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View Full Version : How to speed up bow fps?



dhershberger
01-07-2013, 10:22 AM
Hey everybody so I shoot a bear mauler and I finally got to shoot is through a chrono and fps rating was only 264 fps! The mauler is rated at an IBO of 328 fps which is definately a speed set up but still I would think that there is no way that it could drop almost 70 fps from the IBO rating! I think Bear might have serously fudged their speed ratings on this bow! Is this normal? I'm pretty mad and I'm wondering if I should have just got a Hoyt Rampage XT because Hoyt's speed ratings seem to be more honest. I'm shooting a whisker biscuit which I know slows the arrow down 4-5fps but that isn't too much and I'm shooting 29.5" 350 spine Carbon Express Crush arrows which are around 9.5 gpi. Do yall have any reccomendations on how I can speed up my bow?

Bitterroot Bulls
01-07-2013, 10:25 AM
How much vibration/sound reduction stuff do you have on it?

265ish really isn't too bad for a lot of hunting arrow setups. What is your total arrow weight?

dhershberger
01-07-2013, 10:34 AM
I have a basic trophy ridge shockstop lite for my stabilizer and other than that I have no sound reduction stuff. I'm shooting 100 gr. field tips so if you add the arrow weight which is 280.25 grains plus the 100 gr. field tips, I'm shooting a about a 380 grain arrow. Is that a good speed rating for that arrow weight?

Shaun
01-07-2013, 10:36 AM
What is your draw weight etc. IBO speeds can be fudged alot + or - 3/4" in draw weight and I forgot how much on arrow weight but there tolerences are real loose.

dhershberger
01-07-2013, 10:39 AM
What is your draw weight etc. IBO speeds can be fudged alot + or - 3/4" in draw weight and I forgot how much on arrow weight but there tolerences are real loose.

I'm pulling 72 pounds and I have a 29" draw length.

Shaun
01-07-2013, 10:52 AM
Ok well IBO is set at 5 Grains Per Lb at 30" draw. Like I said there is alot of fudge factor in there! If you are an inch under 30 than subtract 10-15 fps + 4-5 frps for rest. Than 1fps for every 3 grains over the average 5 grains per lb. That is what your bow should be shooting. Most companys hype on IBO when others Run ATA

dhershberger
01-07-2013, 11:03 AM
Ok well IBO is set at 5 Grains Per Lb at 30" draw. Like I said there is alot of fudge factor in there! If you are an inch under 30 than subtract 10-15 fps + 4-5 frps for rest. Than 1fps for every 3 grains over the average 5 grains per lb. That is what your bow should be shooting. Most companys hype on IBO when others Run ATA

I did the calculations and it seems if the IBO speed is correct, I should get speed ratings around 300 fps, not 264. I think bear fudged it.

Shaun
01-07-2013, 11:06 AM
Yes they probably did alot of companys such as matthews fudge there numbers

dhershberger
01-07-2013, 11:08 AM
Dang! I'll probably go with a Hoyt for my next bow because they seem to be a little more realistic with their numbers.

Fink
01-07-2013, 12:18 PM
I think they all fudge them a little.. I shoot a Hoyt Maxxis, that IBO's at 323, and my arrows went through the crono at about 290, if I recall... I do have a 27.5 inch draw though, everything else was pretty well equal.

Shaun
01-07-2013, 12:52 PM
Fink Just for your draw length you loose 25 fps

ssliger
01-07-2013, 01:05 PM
I have the Hoyt Rampage XT. I have the one with the 80lb limbs. My arrow comes in at 405 grains. We chrono'd it at 308 FPS

kerrek
01-07-2013, 06:53 PM
I ran my On-Target archery program and come up with 288 fps. I couldn't find the Crush shaft in the data base, so I used the Maxima hunter kv shaft with a grain per inch rating of 9.8 @ 29.5" length and 72# 29" draw. Have you checked your tuning? Maybe something is not set right.


Just a thought!

ken

Fink
01-07-2013, 07:07 PM
Fink Just for your draw length you loose 25 fps

Thanks. I wondered if that was the case. I suppose they were pretty accurate in their ibo estimate then. I apologize for accusing my bow of fudging numbers

Drhorsepower
01-07-2013, 10:47 PM
Hoyt I believe advertises ata speed which is a little more stringent on specs of the tested bow and arrow. More accurate IMO.

BOHNTR
01-08-2013, 06:30 AM
I liked it better when they were all rated using the AMO system. (60 lb draw, 30" draw, 540 grain arrow- 9 grains per inch) I beleive it gave a much better idea of actual speed for hunters.

RUTTIN
01-08-2013, 07:45 AM
You might also want to look and see if your bow is in spec, and cams are timed right, that can throw off your arrow speeds as well if your bow isn't tuned right.

dhershberger
01-08-2013, 10:47 AM
You might also want to look and see if your bow is in spec, and cams are timed right, that can throw off your arrow speeds as well if your bow isn't tuned right.

Its a solocam so I wouldn't think that cam timing would be the problem, I should probably take it down to the archery shop and get it checked.

RUTTIN
01-09-2013, 07:39 AM
I had a single cam bow that the cam was out of time (rotation was not right) and it robbed me of a little speed and the bow did not shoot like it should until I got it back in time. Good luck and let us know what you find out.

shootist
01-09-2013, 08:12 AM
Have you weighed your arrow? I think it is heavier than 385ish. I'm wondering if you just took the grains per inch (9.5) multiplied by 29.5 inch arrow. If so, you are forgetting all of your components which are quite heavy (fletchings, insert). If you have actually weighed the entire arrow, then disregard my post, otherwise see if you can find a grain scale and weigh the entire arrow.

dhershberger
01-09-2013, 03:06 PM
Have you weighed your arrow? I think it is heavier than 385ish. I'm wondering if you just took the grains per inch (9.5) multiplied by 29.5 inch arrow. If so, you are forgetting all of your components which are quite heavy (fletchings, insert). If you have actually weighed the entire arrow, then disregard my post, otherwise see if you can find a grain scale and weigh the entire arrow.

Good point, I haven't actually weighed my arrow on a grains scale and I should definately do that.

dhershberger
01-09-2013, 03:31 PM
I weighed my arrow and it turns out that I am actually shooting a 401 gr. arrow at about 264 so that gives me around 60 lbs of kinetic energy which is fine with me. Everything makes much more sense now.