The 4x12x40 is a heavy duplex and I like to be able to see whats going on...I have the philosophy that if you can't see what your shooting then how can you hit it.
If you haven't already had the opportunity, have a look at the sight picture seen through target iron sights (e.g 20y or 50m smallbore, or 300m fullbore). The target's black aiming blob is typically 5-6 MOA in diameter, and the front sight aperture is typically about 8-9 MOA in diameter. And yet with only a year or so of practice, an intermediate level shooter can deliver 2.5 MOA groups, and is probably capable of seeing sighting errors or 1MOA or less. And an experienced shooter can deliver groups of about 1 MOA, and is almost always able to see sighting errors of 0.5 MOA and even less.
This is applicable to scope shooting too. Just because you don't have a *big* sight picture, does not mean that you are not capable of extremely fine aiming. Hunter Benchrest uses 6X scopes at 100 yards, and you simply would not believe how accurately they are able to shoot.
It is my opinion that many F-Class shooters mistakenly choose an extremely fine reticle, in the belief that it is necessary to do so in order to aim precisely enough. When I was shooting F-Class, I preferred to use the heaviest reticles I could get (part of the reason was to provide assured contrast against the mainly-black targets that we shoo at; I found that with a very fine crosshair or dot that the reticle would sometimes "disappear"). When I used a Weaver KT-15, which has a heavier duplex reticle than a standard Leupold duplex, I was able to easily resolve my point of aim for each shot to better than 0.1 MOA.
I always wonder why usmc snipers only use 10x
Most of the reason is probably an extremely mundane one - it's because that is what they have been given.
Military weapons procurement is extremely conservative in many ways. Why should a sniper rifle have to be able to chamber and fire machine gun or infantry rifle ammo? Why should a sniper rifle have backup iron sights? Why should a sniper rifle have a fixed-magnification scope? Why should it be of relatively modest power? Why should a sniper rifle not be equipped with a supressor?
Like I said I am not discounting anything anyone said I am going to try it all and hope I can get some groups less then .700 at 100 and maybe some 3/4 moa at 200. Once I have a set load I will cronograph it and do a custom ballitsics table for drop.
Long range shooting is additive and so is precision its only fun when your hitting your target missing is frustrating.
For a rear rest I normally use my mtm ammo box and set my fist on top of that and let the butt of the gun rest on my fist.
There's nothing wrong with the groups you have gotten so far - very roughly, you are getting honest, repeatable, 1-MOA 5-shot groups at 100 yards using less-than-ideal testing techniques. Personally, I think I would be hard-pressed to deliver groups smaller than 1MOA if I had to support the butt of my rifle with my hand, whereas I can confidently deliver 0.5-0.6MOA using the same setup but with a sandbag rear rest.
Also, you are shooting a factory rifle. It is possible that you can get better performance by tuning up a load for it (and by all means try to), and it is also possible that this is simply the limit of what this particular barrel is capable of.
Even if you can't improve on what you have now (consistent 5-shot 1-MOA groups), you should go ahead and do some shooting at longer range. Pretty much anything that groups well at 100 yards would be expected to perform well out to 600 yards. Beyond that, perhaps by 800 yards but *definitely* by 900 yards, the shot-to-shot consistency of velocity will become important (slower shots will land lower and faster shots land higher). So if you want to shoot 800+ yards, it would be worthwhile getting your velocity Extreme Spreads below 50fps.
I was thinking hotter too as 42.0 is the max listed in the loading manuals i'll have to cronograph them and check for signs of pressure normally pressure and velocity arnt linear.
I seated the bullets just so they arnt touching the rifleing at 2.900"
I have federal primers but I wanted to use up the winchester first.
Start using a chronograph ASAP. You're now at the stage (you're getting "basically good" performance) that a chrono will help.
Remington chambers are *LONG*, as you have found out. You'd almost think they were designed by lawyers, eh...? ;-) (I sometime think that they want to make sure that if you drag a round through the mud, chamber it and shoot, that they can protect you from stupidity!). It might not be possible to get near the lands (a friend of mine ended up using Sierra 190s in his Rem 700VS, just in order to be able to reach the lands).
Something worth exploring at some point is whether plain old magzine-length ammo (2.800" COAL) works just as well. It'll have a mile and a half of jump, but this is how factory match ammo is made, and quite often said mag-length factory match ammo will shoot extremely well.
Winchester and Federal primers will likely both deliver good results for you, but it is always possible that there could be a difference, and so it is something that eventually will have to be tested. So if you plan on eventually using Federal primers, you might as well start using them ASAP in your load development. To be honest though, I'd simply choose one or the other, and use it exclusively - save the other brand for another rifle.
If your looking for sub MOA groups don't ignore your brass. [snip]. Again this can be debated but I figure every little bit helps.
Brass prep can't hurt, but it doesn't necessarily help. If it make you feel better, e.g. absolutely certain that nothing has been left to chance, by all means go ahead and do it.
*BUT*, keep in mind that high quality factory match ammo (Lapua, Norma, Federal) is capable of delivering real 0.5 MOA performance in good rifles. By definition, they are not using match-prepped brass. (Also, they are using thrown powder charges too!).
The most cost-effective piece of load development one can do is to spend $500 and stick a known-good match barrel on a rifle. If you're cheap or stubborn, and certainly many of us shooters are both of those in spades ;-), you can always try to see what that factory barrel is actually capable of....
