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Discussion Starter #1
I'm setting up a bow from scratch to take for elk this fall, and I'm about to the point where I need to have arrows ready to start the tuning process. The bow is a Ross CR334, 70lb (not yet confirmed on a scale, but it's maxed out), 30" draw module installed with a NAP Apache drop-away installed. IBO speed is listed at 305fps. I plan to shoot arrows about 30.5"-31" with a 125-grain fixed-blade broadhead. Every chart I've looked at calls for 300 spined arrows.

HOWEVER... I have a pile of Beman Bone Collector MFX 340's laying around. Weight is listed at 9.5gpi. Obviously I'd like to use these, since they're already paid for, but not at the expense of a poorly shooting setup.

For those that know more about this stuff than I do... can I get away with using the 340's, or do I need to suck it up and spend the money on 300's?
 

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I would say you are way underspined with the 340's @70lbs and shooting a 30-31" arrow with a 125gr broadhead you should be down around a 240 or 260
 

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As an ex bow tech I will say not many men need a 30" draw unless you are very tall. Most bows maxed out will pull a bit heavier than rated? Most bows should not be shot with the limbs bottomed out,, back off at least 1/4 turn. Are you sure you really need that long an arrow? I hunt with some pretty big dudes, fallaways set back a hole on the riser and their arrows are not even close to 30"?
 

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Discussion Starter #5
As an ex bow tech I will say not many men need a 30" draw unless you are very tall. Most bows maxed out will pull a bit heavier than rated? Most bows should not be shot with the limbs bottomed out,, back off at least 1/4 turn. Are you sure you really need that long an arrow? I hunt with some pretty big dudes, fallaways set back a hole on the riser and their arrows are not even close to 30"?
I'm 6'4" with a pretty good wingspan. I could cut the arrows down a little bit more, but with that particular rest, that would leave the broadhead in contact with the shelf. I haven't ruled out putting a different rest on, but that's what landed on there for now. I have the limb bolts backed out the 1/4 turn.
 

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Try this at full draw if you are right handed, does your left shoulder hump up (raised in the air) or does it relax on its own without you physcially lowering it your self? Kind of hard to do when your draw length is to short. I was shooting 30" DL, I noticed my left shoulder was not straight, had the hump. I changed my draw length to 30.5" the hump is no longer there. Thats how I find what my draw length is.

The arrow charts mostly for 100 grain weight out front of the arrow. You want to use 125 grain broadheads, disregard what the bow company saids 305fps. it's less than that. I would use the chart that saids up to 300fps. Subtract 5 lbs of bow weight. You using 125 grain broadheads add 3 lbs of bow weight. I would go with the 260's.
 

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I've gotten seven elk with a Hoyt Trykon or my Elite Synergy, both at 62#, using Beman 340 spined arrows and 125 gr. broadheads. Six of them with COC Muzzy Phantoms and one with a NAP Thunderhead. I've never had any issues with the performance of my setup. I tune for perfect flight, FP or BH, out to 50 yards. I couldn't get the 400 spined Beman to have the same POI thus went with the stiffer 340.
 

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Me personally Id go with the 300 spine if your planning on shooting 70#, you ll probably have tuning issues going that light on spine with fix blade heads. You could drop your poundage on your bow and go with those 340 s id take it down to the 60 to 62 lb range and try that. Also use helicial flecthing to get that arrow spinning as soon as possible
 

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Discussion Starter #9
After putting the bow on the scale, I quickly determined that it was in fact a 60lb bow, and not 70lb. I bought the bow used... the sticker is worn, and I took the seller at his word that it was a 70lb bow. Lesson learned.

Regardless, I decided to spend the money for the Archer's Advantage software, and determined that the 340's should work fine. Having minimal arrows out of the setup thus far, the 340's seem to be flying well, and hit the target noticeably harder than my other setup with lighter arrows.

Thanks all for the input, and my apologies for not confirming the weight prior to posting.
 
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