AR-10, LR-308, and how many others are there?

[Grandma]

On the Omen, I met those fellas last year sometime when the wife and I were out in Montana. The bolt carrier they have is a fresh design and help reduce the recoil. I linked them up with the Sniper section back at my unit and they brought a few guns out to Fort Lewis to let the boys shoot them. I had other things going on that day and didn't get out to the range with them. The guys I did talk to were all very much impressed with the system. They all reported the recoil to be less than that of ARs in .308. The advantage of .300 WM over .308 is significant enough that all of our sniper systems are being switched to it. Then having it in a gas gun will certainly shine in a tactical situation. Hunting-wise being able to follow up immediately with a 2nd shot is always a benefit. They are spendy but I like where they are going with it.

I look forward to reading about your project in the future.

 

[grunt0311]

I am reasonably certain my next project is gonna be a big AR. This is the beginning, I know there are several different variations of the "AR-10, but that's about all I know. Other than it will be in 7mm SAUM, it will have a heavy 28 or 30 inch barrel, and of course accuracy is the most important attribute. (Disclaimer) I am not now, nor do I plan to shoot "1000 yard bench rest competition." So all you bench rest types, go find another thread to unleash your negative rhetoric on. With that being said, any helpful advice will be greatly appreciated. What I have in mind is a rifle capable of taking any antlered critter in North America at extended ranges.

I am in the process of finishing my 308 win AR platform. (SR-25 magazine). The A-10 is from armalite and at least the magazines are not innerchangeable. CB arms inc. out of oklahoma have a complete upper with24 inch stainless steel fluted barrel for 899.00. Are you doing the lower yourself as a homebuild or are you buying the lower complete?

 

[grunt0311]

Yes, Carl at Accuracy Systems is the man to talk to when looking for a SAUM in the AR10 platform, but you're going to have to twist his arm to get him to build a 24" upper. The last I heard, his recommendation was that "IF" he does a 7mm SAUM...that it would be more toward the 20" length. As I said, good lucking asking him about the 28"
This isn't as much of an issue as you'd think it would be.

You're going to have PLENTY of energy from a bullet that size, going that speed anyway. It's UNMATCHED in the AR10 platform.
Being able to consistently hit MOA targets on your first shot is where things get interesting anyway.

You're "probably" only going to be able to run something like the 168gr VLD bullets at mag length without having seating depth issues anyway. And that's a best case scenario. Something like the 162Amax would probably even be best suited due to the relationship of high bc to weight ratio.

For example, if you run the 162Amax at a conservative 3050fps from a 24" barrel, you're looking at 23 MOA of elevation (6.6 mil) at 1000 yds and you're still carrying OVER 1000 lbs of energy. (at my bp of roughly 28.45 on most days)

Trying to seat something like a 180 VLD is probably possible, but you're going to run into the ogive getting way down at the case mouth and that's usually too deep to get the accuracy you usually want from a VLD. It's to much of a jump to the lands.
You can do the math with any bullet you want to see how much seating depth you'll have to work with.

Typical mag length is 2.800"
7mmSAUM Case length is 2.035"
A 180 VLD is 1.525" total and .825" from the base to ogive leaving .7" from the ogive to the tip.

If you add .7 (ogive to tip) to the length of a case, you're looking at a COAL of 2.735" if you seat a 180 VLD to so the ogive is at the case mouth (not recommended)...which only leaves you .065" to play with seating depth before you're out of mag length.

So it's possible, but not likely for accuracy. 168 VLD's will be a little better, but I still feel the 162 Amax to be about the ideal bullet for that platform.

Also, using a powder like RL17...you're going to hit pressure signs, long before you actually run out of case capacity, so seating a heavy bullet deeper doesn't really correlate to loss of velocity in the semi-auto.
With other powders, that may not be true.

I purchased a 300 SAUM Armalite Upper a while back and I've been happy as a pig in shat ever since. I've had 3 different bullets (185, 190 and 210 VLDs all shooting around 1/2 MOA) and I've take two of those rounds out to beyond a mile so far.
Longest game KO is 930 yds and I would have no hesitation in going out to 1200 or so.
With the .30 cal 190s VLDs that I'm currently running...I'm carrying almost the same energy at 1000 yds, that you could potentially get with the 162 Amax at the same range. So you're correct in the 7mm ballistics...it will just depend on what bullet ultimately get to shoot the best.

I've been planning to get a 2nd upper in 7mmSAUM built for 2 years now and just haven't gotten around to it.

I am working on a 308 win Ar platform and just about have all of the parts to start putting it together. My question is what do you think the rifle is capable of, distance wise, and what bullets to use medium and long range? The barrel is 20" ss fluted. my scope will be a 6-18x40 leupold. I have a couple boxes of 180 gr. to try out and I have a couple hundred of 150 gt fmjbt and 168bthp for reloading. By the way I am in the process of gathering equipment for reloading which I have never done before. I did spent 3 years in the corps so if you are wonmdering I do still remember how to pull the trigger.

 

[blksno]

I am working on a 308 win Ar platform and just about have all of the parts to start putting it together. My question is what do you think the rifle is capable of, distance wise, and what bullets to use medium and long range? The barrel is 20" ss fluted. my scope will be a 6-18x40 leupold. I have a couple boxes of 180 gr. to try out and I have a couple hundred of 150 gt fmjbt and 168bthp for reloading. By the way I am in the process of gathering equipment for reloading which I have never done before. I did spent 3 years in the corps so if you are wonmdering I do still remember how to pull the trigger.

I would run the 150 and 168s inside 800 yds...you could push the 180s to 1000 or more if you're good with the rainbow rounds
It's CAPABLE of sending them WAY out there...1500 would be a safe bet, but you've gotta really know what you're doing to pull it off, and even then, its 90% luck.
If you wanna send them out to take out critters, I would leave it at about 800 yds. There are much better options for anything past that...again, depending on how well you both shoot together.

 

[grunt0311]

I would run the 150 and 168s inside 800 yds...you could push the 180s to 1000 or more if you're good with the rainbow rounds
It's CAPABLE of sending them WAY out there...1500 would be a safe bet, but you've gotta really know what you're doing to pull it off, and even then, its 90% luck.
If you wanna send them out to take out critters, I would leave it at about 800 yds. There are much better options for anything past that...again, depending on how well you both shoot together.

That was the answer I was hoping for. My thoughts at this time ( when I finish the build) are starting out at 300 yards with scope and working up to 600 yards and if all goes well on up to 800 yards. may play around for a little more but not much. Also hope to do some 1-300 yards open sights. Am now retired as of Sept. and just want to enjoy.gun) Thank you for your input