Author Topic: Project Bison  (Read 8564 times)

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Offline Rancid Crabtree

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Project Bison
« on: January 09, 2008, 09:19:16 PM »
I’ve been asked by a friend (the guy who shot the deer with the broadhead in the brain) To outfit him with a arrow and broadhead combination for a February Buffalo hunt out West. He is using his current whitetail bow but wants more than the 350 grain arrow/broadhead set up he uses for deer. I agree with that. Everything I have heard and read about Bison is that you should be shooting for the heavy carpet that covers the front shoulders. I would expect that this hair is thick and matted and since the hunt will take place in February, that it might also be ice covered. For this reason, I will be shooting for an arrow weight over 700 grains.



After looking around for arow shafts, I settled on Carbon Express Heritage with the wood grain look. These shafts weigh around 12 grains per inch. The shafts are on order. Next, I picked the Wensel Woodsman as the broadhead for this hunt because I wanted him to use a strong, cut on contact head. The 3:1 aspect ratio of the woodsman means greater penetration. I ordered from 3Rivers, a half dozen 125 grain Woodsmans and since he will be screwing these into a carbon shaft, I also got some 100 grain steel adapters that are needed to mount a glue on style head to a carbon arrow. For added weight, I also got 50 grain brass arrow inserts instead of the normal 15 grain aluminum inserts. I also got him some brass weight washers.



I am trying to create a front heavy arrow (FOC moved forward) after reading Dr. Ashby’s report on extreme FOC arrows and their increased ability to penetrate. So far, that adds up to 285 grains at the tip alone. The shafting weighs 12 grains per inch and he uses a 29 inch shaft for 348 grains of carbon. He is using a luma nock and (3) 5 inch barred turkey feathers so that should add another 30 grains putting us at 663 grains so far.

Since my son and I are working on a broadhead collection, I used one of the Wensel Woodsmen to do a little testing. The woodsman has a very sharp tip but bison bones are big so I filed a secondary tip angle which shortened the head by about an 1/8 of an inch but will make the tip less likely to bend or curl upon impact with a large bone. I am planning on a worst case scenario in that he hits a rib on both sides of the bison.



Next, I took the woodsman and sharpened it to a fine edge and then lapped it on ceramic plates to get a mirror finish on the cutting edge.





In an effort to show my friend the benefits of a cut on contact head, I set up an experiment where he and I used two very common and popular heads on the market. A Muzzy and a Thunderhead that were in my collection. I used a short length of shaft and some sponges to keep the arrow from sliding around on the scale.





I used a very thick and heavy piece of boot leather as the test medium. I placed the leather over each broadhead and by holding the leather out at the edges, pressed down until the head passed thru the leather. My friend watched the scale to check the poundage. I started with the Muzzy. I pushed down until I reached 30 pounds of force and I could not get the tip to go thru the leather.



Next, I used the Thunderhead and when I applied 24 pounds of force, the head came thru but ripped the leather until the blades could start cutting. The thunder head hole is to the right on the picture above.



Lastly, we used the Woodsman and It went thru the leather so fast and with such ease that we repeated the test several times to make sure we could trust the results. After 4 tries, we kept coming up with the same results. It took 6 pounds of force to slice thru the leather and there was no tearing, just clean cuts. There are other heads on the market with cut on contact tips that are just as good but I think the Woodsman was a good choice for this hunt.

I hope to have the shafts in a few days so I can begin to construct the arrows. In order to reach the 700 plus final weight, I have decided to use a few 27 inch lengths of .065 string trimmer (weed whacker) line that will be placed inside the arrows. This will ad length from front to back but will not change the arrow spine which is 350. I will post more as the project progresses.

 
Any day in the woods is a good day.

Offline Rancid Crabtree

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Re: Project Bison
« Reply #1 on: January 10, 2008, 08:00:36 AM »
Well, it seems that I was not re-inventing the wheel with my broadhead test. Watch the attached video. Dale from 3Rivers does it with a soft (and thinner) tanned elk hide. My hide was full grain so it took more force for my test. He also did his test with what looks like a Magnus head. I think the bones and heavy carpet over the shoulder of a bison warrants going overboard in terms of penetration.

I should have known Dale would have done this sort of test. He is as anal as I am. Dale's Parents live about 5 miles from mine. I saw him at Compton last year. He still occasionally hunts in Rosholt.

http://www.youtube.com/watch?v=tpHpVR5SUX8




Any day in the woods is a good day.

Offline Rancid Crabtree

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Re: Project Bison
« Reply #2 on: January 13, 2008, 08:44:46 PM »
The shafts showed up in the mail on Sat., so I cut them to length and epoxied the 50 grain brass inserts in place. On Sunday, while smoking 15 pounds of bacon, I had some time to work on the bison arrows again. The fellow asked that I use barred feathers and crest the arrows. The colors he picked were black, red and silver cresting to match the fletching.



While the cresting was drying, I assembled the 125 grain Woodsmen and the 100 grain steel adapters. I also placed 2 brass weight washers on the heads. Total head weight: 235 grains.





Over the course of the day I was able to get two of the shafts fletched.



To boost the arrow weight, I am messing around with string trimmer (weed eater) line. 4 strands is the max I can fit inside the shaft. I plan to weigh the arrows tomorrow. My guess is that 4 strands might be too much.



Any day in the woods is a good day.

Offline Rancid Crabtree

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Re: Project Bison
« Reply #3 on: January 25, 2008, 07:17:48 AM »
I finished all the bison arrows/broadheads and they were picked up by the hunter yesterday. We shot a few test arrows in my shop. The final weight came out to 760 grains. By using (4) 10 inch lengths of weed eater line bundled together and positioned in the front of the shaft, I was able to get a 15% FOC. All the heads are razor sharp and ready to go. I had him take a few shots through the chronograph and he was consistently shooting 200 FPS with his 70 pound Jennings. He will practice with the broadheads for a few weeks and the I will give them one last hone before he leaves for the hunt.


His new arrows will have 67 foot pounds of KE at point blank but more importantly, they will have .674 Lb/Sec. of momentum even at 40 yards he will still be at 63 foot pounds of KE and .654 Lb/Sec. momentum


His whitetail arrows weigh 353 grains and shoot 285 FPS, giving him 64 Foot pounds at point blank but only .446 Lb/Sec of momentum. At 40 yards, he drops to 55 Foot pounds and .414 Lb/Sec of momentum.


That is a 150% increase in momentum at point blank and 158% increase at 40 yards. These will be deep driving arrows. Now he just has to hit the right spot.
Any day in the woods is a good day.

Offline Rancid Crabtree

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Re: Project Bison
« Reply #4 on: February 25, 2008, 07:14:26 AM »
I just got word from the Bison hunter. He has his bull. He got penetration on both sides but the arrow did not completely pass through and exit the far side. He got both lungs and the heart and the beast broke his arrow in 3 pieces.


Live weight 2,4000 pounds, Hanging weight (without head, hide, hoofs or guts) 1,109 pounds. Total boneless meat is 717 pounds. It scored in the SCI top 20. I hope to have pictures soon.


the guy's partner got his bull with a restored Sharps rifle and put 6 shots in the boiler room before his bison went down.

Any day in the woods is a good day.

Offline Rancid Crabtree

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Re: Project Bison
« Reply #5 on: February 28, 2008, 07:03:25 AM »
The hunter stopped by my house today to drop off some pictures of his bison and to show me the arrow (all 3 pieces of it) The broadhead was as sharp and as good as new.









As stated, the entire head came thru the far side but the arrow did not completely pass through and out of the bison.



When the hunter stopped by last night with the pictures, he also brought along a big bag of bison fillets and roasts and steaks and burger. He told me that after doing the math, it would take a year to eat all the bison even if he ate 2 pounds every day. On top of that, I processed a few deer for him this year. I think he is set for red meat for a while.
Any day in the woods is a good day.

 

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