How Much Freebore? - Wby 257 Mag.

[RickKr]

I've progressed with re barrelling my Wby 257 Mag., with a Bartlein 1-10 twist, 26". My gunsmith is chambering it now and mentioned the reamer does not provide any freebore. We've talked about a throating reamer and the question of "how much". He is looking to me for this answer. My understanding is that Weatherby mags are known for having a lot of freebore, but I don't know anything about how much this gun had or would be good to provide in this new barrel. What reading I've done tells me about freebore as a way to manage pressure and about more or less for seating bullets closer to the lands, reducing the jump and having an effect on accuracy.

I do not plan on shooting anything over about 120 gr. with this gun. My GS's comment was that recoil will be greater with less freebore and that pressures should not be of much concern. I'm not much interested in having the recoil be much greater than it was, but I did not shoot it much previously. At the time, I also shot my 270 and 308 and didn't care for the recoil of them, but I've shot the 308 a lot more since and now a 30-06 and have become much more accustomed to their recoil. Loads in the 270 were near max. with H4895 and 150 gr. bullets. Loads with the 30 cals. were moderate with IMR 4064 and 150 gr. up to 190 gr. bullets.

I am interested in comments on the pros and cons of freebore for this gun, particularly about how much.

Rick

 

[Gary in MD]

Are you hand loading for it? Do you think you will ever sell it?
Usually if you cut the free bore too much then it is not recommend to shoot factory ammo because it will raise pressures.
Also if you sold it, it could be dangerous for that person to shoot factory ammo with no free bore.
Some guys will have a barrel chambered with little or no free bore and it can increase the accuracy potential of the rifle for the custom hand loader.
Just some thoughts.
Gary

 

[RickKr]

Are you hand loading for it? Do you think you will ever sell it?
Usually if you cut the free bore too much then it is not recommend to shoot factory ammo because it will raise pressures.
Also if you sold it, it could be dangerous for that person to shoot factory ammo with no free bore.
Some guys will have a barrel chambered with little or no free bore and it can increase the accuracy potential of the rifle for the custom hand loader.
Just some thoughts.
Gary

Yes, handloading for it. But, I have two boxes of Wby and one of Nosler factory ammo.

I do not plan to sell it; it is "precious" to me. But it will outlive me, so the possibility of someone down the road shooting factory ammo in it is highly likely.

My understanding is there is currently some freebore beyond the bullet in the Wby factory rounds (100 gr. Spitzer), created by the reamer used to chamber it. Don't know how much, so I'll examine it to see if I can figure out how much.

Rick

 

[RickKr]

This thread is informative: 257 WBY with or without Freebore

My GS said to shoot it as is and see what I thing, primarily about the recoil. I believe I'll go with that.

 

[Stan Taylor]

My opinion is this tell your gunsmith put about .400 in it and go on.

 

[AckleymanII]

I have had several with my custom reamers, Zero freebore with 1.5 degree leade angle to .030 freebore, they shoot incredible.

Forget what happens to the gun when you are dead. Have him engrave on the barrel opposite the caliber stamping, ZERO FREEBORE

Rock On!

 

[MagnumManiac]

If you’re going to be running ANY type of factory ammo, you are going to need the factory SAAMI freebore of .376”. Period.
If you do not, even START LOADS in every manual are going to be too hot.
I build many Weatherby chambered rifles, zero freebore is a bad thing in these, it will only lead to excessive pressure.
The best throat lengths are actually .500” long at .0005” over bullet diameter.
The only Weatherby chambering with zero freebore from the factory is the 240 Weatherby.

Cheers.

 

[AckleymanII]

If you’re going to be running ANY type of factory ammo, you are going to need the factory SAAMI freebore of .376”. Period.
If you do not, even START LOADS in every manual are going to be too hot.
I build many Weatherby chambered rifles, zero freebore is a bad thing in these, it will only lead to excessive pressure.
The best throat lengths are actually .500” long at .0005” over bullet diameter.
The only Weatherby chambering with zero freebore from the factory is the 240 Weatherby.

Cheers.

Oh hell no!

FIRST ORDER OF BUSINESS-FORGET FACTORY AMMO

zero to .030 freebore is the way to go, and forget ever shooting factory ammo, they would not chamber in the rifle anyway.

I have worked up loads for more than a few.

26" barrel-10twist-accuracy nodes as follows
100g at 3850
115 at 3600

26"-9T
110g accoubond and 115g berger vld hunting
3550 fps

30" 10 twist
100g at 4000,

tiny groups abound...TINY!!!

with a good muzzle break on the rifle, you see the deer drop as the gun recoils....sweet!

Typical rifle with zero to .030 freebore takes 12-19 rounds of load development per bullet type...dumb butt simple to say the least.

After you have worked up loads for half a dozen of these with short freebore, you are hooked for life. Shorter freebore also gives you 2x the barrel life over a standard chamber.

.400 freebore chambers does keep gunsmiths spinning on new barrels every 600 rounds!

 

[MagnumManiac]

Tiny groups happen regardless.

600 rounds? Wow, you must torch barrels.

Cheers.

 

[BD100]

THE factory freebore length for the 257 Weatherby is .378.

I had my smith chamber mine at .250. This has worked wonderfully for both handloads and factory rounds(although I rarely shoot factory ammo). For such a high intensity round, the gun is just stupid accurate. RL-25 and 115 Ballistic tips at 3450 provide repeatable sub moa groups out to 500...so can't ask for much more really. Not sure how much more accuracy I could eek out with anything less than .250 anyway. Additionally, I like the ability to be able to shoot factory ammo in a pinch and also plan to pass the gun off to my son...who may or may not reload.

 

[BD100]

The only Weatherby chambering with zero freebore from the factory is the 240 Weatherby.

Cheers.

^^^This is incorrect. The 240 comes from the factory with .169 of freebore.^^^

 

[Ironworker]

My 257 WBY is chambered in a Bartlein 26" 10"twist Rem Varmint contour with a factory freebore .Its a Tac driver ,74grs of Re#26 pushes a 90gr Sierra TMK at 3900 fps

 

[AckleymanII]

I shot the 85g Noslers at 4137 fps with IMR 4831, 26" 4g Krieger-10T with zero freebore chamber.

When Deer hunting, you can get away with shooting 8-15 rounds a year including verifying scope zero. On the other hand, start using the rifle as a long range varmint rifle, 600 rounds a year is normal. Chucks, crows, coyotes, and jack rabbits were normal targets.

The 257 weatherby with zero freebore was a logical step up from a 6/284 where I was shooting the 85g sierra bthp at 3600.

I measured leade growth before I loaded a box of 50, chased the lands accordingly.

 

[MagnumManiac]

^^^This is incorrect. The 240 comes from the factory with .169 of freebore.^^^

Sorry, the only factory chambering WITHOUT traditional Weatherby freebore.
Did you know when the cartridges were still proprietary the freebore for all chambers starting at the 257 thru 340 had .500” straight freebore .0005” over bullet diameter.
The 378 had .750” freebore as above and the 460 had 1.00”.
People whinged, so when putting them forward to SAAMI, they were reduced to .376”, why you say .378” is not what I see.
These cartridges had already been on CIP lists for decades before SAAMI specs.

Cheers.

 

[AckleymanII]

It is easy to make 257 weatherby brass out of 264 win mag or 7mm rem mag brass, one pass through the full length sizer, and you have a perfect double radius shoulder...neck is shorter than factory.

Now plan for success. Seat a bullet in that piece of brass, send that piece of brass to JGS, PTG, and have them make a reamer with .030 freebore, Neck clearance for the brand of brass you choose, Winchester is the best brand to use unless you can find some RWS.

 

[BD100]

Sorry, the only factory chambering WITHOUT traditional Weatherby freebore.
Did you know when the cartridges were still proprietary the freebore for all chambers starting at the 257 thru 340 had .500” straight freebore .0005” over bullet diameter.
The 378 had .750” freebore as above and the 460 had 1.00”.
People whinged, so when putting them forward to SAAMI, they were reduced to .376”, why you say .378” is not what I see.
These cartridges had already been on CIP lists for decades before SAAMI specs.

Cheers.

From weatherby.com....

What is the throat length (free bore) on your Weatherby rifles chambered for Weatherby magnum calibers?​

Cartridge	Throat length (free bore)
224 Weatherby Magnum	.162
240 Weatherby Magnum	.169
257 Weatherby Magnum	.378
6.5 WBY RPM	.105
6.5-300 Weatherby Magnum	.2037
270 Weatherby Magnum	.378
7MM Weatherby Magnum	.378
300 Weatherby Magnum	.361
340 Weatherby Magnum	.373
375 Weatherby Magnum	.373
378 Weatherby Magnum	.756
416 Weatherby Magnum	.239
460 Weatherby Magnum	.756
30-378 Weatherby Magnum	.361
338-378 Weatherby Magnum	.361

 

[MagnumManiac]

Your point is?
Was I quoting Weatherby? No.
Was quoting CIP and original reamer prints.
SAAMI has the full list of modern Weatherby chamberings. There was a time before SAAMI, you know?

 

[BD100]

Your point is?
Was I quoting Weatherby? No.
Was quoting CIP and original reamer prints.
SAAMI has the full list of modern Weatherby chamberings. There was a time before SAAMI, you know?

Go back and re-read your initial post...you WERE quoting SAAMI specs and said nothing about CIP!! First you said the 257 has .376 of freebore, which is incorrect. Then you stated the 240 has zero freebore, which is also incorrect. THEN you said chambering a Weatherby round with anything less than SAAMI freebore won't allow you to shoot factory ammo, which is also once again incorrect. You're spouting off incorrect information that isn't helpful to the OP or anyone else gleaning information from this thread.

 

[MagnumManiac]

Incorrect information....really!
Factory Weatherby ammo fired in non-Weatherby chambers is a disaster waiting to happen.
Have you done it?
You want to get picky about .002”, go ahead.
I didn’t mean zero freebore, I meant what I later said, anyway, quoting Weatherby does not mean you know DIDDLY SQUAT.
You spouting off that you have a freebore length of .250” is NOT helping the OP, just more internet BS by another keyboard warrior. Fire some factory ammo in your short throated Weatherby. Hahaha.

Another on the ignore list.

 

[BD100]

Factory Weatherby ammo fired in non-Weatherby chambers is a disaster waiting to happen.
Have you done it? Yup! Many a times, in both my 257 and 270 Wby's throated at .250. Have had zero issues with either, even in Texas summer time temps. .250 is what my smith recommended as he's built hundreds of Weatherby's. So far, his .250 recommendation has worked wonderfully with both factory and handloads....not a single disaster.

I didn’t mean zero freebore, I meant what I later said, anyway, quoting Weatherby does not mean you know DIDDLY SQUAT. Don't flatter yourself. I didn't post freebore numbers because of you. I simply posted Weatherby's advertised freebore numbers as a point of reference for the OP and other readers.

You spouting off that you have a freebore length of .250” is NOT helping the OP, just more internet BS by another keyboard warrior. Fire some factory ammo in your short throated Weatherby. Hahaha. Actually, it does help the OP as he created a post titled "How Much Freebore". I answered based on my actual experience. You sir have zero reading comprehension!