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#1 Bennie

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Posted 18 December 2010 - 11:24 PM

I shot these groups the other day and have not been able to go shooting since. I want to shoot it off a bench next time. I shot these off a rest on the tailgate of my pick up. The 25 yard group looks good to me, but I think I can improve the 50 yard group a little bit. The vertical looks good, but you can see I am stringing horizontally. I think the horizontal stringing is because I am not holding the rifle level. I hope to go out shooting again soon and figure it out and also make my self some kind of drop chart for shooting past 50 yards. That seems to be where it starts needing me to use hold over.Questions?1. What do you guys think about the horizontal stringing?2. What do you guys use to make your drop charts and how do you weather proof them? Hope to see some new ideas and examples on this one.Posted ImagePosted Image

#2 A17Shooter

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Posted 19 December 2010 - 01:30 AM

Horizontal stringing may be wind. Pellets have very bad BC numbers and that effects the wind drift. The Hawke Chairgun Pro is ballistics primarily for airguns with BC #s for pellets shipped with it. It downloads for free. Download at WWW.Hawkeoptics.com . It will help you with your charts.

#3 ShooterJohn

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Posted 19 December 2010 - 08:52 AM

I'm going to bet wind too on the horizontal stringing. But nice shooting none the less.

#4 Bennie

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Posted 19 December 2010 - 09:12 AM

I was thinking it was something I was doing. It was not windy. 4 MPH at the most. I am still getting used to this rifle and trigger. These groups are in the first 50 shots out of it. I hope to go and shoot it off of a bench to day and see what happens. It is much more windy to day so I will see what happens. I was watching my pellet in the scope on my 50 yard group and know that I was tilting my rifle a little bit counter clock wise to watch this happen so I could see the pellet when it was not behind the vertical crosshair. It was something new to me to see the pellet going to the target in the scope, so I know I was not following through on my shot as I normally do. Will a 0 to 4mph breeze move a pellet 3/4 of an inch at 50 yards? Will every 10 yards after 50 be close enough for a drop chart out to 100 to stay moa or will I have to go shorter??

#5 ratassassin

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Posted 19 December 2010 - 09:47 AM

To make trajectory maps for my springer air rifles, I tape a target with multiple 1 inch bullseyes on a cardboard box and shoot a 3 shot group off my knee (to simulate field conditions) every 5 yards from 10 to 50 yards. Then I type it up listing the pellet, the variable scope's preferred magnification setting at which the trajectory was determined (e.g., 9x), list the yards and number of inches above or below the center of each bullseye where point of impact occurred at each yardage. I tape it to the rifle stock using Scotch tape across the whole map to waterproof/dustproof it. Easily removable without damaging the stock. Sometimes if I need to make a field expedient trajectory map, I'll write up a basic trajectory map showing how much holdover or holdunder is required at 10, 25, 35, 40 and 50 yards on a piece of blue tape with a Sharpie and stick it on the stock butt. Again, easy to remove without leaving goo on the stock. Even though it's time consuming, I've found it's much more accurate to make a real life map for your rifle and pellet of choice than rely on the trajectories determined by ballistics programs which just haven't been very accurate for my pellet rifles.

#6 A17Shooter

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Posted 19 December 2010 - 12:47 PM

Bennie,Checked the 50 yd wind drift with the ballistic program. With 850 fps MV, using the JSB Exact 15.9 gr pellet and 5 mph wind speed blowing at a right angle to your line of fire, the calculated drift at 50 yds is 1.7". Since I don't know the MV or the pellet you're using this is just an approximation of what would happen with a typical gun. Like Ratassassin says the ballistic programs are not gospel. One thing that I've noticed is that the BC of pellets is listed differently from different sources and BC is a key indicator of how that pellet is going to fly.

#7 ratassassin

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Posted 19 December 2010 - 01:39 PM

That's true and a good point about the BC's. I don't think the pellet manufacturers even publish BC's for their pellets, do they? I only remember seeing the BC's listed on StraightShooters' website and I think they derived them from their chron testing. (Not sure.)

#8 A17Shooter

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Posted 19 December 2010 - 03:41 PM

I haven't seen anything from the pellet manufacturers about BC's. An example of the inconsistencies is the Eun Jin 29 gr 22 pellet. It actually weighs in the 27.5 gr region. The BC is listed in the Hawke database as .035 and Straight Shooters as .047. With the .035 BC at 850 fps MV the calculated 50 yd drift is approx 1.47" while the .047 BC results in a calculated drift of 1.08". Extending the range to 100 yds the .035 BC shows a drop of 15.8" and a wind drift of 6.3" while the .047 BC calculates a 14.3" drop and a 4.5" wind drift. Of course while these calculations are fine, most of us fire a shot and spot from that out in the field.

#9 crazyhorse

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Posted 20 December 2010 - 10:05 AM

I use both Straight shooters and link below for BC...,...and,as stated above,good idea to verify software ballistic dope on target,although you need very calm conditions to establish a good baseline....http://www.photosbyk.../pelletdata.htmAlso, I use this link for calculating trajectories:http://www.arld1.com...rdonesteve.html

#10 Bennie

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Posted 20 December 2010 - 10:06 AM

Well I went shooting yesterday and it was real windy. I learned a lot. Pretty humbling to tell you the truth. I need more practice if I plan on hunting in a strong wind. The wind was blowing I would say 8 mph with gust up to 26 mph. I had a real hard time getting most of my 5 shot groups to stay in side of 1 inch at 50 yards. A couple of times I missed where I was aiming by 2 1/2 to 3 inches. I was pretty embarrassed by my own groups, but like I said I learned that I need a lot of practice if I plan on hunting in the wind. It also beat sitting on the couch and staring out the windows. I am shooting 18 grain JSB Exact Heavy's. Just trying to get a feel for this rifle and what I can do with it at this time.

#11 ratassassin

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Posted 20 December 2010 - 03:15 PM

Nothing to be embarrassed about, Bennie. Wind can really mess with pellets.




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