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Post by tbass on Dec 30, 2008 23:20:05 GMT -4
Before we get into what used to be a hot topic, I want to give some info about the current set up.
Hoyt shooting 29in carbon arrows at 327 fps with a 76lb draw and I am 15 grains over IBO. Thats 395grains for those who are not so good with math.
I have had issues with not getting a pass through with this set up. I used to shoot an Oneida Eagle bow at about 230fps if I was shooting down hill in a strong wind. I shot 2219's at 30" and 100Gr thunderheads. I actually lost arrows on pass through shots with that bow. I can recall shattering a spine and still getting a lung and had the arrow stick in the ground several inches under where the deer stood.
I am seriously thinking of going back to the heavy aluminum.
Anyone else have any thoughts on this? An arrow of nearly 400 grains at this speed should not be this bad.
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Post by skwirl on Dec 31, 2008 17:14:33 GMT -4
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Post by tbass on Dec 31, 2008 17:51:27 GMT -4
I read that after I posted this and it does little to help me understand this. This example has significantly different speeds and I'm not sure about the weight.
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Post by mrlongbeard on Dec 31, 2008 22:03:44 GMT -4
for pass thru weight is the way to go. with the extra weight it absorbs the extra energy from the bow. REMEMBER SPEED ISN'T EVERYTHING. energy and a good broad head are better. those 2219's you use to shoot far out weight those carbons. why not try a heavy carbon arrow or one of the carbon/aluminum hybrids or a heavier broad head
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Post by Buckslayer on Dec 31, 2008 22:09:52 GMT -4
you dont need to be shootin 76 lbs way overkill 60-70lbs is fine.use a muzzy or thunderhead fixed blade 5 grains per lb rule on the shaft
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Post by jeffpahunter on Dec 31, 2008 23:46:51 GMT -4
Any idea what the arrow weight is/was on the 2219's, completed weight ? If not I can calculate it to get an approximate total weight. I have software I can plug arrow weight and speed into and it calculates KE. You may be surprised as we MAY find that difference in KE between the two is minimal, maybe, don't know for sure. The exchange of arrow weight for speed in relationship to KE often equals out or comes very close in many cases, again don't know for sure until I plug this in.
Are you still using the T-heads ? If not what type of head are you shooting.
BTW, I shoot 380 grain carbons out of all 7 of my bows at anywhere from the low 260's - the low 270's and I've never had an issue with pass thru's.
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Post by tbass on Jan 1, 2009 2:21:56 GMT -4
I am currently using 100gr FirstCut mechanicals by Eastman outfitters because I couldnt get the thunderheads to hold a group. I honestly don't have any idea what the weight overall was on the 2219.
As for 76lbs being overkill, I choose to shoot a high draw weight to get greater performance and I also have no problems pulling it back in any position with no excess movement. At a higher poundage I can shoot a heavy arrow flatter than a person with a 60lb bow. If I shoot a 400gr arrow at 60lbs it does not fly as flat or as fast as it would at 76lbs. I wanted 80lb but the Hoyt guy told me I'd have to wait for a special order, so we picked the bow on the shelf that had the greatest poundage within safe adjustment limits. I want overkill like I had with my Screaming Eagle.
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Post by jeffpahunter on Jan 1, 2009 10:19:05 GMT -4
Immediately there I now see one difference that will impact penetration. While I'm in no way bashing mechanical heads and some may argue otherwise it's common knowledge that a mechanical head will not achieve the same penetration as a fixed blade head. To compare penetration of the T-heads you used to shoot to the mechanicals your now shooting is not an apple to apples comparison. A mechanical head HAS to expend some amount of the arrow's energy or KE to open the head and deploy the blades, like it or not, agree or disagree but this is fact. Also if your mechanical heads have a larger cutting diameter or more blades, again this impacts the ability to penetrate.
Having done extensive testing of many things in archery over 35+ years I've been involved with it I am always a bit reluctant to use two shots at two entirely different game animals as an "equal" comparison. Granted your talking about Deer here but in each case there's no guarantee that in each case the deer was hit at the same exact spot, the shot angle was exactly the same, the deer had the same body structure or characteristics, the distance was exactly the same,....all things that WILL impact an arrows penetration.
Granted when it comes to such things in archery I admit I get very anal when it comes to testing but for data to be the most accurate and usable when doing any comparison you must remove as many variables as possible and if not able to remove some take the remaining ones into consideration as to whether or not they are enough to affect your results, and in your comparison IMO they are having a sizable affect on penetration.
Example..I recently did some testing using FOB's. FOB's are a plastic device that fits to the tail end of your arrow instead of fletching it with vanes or feathers. The FOB has 3 fins enclosed inside a circular ring that might resemble a turbine motor. The concept is that if sized properly the FOB fit's snugly on the shaft just inside the nock, quicker than fletching an arrow, reusable and they pop/slide off the shaft when they contact the target and lay on the ground marking where the shot impact occurred and they fly as good or better than vanes or feathers.
I just couldn't entirely come to grips with how these things having to be pushed or slid off the shaft upon impact could not have some affect on penetration. For testing I went to a friend who processes Deer and got a fresh deer hide. I stretched this hide out tight between a frame and placed a new foam target butt about 3 ft behind the hide so that an arrow had to pass completely though the hide before impacting the target butt. The hide was to serve the purpose of causing the FOB to pop off and the target butt was to measure the penetration. Notice I said new target butt as using a used one would inject a variable into the test results due to the fact that if one arrow hit a soft spot in the butt while the other hit virgin foam the resulting penetration would not be a fair comparison. I also shot through my chronograph and charted the speed of each arrow shot since speed is a relative factor of KE and penetration. Once ready I shot an arrow with an FOB on it from 20 yds, through the deer hide and into the target butt. Recorded speed of arrow and how far the arrow penetrated the target butt. Now I used an arrow fletched with 4" feathers that I shoot and repeated the process ensuring that each shot struck the deer hide and target butt at a new virgin location. I repeated this process 5 times for each arrow gathering the data each time. My goal was to prove or disprove that these FOB's have an impact on an arrow's penetration. I then averaged out the penetration for the two different groups of arrows shot, 5 shots each group. The only difference between arrows from one group to another was FOB vs feathers.
The end results revealed that while the FOB did work as advertised by slipping right off the shaft over the nock upon impact with the deer hide, the recorded distances that the arrow continued on it's flight and sank into the target but WAS slightly impacted by the FOB. The arrows with feathers traveled an averaged 2.18" deeper into the target butt. Out of 5 shots per group never once did an arrow with the FOB fail to fall short in penetration to an arrow with feathers. Now don't get me wrong, I'm not implying that FOB's are junk, don't work or garbage. The results of my test IMO would likely have little if any impact on the penetration on a deer.
I was purely testing to see if indeed they have NO affect on penetration as advertised.
My point being that the most accurate testing/comparison HAS to have has much control as possible with as many variables removed as possible for the results to be TRUE indicative data.
Sorry to get off topic and so long winded tbass, my apologies but just wanted to explain some things to help your understanding of your scenario.
Later today I'll come up with an estimate on the 2219 and plug it into my software so we can compare the KE of both arrows.
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Post by jeffpahunter on Jan 1, 2009 11:09:17 GMT -4
OK tbass, I did some homework here.
2219 W/100 gr Thunderhead = 560 grains, speed of 230 fps = 66 ft. lbs of KE.
Your current carbon arrow @ 395 grains complete, speed of 327 fps = 94 ft. lbs of KE.
Your current arrow has almost 33% more KE that the 2219 you used to shoot.
Also tuning and the resulting arrow flight will have a major impact on penetration with any head. No way insulting you or whoever tuned your bow but you commented that you could not get the Thunderheads to "group" from your Hoyt. While it's common knowledge that approximately 270 fps seems to be the "magical number" at which it CAN become difficult to get fixed blade heads to tune and fly correctly it's not impossible, but the tune of the bow becomes much more critical. Even using mechanical heads, at extremely high speeds it's not impossible for an arrow to whip violently back and forth even if the tune is just slightly off, the increased speed magnifies any flaws in the bows tune. Any flaw in an arrows flight greatly inhibits it's ability to penetrate. Again....in no way am I insulting your ability to tune a bow or the person who may have if you didn't,....I'm purely mentioning this from experience to try to help solve your dilemma.
Hope this information helps you some. If I can be of further assistance please don't hesitate to ask. I enjoy things like this and being able to help from from time to time.
Jeff
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Post by tbass on Jan 1, 2009 16:26:13 GMT -4
I understand the loss of energy with mechanicals. That is the reason I want to shoot with higher poundage. I am trying to not only reduce margin of error in distance through a flatter trajectory, I am trying to get as much momentum as I can. I understand KE but a heavier object at a slower speed is harder to stop than a lighter object at higher speed. That is how I have usually looked at it.
idk if this is a good practice or not, but when i shot the 2219's I used to shoot the arrows into multiple targets and any arrow that didnt hit within 2 inches of where I aimed at 20yds I set aside. Those arrows i would heat with an alcohol lamp and turn the insert about 20degrees and try again. Often it fixed the issue, but I dont fully understand why.
Can your software estimate how fast my current setup would be with 29inch 2219's with 100gr heads? The more momentum and KE I get the better. Although I don't think I want to get below 275 fps unless I have to. In addition, I think one of my cams was crooked when i bought the bow. I have cable wear in the area furthest from the cam where the cam touches. The bow is only 300-400 shots old. I miss my high country and my screaming eagle. I never had these problems with them.
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Post by mrlongbeard on Jan 1, 2009 17:45:09 GMT -4
try the cut on contact broadheads like the g5's, slicktrick. turning the heads 20 degree change the way the arrow plans by straighting the head alignment
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Post by tbass on Jan 1, 2009 18:58:23 GMT -4
That makes sense. Also, the first cut broadheads do cut on impact. That's why I chose them over standard mechanical heads. If I could turn the heads in the carbons I might go back to the thunderheads. I don't know much about g5's but I keep hearing about them.
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Post by mrlongbeard on Jan 1, 2009 19:05:04 GMT -4
one thing that will help is to get a digital scale and weight each item. if you weigh five broadheads that are suppose to weigh 100 grain. you will notice i said suppose to. the difference can be as much as ten grains.
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Post by tbass on Jan 1, 2009 20:00:08 GMT -4
if my dream comes true and I get a reloading outfit for my bday in Feb, I will give that a try. I do wonder how big a difference a few grains makes in speed and stuff. Maybe if i toy around this spring I can run some sort of tests.
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Post by jeffpahunter on Jan 1, 2009 23:42:48 GMT -4
OK tbass, finally able to get back to you with some more info.
In order to calculate speed the software asks for some details that I did not have, but I used what I did have available and what should be fairly close guesses for the 3 missing pieces.
Using your current set up we know you have 395 gr. arrow, 76 lb draw weight & 327 fps. What it asks for that I didn't have was draw length, string accessories and bow efficiency. Since the first 2 to me were/are the easiest to approximate I plugged in 29" draw length given your arrow length and I selected peep site, nock point and the typical string silencers most people use as the string accessories then I kept changing bow efficiency until it calculated your 327 fps current speed.
Once here I left all the bow specs the same but swapped out your current 395 grain arrow weight and replaced it with 560 grains for a 2219 arrow. At these spec's it calculated the speed to be right at 280 fps. I also checked through my records of my personal bows and many that I have done for others here in my shop and the speed change in relationship to the change of arrow weight seems to be real close so it's safe to say you'd be shooting around 280 fps +/- a few.
Now here's an interesting thing for you. 395 gr. arrow @ 327 fps = 94 ft. lbs of KE. 560 gr. arrow @ 280 fps = 97 ft. lbs of KE. Although your speed decreases by 47 fps your KE actually increases by 2 ft. lbs. Either way, 94 or 97 lbs of KE is WAY more than needed for a Pa. Whitetail, it's more than enough for dangerous African game.
In your last post you commented about having to heat and turn some inserts on your arrows in order to improve/correct grouping. This is typically an indication of a shaft that is not squared off properly when the arrows were cut and built. The cut is not at 90* square and as a result the insert is slight crooked which in turn puts the broad head slightly crooked. Always remember that a broad head steers the arrow, the fletching only stabilizes & guides the arrow. If the insert is crooked and thus the head crooked it's much like a front end on a car being out of alignment. Another thing it could have been was a broadhead where the shank was not truly straight. This would also have the same impact. This is where spin testing of arrows with broadheads becomes of greater importance. This issue like most all others is greatly magnified as speeds increase.
Hope this helps a bit more.
Let me know if I can help any further.
Jeff
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