dustinflint says

More expensive to feed, but worth it.
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Re: dustinflint says

Post by Jerry G »

The vertical scale is in inches and the horizontal scale is in yards. The actual angle of attack is in minutes, not degrees. Near as I can figure the angle of attack of my 142gr 6.5mm is 10 minutes.
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Re: dustinflint says

Post by thauglor »

From the plot, Arctan (55/(500*36))= 0.175 degrees, which is just a tad over 10 minutes that Jerry says.

We are shooting bullets here, not artillery.
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Re: dustinflint says

Post by SteveD »

That is interesting.

Thanks for the info.
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Re: dustinflint says

Post by Snake »

I have a comment about the 'weight' testing. I have no issue with its application to small bore but observation and anecdotal evidence demonstrates that on a high power Ram.....that area described in the drawing as the 90 gram....is the dead zone on the big ram. Off center and edge hits readily takes them off.....its the 'good' center hits that are the problem
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Re: dustinflint says

Post by SteveD »

Thanks for the observation Snake.

I have purchased a force gauge (pictured earlier in the thread) and will make measurements of the force to topple a HP Ram as soon as I can.

If you or anyone have/has special concerns about specific locations on the Ram, please post here so that I can be sure to make measurements at that point. Maybe describe it in terms of the blocks made by the lines on this diagram.
Ram%20with%20MOA%20lines%20and%20red%20rectangle.png
Left to Right, Vertical 1, 2, 3, 4, 5, 6
Top to Botton, Horizontal 1, 2, 3, 4, 5
The red rectangle is in box 3,3
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Re: dustinflint says

Post by dustinflint »

Please check box 4,5 for me, thanks.

Dustin
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Re: dustinflint says

Post by Jerry G »

You need to push where the lines cross. I think you will find that shots on the face side of the front leg and below the head will spin the back end forward and the ram will fall forward most of the time. The front leg/body junction is the worst place to hit the HP ram.

On scaling up from SB to HP, the SB ram I used weighs 1 lb 10 oz. If the up scale from SB to HP works, the HP ram should fall over at around 4 lbs of push on the horn and around 11 1/2 lbs at the leg/body junction. And that is a big if.

You really don't shoot them there Dustin, do you? :ymdevil:
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Re: dustinflint says

Post by SteveD »

Will do Dustin!

Wondering if this chart might work better?

The red square is in box 10, 12
Ram with 20 px gridlines and numbers red square at 10, 12.png
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Re: dustinflint says

Post by glen ring »

Well now...I was planning on trying to make a big bore match with my 30-30 and was hoping to just HIT a Ram period. If you guys are aiming for and hitting specific points on a 500 meter Ram you're way, way out of my league.
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Ram force measurements

Post by SteveD »

I did some measuring today. It was after a match and several more hours of practicing so I didn't feel like doing a lot of spots so I started with the two that are thought to be most troublesome.

Grid 13, 9

Ram 1, 12.27 lbs
Ram 2, 11.96 lbs
Ram 3, 13.13 lbs

Grid 12,16, I think this is the spot Dustin was asking for.

Ram 1, 8.9 lbs
Ram 2, 9.71 lbs
Ram 3, 14.16 lbs
Ram 3 repeated, 12.50

I repeated the last measurement as it was significantly different than the other two Rams which were quite well correlated. As for was applied to the Ram the rear leg slid rearward. This seemed to engage the foot of the front leg against the stopper on the rail.

If we continue the translation I did of Jerry's Smallbore Ram measurement, the 170 line translates to 8.24 lbs. Pretty close to Ram 1 and 2.

So now the $64 question. Why does it take 1,000 f-lbs of energy to do 14.16 pounds of work? And even that, not 100% reliably?
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Re: dustinflint says

Post by boats »

64,000 question ?

Big reason for knock over inconsistency is target inconsistency. Rams are set on rails that may or may not be solid, some have wobble that can absorb energy. Some rails are wider too. We used to see considerable change in knock down on wet muddy days when the Rams fell into wet red dirt, sticking to the steel. Club went to mulch behind the line to avoid mud build up. Some say cratered steel with bullets impacting dents and rough spots make a difference, but I am not so sure about that. Does the steel temper make a difference ? I don't know.

Personaly I don't worry about it, my rifles will knock over most not all Rams, IF I hit them.

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Re: Ram force measurements

Post by thauglor »

SteveD wrote:So now the $64 question. Why does it take 1,000 f-lbs of energy to do 14.16 pounds of work? And even that, not 100% reliably?
I did some quick calculations using a 140gr bullet at 1930ft/s at the rams. First I guessed half the momentum would transfer over to the ram, and using the formula deltaMomentum= Force*deltaTime, I got a force of 10500 lbf. That obviously was wrong or we would be sending the rams flying like we do smallbore chickens.

I had to cut it down to 0.05% of the momentum of the bullet to transfer into the ram to get the 10 lbf.

To me this confirms my thoughts that most of the momentum of the bullet is spent on disintegrating it to peices. I bet that if you used the same 140gr bullet but shot it slow enough so that it wouldn't disintegrate you would need a lot less speed. Helps explain another poster's results with heat treating his bullets.

Also leads me to believe that a true scientific answer to this will take so much work you will be able to write a dissertation and get a PhD in the process.
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Re: dustinflint says

Post by Jerry G »

The 138 to 142 bullets at just a little over 2600 FPS seem to do the trick. If you put a high speed camera on the ram, you will see the bullet turn into a grey puff if you shoot them too fast. If you shoot a thin skin bullet too fast, it comes apart before it gets to the ram. We saw that happen shooting a 6mm rem at 3100 fps. The bullet was a 90 gr something, I don't remember.

On the subject of knocking down different rams, pads on the feet are not always perpendicular to the ram and not all stands are level. I have shot at a range at Missoula when a strong wind was in your face it was harder to knock down a ram. Mud on the bases make them harder to knock over. There are lots of variables that we can't control when we are shooting.

Steve, thanks for the info on your tests.
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Re: dustinflint says

Post by cslcAl »

I'd like to include the late Dan Theodore into this discussion. He would be all over this if he were still alive. Check out this old post.
viewtopic.php?f=2&t=6972&p=57086&hilit=Ramentum

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Re: dustinflint says

Post by SteveD »

I particularly like:

"We want a high "Ramfficiency;" that is a Ramentum divided by recoil." Although I would propose to spell it with one 'f', too many vowels in a row otherwise.

thauglor

Pretty much what I have been thinking that the overwhelming majority of the energy of the bullet is expended in turning it to dust and very little is applied to the Ram. This correlates with the thoughts on increased momentum. More momentum, slower heavier bullet, better transfer.

Do you have a link the discussion on hardening bullets?
Last edited by SteveD on Mon May 02, 2016 9:51 pm, edited 1 time in total.
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