300WBY issues!!!

[wisconsinteacher]

I acquired a Sako 300WBY from my late FIL. I have it in a McMillan stock and had a brake put on it because it was a monster to fire. Before the brake, I never shot a decent group because it was hard to shoot off the bench. Now that it has a brake, it is very easy to shoot but I can't get it to group. I worked up a load with IMR7828ssc/180 Accubonds and at 84gr, I blew a primer but the rounds prior didn't show issues like heavy bolt or really flat primers. I backed off to 82gr and have tried different seating depths and every time the groups are 2 kind of close then 1 3-5" out. I have cleaned the gun a few times and get patches white but nothing is helping. I'm thinking there is a carbon ring and the throat is still dirty. I ordered a bore scope and it should be here soon to confirm. I put a new scope on it last night and hope to try some loads with 180 B-tips to zero and a test group.

Has anyone ever had pressure issues on loads below book max or ever fought a 300WBY before? I'm ready to leave it at the range if it keeps frustrating me.

 

[454]

I've had two 300 Weatherby's. One was an older Vanguard and it grouped well with factory ammo and my loads. The other was a newer MarkV and it grouped extremely well with a couple different factory loads but I never got better than around two inches with anything I tried to load for it. It's expensive but maybe cheaper in the long run if you try a box of factory loaded ammunition through it and see what's it's capable of.

 

[rjthehunter]

I acquired a Sako 300WBY from my late FIL. I have it in a McMillan stock and had a brake put on it because it was a monster to fire. Before the brake, I never shot a decent group because it was hard to shoot off the bench. Now that it has a brake, it is very easy to shoot but I can't get it to group. I worked up a load with IMR7828ssc/180 Accubonds and at 84gr, I blew a primer but the rounds prior didn't show issues like heavy bolt or really flat primers. I backed off to 82gr and have tried different seating depths and every time the groups are 2 kind of close then 1 3-5" out. I have cleaned the gun a few times and get patches white but nothing is helping. I'm thinking there is a carbon ring and the throat is still dirty. I ordered a bore scope and it should be here soon to confirm. I put a new scope on it last night and hope to try some loads with 180 B-tips to zero and a test group.

Has anyone ever had pressure issues on loads below book max or ever fought a 300WBY before? I'm ready to leave it at the range if it keeps frustrating me.

So you haven't fired a decent group out of it yet right?

I'd change up bullets and powders. Have you tried any different powder? I don't have experience with the 300 wby, so can't speak to the specifics of it, but make sure the barrel is free floated, action screws are tight, scope is holding true, then start trying different powders. It's a nice rifle. Sakos are known to be accurate rifles.

 

[noharleyyet]

Had one MkV FiberMark (IIRC)...good accuracy if it was spotless clean. A mule kick at the range, got rid of it before I was permanently flinched. Expensive to feed...now they all are.

 

[perma]

I'm ready to leave it at the range if it keeps frustrating me.

Well don't do that, some idiot like me would pay you for that!

All kidding aside; I'm reloading my Mark V and haven't had any pressure issues. Right now, I'm using 180 ABs and I have about a 0.75" group with 87g of H1000 on once fired weatherby brass. Id keep on the ABs personally. Maybe see if you can get good groups with factory ammo. The cheap led tip weatherbys group around 1" MOA at 100 yards from my experience. YMMV.

 

[std7mag]

I hate to say it! I know lots of people love them!
But try a different bullet.
I tried seating the Accubonds from touching to 0.120" off the lands.
Maybe I should have gone further.
But i just couldn't get them to group.
In 3 different rifles.

Funny thing is that the Ballistic Tips group well.

Anyways, try a different bullet.

 

[406bert]

im a big fan of the accubond but some rifles just dont like them lol id personally try a different bullet or maybe a different powder!

 

[huntnfisher]

When I had my Mark V Sporter in .300 Wby mag, it shot 1" groups with Weatherby Premium Ammo in 165 grain Ballistic Tips. Yes, it was a mule kick off of the bench, but recoil doesn't bother me as much as it does some people. Just don't need a .300 Wby mag for where I hunt, and I made a nice profit on it.

 

[Boarmaster]

I've had two 300 Weatherby's. One was an older Vanguard and it grouped well with factory ammo and my loads. The other was a newer MarkV and it grouped extremely well with a couple different factory loads but I never got better than around two inches with anything I tried to load for it. It's expensive but maybe cheaper in the long run if you try a box of factory loaded ammunition through it and see what's it's capable of.

Good advise.

 

[jimh406]

My brother worked up the load for mine. He did a lot of research and settled on Hodgdon 7828 with Federal 215M primers and Nosler 180 Partitions. My powder weight is between your two loads. According to the Hodgdon site, the weight is same for both powders.

 

[tom338]

A friend had one, the only thing we could get it to shoot was factory ammo. And only 1 type of factory ammo

 

[bogey]

Well don't do that, some idiot like me would pay you for that!

All kidding aside; I'm reloading my Mark V and haven't had any pressure issues. Right now, I'm using 180 ABs and I have about a 0.75" group with 87g of H1000 on once fired weatherby brass. Id keep on the ABs personally. Maybe see if you can get good groups with factory ammo. The cheap led tip weatherbys group around 1" MOA at 100 yards from my experience. YMMV.

This is pretty close to what I did for my 300 Weatherby, it was much more accurate below max, but still a slightly compressed load. I am giving up some speed (50fps vs max) but the accuracy was better. It was much easier that messing with seating depth.

I would clean the heck out of it, both copper and solvent. You may have to get a little more aggressive to get the throat cleaned. Good luck!

 

[wisconsinteacher]

Well, I believe I'm on the right track. I cleaned it really well and took it out one more time. It was bad!! 13.5" group with 180 Btips at 100 yards. I got home and put the bore scope down it. As I was removing it, I caught a little copper in the muzzle brake. I looked closer and found a few spots of copper at the very end of the brake. The dang bullet is touching the brake as it leaves the muzzle. I contacted my smith and he is going to open it up a few thousands to get a clean pass.

This explains the 2 shots touching and 1 way out in left field. I'm guessing the 2 touching came out clean and the 1 4-7" away hit the brake. I'm looking forward to seeing what it will do once it is fixed.

 

[perma]

Well, I believe I'm on the right track. I cleaned it really well and took it out one more time. It was bad!! 13.5" group with 180 Btips at 100 yards. I got home and put the bore scope down it. As I was removing it, I caught a little copper in the muzzle brake. I looked closer and found a few spots of copper at the very end of the brake. The dang bullet is touching the brake as it leaves the muzzle. I contacted my smith and he is going to open it up a few thousands to get a clean pass.

This explains the 2 shots touching and 1 way out in left field. I'm guessing the 2 touching came out clean and the 1 4-7" away hit the brake. I'm looking forward to seeing what it will do once it is fixed.

That’s a crazy way to find that out.

 

[wisconsinteacher]

I shot the gun today without the brake and it produced a 1.6" group using the same ammo that made a 13.5" group the day before. I will be sending the brake to be opened up this week.

 

[cahunter805]

Well, I believe I'm on the right track. I cleaned it really well and took it out one more time. It was bad!! 13.5" group with 180 Btips at 100 yards. I got home and put the bore scope down it. As I was removing it, I caught a little copper in the muzzle brake. I looked closer and found a few spots of copper at the very end of the brake. The dang bullet is touching the brake as it leaves the muzzle. I contacted my smith and he is going to open it up a few thousands to get a clean pass.

This explains the 2 shots touching and 1 way out in left field. I'm guessing the 2 touching came out clean and the 1 4-7" away hit the brake. I'm looking forward to seeing what it will do once it is fixed.

Glad you got it figured out. I’m going to guess whoever installed the muzzlebrake didn’t dial in off the bore and just off the outside of the barrel which can be far from concentric.

 

[Fire_9]

Well, I believe I'm on the right track. I cleaned it really well and took it out one more time. It was bad!! 13.5" group with 180 Btips at 100 yards. I got home and put the bore scope down it. As I was removing it, I caught a little copper in the muzzle brake. I looked closer and found a few spots of copper at the very end of the brake. The dang bullet is touching the brake as it leaves the muzzle. I contacted my smith and he is going to open it up a few thousands to get a clean pass.

This explains the 2 shots touching and 1 way out in left field. I'm guessing the 2 touching came out clean and the 1 4-7" away hit the brake. I'm looking forward to seeing what it will do once it is fixed.

Are you taking it to the same gunsmith that installed it? If you are, I would find a new one. That is absolute garbage and opening it up is not the answer. The barrel needs to be cut back and rethreaded.

 

[wisconsinteacher]

Are you taking it to the same gunsmith that installed it? If you are, I would find a new one. That is absolute garbage and opening it up is not the answer. The barrel needs to be cut back and rethreaded.

In his defense, the brake needed to be opened by the smith and I don't think he opened it enough. I put a caliper on it and it is .317" so only .01 over bore. Everything I have read it .025-.030" is where it should be. The threads and brake appear to look straight and even.

Hopefully I can get this figured out and back at the range in a the next month.

 

[Wind Gypsy]

Sounds like a threads not being centered on the bore may be an issue as well. I'm not real well versed on standard clearances for opening but 0.009" does sound pretty tight.

Further edit: just put calipers on a 0.308 suppressor end cap and got like 0.390" and a 6.5 or 7 mm brake and got 0.300" so it seems some more clearance isn't unusual.