Well DIY I'ms sorry but I have a bit more seasons under my belt then you and successful hunting all eastern and most western big game. You have your opinion and I have mine so we can agree to disagree. But I'm not mistaking KE for momentum. Without KE (speed and mass) you won't have momentum. In days of yore before compounds when bow reaching 180 fps were fast a heavy arrow/broadhead combo was pretty much a necessity for good penetration. But with today's speed bows you don't need heavy arrows. It's simple physics really. If your BH is sharp and your aim is true you will kill any deer or black bear with an arrow/BH weight of about 400 gr. Now if I were after bigger critters like brown bear of larger African game the yes I would want a heavier combo. You for get to mention as some readers may not be aware of is that if you use a heavier BH you may have to also go to a heavier spined shaft to compensate for it.
I feel I needed to edit this post because while I see your need for a heavy shaft/BH combo I don't feel it is necessary for deer or blackies. That being said your reasoning is the same reason I like using a .45-70 for these same animals when I could just as easily use a .243. Same principle just different tools. The animals will be just as dead.

Going to relate this a little farther. Let's say you have a bow that shoots a 420 gr arrow with a sharp 2 blade BH at a modest 300 fps. That will give you a KE of just shy of 85 ftlb. (with a momentum factor of .56; :whatever the heck that means)
Now take that same bow and replace the 100 gr BH with your 175 gr 4 blade BH. The weight difference in the BH alone will lower your speed down the 285 fps. Your KE will be about 89.3 ftlb. (and a momentum factor of .63 slug ft/sec). However now your arrows may be under spined with the heavier head. So now you have to go with a heavier shaft. So we move up the the next spine. Now your shooting a 600 gr arrow and your speed has dropped to 264 fps or there about. Now you have a KE of 92.9 ftlb. (with a momentum factor of .70)
So with your heavier BH you will lose approx 36 fps, over 10% in velocity and gain almost 8 ftlb of energy and your momentum factor will increase by .14 slug ft/sec.
Additionally your 4 blade design will create more friction as it travels through bone and tissue than a cut on contact 2 blade BH. So your slight gain will be diminished by the design itself. Not to mention those heavy arrows will likely be way over spined for your bow.
You can disagree with me which you probably will and I can live with that. I'm just giving my personal opinion base on fact and figures.

And still you got it wrong.

I am not speaking of opinion. Im speaking of fact. You are mistaken.

[QUOTE=bronko22000;4355405]But I'm not mistaking KE for momentum.

Yes. Yes you are.

Yes, high momentum and low KE setups. Thanks for proving my point and reversing your erroneous position.

Hear again you are wrong. (thats not an opinion by the way, its a self evident truth)

And yet you continue to get it wrong.

That is true even with a field point. But not all aim is true and animal move before the arrow strikes. You are speaking of a perfect world. Bowhunting is seldom perfect. Stuff happens so being properly geared 100% of the time and prepared for the worst case, makes those few times when perfection happens, even sweeter. Plan and build for the worst and there will be fewer "I hiut a big buck and cant find it" threads.

You are making my point again and sometimes deer can absorb a great deal and keep on living so gear up with heavy setups like you are trying to kill large animals and you wont be disappointed.

That is so obvious as to not require mention. Stick with me, we will get your mind right.

[QUOTE=bronko22000;4355423] Going to relate this a little farther. Let's say you have a bow that shoots a 420 gr arrow with a sharp 2 blade BH at a modest 300 fps. [quote]

"Modest" 300 FPS???. LOL

Actually the KE will be less than 84 so your calcs. are not correct. The .559 slugs (that you dont understand) is what keeps the arrow going forward and is far more important than KE.

[QUOTE=bronko22000;4355423] Now take that same bow and replace the 100 gr BH with your 175 gr 4 blade BH. The weight difference in the BH alone will lower your speed down the 285 fps. Your KE will be about 89.3 ftlb. (and a momentum factor of .63 slug ft/sec). [quote)

Yes, more momentum and more penetration and a more lethal setup. You are starting to catch on (quite by mistake so stick with me and we will get your mind right)

Yes, now you are getting it, More Momentum and less fret over KE. You are on a roll. And again, the obvious statement about properly spined arrows. It goes without saying.

[QUOTE=bronko22000;4355423] So with your heavier BH you will lose approx 36 fps [quote]

Who cares? Speed does not kill. Momentum does. Its drives the arrow forward.

Yes, yes, yes. Now you are getting it. Momentum kills. Its keeps the arrow moving forward. You are starting to catch on.

You mispelled "do more damage and cut more stuff to make the animal bleed".

You continue to assert that a hunter is given only one set of arrow shafts to use his entire life. I will say it clearly YOU NEED TO PROPERLY SPIN THE SHAFTS TO THE HEAD WEIGHT YOU USE. This is obvious so I dont know why you think people dont already know this.

You have offered opinion, I have offered self evident truths. Im operating with facts and you are making statements in error and bad opinions. (and spending far too much time thinking people dont understand how to spin their arrows for some odd reason)

Well you go on thinking you need massive amounts of weights while I'll just go on killing deer, bear and antelope and getting complete pass throughs and flatter trajectory with my 100 gr. BHs while you continue to shoot your slow heavy arrows and pulling them out of the dirt after the buck of a lifetime ducks the string at 35+ yards. God bless and have a nice day.

LOL at duck the string. The live weight of all the animal I killed with my bow last season came to over 4,400 lbs. 8 species in 7 states including 2 Pope and Young bucks. No animals ducked my string. That is not even a real thing for the experienced bowhunter that knows what he is doing. I think this discussion was good for you. I think you came away with a better understanding of arrow/broadhead lethality and ballistics as they relate to bowhunters. I think you are starting to catch on.

Not really. I did learn a couple things. One about momentum and KE although different have the same results. Two, an arrow of 400-450 grs is plenty for any NA big game when the proper BH is used. And three you think you are right every time. And you can't tell me deer or antelope don't duck the string. I've seen it too many times. If you don't believe that I know you're just blowing smoke.

If you are doing it wrong and not reading the animals behavior and stretching your shot distance and shoot a light weight rig that makes the bow very loud due to a light arrow, certain game will react. One of the many benefits of heavy arrows and High FOC setups is how quite it makes the bow.

Granted I'll give you that. But if you go too heavy, even though you have more energy (call it KE or Momentum it doesn't really matter) your arrows may not fly as well as they would if they were properly spined for your draw weight and length. Too light will also have the same effect. I shoot 63# and shoot a 29" shaft with 100 gr head. My recommended spine for my Gold Tip arrows is 340 (8.2 gpi). However I go with a 300 (10.9 gpi) which gives me more weight and better arrow flight/groups. The IBO minimum of 5 gr per lb of draw weight is too light for hunting IMO. It makes the bow too loud and puts a lot more stress on the equipment.

But it does matter and clearly you still fail to understand or grasp the differences in KE and MO as it applies to bowhunting.

Nonsense. Pure nonsense. You continue to operate under the misconception that a bowhunter will simply select the wrong spine for their arrows and wont match the spine to the bow speed and head weight. Its a given that hunters will select the proper spine so I cant for the life of me understand why you keep bringing up a moot point. Its a non-issue and you can expect that arrows will be spined to the bow and broadheads selected. Whether shooting 85 grain heads or the Bishop 600 grain broadhead, all know that your arrow has to be spined and why arrows come in more than just one spine. You do, I do it, all bowhunters do it so I don't understand why you think bowhunters will shoot a heavy head but select the wrong spine.

Cool story. Make sure you get the correct spine for the broadhead weight you shoot. That is a non-brainer. You are going to grasp this eventually, Keep reading, Im not ready to give up on you yet.