7mm mag

[308Nut]

Check with a bore scope to see if there is a 'carbon ring' in the throat. These can cause high pressures in even SAAMI spec rifles and loads. You may be reducing it with some cleaning but not enough to elilminate it. Normal cleaning does not typically prevent or eliminate carbon rings even though it may slow them down or reduce them a bit. Once they appear they can cause problems such as what you are having. GM top engine cleaner can help. JB or IOSSO will definately get rid of it but it can polish the metal in the proccess which will cause copper fouling to occur faster so don't over do it and only do it at the throat area. Another way you can tell is to clean the bore the best you can and then push a nylon brush past the muzzle in a dry bore, then pull it back at a slow pace. All should be smooth and then it will come to a stop or offer more resistance depending on how hard and fast you are pulling where it meets the carbon ring if there is one. I don't use a bronze brush for this because the nylon 'glides' easier and is smoother so you can feel it better. I sometimes use bronze for a deep cleaning but use the nylon to look for any carbon rings.

 

Also, a super polished chamber can cause tougher extraction. Similar to a barrel that is lapped properly or not. A polished bore will make copper fouling a problem. Not smooth enough and you have the same problem. Excessively rough chambers can cause sticky extraction and super polished chambers cause the same thing. There is a balance there.

 

If it is not a carbon ring, it is most likely a fouling problem. Try working up a load with a dirty barrel. For my 6.5 it takes 6 shots after even a minor cleaning to settle back to normal. I have the same problem you have only in reverse. The first 5-6 are sticky and then everything is normal. I now use reduced load for foul shots. Every gun is different and there are few hard and fast rules.

 

Let us know what you find.

[Couesdeer]

You can always rebarrel!

I know where you can get a 26" Hart barrel in 257 Weatherby threaded for that action.

[reganranch]

You can always rebarrel!

I know where you can get a 26" Hart barrel in 257 Weatherby threaded for that action.

 

5 steps in the right direction.

[jwhernandez]

We'll I dropped my gun off at the gun smith hes gonna mount my scope for me and find a load for my gun after he fixes itwhat do yall think the max range is for a seven mag

 

[jwhernandez]

I dropped my rifle off the gunsmith suspects carbon buildup hes gonna fix the problem and mount my new leupold scope and work up a load for me what would yall say the max effective range is for a seven mag is?

 

[308Nut]

what would yall say the max effective range is for a seven mag is?

 

Hard to say with such little info.

 

What is your intended target(s)? What bullet(s) do you intend on using?

 

I agree with your smith about the carbon buildup.

[jwhernandez]

I guess for deer im assuming around 160 grain and I appreciate everyones input and help this site is great there is alota knowledge between everyone my wife bought me the mark4 8.5+25+50 tm I was thinking around 700 to 800 yards

 

[firstcoueswas80]

The gun is lethal Farther then you can shoot accurately.

[jwhernandez]

Sweet idont usually take long shots except for when im practicing but it all about options