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Thread: upgrade my Scepter III with Nitrous X cams

  1. #1

    Default upgrade my Scepter III with Nitrous X cams

    Would very appreciate a technical advice of upgrade details from Scepter III straight limbs fury cams (29") to Nitrous X cams the same draw length. Now I shoot within 1340-1360 FITA and would like to try get better results with this setup.

  2. #2


    The Fury cams are a great cam, but so are the Nitrous cams..... That beign said you are going to make a hugh change and I think your scores are not going to increase and if they did not by much going to the Nitrous from the Fury. Remember that when you change cams your draw weight is also going to change, I would have to check to make sure how much. You will also need new string and cables. So right there you are looking at new limbs, cams, string and cables to keep everything as is right now. To me this is a hugh change and I would not do it if I was shooting in the 1350's FITA right now looking for more points.

    I am not letting you not to change, but make sure you check out the amount of $ it is going to take. If it was me I would keep the bow you have right now and pick up a new one. It will cost a little more, but then you have 2 great bow and not a bunch of extra parts laying around.


  3. #3


    Very smart answer. Thanks a lot.

  4. #4

    Default Not much info

    arnoldas -

    I enjoy tinkering with Martin bows myself, & have recently converted a couple of older models from Fury to Nitrous X cams, primarily for the shoot through system and higher let-off. The FuryX cams were only available in 65% let off.

    Unfortunately, background info on the Martin charts here on the website is lacking for the Scepter III with straight limbs. That being said, I will try to give some insight on the issues raised by LeEarl.

    If the Fury cams on your bow currently are #2 (my guess) or lower, then you will likely need "A" base Nitrous cams, which are the smallest base size. These will not change your draw weight as drastically as the larger B or C sized Nitrous cams, because the A base Nitrous body is similar in size to the #2 Fury cams.

    I would suggest you print out the Fury cam charts and the Nitrous cam charts from this page, and compare them closely. By doing this, I was able to conclude that the 1999 Fury and the Cougar 2000/Cougar III line of bows were very similar in geometry. The Fury just had ~ 1/2 less brace height, but the riser length and limb angles were virtually identical. (It also helped that I had a Cougar III of my own to compare side-by-side.) These were similar enough that I was able to use the exact same Magnum limb code, cam and string specs for my Fury conversion. The draw settings are just 1/2 inch off.

    You may not be as lucky, since Martin has not offered the Scepter with straight limbs as a standard model in a while, so they are not on the charts. You may try looking at the P3 stats as a close comparison. Also, the 2007 Martin line up has a Scepter 4 with Furious cams, which is a modular version of the Fury cam with shoot thru convertability. You may want to see about using those cams instead of Nitrous.

    Another option is to contact Crackers, a custom bowsmith via the website. He has converted many Martin bows to Nitrous cams; he helped me with string specs on my Fury Elite conversion to NosX, and I know he has done some Scepter 2 & 3 models in Magnum limbs (14" straight limbs), so I feel certain he has probably put 16" straight limbs on some as well.

    Best of luck to you.


  5. #5


    thank you so much, very much, dgmeadows!

    kindest regards from rainy Lithuania,

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