Making a throat last with 7mm WSM

[mlcasmey]

I've read a lot about how some of the high speed magnums eat throats for breakfast. I'm interested in building a medium to long range target rifle using the 7mm WSM. What are some steps I can take to lengthen the life of my barrel and yet get the most of my rifle. For example shoot lighter rounds at slower speeds, shoot heavy rounds at slow speeds, shoot any round at slow speed, do anything else .......?

I'm going to have a custom reamer made to match my trimmed and turned case using any bullet I want. So what weight and charge would be good for longevity.

I'm kind of partial to SMK's.

Thanks, Mike.

 

[bigedp51]

At 43,000 cup the peak flame temperature is just reaching the melting point of modern barrel steels. Your 7mm WSM is at approximately 53,000 cup or 63,000 psi and a temp of 3,200 to 3,400 degrees F.

You have two choices, buy a 30-30 Winchester its chamber pressure is below 40,000 cup and it isn't a barrel burner. Or just shoot your 7mm WSM and not worry about it and when the barrel is shot out just buy a new one.

It's too late to join the Navy and fire the big barrel burners.

USS Wisconsin Fires 16 Inch Guns
http://www.military.com/video/forces/navy/uss-wisconsin-fires-16-inch-guns/918274871001/

 

[bozo699]

At 43,000 cup the peak flame temperature is just reaching the melting point of modern barrel steels. Your 7mm WSM is at approximately 53,000 cup or 63,000 psi and a temp of 3,200 to 3,400 degrees F.

You have two choices, buy a 30-30 Winchester its chamber pressure is below 40,000 cup and it isn't a barrel burner. Or just shoot your 7mm WSM and not worry about it and when the barrel is shot out just buy a new one.

USS Wisconsin Fires 16 Inch Guns
http://www.military.com/video/forces/navy/uss-wisconsin-fires-16-inch-guns/918274871001/

Good Lord Ed what has changed in you, your posts make sense! This is my thoughts exactly, well written Ed.Barrels are no different then powder or bullets, shoot until there gone and then order more! as far as your custom reamer and any bullet you want Mike I never heard of that before, when I have a reamer ground, having two done right now I have them ground with a specific bullet in mind so I can get the free bore I want and need. There would be a large difference between 90 grain plinker bullets and say 185 grain hybrids as far as needed freebore.
Wayne.

 

[bigedp51]

bozo699

Some questions I just don't get, if you buy a Corvette why cry about gas mileage when you should have bought a Toyoda Prius and gotten 50 miles to the gallon.

The 280 Remington has a smaller base diameter and a much longer case to grip the chamber walls with corresponding much less bolt thrust. (easier on the rifle)

I can remember when I was younger and being a Jack O'Connor fan and thinking the .270 Winchester was the best non-belted magnum in the world.

But the last hunting rifle I bought last year was a 30-06 because it can do anything you want it to.

Newfangled barrel burning magnums..........Bah Humbug

 

[MrMajestic]

Newfangled barrel burning magnums..........Bah Humbug

Somebody gotta keep the barrel manufacturers working a third shift! ;D

 

[Steve Blair]

bozo699

Some questions I just don't get, if you buy a Corvette why cry about gas mileage when you should have bought a Toyoda Prius and gotten 50 miles to the gallon.

[br]
I agree with you but the new Corvettes actually get pretty good gas mileage.

 

[bigedp51]

mlcasmey

On my 30-06 I have two loads one for open field shots and one for in the wood where 40 yards is a long shot. My open field load is a 150 grain bullet loaded warm, my woods load is a 170 grain flat nose made for the 30-30 and loaded to approximately 2500 fps.

You could down load your 7mm WSM to 7mm Mauser velocities or even practice with light Trail Boss loads and take the "load" off your barrel.

Sorry but I'm just not a fan of the new short stubby magnums and do yourself a favor and make sure your chamber is always bone dry and free of any oil to minimize bolt thrust.

 

[mlcasmey]

The reamer comment just meant I will build a reamer for my bullet of choice, not every bullet. I was just not sure if the lighter ones are harder on the throat than the 175 or so. Just worded that poorly. We are on the same sheet here.

Not worried about MPG. I drive a 500 HP Dodge Challenger.

Just curious if there was such a thing as being kind to the barrel and still get performance.

Just cause I have 500 ponies under my foot does not mean I hit the rev limiter every time I shift.

I'm a paper puncher, not a hunter so a tiny moa is all I care about. If I have to re-barrel so be it. Just wanted to know if pushing a hi accuracy round a bit friendly was even possible.

 

[bigedp51]

overbore post deleted

 

[mlcasmey]

Like they say bigdp51. There is no replacement for displacement. Although mine is 1970 Plum Crazy Purple.

How about we close this thread before it morphs into a muscle car vs toy car chat.

 

[bigedp51]

Your correct, I deleted my post because it was "Plum Crazy".
(sorry I carjacked your posting) :-[

 

[bozo699]

I don't think you should delete your thread I think it is a good thread
Wayne.

P.S Ed I wished you would have left your post up I wanted to comment on case lubing!

 

[bigedp51]

I don't think you should delete your thread I think it is a good thread
Wayne.

P.S Ed I wished you would have left your post up I wanted to comment on case lubing!

The farm bill pasted so here some case lube for you bozo699.

 

[treeman]

the f-0pen team went from 6.5-284 to .284 to 7wsm... they should have stayed with the 284. Who knows what's next?

 

[Steve Blair]

the f-0pen team went from 6.5-284 to .284 to 7wsm... they should have stayed with the 284. Who knows what's next?

[br]
Now, they must have both a 7mm magnum and a .284 Win.

 

[bozo699]

Thanks Ed I got quite a chuckle
Wayne

 

[rogn]

I shoot a Lyman 135gr tumble lubed bullet ahead of 13gr of AL-7. Gives about 1200FPS and 1-2"groups out of a Savage and a Remi 7WSM(aftermarket barrel). I think well run out of lead before the throats burn out. Sure they will turn in small groups at 400+ with the case stuffed full of H-1000, but I just love the light "pop" with no recoil. Sorry, just a couple of pennies I had to let go.

 

[hogan]

What can do to maximize barrel life? Is that really the question?

Chrome-moly steels are documented to be longer lasting than stainless. Unlike ss barrels which develop flaking errosion patterns, c-m steels develop cracking which does not produce the voids in surface of stainless barrels. A bore w/o voids or gaps will retain accuracy, relatively speaking, by not stripping jacket metal or lead as bullet transits.

No free lunch. If velocity is your game; and you must have short-action receiver, then you're looking minimal barrel life. A .280rem or .280AI is in same realm as .30-06 and .308win for barrel wear; which is to say among the longest-lived of velocity capable standard cartridges. The 7mm-08 is your best solution, unless want to wildcat with something like 7mm XC or experiment with mild pressure loads in .284win.

Have you seen Lee's Modern Reloading #2? The pressure data makes the book invaluable.

One guy mentions the .30-30 above as a low pressure option. The 6.8spc has a potential and being based on the .30rem case which is a rimless .30-30 could be promising necked up or down.

Cast bullet (boolit, to differentiate from jacketed) is really the holy grail. Unlimited barrel life and tremendous potential for experimentation and tweaking. With correct lube and alloy, velocities can rival jacketed. For hunting the penetration is better from hardcast than anything other than a solid. Much history of precision shooting w/cast bullets.

Owning a decent mold or two gives you options you don't have otherwise. Many fine performing powders with cast loads aren't in great demand by most, so may still be on the shelves. Many cast shooters also report that their barrels perform better with jacketed bullets if they've been "seasoned" by cast boolits. Brass also lasts forever...

 

[Bob3700]

The throat of a 7mm WSM is sort of like the rear tires on a ZO6 Corvette. You don't really expect them to last long. Front tires either.

But if I was hell bent on shooting that cartridge and wanted to get as many rounds as I could out of the tube here would be my approach.

First. Once the bbl was fitted and chambered, have it salt bath nitrided (hardened).

Next, use your bore scope to keep an eye on the condition of the throat. At what rate is the steel beginning to crack.

Third, use a lapping paste to keep the throat as smooth as possible.

Last, shoot light wt. bullets with a short bearing surface. Less heat/time generated in the throat of the bbl. The problem there is that light bullets and LR usually don't appear in the same sentence.

That is probably the best you can do.

A friend who shot F-Open had a custom 7mm WSSM shooting the Berger 180 VLDs and the bbl didn't make 700 rds before it was toast. So If I was going to "PLay" at shooting paper at LR, I would look to a cartridge that would give me more opportunity to shoot (more bbl life) and learn the game.

Just my thoughts.

Bob

 

[Kings X]

Mike,
Is there some reason that binds you to a magnum? Do you already have the action or the bolt body?
Running it at 284 speeds doesn't get you the advantage of the magnum.
The F-Open team had a ruling that required team members to use a magnum case driving a 180 Berger at 2950 (I think that was the rule). Most of them had to buy new actions or new bolts. Brass had to be prepared, new powders tried, new primers, new dies. All for a slight increase in speed. It was a challenge (still is to some) to get the short mags to shoot as accurate as the 284s.
Some get 2500 rounds out of a 284 at 2850 (180 grain bullet) but only 700 with either of the short mags at 2950.
Run the numbers. At 2800 the wind drift is about 6.2 inches per mile per hour. The same bullet at 3000 has a drift of 5.6" We are talking about [normal]worst to [normal] best speed only being 3/4" drift difference. The question being is that 0.8" worth the barrel life?
If it is to you - build the magnum that you want.