Maverick223
Member
True, which is why DMR optics typically have moderate magnification.
How so? I've never heard of the objective affecting the parallax.
Magnification per Yardage
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Pete D. said:
Let's be clear about the role of coatings on optical lenses, they attenuate specific wavelengths of light. In other words, they don't allow more light to be transmitted, in fact they reduce the transmission which in turn, if done well, improves the quality of the image, not the quantity. The amplification of noise has been an age old problem for any device that amplifies a signal.
Maverick223 said:
The exit pupil is typically calculated by dividing the objective lens diameter by the magnification. The larger the objective, the larger the exit pupil at all magnifications. If the eye is centered in the scope tube there is no parallax. Intuitively, you'd think that the smaller the exit pupil the greater the chance of good alignment between the center of the tube and the eye. Perhaps this is why a larger objective could result in more parallax issues compared to a scope with the same magnification range but smaller objective. Just a thought.
Zak Smith
Member
That's true. A trick to reduce parallax error is to put a cardboard "reducer" in front of the objective that has a smaller aperture than the objective lens.
I haven't seen kis2 post anything about this, so I'll just spit something out and he can correct me if I'm wrong. I've kept up with some of his posts and it appears to me that he does shoot some competitions using a .308; and when he talks distance shooting, he isn't talking about 450 yards either. From the pics I've seen, his "shooting range" extends to distances of as far as the eye can see. Yeah, I'm jealous.
^^^That's true TonyAngel! I've only been to one of Zaks competitions, but plan to attend more regularly, it's just such good training. I think I learned more about my rifle in 60 rounds at one of those comps than 300 on my own. F-class is a good experience too, just different. and less scenic.
Though I've had some success, I'm revamping my bolt to come back built for 600+yd shooting. The longest place I've found with a real good solid backstop is about 1250yds, and I plan to try and touch it. As best a .308 can do that.
Don't be too jealous though TonyAngel, the only places where one can see as far as the eye can, are places without trees
I've learned a lot in my past two threads or so, and most of you have been posting in them, so thanks for the new knowledge! lots of good learning happening.
Though I've had some success, I'm revamping my bolt to come back built for 600+yd shooting. The longest place I've found with a real good solid backstop is about 1250yds, and I plan to try and touch it. As best a .308 can do that.
Don't be too jealous though TonyAngel, the only places where one can see as far as the eye can, are places without trees
I've learned a lot in my past two threads or so, and most of you have been posting in them, so thanks for the new knowledge! lots of good learning happening.
yeah, I think if I stepped up, I'd step up big. Like to a .338LM. something where it's extremely difficult just for me to find a place that has room for it to stretch its legs.
that said, .308 is so gosh darn entertaining, I think it'll be awhile before I'm bored
that said, .308 is so gosh darn entertaining, I think it'll be awhile before I'm bored
kis2 said:
I've been going back and forth between an AWM chambered in .300 Win Mag or .338 Lapua Mag. I finally decided that .338 LM would be a waste for me. Our longest range is 1,000 yards and the USMC base I shoot on doesn't put any reactive targets out past 900 yards. I can nail those targets with my .308 Win and considering that I have dies, cases, bullets and powder for .300 Win Mag, that's what I'm sticking with.
Zak Smith
Member
"Get Both"-- get it in .338LM and then buy a .300WM bolt body and shoot 7RM... best of both worlds. I am tempted by the AX338, but smaller bolt heads are not available.
kis2, this is your thread so I apologize for getting off topic a bit.
I forget the BC of the 208gr A-MAX but it's over 0.5 I'm sure. That's what I use with Reloder 22 in my current .300 WM and get excellent results. I bet the load I have worked up will shoot great in the AWM too.
There's a switch barrel kit for the AWM with two bolts, two barrels and two magazines for .300 WM and .338 LM. It adds $2,000 or so to the cost and that was my plan initially, but I figured that the .338 LM barrel, bolt and mag would just sit in the safe. If I buy the .300 WM, I could simply order a 7RM barrel for it ... right?
kis2 said:
I forget the BC of the 208gr A-MAX but it's over 0.5 I'm sure. That's what I use with Reloder 22 in my current .300 WM and get excellent results. I bet the load I have worked up will shoot great in the AWM too.
Zak Smith said:
There's a switch barrel kit for the AWM with two bolts, two barrels and two magazines for .300 WM and .338 LM. It adds $2,000 or so to the cost and that was my plan initially, but I figured that the .338 LM barrel, bolt and mag would just sit in the safe. If I buy the .300 WM, I could simply order a 7RM barrel for it ... right?
Zak Smith
Member
What I suggested is what I did. You can just buy the bolt body, magazine, and then an aftermarket barrel in 7 - might even be able to find a "used" bolt body. I've been shooting the 7 setup for the last couple years, but before that I shot thousands of .338 through it. I do like the 7, but the 338 has a special appeal.
But to your last question- yep, simple barrel change.
But to your last question- yep, simple barrel change.
Maverick223
Member
Thanks for the info, 1858 & Zak Smith. I always thought that the "cardboard (or duct tape) reducer" was an attempt to reduce glare and aberration when a sunshade wasn't available.
Can't speak for '58, but I like the 190SMK (0.533), 208A-Max (0.648), 240SMK (0.711). I haven't gotten around to it, but I want to try 210SMKs (BC of 0.629) in the near future. So far I like the A-Max the best, with the 190SMK being a close second (I believe the 240s are just a bit too heavy and long to reach a decent velocity so I doubt that I'll buy more).
I am considering a 7mmRM after I wear out my .300Winnie...I take it you think that is the right move?
Zak Smith
Member
7rm : .300wm :: .260 : .308
Maverick223
Member
Ain't no way! The .300WM isn't that bad...the three-oh-8 is a poor excuse for a LR rifle cartridge [ducks*].
*Then realized I didn't need to because the poor folks were shooting those wee little .308s that couldn't reach out this far.
Zak Smith
Member
You're right-- it's not proportionally as bad ballistically. But it does burn 10gr more powder.
Maverick223
Member
True, but it doesn't burn up barrels quite as fast either, so that should even things out a bit. That said, I still believe that is destined to be my future barrel, because ballistics are a bit better, with less recoil/blast, and bullet choices increase by a fair margin. If offered in the rifle to begin with, it is almost certainly the route I would have went.
"kis2, this is your thread so I apologize for getting off topic a bit."
No apologies needed 1858, I think it's a great discussion.
"*Then realized I didn't need to because the poor folks were shooting those wee little .308s that couldn't reach out this far. "
HA
No apologies needed 1858, I think it's a great discussion.
"*Then realized I didn't need to because the poor folks were shooting those wee little .308s that couldn't reach out this far. "
HA
Maverick223
Member
I figure i'll be fine till I get within tomato range.
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