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ALCOAR
10-18-10, 16:58
Hi gents, I had my range session yesterday morning ruined by what I can only describe as mirage or some kind of environmental disturbances.
The conditions I was experiencing involved my sight picture being distorted by what appeared to be waves of gas...extremely noticeable so much that it created multiple cross-hairs on the target or all together made the target almost impossible to see. It seems to precede and get worse after a shot so I seem to think its a barrel heat mirage but I am only using 10x NF's on a SPR and Recce rather than high magnification in which usually one experiences mirage effects. I am shooting prone for groups at 100yds in 65-70 degree conditions, less than 5 mph of wind and my firing path is setup directly over concrete as opposed to dirt or grass, etc.

Anyone diagnose what was going on and how to potentially avoid or remedy this in the future...thanks in advance for any suggestions or thoughts.

Update: I went this morning a tad bit earlier than last range visit and no mirage or effects described above and that hopefully was my first and last episode....weird, weird stuff was going on is all I can say:)

DMR
10-21-10, 14:02
Depending on your shooting tempo it may just be heat from your barrel. I have had such a problem several times shoot groups out of my DMR's with the scope on 10x. Enough heat I would have to just hold center on the orange blob at 100m. Here is a sample group of one of my early rifles shot in such conditions. This is a 15 round group at 100yards:

\Hum, I will have to reload that link.
http://pro-patria.us/DMR/DMR52grtest2.jpg

Have to agree with the others. Not sure how the heat off the barrel would affect your cross hairs.

taliv
10-23-10, 15:52
The conditions I was experiencing involved my sight picture being distorted by what appeared to be waves of gas...extremely noticeable so much that it created multiple cross-hairs on the target or all together made the target almost impossible to see.

been scratching my head on this for a couple days before I decided to respond.

Maybe I'm just dense, but I can't figure out how any external condition would look like multiple crosshairs. No matter how bad the distortion from change in temperature is between you and the target, I'd think the reticle would remain crisp (and singular) on a properly adjusted optic.

Perhaps with binocular optics you could get double-vision. And your reticle could appear fuzzy if your eyepiece isn't set right.

Very curious to know if you ever figure that out.

ALCOAR
10-23-10, 16:23
You can read about similar mirage distortions on SH but the waves of "gas" distort the crosshairs basically.....hard to describe with words.

taliv
10-23-10, 16:45
i'm very familiar with mirage that distorts your vision of the target. i just don't see how it could change the reticle

TAZ
11-04-10, 22:44
I dont have a lot of precision exerience with gas guns, but it sounds like heat rising from the barrel, or more likely the gas tube. The thin tube would probably heat up rather fast and the shed the heat just as fast.

Seems easy enough to diagnose if its weapon related or atmospheric. Go out with a cold weapon and look through the scope. If there is mirage then its atmospheric. If no mirage, fire a round and see if mirage begins... rinse and repeat till you get mirage.

ICANHITHIMMAN
11-04-10, 22:51
I have experinced this on a 260 rem. Barrel just got to hot scope was mounted real low. Had to let the rifle cool and slow my pace

Mute
11-25-10, 14:23
Sounds like barrel heat. The environmental conditions you describe should not produce the kind of mirage you're noticing. You can always lay a thin piece of cloth across the top of the barrel to absorb some of the heat coming off the barrel.

ALCOAR
11-25-10, 15:38
You gents are most likely dead on about barrel heat being the cause as I was expierencing this effect while using a nxs 2.5-10x24 that is several inches shorter than a traditional 10x optic and so more of the barrels heat rises in front of this particular optic. I have thought about going with the piece of venetian blind and two pieces of velcro but I have not had this effect come back and screw my shooting up since that one session so I will refrain from going all "interior decorator" on my rigs until I have to :)

mark5pt56
12-03-10, 06:36
I've seen mirage bands on certain precision bolt guns, namely the Sig.

http://www.sigsauer.com/sigstore/ShowProductDetails.aspx?categoryid=29&productid=323

If on max power, try backing it off some

if you must and I've never done this--

Idea's to mitigate the effects
use "tactical" rubber bands to attach the "blind" to the scope sunshade, long enough to divert the heat wave.
sunshade
longer rail and solid covers on top
longer rail and if not using a front sight-slide the solid cover forward of the rail like a diving board to act as a mirage band

ALCOAR
12-03-10, 13:09
I've seen mirage bands on certain precision bolt guns, namely the Sig.

http://www.sigsauer.com/sigstore/ShowProductDetails.aspx?categoryid=29&productid=323

If on max power, try backing it off some

if you must and I've never done this--

Idea's to mitigate the effects
use "tactical" rubber bands to attach the "blind" to the scope sunshade, long enough to divert the heat wave.
sunshade
longer rail and solid covers on top
longer rail and if not using a front sight-slide the solid cover forward of the rail like a diving board to act as a mirage band

Thanks Mark for weighing in and as usual its with excellent information. I have backed off a bit @ 10x a time or two when experiencing mirage effects and it has helped a bit.

I must admit I hate seeing rail covers on the top rails and so I honestly never even thought about taking some xtm's(wont require removal of front buis) and using 4 of them on the top rail to negate this should it happen in the future. Solid tip there brother:)

mark5pt56
12-03-10, 14:07
No worries, hope it helps out!