Precision Reloading For Long Range Hunting by Jerry Teo

[terry]

Here is my problem: I have had a gunsmith rebarrel my Weatherby Mark V action to a Hart custom 338-378 Weatherby caliber fluted barrel. I have shot several powder loads with Reloader 25 and H870 powder behind a 225g hornady SST and Speer Softpoint BT. My groups range from 12 to 14 inches at 300 yds. In the process, he trued the action and opened-up the bolt face of the bolt. Also, the action is bedded with the complete barrel free-floated. Is there a way that I can check if the work that the gunsmith did is correct? If I could do this, it would help me in going forward with following all of the great reloading information that I have learned from JERRY TREO!

[Mysticplayer]

Be honest, are you having trouble with the recoil during firing?

that is a very big boomer and you give no other specs on your rifle. Flinching or inconsistent form is a huge cause of inaccuracy. Can you shoot other smaller cals well under MOA consistently?

Also, did you work up your loads at 200yds? Even though you have a cannon, winds will still blow you around at 300yds. Use wind flags and shoot on calm days. Keep your barrel cool.

Do you have a solid fit between the front rests and your stock? Any type of twist and roll or bounce will affect groups. If you are using a bipod, stop unless you know you are sub MOA proficient.

A solid bench, pedestal front rest and proper fitting front and rear bags are very important in this tuning process.

To get sub MOA groups, you must be ABLE to shoot sub MOA groups. Any issues with your scope? Loose parts?

Check your throat length. Can the bullet fully engrave in the lands BEFORE leaving the case neck? Size a case and just seat a bullet into the neck (no powder or primer of course). Chamber and extract. Did the bullet get pushed back into the case?

If yes and you have got all the other areas covered, work up a load. If no, then the barrel is hooped as any freebore negates the chance of bughole accuracy.

Jerry

[terry]

Thanks a bunch for helping me! I have a 300 ultramag necked-up to a .338 cal. built on a Mark V action. I can shoot sub MOA groups with this gun when shooting a 200g. Nosler. So, recoil has not been a problem. Also, I am using a gun rest that is weighted with a strap behind the butt of the stock to do away with recoil during tuning of the rifle. Also, the barrel has a muzzlebrake. There was no wind on my shooting range which has flags.

From the pointers that you gave me, I need to check throat length. I am seating my bullets deep to load from the magazine. I guess that I may have to use it as a single shot if that is the problem. Plus, from the way you write, the freebore increases the throatlength which throws-in another variable. If I can fully engrave the lands before leaving the case neck, how far back should the bullet be placed before the lands?

Also, I did not work-up a load but shot three grains below what was considered maximum for the bullet. Thanks for letting me know that I skipped a basic procedure. Now, I will work-up the load.

Jerry, thanks so much for your help. It is much appreciated. Later, I will give you an update.

Terry

[terry]

Regarding my accuracy problem with my 338-378, the gun builder who built the gun says that it may be a problem with his muzzle-brake. He said that if it touches the brake in any way, the bullet will be unstable. With 4 moa accuracy, he thought that it was a major problem with the rifle itself especially with it being a custom gun with a Hart Barrel. Thanks for all of your help which will help me do a better job in the future with my loading.

[Mysticplayer]

Terry, very glad that I could be of help.

As long as the bullet will fully engrave before leaving the neck, really doesn't matter how far off you are. Just fit to the mag and work up your load using the tuning suggestions in my article on the home page.

You will be able to dial your rifle in that way.

As for hitting the brake, yes, that is very bad. Quick check, look down the bore from the chamber side and if you see any shadow from the brake, exit hole it too small.

The hole should be 20thou bigger then the bullet diameter ASSUMING the hole in true to the bore.

Jerry