The Accurate Reloading Forums
Decreasing MOA with distance; does it really happen?
07 June 2007, 08:38
ireload2Decreasing MOA with distance; does it really happen?
Compensation in the vertical axis is known to be a characteristic of the Lee-Enfield.
As far as the shoot two pieces of paper test you would have a very hard time convincing me that the impact with the first piece of paper would not affect the group size on the second sheet of paper. Some varmint bullets have a hard time staying together with out hitting anything.
I have observed the phenomenon with a .25-06 that I own. It could be related to the scope parallax or it could be that there is a berm next to the 200 yard target frame and the 100 yard frames are exposed to the wind. But it normally shot a little better MOA wise at 200 yards than at 100 yards.
07 June 2007, 15:46
sonofagunquote:
Originally posted by vinconco1:
Does anyone have any idea if shooting through 4 or 5 pieces of paper at the same time would have any effect on the bullets flight. That is one experiment I could set up and it would seem to be a rational place to start before trying to line up targets over extended range.
Just this weekend I shot groups at 100 yds that measured around 1 moa and then at 300 yds that were .45 moa. I did this twice in a row. I know that this doesn’t prove anything but I have had this experience quite often in the past. One set was fired in calm conditions and the (smallest) group was fired in driving rain with about a 15 mph full value wind. I have an indoor shooting position right next to my loading bench. .308, 175 SMK, 2650 fps
Which set was fired in which conditions? Post pics of the groups here. Same gun & ammo? What was load? More details are needed.
I've done it in the past and don't remember the paper doing much to change the bullet's flight - don't use a heavy target weight paper but lighter weight such as a standard printer uses. It is a very interesting test - you should see the same group shape only expanded as the range increases.
Bob Shaffer
08 June 2007, 02:59
vinconco1Sonofagun;
As it turned out the group fired in the rain and wind was the smallest. Same gun, same load. 308 PSS, 175 smk, 2650 fps (all this was detailed in my post you quoted)
How do you post pic on this forum? Other forums allow uploads but this one looks like it wants to link to a place the pics are stored or something.
Help me out with this and I'll post them this weekend.
08 June 2007, 08:50
sonofagunquote:
Originally posted by vinconco1:
Sonofagun;
As it turned out the group fired in the rain and wind was the smallest. Same gun, same load. 308 PSS, 175 smk, 2650 fps (all this was detailed in my post you quoted)
How do you post pic on this forum? Other forums allow uploads but this one looks like it wants to link to a place the pics are stored or something.
Help me out with this and I'll post them this weekend.
Simultaneous bullet imprinting at multi ranges is still needed here to prove anything. If you get a 1/2 (or.45 MOA) group at 300 yards, what was the MOA dispersion of these SAME shots at the shorter ranges? OR if you shoot 1 MOA @ 100 yards, what is the dispersion of SAME shots @ 300?
Yes, pictures have to be "hosted" elsewhere and then they can be shown here - someone else here can probably explain this better than I can or look for instuctions elsewhere on this site (try Forum Suggestions and Help).
Bob Shaffer
08 June 2007, 16:25
vinconco1Sonofagun;
All I need now is the "permission" to post. I have scoured the site and have not found how to "get" this permission yet but I posted the question in the Administrative Forum so I should have the capability soon.
As I said earlier in the thread, I would love to do the dual printing of the shots but my 300 yd target is up on a hill and my 100 yard target would have to be 20' high to line them up, so for now I will have to be satisfied with keeping my records and see how the averages work out over time. I already have a large file of targets from many rifles and I will go through them to see how many fit these criteria and post them.
I found Toadhead's links interesting and it seems that the idea of decreasing MOA is not new and is at least supported by the math.
11 June 2007, 00:54
ireload2Vinconco,
You have to put your photos on a photo hosting site lie photo bucket.
Then paste the url into the window that opens when you lick the little photo icon next to the white envelope above.
11 June 2007, 00:55
ireload2quote:
Simultaneous bullet imprinting at multi ranges is still needed here to prove anything.
This will never happen......
12 June 2007, 07:23
243winxb We may never know.
14 June 2007, 21:03
sonofagunquote:
Originally posted by ireload2:
quote:
Simultaneous bullet imprinting at multi ranges is still needed here to prove anything.
This will never happen......
Uhhhh, and why not?
Bob Shaffer
17 June 2007, 21:28
Jim w.It's been done.
There was an experimenter who set up one of those Oehler Home Ballistics Labs with accoustic target at 100 yards and a paper target at something over 300 yards. So he could plot shots at two ranges with no risk of a close paper target disturbing the bullet flight to a far paper target.
He said that in NO case did ANY caliber or load EVER give a smaller MOA group at the longer range than it did closer. No statistics, no comparisons, the SAME bullets at two ranges. The particulars are out there on one of the boards or in one of the serious journals.
F.W. Mann set up rows of tissue paper targets to watch bullet precession, nutation, and whatall else might affect accuracy. Most of his trials were at relatively short range and would not likely pick up the legendary phenomenon of bullets "going to sleep" and getting more accurate as they went along.
I think one of the US Arsenals did similar at longer distances but do not have data.
18 June 2007, 05:09
ireload2quote:
Originally posted by sonofagun:
quote:
Originally posted by ireload2:
quote:
Simultaneous bullet imprinting at multi ranges is still needed here to prove anything.
This will never happen......
Uhhhh, and why not?
The impact of bullet against the paper puts another variable into the results.
18 June 2007, 05:12
ireload2quote:
Originally posted by Jim w.:
It's been done.
There was an experimenter who set up one of those Oehler Home Ballistics Labs with accoustic target at 100 yards and a paper target at something over 300 yards. So he could plot shots at two ranges with no risk of a close paper target disturbing the bullet flight to a far paper target.
He said that in NO case did ANY caliber or load EVER give a smaller MOA group at the longer range than it did closer. No statistics, no comparisons, the SAME bullets at two ranges. The particulars are out there on one of the boards or in one of the serious journals.
F.W. Mann set up rows of tissue paper targets to watch bullet precession, nutation, and whatall else might affect accuracy. Most of his trials were at relatively short range and would not likely pick up the legendary phenomenon of bullets "going to sleep" and getting more accurate as they went along.
I think one of the US Arsenals did similar at longer distances but do not have data.
This example might be workable if the calibration of the acoustic screen is accurate.
Buit then again it is only one example and there are millions of rifles and shooters out there.
Parallax might account for the differences.
21 June 2007, 19:30
sonofagunParallax error could be eliminated by testing using a rail gun.
Bob Shaffer
22 June 2007, 08:40
ireload2quote:
Originally posted by sonofagun:
Parallax error could be eliminated by testing using a rail gun.
That is true. You may be looking to prove it can't happen. As long as there are millions of shooters out there with varying conditions and parallax there will be reports of decreasing MOA from time to time. It might be interesting to talk to an experienced rail gunner.
18 September 2007, 05:51
ireload2I called Sierra and talked to the ballistics technician named Paul Box. He said that long bullets such as the 6.5 142MK will not be settled down at the shorter ranges and will shoot smaller MOA at longer ranges. He said all of Sierra's QC testing was done with 10 shot groups at 200 yards except for military qualification testing which is done at 300 yards. If any one wants to dispute the issue they can call the bullet companies and report what you get back here.