FPS for modern Mechs

[Shifty11]

I'm curious what the general consensus is with FPS for effective mechanical broadhead deployment. Does it need to be greater than 300FPS? What's a minimum FPS you'd find acceptable to run a mech on elk? Thoughts?

 

[TL406]

Function of arrow weight and speed, not just speed, so not a simple answer.

If you had at least 275 fps and at least 425gr TAW, I wouldn’t worry about penetration issues.

An arrow going 300+ fps is rippin’.

 

[Shifty11]

I certainly don't have a hunting arrow doing 300fps, I was just using it as a frame of reference. Though I wasn't necessarily asking about penetration, it's definitely noteworthy!

So the current thought is 275fps to get adequate blade deployment on a mech? Anybody else have thoughts or experience on this?

 

[diamond10x]

There is a number of variables to this, you can't just get a hard number across the board. One has to take into account blade size, cutting diameter, number of blades, method of blade deployment, TAW, etc. IMHO an adult shooter shouldn't have any issues ever with blade deployment shooting adult specs at any huntable distances. With modern advances in archery the only deployment issue should be from a faulty head and negligent user not checking equipment before hand.

Personally I have a TAW of 475 gr, 71 lbs of draw weight, and 28.5" draw, according to my sight tape I'm around 275 fps. I currently shoot both mechs and fixed. I've killed animals out to 86 yards with the mechs getting complete pass throughs with no difference in performance than animals that were at 15 yards.

300 fps is zipping along, I would argue that 95% of bows set up for hunting aren't even close to touching 300 fps.

 

[Beendare]

I think Speed is the wrong way to look at this....it's more about arrow weight.

150fps is plenty to open a BH I would think.

The facts; Speed increases the resistance on impact, more speed = more resistance.......then pair that with an inefficient BH like a 3 blade over the top head and if you don't have enough arrow weight to keep the momentum of the arrow moving forward- it can limit penetration.

It's usually a non issue with the avg setup...but in the extreme- something like a 250g arrow shaft paired with a 100g over the top mech head might stop short....where a 400g shaft with the same head would give you much more penetration.

This also explains why the tapered COC fixed heads are less dependent on bow and arrow weight as they penetrate effortlessly.

 

[Backyard]

I'm curious what the general consensus is with FPS for effective mechanical broadhead deployment. Does it need to be greater than 300FPS? What's a minimum FPS you'd find acceptable to run a mech on elk? Thoughts?

What is your arrow’s KE using that weight of broadhead out of your bow? And what does the bh manufacturer recommend for minimum KE to effectively open and penetrate an elk?


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[WCB]

Blade deployment for the average shooter is not an issue. Penetration is what I would worry about. Like others have stated there are too many designs and variables to make a blanket statement on it. But most? all? mechanical manufacturers should have a KE recommendation. I would also contact the manufacturer and ask what that recommendation means. KE to open head or KE to open head and get efficient penetration?

 

[MattB]

I certainly don't have a hunting arrow doing 300fps, I was just using it as a frame of reference. Though I wasn't necessarily asking about penetration, it's definitely noteworthy!

So the current thought is 275fps to get adequate blade deployment on a mech? Anybody else have thoughts or experience on this?

That is way off base, where did you come up with that?

 

[Shifty11]

That is way off base, where did you come up with that?

The first responder, if you read the thread. It’s just a starting point/baseline to an overall conversation. That’s why I asked for others to chime in their personal experience. Please pay attention before responding.

 

[MattB]

The first responder, if you read the thread. It’s just a starting point/baseline to an overall conversation. That’s why I asked for others to chime in their personal experience. Please pay attention before responding.

No, he didn't. He suggested 275 fps and 425 gr. arrow weight for adequate penetration - not blade deployment. Please pay attention before responding.

 

[Shifty11]

I think I stated the question wrong, based on the answers. I’m not looking for advice or folks’ opinion on what I should or shouldn’t do, or what the manufacturers recommendations are.

I’m interested in people’s personal experience in mechanical blade deployment, and what your avg FPS is. If you had failures, could you find any empirical evidence as to why? And was it FPS related, or not?

 

[Shifty11]

No, he didn't. He suggested 275 fps and 425 gr. arrow weight for adequate penetration - not blade deployment. Please pay attention before responding.

You’re so much better at this than I am.

But you the missed the point entirely. Really appreciate you chiming in tho . Super constructive and helpful to addressing the point of the thread.

 

[Beendare]

I think I stated the question wrong, based on the answers. I’m not looking for advice or folks’ opinion on what I should or shouldn’t do, or what the manufacturers recommendations are.

I’m interested in people’s personal experience in mechanical blade deployment, and what your avg FPS is. If you had failures, could you find any empirical evidence as to why? And was it FPS related, or not?

Ok, I shot mech heads for about 7-8 years, Zero failures-. I shot 5 elk with mech heads- a couple frontal, Spitfire BH's. I was shooting 70#-80# back then with a 440g arrow.

Now, there are a couple reasons for the Zero. I took good shots, I tuned for Fixed heads first, I shot heavier spine and I spin checked them.

Most of the "Failures" you will hear about are usually operator error. I have seen a few cases of what I would call a failures with mech heads;
A couple were due to a very light arrow- 350g TAW...and a couple where one or more blades were popping loose when he took them from his quiver making the arrow do loop d loops.

 

[Shifty11]

Ok, I shot mech heads for about 7-8 years, Zero failures-. I shot 5 elk with mech heads- a couple frontal, Spitfire BH's. I was shooting 70#-80# back then with a 440g arrow.

Now, there are a couple reasons for the Zero. I took good shots, I tuned for Fixed heads first, I shot heavier spine and I spin checked them.

Most of the "Failures" you will hear about are usually operator error. I have seen a few cases of what I would call a failures with mech heads;
A couple were due to a very light arrow- 350g TAW...and a couple where one or more blades were popping loose when he took them from his quiver making the arrow do loop d loops.

This is a great comment, thanks Beendare

 

[MattB]

MBH’s don’t work like bullets, there isn’t a lower threshold in terms of FPS that is required to actuate the blades. Most would deploy if you slowly pushed them into a target by hand.

The fundamental issue is that MBH’s generally have inefficient blade profiles and wildly different profiles in terms of cutting diameter, number of blades, and blade angles which adversely impacts penetration depth. As such, they require more energy than fixed blades and no generic right answer exists for “what is enough?”.

What a bowhunter really needs to balance is the BH profile with their arrow weight and velocity, the latter of which is primarily a function of poundage and draw length.

For elk, I personally would not use a wide or multi-blade MBH unless I had a longer DL or was shooting 70#+ and had adequate arrow weight (450 grs.).

For folks who don’t know what they don’t know about archery/bowhunting, I highly discourage the use of MBH’s as most use them to avoid bow tuning - very important to the overall process.