speed questions

tremolo · 09-07-2004, 11:18 AM

Hey guys I have a centerfire Pse firestorm lite with an ibo rating of 300 fps. I had it chronographed at 220 that with three shots. Im just wondering if this is a respectible speed for a bow rated at 300 fps. I know that a bow setup for hunting will not shoot ibo speeds but 80 fps slower seems like quite a drop.

Here is my setup:
Pse firestorm lite
60#s maxed out and 29" draw
String leeches
peep sight (tubed type)
string loop with a brass knock next to it
terminator hunters 4560 with 100 gr. tip (total weight 463gr.)
doinker D2 4"
Release

im getting about 49.77lbs. on eastons Ke calc. Id like to increase this too if i could. I am thinking about getting a little lighter arrow maybe goldtips, change the peep to a tubeless type, and if you guys say i dont need a knock next to the string loop i will get rid of that too. the loop doesnt look like it is going to move with it there.

thanks
vince

Kanga · 09-07-2004, 12:17 PM

Going to a lighter arrow is not going to give you more KE as the arrow weight is one of the factors.

If you want to get more speed with your current arrows lighten the string up.
IE get rid of the peep tubing and the brass nock

tremolo · 09-07-2004, 12:44 PM

how much would you think the brass nock and the peep tube be worth? Also the bow is ajustable from 80 to 65% let-off it is set to 75% if i dropped it to 65% would that help anyhting, and if so bal park how much?

thanks

Vince

NorthJeff · 09-07-2004, 02:10 PM

I've seen the tubed peep take about 12fps out of a bow, or about 5% at your speed and set-up. Not sure on the string leeches, but depending upon where they are located on the string, they could be robbing you of energy as well. Try a small, machined aluminum peep lined up with your loop, and maybe some limb savers as a compromise to the string leeches.

G2 Shooter · 09-07-2004, 04:34 PM

The IBO ratings on bows is very misleading to what you can safely get with a hunting arrow. That speed is calculated using a 30" arrow at 5 grains/pound with the bow set to it's maximum draw weight. Even then, I have not seen many bows reach their advertised IBO rating. In your case, that would be a 300 grain arrow. Flying at 300 fps would give you around 60 ft/lbs of energy but would probably destroy your bow in a few shots. Some bows also have a minimum arrow weight posted on the limbs. Many times that min weight is heavier than the arrow they use to achieve the IBO speed.

Your arrows are pretty heavy. Carbon Express advertises 11 grains per inch for the 4560's. You can try a lighter arrow and if you can get a total arrow weight around 350 grains (6 grains/pound), and a speed of 250, that would give you the same KE but with a faster arrow. I wouldn't go any lighter than that.

With all of that being said, I would pull off the tube peep and put on a hunter peep. You just have to make sure that it is aligned with your eye at full draw. Get rid of the brass nock. I just use the string loop. It gets tight enough on the serving so that it won't move. I would not try a lighter broadhead as that would probably mess up you FOC. After that, measure your arrow speed with and without the string leaches installed. See if you gain any fps. If you do, decide whether the speed is worth any additional noise from the bow. The only other possible factor is what rest you are using. Whisker Biscuits rob you of a few fps also. If you are using a WB, you will have to decide if the speed loss is worth the convienence of having an enclosed rest.

Just my 2-1/2 cents,
Steve

KBacon · 09-07-2004, 04:52 PM

If you shoot a lighter arrow you'll gain quite a bit of speed.. those terminators are heavier than most aluminums. I've seen that bow shoot 290 fps at 30" and 70# w/ a 350gr arrow. Your arrows are prolly about 550gr or so depending on points and fletching setup.

Bigpapascout · 09-07-2004, 06:55 PM

Ill bet it sure is quiet shooting those heavy arras

H80Hunter · 09-07-2004, 11:23 PM

Im shooting the 6075 Terminators this year (they are actually my first experience with carbon) out of a TRX @ 68 pounds and I can tell the the pins are definitly closer together (ie flatter traj.) than the 2315s out of my old bow, but that is definitly the bow too... that said, the Terminators are heavy, but I am not a speed freak, and I get plenty of KE with them... next year I may try a lighter arrow, but this is my first year with carbons, a release, a modern bow, and all those gadgets...

tremolo · 09-08-2004, 12:20 AM

Sorry about not posting while you guys are trying to help me out, I was at work. Well... my arrows weigh in at 473 with the 100 gr. field point on it(used a reloading powder scale) and i know that it is a very heavy arrow i was thinking about some goldtips i calculated out to somewhere around 350 gr. As for limb savers i already have those on there too, do you need both leaches and limb savers or do i go with one or the other? As for a rest it is just a double prong type that came with the bow. I was thinking about chaning to a drop away rest but i will wait till next year when i have more time to fine to it before hunting season.

thanks for the help guys

vince

HighDesertWolf · 09-08-2004, 04:22 AM

The IBO speed is determined with the maximum pound of draw in your case 60 lbs with an arrow that weighs 5 grains per pound which would equal to 300 grains and a 30 inch draw, draw length plays a major part in a bows speed. With your setup I would have guessed it would shoot around 220 fps. I would lose the tube style peep sight and go with a Shurz-A-Peep sight that should gain ya around 5 to 10 fps. If you position the string leeches just right they can actually work like speed buttons position them about 3 to 4 inches from the cams that should give you another 5 fps. You didnt say how long your arrows were but if cut your arrows down to where at full draw the end of the arrow should be flush with forward part of the riser basically if you have a 29 inch draw your arrows should be in the ball park of 29 to 29 1/2 inches long. According to some info I have your arrows are about 31 inches long if you can lose 2 inches off those arrows that will drop your arrow weight about 22 grains, that should give you another 15 fps easy. If you follow everything I explained you should gain about 25 fps that will put you up to 245 fps which is a very respectible hunting velocity and should also give you a little more Kinetic energy according to my KE calculator the way your setup is now you are producing 49.77 lbs of Kinetic energy but by following my advice you should be getting 58.79 lbs of kinetic energy. I hope this info is helpful.