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Posted

Momentum = Mass X Velocity.  My bow is a Martin Prowler mid-level bow that maybe shoots 250 f/s.  Can't do anything about the speed part of the equation as I have it maxed out at 65 lbs so I decided to play with heavy arrows this year.  They fly the same as my lighter arrows with a noticeable drop coming at 25 yards as oppose to 30 yards with lighter arrows.  I am losing 5 yards of distance, but I don't shoot long distances.  I did not use any chronograph, completely non-scientific with my set-up.

Posted

Gill,

I wondered what buckboardjr had for momentum and ke....I just went to chrono my new arrows i built and bow shop's chrono is down.....but nearest i can figure with exact arrow weight of 429 grains and a guess of bow speed at 325 (i was 352 with a lighter version of the same shaft) im at a ke of 100 and a momentum of .62. I could easily go a bit heavier but i have my foc where i want it and i never had a problem with the lighter arrows. I believe that the best setup will be a balance of arrow weight and speed....trajectory is a factor too...

Posted (edited)

I shoot an even lighter arrow than the rest of you. My fixed blades don't have a problem penetrating even the shoulder. I managed to blast thru the shoulder with 67lbs. of KE. At some point it is all about how far in the dirt do you plan too shoot.

Edited by Chas0218
Posted

For sure Chas! Im just working a few different arrow weights trying to find the best blend of ke, momentum, foc balance and trajectory. I build my arrows so its really a simple thing to adjust arrow weight.

Posted

If you read all of Ashby's data, it leads you to a 550 gr. arrow package min. This will get you through Shoulder/ Scapula "WEBS and ball",and the Humerus and sternums!!  The scapula/shoulder is easy to penetrate as long as you don't hit the Ball web which is right there, and it's easy to accidentally hit it in your kill zone. Even worse on 3.5 yr olds and older. The bows love the heavy arrows as well. They are much quieter and a little bit more power is extracted from the bow as well. It's very hard to sell this approach to people as it is not main stream and the mechanicals do massive damage when  they get inside. On misplaced gut shots I favor mechancals because they cut such a large swath, the deer hemorrhage out. Like I said earlier this data is to get you in to the vitals and out the other side for easier recovery when things go "WRONG" not when things go right. To those who have been shooting deer for 20 plus years, a 550gr arrow out of your modern bow will still be quick compared to your old setup from 20plus years ago. I am just passing this info on, as a lot of people have not even heard of Ashby. Many will dismiss it after a few minutes of reading because they will say it's for African game. Use what you want and are comfortable with. 

Posted

I have an old PSE. It's not fast by today's terms of speed bows. I've tried a couple different ways to increase speed in an effort to lessen drop of trajectory. My inability to assess distance over 25 yards in the woods was the driving force of my quest for flattening arrow flight. Obviously speed would help in that department. I have since learned you have to work with what the bow you have in your hand will give you. I tried lighter arrows and heads. I even tried an overdraw rest. Both increased speed but sacrificed other parameters. When both used together....wow.

Fast as it could deliver...but ..loud, not consistent, and unforgiving on form. The overdraw was ok by itself, but it was the unforgiving on form part that was undesirable for hunting. Target yes but hunting no. As for arrow weight the overdraw effectively made a heavier wall shaft shorter and lighter. Good for me with the 31 inch draw. Good for kinetics too. I wanted more speed yet, so went carbon and dropped approximately 80 grains total arrow finished weight. Not much faster. About 10 fps. I have my own chronograph so I checked it. What I got was as much as that bow could do to lessen trajectory with speed on it's built in level. I hunted one season with that setup and was very unhappy with results on a buck. I got the deer in the freezer but not without 2 arrows of which did not pass thru. I since removed the overdraw that gave me significant speed increase but it lowered the effective brace height causing loss of consistent arrow launch in less than desirable form position. Actually went heavier shaft and an inch longer and back to heavy fixed blades. Told myself 25 yards or less, cause that's what the bow will do effectively with my poor trajectory assessment. It's not really "jarts" anyway...so I live now with 242 fps flat enough to 25 yards of pass thru shots from a 465 grain arrow driven quietly by 70 lbs at 31 inches. Beyond that is pushing the bows limits and my human error.

I would much rather catch a fast baseball than a slow bowling ball in my hands....if ya know what I mean!

Mark

Posted

I just shot 2 combinations last night. One was 462gr at 70lb out of a Switchback XT and the trajectory is totally fine out to 30 yrds. Same pin in other words.  The other combo was 612gr out of a Monster at 68lbs. This too was good out to 28 yrds. Talk about sinking an arrow. both of these is with a quite heavy FOC which when you read Ashby's data is where you want the weight. He builds Ultra FOC arrows way out of scope of what is suggested in all the charts you'll read. If you think about it, the wt at the forward end will create more penetration than distributed through out the arrow. Example being hitting a short punch/chisel verses a long one. Though Kinetic energy and momentum play an important role in gauging things, the fact that resistance to penetration goes up exponentially as velocity increases should lead us to gain the kinetic energy and momentum more with mass than velocity. One cool comparison is by shooting a 700gr arrow in to a gallon jug of sand at lets say 190ft. /sec. It will go all the way through . Now shoot a 357 mag in to it at 300 gr and 1100 ft. per sec. The 357 has way more KE and Mom. which is derived more from speed than mass. It doesn't make it through.

  • 2 weeks later...
Posted

Got a bunch of assorted brass weighted inserts delivered yesterday....tests start tomorrow....i will be trying a 500 and 600 grain arrow tomorrow...i get 34 yds with 1 pin at 429 grains...i think the 500ish arrow is gonna be the best blend of trajectory and penetration. Ill build the arrows tomorrow and give it a try. I have a new block to shoot and im gonna see the difference in the penetration of the three arrows ill take a some pics and post my test results though the chrono isn't here yet...

Posted

i get 34 yds with 1 pin at 429 grain

Just curious what are you targeted in for and what poundage are you pulling?

Posted

Im at 72 lbs and I sight in so that at im with in less two inches at the high point and at the low point 34. I use a single pin adjustable sight with a scale. As long as i get a max point blank range of 30 yds im happy so im shooting heavier arrows. After doing more research im leaning towards Dr Ashby, though not to the extreme he takes it.

Thanks buckboardjr for getting me thinking and researching a bit more.

Posted

October is always so friekin' windy so I think the heavier arrows will resist drift more.  Going to use my Grim Reaper expandables on my 500 gr. arrows for windy days and use the slicktrick fixed for wind 12 mph or less.  Common sense approach that will deliver the best compromise between accuracy and penetration.  Now just have to keep the little gremlin off my shoulder that whispers in my ear that says "shoot quick.....he is getting away" LOL.

Posted

For a compound, I shoot an 80lb obsession phoenix with 540g arrows and rage hypos.  The results have been outstanding.  I also tend to think that the problems reported with rage were due to set ups not well designed for mechanicals (low poundage or failure to improperly install the head).  I could be wrong, but I won't be moving from rage anytime soon.  Last year, my buddy was laughing at my first blood trail of the season (all of thirty yards) as we were finding chunks of lung, large chunks.  That said, I have also hunted with slick trick standards and they did the job just fine too - not as dramatic though.

 

With the recurve, I use 630g arrows and a Strickland helix single bevel two blade.

Posted

After testing this weekend my final choice is a 225gr. steelforce traditional 2 blade attached to 300spine Gold tip hunters. I think it ended up at 530gr. total. These 3 to 1 slope heads are single bevel rh twist and compliment my vanes in flight. I seem to have no left/right flyers even when punching the release. It's everything Ashby asks, to include cut on contact, tanto bone busting tip. The only thing it doesn't have that Ashby requires is being made one piece. The FOC is Ultra, The heads twist through the animal/target for longer wound path.I can feel this when pulling arrows from target. In the wind at 50yrds they shine through. They even hold a flatter trajectory than an arrow of same weight distributed throughout the arrow and I have no explaination for it. And it's a lot. Like 2.5 inches less drop at 30yds. I'll post a pic or two tonight. The trajectory is acceptable in both the Monster and Switchback.

Posted

Here's the pics of the steelforce traditionals. Total arrow pkg. wt. 535gr.  Broadhead 225gr. AMO FOC 20.5%. These fly like a dream out of my Mathews Monster M6 with M7 modules on it and my Mathews Switchback XT! You can only get these heads at 3 rivers archery!post-147154-0-41197500-1443562040_thumb.jpgpost-147154-0-35256200-1443562104_thumb.jpg

Posted

I'm not ready for a broadhead change but I'm here to tell you a 500 grain arrow with 20% foc hits very hard and like buckboard said they fly way better. My son is shooting great groups at 30 that I haven't ever seen from him. I'm shooting a 225 grain rage basically when you add weighted insert and weights. Those 2 blades are serious!

Sent from my XT1080 using Lake Ontario United mobile app

Posted

Wind doesn't budge a ultra high foc arrow at all and when I torque a shot on purpose its unreal but the arrow goes nearly the same...everyone should use heavier high foc setups no matter your broadhead

Sent from my XT1080 using Lake Ontario United mobile app

Posted

Sounds like a good set up justtracytrollin! I am all bumbed out. My lower back went out Wed. Morn and I missed last 3 days of work. Getting better now. My try the bow again tomorrow. Good luck fellas and shoot straight!

Posted

I see they recommend matching a right helical vane set-up to match a right bevel for those steelforce-type of heads.

Posted

For all the Rage haters, here's a pic of the bear I shot yesterday with my 500 grain Carbon Express, Piledriver arrow and a Rage extreme chisel tip, 2 1/4" cut. That knife is 4" long. That was the entry hole and it was a complete pass thru and the bear only went 40 yards. Rage for me until they stop making them.

Total Chaos

post-141352-0-51598100-1443963463_thumb.jpg

Posted

I checked today and I'm on the light side for FOC. 15% by the calculation formula. I suppose if I bumped up to 125 gr heads it would help my situation more. Could also change the inserts.

Total Chaos

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