Problems Grouping with my Thompson Center 300 Winchester Magnum

[Dontana]

I purchased a 300 win mag pro hunter barrel for my encore about 4 years ago. I have bought hundreds of dollars worth of Magnum loads from different manufactures and cannot get sub MOA groups at 100yrds... I have a Bushnell Elite 4200 2.5-10x40 mounted on it but just bought a Vortex Viper 4-16x44 Dead Hold BDC and would like to start practicing some long range click shooting but need it dialed at 100 first. Yes, shooting from bench in lead sled. Anyone own this gun and have similar struggles? Have you found an ammo that performs well?

Thanks for the help,
Don

 

[LeddSlinger]

I hand load, but have you tried Federal Premium or Black Hills Match ammo yet?

If only using the cheap factory ammo, I wouldn't expect much.

You are not strapping the rifle down to the lead sled are you?

 

[Jud96]

The stock maybe rubbing against the barrel somewhere causing the bad groups. If you free float the forend this will help.

 

[Dontana]

Thanks guys. Not sure if I've tried the Federal Premium and have not tried the Black Hills Match. I have progressively bought more expensive ammo. The last box and the best groups have been with a small semi custom Montana company- HSM. They load with Berger bullets - 185 grain.

The forearm stock is independent of the buttons stock. It is a single shot that breaks open. Can the forearm stock still interfere?

 

[benchracer]

Sub-MOA from a break-open single shot with factory ammo is asking a lot. If the forearm is touching the barrel, it WILL have a negative effect on accuracy. As previously mentioned, try some Black Hills Match ammo in your rifle. If you don't get sub-MOA with that, you are not likely to see that level of accuracy from factory ammo in your rifle.

Once you have made sure that you don't have any stock-to-barrel contact issues, you may wish to learn to load your own ammo. Just having the ability to tune seating depth could make a big difference in your rifle. Or not.

To wring the best accuracy from a given rifle, a person needs to do everything possible to stack the odds in their favor. Your current approach is doing exactly the opposite. Realistically, if you have gotten 1.5 MOA from your rifle with any factory ammo, I would consider that to be good enough to hunt with out to 500 yards or so. If you can achieve that, I recommend that you spend your time and money on practice, rather than focusing on making your rifle do something it was never designed to do.

 

[LeddSlinger]

It's a Thompson Center Encore fellas! The forearm of the stock attaches directly to the barrel! So I wouldn't worry about that very much...

Those rifles will group sub MOA with the right ammo or hand load recipe. No reason a break action can't shoot with excellent accuracy.

However, HSM is CHEAP ammo. I have only tried HSM once in my life and it was junk. You will find all kinds of mixed reviews about it on the internet. Some have good luck with it, some folks (like me) have bad luck.
Either way, mixed reviews = poor ammo quality and consistency. You will find many less poor reviews on the more expensive ammo.

If your rifle won't shoot Federal premium ammo into sub MOA groups, then it may not shoot anything that well. I would just foot the bill and get a box of Federal Premium ammo and a box of Black Hills Match ammo, both with 180gr bullets, and try it out. I'd be willing to place a wager that it can put one of those into a sub MOA group at 100 yards if the shooter is doing his part.

 

[Dontana]

I will try the premium ammo. I am also going to reset the scope and scope rail with some blue loc-tight- make sure everything is solid.

 

[WAMBO]

I am working on the same rifle for a friend who had the same problem with factory ammo.
So far with H4831SC and 180 NBT's it has produced sub moa 3 shot groups
out to 300yds so far, like DrillDog has stated it is possible with hand loads.

 

[trcuda]

First, let me say that I have 10+ years experience with the Encore and another 10 or so with its smaller sibling the Contender so I have learned a little about how to make them shoot over the years.

!. You must have the forend free floated other than the attaching screws to get consistent results. Good news is that there is an easy way to do this. Run down to your local hardware store and pick up several small rubber washers. Usually they are in the plumbing section. The center hole is slightly larger than the 8-40 attaching screw and the OD is about 1/2" One of these between the bbl and forend at each screw should be enough. (a dab of grease on each washer will hold it in place while you attach the forend)

2. Ditch the lead sled. It does nothing to promote consistent shooting and teaches you bad habits! Use a sandbag for the rear and even a cheap front rest is better than the sled. Place the front rest as far back on the forend as you can without hitting the action. Make sure you get it in the same place for every shot. The Encore, especially in carbine form, is extremely sensitive to bag placement.

3. The Encore tends to have excessive headspace in the magnum calibers.. TC chambered them to the SAMMI max depth and I have yet to see a mag case that had a belt that met the minimum SAMMI dimension. Best results will be achieved by handloading, setting your dies so that your cases headspace off the shoulder instead of the belt. You will also find a large variation of belt dimensions from case to case even on cases from the same manufacturer! Keeping you loads somewhat below max with the magnums in the Encore will also help with accuracy.

 

[Dontana]

Wow- awesome info. I know the gun can do it, hopefully with all this info I can put it together! Thanks to all!!

 

[LeddSlinger]

Good luck! Let us know how the premium ammo shoots. Maybe even post some target pics

 

[RT2506]

I am glad that you wrote this because it saved me the time. I was going to say about the same thing. I agree with this 1000% especially about the lead sled.

First, let me say that I have 10+ years experience with the Encore and another 10 or so with its smaller sibling the Contender so I have learned a little about how to make them shoot over the years.

!. You must have the forend free floated other than the attaching screws to get consistent results. Good news is that there is an easy way to do this. Run down to your local hardware store and pick up several small rubber washers. Usually they are in the plumbing section. The center hole is slightly larger than the 8-40 attaching screw and the OD is about 1/2" One of these between the bbl and forend at each screw should be enough. (a dab of grease on each washer will hold it in place while you attach the forend)

2. Ditch the lead sled. It does nothing to promote consistent shooting and teaches you bad habits! Use a sandbag for the rear and even a cheap front rest is better than the sled. Place the front rest as far back on the forend as you can without hitting the action. Make sure you get it in the same place for every shot. The Encore, especially in carbine form, is extremely sensitive to bag placement.

3. The Encore tends to have excessive headspace in the magnum calibers.. TC chambered them to the SAMMI max depth and I have yet to see a mag case that had a belt that met the minimum SAMMI dimension. Best results will be achieved by handloading, setting your dies so that your cases headspace off the shoulder instead of the belt. You will also find a large variation of belt dimensions from case to case even on cases from the same manufacturer! Keeping you loads somewhat below max with the magnums in the Encore will also help with accuracy.

 

[BountyHunter]

Google "Mike Bellm" and go to his website.

He is one of the main TC gurus and has all the tricks and tweaks.

Start with the hinge pin.

 

[ohiohunter]

^^^^ This, look up Belm and get an oversized pin and smooth out/lighten the trigger.