightly different set up. I shoot 55 lbs with it at the same draw length, however it has a much faster cam on it. It has an IBO speed of 324. I might want to take that into consideration and err on the high side, say go to the next block in draw weight choices or something. That would put me at 259 grn of arrow weight, which is still less than the IBO standard.
Basically if you shorten your draw length or go to the lower end of your weight range you are decreasing the amount of power your bow can develope. A 60-70 lb medium cam bow set at 60 lbs with a 27 inch draw length will simply not produce any where near the energy a 70 lb bow at 30 inches with a speed cam will. So why would you need the same weight or spine arrows? You don't.
Technically you should be able to shoot what ever weight arrows will let you achieve the advertised speed of the bow and it should be able to take it, since it is producing the same amount of energy either way. The shock and vibration should be equal with either set up. I don't know if I would suggest it though, but on paper it is sound.
Personally my opinion is that the only reason you should shoot light arrows is if you are competing in 3-D and the extra speed will actually gain points. I would make sure that the reduced weight actually gave you enough speed to make your trajectory better though, you might be surprised in some cases. It takes quite a bit of speed to actually make a difference sometimes.
Other wise I would shoot heavier arrows. They seem to fly better for me, are quieter and much better on your bow. Where the above says I can shoot a 259 grn arrow, and I would probably get above 280 fps with it I choose to shoot 450 grn arrows, especially for hunting. I don't shoot 3-d though or worry about range estimation. I practice the way I hunt, and when I hunt I don't guess at yardarge so speed and arrow weight is not a concern for me.
Good luck,
Paul
12-31-2005, 05:00 PM
#6
Thread Starter
Join Date: Jul 2005
Location: lehigh valley, pa
Posts: 128
RE: less then 5 grains per pound
thanks for the responces guys. I was hoping for eeking out some extra fps. I have a 27.5 inch draw and shoot a pro 40 freedom. I love the bow accurate as anything just pretty slow.
mike
mike
12-31-2005, 06:31 PM
#7
Nontypical Buck
Join Date: Dec 2003
Location: Idaho
Posts: 2,072
RE: less then 5 grains per pound
I would say that the difference from 260 to 280 would be very minimal up to the 35 yard max. I would look for a larger shaft also to cut lines as the HC turns into a shootout. Good luck..............................
By the way. What speed are you shooting now??????
By the way. What speed are you shooting now??????
01-01-2006, 05:22 AM
#8
Thread Starter
Join Date: Jul 2005
Location: lehigh valley, pa
Posts: 128
RE: less then 5 grains per pound
ORIGINAL: Elkcrazy8
I would say that the difference from 260 to 280 would be very minimal up to the 35 yard max. I would look for a larger shaft also to cut lines as the HC turns into a shootout. Good luck..............................
By the way. What speed are you shooting now??????
I would say that the difference from 260 to 280 would be very minimal up to the 35 yard max. I would look for a larger shaft also to cut lines as the HC turns into a shootout. Good luck..............................
By the way. What speed are you shooting now??????
Last time I put a few arrows thru a chrono I was at 242 if I remember correctly. This seems about right. I had an Ultra Mag before this Bow and I was shooting at 252 (using the same chrono)and the advertisedibo speed was 300. I do not know the advertised ibo for the pro 40 but it has similair specs to the independence which was about 290. So doing the math i think the 242 is correct. And I am using the same arrows, just dropped to 75gr heads.
Like I said I love the pro 40. I don't see myself letting this bow go, will keep for indoor after I get a bow strickly for 3d next fall. Man that semes like a long way off.
Thanks
01-01-2006, 08:54 AM
#9
Nontypical Buck
Join Date: Dec 2003
Location: Idaho
Posts: 2,072
RE: less then 5 grains per pound
DOPVFT, if you want to eek out a little more speed, feathers might help out and bring your FOC a little more foward also. I shot the NWTC a couple of years ago in the HC. I was convinced that the greater speeds would help me out. I spent ALOT of time at the range trying to figure out the fastest, quickest setup thinking that would help out, and as stated above by someone else, I was very surprised that there was not much difference within 35 yards. The lighter arrows changed my point of impact higher on the target, these results got me real excited. But when I changed the gang adjustment so 20 would be on, all my pins were already correct. Conclusion, I had reached a point of diminishing returns, meaning that I now had a more critical to shoot bow with the same pin gaps, go figure. I have shot open class with bows in excess 300 fps, but have shot my best scores and won more tournaments with bows shooting in the 280 fps. Again, I feel that there is diminishing returns in most cases. Just remember, take the gimme's and hold your own on the long and good luck.......
