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Well I gave up on my 308, AR10. I bet I tried 20 different reloads to try to get it dialed in. No luck past 200 yds.

Was going to rebarel in 6.5 Creedmore, but then I remembered I have a Remington 700, in 7mm mag that I have not shot in about 20 yrs.

Well, put the Vortex PST II on it and took off to the range. Had some reloads from the 90's and figured we will see how it does.

Shooting 150, 160, 175 gr reloads and it appears that the 150 are the best groups at 200 yds.

Anyone on here shooting 7mm for long distance?

If so would like to pick you brains on different powders and bullet weight.

I am presently using H4350 and IMR 4831.
 

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hostilenativelibertarian.
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;)160-162 grn,spbt or better,h4831!:blink:BTDT.
 

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Generally 7MM Rem Mag will give you a shorter barrel life as the round is rough on barrels.

This is because of several reasons:

1. The amount of propellant burned gives you more heat that transfers to the barrel.

2. The 7MM bullets are generally longer and the longer the bullet the more heat is built up from friction. This is readily noted with a good borescope that will give you a angle look downbore. On the tops of the lands the friction/heat "check" the barrel. In other words looks like a dried out mud hole with cracks.

3. Once the cracks get going they shave off bullet jacket material and start building up copper deposits on the tops of the lands. when you start shredding copper off the bullets the center of gravity changes and groups open up.

4. Guys that shot 7 mags at long range figure out pretty quick the barrel life is about 500 rounds.

For longest barrel life in magnums a 30 cal will hold up a tad longer. Perhaps 700 rounds.

If you stay with the lighter 30 cal bullets you may stretch it to 1000 rounds.

The same bullets in 308 should give you much longer barrel life assuming you clean your rifle.

Worst thing you can do is shoot, let it cool off and shoot it again. Think of it this way, when propellant burns, it leaves carbon right? What is hardest substance known? Diamonds which are carbon.

So if your barrel cools down, forms carbon, then the next bullet down picks up the carbon by embedding it in bullet jacket and does a number on the rest of your barrel.

So moral of this story is shoot, clean within seconds after you get through and the carbon comes out easily. Let it cool and you just did it to your barrel.

308 match barrels are generally gone at 4000 to 5000 rounds. 308 ammo acceptance barrels lasted 15,000 to 17,000 rounds. Why? They are shot fast, removed and sent for cleaning and not fired again unless they are clean.
 

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The 7 RM in a decent action, like the 700, trued and squared, with a good trigger, with a good quality barrel is fully capable of outstanding accuracy at distance. Most folks that shoot long distance kow all too well about modern barrel treatments that preserve the barrel life and prevent fouling buildup.
If you want to test the accuracy of your as is 7 RM, try the Lyman Manual accuracy load for the 140g with 4350, right out of the book. That load should shoot sub .5 inches, if you do your part.

By the way, a real problem with the 308 AR is that they are not mil spec, most sold today are of a DPMS design, made by different makers, with parts of different specifications. Old story, put a bunch of parts together each at the far side of no common specification and you get a mess, and a very common complaint. I only build with Armalite pieces and parts. Armalite is the only AR-10, AR-10 is their registered name. The DPMS 308 AR and Armalite AR-10 pieces and parts do not properly interchange, magazines do not even fit each other.
 
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