TC Encore 300 mag accuracy problem

[9point]

I am trying to get a good confident zero with a new 300 Win Mag barrel and am having a few problems. Here is what I did: I started off using winchester Power Point 180gr. ammo and after about 12 shots had a nice 2" group at 100 yards. Please remember this; I am new to high powered rifles so a 2" group is good for me. Feeling good about where my gun was hitting I decided to switch to a different ammo that I will be hunting with in AK next month: Winchester Supreme Elite XP3 180 grain. The first two bullets hit 6" low dead center so I adjusted the scope and dialed it in to the bulls eye. Q. Why would faster ammo of the same grain hit lower?

Three days later back at the range and shooting the XP3's again and my bullet totally missed the target for the first 3 shots before it starts hitting back close to where it was two days prior. The barrel was cleaned with Hoppes cleaner, a bronze brush, and then dry patched following each session at the range. TC Arms, Inc informed me that their barrels need to be fouled inorder to get good accuracy. I am having a hard time believing this since serving 22 years in the Army I have always believed a clean weapon is an accurate weapon.

Can someone please shed some light on the problems I am having? I have 3 weeks until my moose hunt and I do not feel warm and fuzzy about this rifle. Thanks!!

 

[Deathray7]

Fouled bore

Fouled bore

I have run into several rifles now that wouldn't shoot well until four or five rounds had gone down the tube. And I couldn't shoot enough (2 1/2 boxes at one sitting!) to foul them to the point where it wouldn't shoot accurately anymore.

How many total rounds have you shot through it? A lot of rifles don't start to shoot until 3 or 4 boxes have been shot through them.

And remember that some rifles are finicky about the brand of ammo, weight of the bullet, and even between individual boxes of ammo.

Keep trying different weights and brands until you find one that shoots well, and then buy several boxes (from the same lot number) of it.

And just remember, where you put the bullet is more important (most of the time) than which bullet style or weight you're using.

 

[AlleninAlaska]

Winchester Supreme Elite XP3 180 grain. The first two bullets hit 6" low dead center so I adjusted the scope and dialed it in to the bulls eye. Q. Why would faster ammo of the same grain hit lower?

Faster ammo is in the barrel a shorter length of time during the recoil proccess. Not saying that accounts for the whole 6" low group, but at least a portion of it.

Three days later back at the range and shooting the XP3's again and my bullet totally missed the target for the first 3 shots before it starts hitting back close to where it was two days prior. The barrel was cleaned with Hoppes cleaner, a bronze brush, and then dry patched following each session at the range. TC Arms, Inc informed me that their barrels need to be fouled inorder to get good accuracy. I am having a hard time believing this since serving 22 years in the Army I have always believed a clean weapon is an accurate weapon.

I always shoot fouling shots with the ammo I am going to use for hunting. You also have the cold barrel VS hot barrel effect. A 2" group with 12 rounds at 100 yards is not a bad group.

 

[9point]

# of boxes shot

# of boxes shot

Deathray7:

I've shot 3 boxes of 180 gr Winchester ammo. I plan to shoot at least one more maybe two before my hunt in 3 weeks.

 

[Deathray7]

One other thing to check

One other thing to check

Scope rings and bases: Make sure they're still tight (and maybe lock-tite them on for good measure).

When you start in on this next box of ammo:

1. Shoot 3 or 4 times at a separate target and don't worry about that target.

2. Then shoot a 5 round group at a clean target from sandbags on a bench, concentrating on squeeeeezing the trigger. If you're shooting a 2" group, you're good to go.

3. Take your worst shot of the 5 and disregard it (even benchrest competitors occasionally have fliers) and using the center of the 4 tight shots, use that to determine where to adjust your scope (usually 2" high at a 100 yards).

4. Don't clean it! Put the rifle away until your hunt (only check it if you travel a long ways to your hunt location, should only take 2 shots).

5. When you shoot your 70" moose, just tuck the crosshairs behind the shoulder and make sure you post lots of pictures on this website.

 

[9point]

Will do! I can't wait to just get there and experience the outdoors much less harvest a bull. When using sandbags do you put one under the stock as well as the forearm? I've also seen guys hold their non-trigger hand infront of the scope over the barrel to hold it down but have not tried that one yet.

 

[Deathray7]

Sandbag procedure

Sandbag procedure

It's okay to put sandbags under the stock, but make sure they don't interfere with your normal stock-to-shoulder position. They are there to steady the rifle butt and reduce "wiggle".

For the sand bags under the forearm; I like to LOOSELY grip the forearm with my hand between the forearm and the sandbags. Don't grip too hard or you'll be able to see your pulse as the image "jumps" in the scope in time to your heartbeat. This loose grip will also help control muzzle jump as the round goes off. Remember to squeeeeze.

Never let the barrel touch anything during hunting or sighting in. This can affect accuracy big-time! I don't even let my fingers touch as I grip the forearm.

Also, don't forget to let the barrel cool to a consistent temperature if you're somewhere warm. One shot every 2 - 3 minutes if it's above 65 degrees. And don't "overshoot", 1 box per range session should be the max unless you're shooting varmint calibers.

Great cartridge selection, great rifle selection, have fun!

 

[Fort Valley Man]

Hey 9point, I experienced the same thing with my .270 and 7mm-08 barrels . I thought I was losing my mind. I would leave the range zeroed for 100 yards to the POI that I desired. I would go home and clean the barrels only to learn with I returned to the range that I would miss the entire page as I was shooting high. After the about 5-6 fouling shots, the barrel would print a group where I first zeroed the barrel. I agree with whoever posted above to clean the barrel, shoot a half a dozen fouling shots, then if it prints where you want it, hunt with a fouled barrel until hunting season is over.

 

[brav01]

I can't believe I started to answer a 5 year old question.

 

[323]

Is this a record for revising a thread?

 

[Amigo Will]

It should be fouled enough by now

 

[highestview]

I have a Thompson Center .300 Win mag that did the same thing. It turns out that the threads from the factory were sized improperly. I figured that out when no amount of loctite could keep my shots on zero. They would vary by as much as 8 inches veritcally. I took it to Precision Arms here in Anchorage and he told me that the threads were too small for the screws that came with the scope bases and so they would never actually set in enough to hold the scope base down properly. He said he's seen it before and apparently they get sloppy in their threading of the scope base screws. He tapped out the threads to the correct spec and put new screws in and it fixed the whole problem Take it to a gunsmith and have him check the threading.

 

[norsehunter]

I can't believe I started to answer a 5 year old question.

Hehehehehehe.