As
@Mighty Mouse said you should be above 265 fps with that setup. Either it's not set at 70# & it's 60# or something is off with a measurement.
I do custom arrow builds and setup a lot of people for hunting. It really depends on what you consider your max ethical range on your target game. The reality of any setup is that there are tradeoffs taking place. You can minimize those but not eliminate them. You have Iron Will Broadheads so penetration will not be a concern. I'd be focused on range error, time in flight, durability & noise. Those are the easiest levers left to pull. You're not going to gain that much lethality from your bow to a new one as far as speed goes.
I'd personally lighten you up to around 430 grains TAW. That would increase your launch velocity around 10%. Also, I don't think you need a 300 spine. 330-350 cut short would be perfect. Here's a few things to consider:
- I consider there to be a minimum weight I'd recommend anyone shooting. That varies by archer but somewhere around 400 grains is the lowest I'd go for the average archer.
- Below that you're compromising structural integrity. You can use premium materials like titanium to go lower, but it's costly.
- At higher velocities tune gets a lot more finicky.
- Archery is a probability game. Once you've let the arrow loose you want to have have as much on your side as possible.
- Arrow flight has to be perfect. Shoot a properly setup arrow, tuned bow enough vane and a well designed broadhead. That gets it flying straight to where you want it.
- Range error is paramount. Bone is above and below vitals. Minimize distance or maximize velocity.
- Time in flight is significant. Animals get a vote to move and the longer you leave the polls open to more distance they can move. Minimize distance or maximize velocity.
- Maximize penetration. Choose a broadhead that is designed to penetrate well for your target species and your setup. If you reduce arrow weight down - make sure to make up for that with the broadhead design, sharpness, etc. You're fine with the IW. I wouldn't shoot the Sevr at an elk personally.
My setup is always designed around a 50 yards shot with +-5 yard range error putting me within vitals on an elk. Then I want to be able to have a follow up shot at 80+ yds if presented to put another hole in them. For me, that's 294 fps and a 445 grain arrow. But that's with 30" draw, 70# & 335 IBO bow.
My drop per yard at 50 yds is ~1". So if I aim center lungs and it's actually 55 yards I'm still in. I'm very sensitive to range error. I want to be able to estimate and let it go within 50 yards. Of course I'll range if I can but I've been busted ranging more times that I can count.