Throat burned out or not???

[dok7mm]

Nope, not what I said. If you don't have a comparator, use your OAL instead of a comparator. It's not as accurate, but will work.

So, one more time. Seat a bullet (we're talking the bearing surface) approximately .280 inches into neck, measure your OAL make 3 of these (6 is better, shoot in 2 groups of 3). Then seat another group .010" OAL deeper and so on, until you see the junction of the bearing surface/ ogive very near the mouth of the case. That's as far as you go. No offence, but you really need to find an experienced reloader to show you, step by step, until you get this squared away. We all started at zero knowledge, so don't feel bad.
Good luck at figuring this out.

PS. You can shoot the test at 100 with a starting load.

 

[WildRose]

I have a used 7MM Weatherby mag in a Mark 5 action that will not hold any kind of a group less than about 3". It was made in Japan in Jan. 1994, 26" SS #2 contour. I seat a 175gr Speer GS just into a new case which gives me a total COAL of 3.781. I place in chamber and close the bolt, after removal the total COAL is 3.767. Which leaves only 14 thousands of bullet in case when the bullet hits rifling. That gives me a free bore of about .402. The Speer GS has a lot of bearing surface, any other bullet will leave the case before it hits the rifling, really not good! Am I missing something important here or is the throat gone? What is good free bore on replacement barrel?
I got this weapon for long range Mule Deer and Elk so I want the extra velocity. Now, long range for me is about 500 yds. my eyes and reflex isn't what they were many years ago.
Thanks for any information on this post.
AIRBORNE

Weatherby's traditionally have very long throats with a very slow, gradual ride into the lands pretty much completely unlike any other American manufacturer.

The other problem is that they tend to have slow twist barrels so you can't keep just using longer and longer/heavier bullets chasing the lands when the do erode because you won't be able to stabilize them.

The way to tell what condition your throat is in is to have a competent gunsmith stick a borescope in it and tell you what it looks like.

 

[WildRose]

Sent JE Custom a text, will see what he has to say.
AIRBORNE

Mono's are about 10% longer than lead core bullets of equal weight so I'd throw a vote in too on looking at them. Pay close attention to twist rate recommendations though because the mono's also have to be spun faster than cup/core lead bullets of the same weight to stabilize due to the extra length.

 

[Capt RB]

Ok I understand the seating depth test and have on hand the 154 by Hornady and the Sierra Gamekings, Nosler and Rem Cor-Loc. The 154 H and the Nosler and Cor-Loc are flat base bullets only the Sierra is BT. So what you are suggesting is to seat the base of the 154 even with the base of the case neck, then each of the next 10 bullets are to be seated a +.005 deeper into the case, right????

Yes. If your first load measures 3.40 (example not fact) then 3.390, 3.380 3.370 3.360
Yes I know that the 154 is a flat base. They shoot well just don't have the ballistics of a more streamlined bullet. With the 10 twist your really not going to be able to take advantage of many high bc bullets to begin with. However many flat based bullets will work out past mpbr in this caliber. I'd also look to the hammer bullets they tend to be easy to tune and with the extra speed you can make up some of the ballistic disadvantages

 

[PDRENNER]

Ok I got it!
So I am not to worry that every bullet Leaves the case neck in an unsupported jump before slamming into the rifling?
You are surely correct in that a good gunsmith needs to check it out. If I knew of one within driving distance, I would hand deliver this problem child for a look see!
AIRBORNE

 

[lyotehunter]

Try a 175 hornady ELX. and see what that does before you spend lots trying to fix. I would find a bore scope also.

 

[tbird1964]

I bought a 7mm weatherby in the 70's and was the worst gun I ever bought and would not group at 100 yards. Took it back to Oshmans in Houston and they gave me my choice of any on the rack to replace it. I took a 300 win mag in Sako and to this day it will group under and inch at 100 yards.

 

[DUSTY NOGGIN]

So I am not to worry that every bullet Leaves the case neck in an unsupported jump before slamming into the rifling

i do believe you want the bullet still in the case as it starts the swage through the rifling

you should either find a bullet that has more bearing surface like a flat base , or a round nose , or heavier ( that will still fit in the mag well )

but a new barrel gets my vote,

 

[Orange Dust]

Try this: Clean the barrel to the bare metal. Try IMR 7828 powder and a 150gr Nosler Ballistic tip with a magnum primer. CCI or Winchester is fine. Load it to the same OAL as a 154 factory load. If you cannot find a load that will shoot an inch or less take it to a gunsmith. This has shot well in every Weatherby I have encountered. Most of them were most accurate at or near maximum.

 

[PDRENNER]

Dusty I am sure you are correct in that for proper support the butt end of a bullet must still be in the case as the nose enters the rifling. Now my first post stated that a bullet with a very long bearing surface, Speer GS in 175gr, was only in the case by 14 thousand when the nose entered the rifling and engaged the rifling. Even that little amount is not enough to support the bullet. Any bullet with less bearing surface is out of the case prior to slamming into the rifling. I THINK, that is my problem, but then I am not qualified to know for sure, that leads to my post here to get information from those that are qualified. This site is a great place to pick the minds of very qualified craftsmen!

 

[Orange Dust]

Dusty I am sure you are correct in that for proper support the butt end of a bullet must still be in the case as the nose enters the rifling. Now my first post stated that a bullet with a very long bearing surface, Speer GS in 175gr, was only in the case by 14 thousand when the nose entered the rifling and engaged the rifling. Even that little amount is not enough to support the bullet. Any bullet with less bearing surface is out of the case prior to slamming into the rifling. I THINK, that is my problem, but then I am not qualified to know for sure, that leads to my post here to get information from those that are qualified. This site is a great place to pick the minds of very qualified craftsmen!

The very long freebore gives the extra expansion room before hitting the rifling that allowed the Weatherby cartridges to exceed others of similar size in velocity. You cannot reach the rifling in this cartridge with any bullet that I know of and still feed it through the magazine. This freebore can be a problem with the newly popular VLD bullets. Some will shoot ok in this cartridge and some will shoot like a shotgun. The cartridge was designed for flat based bullets. It seems to like the short boattail on the Nosler Ballistic tip line. There are some VLD bullets that like to jump aways, but, like I said earlier, try the 150 BT, and some 7828. This is a known combination that will shoot well, if the rifle is sound. Forget about the lands, freebore, and just load to factory length.

 

[PDRENNER]

Orange
I clean with Bore Tech Cu+2, is that not a good cleaner?
I don't have the Nosler BT but do have 2 other 150gr and 1 other 154gr slugs to try. The 7828SSC and CCI-250's I have.
AIRBORNE

 

[Canhunter35]

Dusty I am sure you are correct in that for proper support the butt end of a bullet must still be in the case as the nose enters the rifling. Now my first post stated that a bullet with a very long bearing surface, Speer GS in 175gr, was only in the case by 14 thousand when the nose entered the rifling and engaged the rifling. Even that little amount is not enough to support the bullet. Any bullet with less bearing surface is out of the case prior to slamming into the rifling. I THINK, that is my problem, but then I am not qualified to know for sure, that leads to my post here to get information from those that are qualified. This site is a great place to pick the minds of very qualified craftsmen!

You're overthinking it. That 175 probably cannot be stabilized by a 10twist. Try the 150 nosier ballistic tip. They are easy to load for. Load it to the depth recommended by nosler and go in .5gr increments using imr7828 starting at min and stopping at max or first sign of pressure. If you cannot get under an inch like orange dust said, take it to a gunsmith

 

[Orange Dust]

Orange
I clean with Bore Tech Cu+2, is that not a good cleaner?
I don't have the Nosler BT but do have 2 other 150gr and 1 other 154gr slugs to try. The 7828SSC and CCI-250's I have.
AIRBORNE

Get some and try them. Don't care what you use to clean bore, just make sure all the carbon and copper are gone.