Tight barrel issues.

[Trm82]

For all you experts out there is there any way to loosen up a barrel with out shooting the crap out of it ?
I bought a semi custom rem 700 in 257 wby and it has a premium barrel of some kind not sure what make (so maybe it's not so premium ) but it didn't have a lot of free bore when I got it so I had some freebore added.
I load my own usually but I tried some Weatherby 100 swift scirocco and before the freebore was added groups were not good at 200 yard but speed was 3690 FPS and the velocity on the box is 3575fps and the once fired brass from the factory ammo the primer pockets are may be good for one more shot and it's the same after the freebore was added
After the free bore was added they now shoot 1 inch at 200 at about the same speed but still have pressure.
I tried a few loads with RL26 and 100 ttsx and 70 gr gets me 3680 FPS.
So I have some KG bore polish and just wondering if using some of that might help or do I just need to tune loads right back till no pressure is present.
Thanks.

 

[elkaholic]

For all you experts out there is there any way to loosen up a barrel with out shooting the crap out of it ?
I bought a semi custom rem 700 in 257 wby and it has a premium barrel of some kind not sure what make (so maybe it's not so premium ) but it didn't have a lot of free bore when I got it so I had some freebore added.
I load my own usually but I tried some Weatherby 100 swift scirocco and before the freebore was added groups were not good at 200 yard but speed was 3690 FPS and the velocity on the box is 3575fps and the once fired brass from the factory ammo the primer pockets are may be good for one more shot and it's the same after the freebore was added
After the free bore was added they now shoot 1 inch at 200 at about the same speed but still have pressure.
I tried a few loads with RL26 and 100 ttsx and 70 gr gets me 3680 FPS.
So I have some KG bore polish and just wondering if using some of that might help or do I just need to tune loads right back till no pressure is present.
Thanks.

You might try the Tubbs bore polish system.

 

[Jud96]

How many rounds are down the barrel? You can't speed up a barrel anymore than it's going to after 100-200 rounds are down it. Speed isn't everything, if it's shooting consistently under 1/2 MOA then the extra 100fps isn't worth pushing for. Weatherby ammo is known to be loaded hot and their published velocities are often very high. I wouldn't worry too much about it. I'm sure the barrel will shoot good and get plenty of speed once a proper load is worked up.

 

[Coyote Shadow Tracker]

If you are getting good groups why do you want to increase the FPS? All my rifles and loads go for best accuracy first and just look at FPS to put into my program for accuracy at distance.

 

[Trm82]

If you are getting good groups why do you want to increase the FPS? All my rifles and loads go for best accuracy first and just look at FPS to put into my program for accuracy at distance.

I don't want more speed , I'm happy with the speed but I can't shoot it there. Factory or loaded brass won't last where it's at.
I'm going to have to try different powder or cut it right back with the RL26 to get this brass to last.
I've always loaded my own but since this was going to be a hunting only rifle and no targets I was pumped to have factory shoot so good but for the price of that stuff I'd still like to use the brass in the future and not get maybe two firings.

 

[AZShooter]

I seriously doubt you have a tight barrel. If you want to know you could slug the barrel.

. Any number of differences in the chamber configuration can increase pressure. The most likely causes are the amount of freebore, and neck clearance for bullet release.

Do you know the dimensions of the reamer or the chamber?

Have you tried a simple test to see if a bullet will enter the neck of a fired piece of brass? If you have difficulty putting a bullet into the case mouth the neck dimension of the chamber is too small which would cause excessive pressure. If you discover this is the problem, neck turning would solve it which means you cannot shoot factory ammunition. Having enough neck clearance will also improve accuracy IF this is the issue.

Weatherby's freebore for the 257 Weatherby is .378". If your freebore is less than it could be the cause of the excessive pressure.

The best solution is to buy the components and work up a load for your rifle.

 

[JAYgs8163]

Just shoot it. Develop load as you mentioned by dialing it back. The barrel is going to change as you shoot it and pressure should drop. Dial the load back in .50 increments until pressure is gone and then search for accuracy node. Good luck. I've used Tubbs final finish before on a crude factory barrel with excellent results but never in a premium barrel. I've got rifles also that after 200-300 rounds needed new load developed as the barrel just changes the more you use it. As I said in the beginning, "just shoot it" but with a reduced load. Factory Weatherby ammo is expensive so I feel your pain.

 

[wonderman4]

I agree with AZShooter. Unless you slug the barrel and know for sure, you don't know the barrel is under sized.

I would think your problem is in the free bore. Have you measured that??

 

[Bruce Treloar]

For all you experts out there is there any way to loosen up a barrel with out shooting the crap out of it ?
I bought a semi custom rem 700 in 257 wby and it has a premium barrel of some kind not sure what make (so maybe it's not so premium ) but it didn't have a lot of free bore when I got it so I had some freebore added.
I load my own usually but I tried some Weatherby 100 swift scirocco and before the freebore was added groups were not good at 200 yard but speed was 3690 FPS and the velocity on the box is 3575fps and the once fired brass from the factory ammo the primer pockets are may be good for one more shot and it's the same after the freebore was added
After the free bore was added they now shoot 1 inch at 200 at about the same speed but still have pressure.
I tried a few loads with RL26 and 100 ttsx and 70 gr gets me 3680 FPS.
So I have some KG bore polish and just wondering if using some of that might help or do I just need to tune loads right back till no pressure is present.
Thanks.

I wouldn't use a brush or cloth on a jag as this tends to round off the sharp corner of the lands.
Would suggest casting a metal lap in a clean barrel free from oil and lapping using great care not to misalign the rod. Use a plain metal rod, not a plastic covered rod that would have grit imbedded and could wear the lead into the chamber. Lapping works well on top of the lands but less on the grooves.

 

[L.Sherm]

If you dont know what your doing lapping can kill a barrel. Lead lapping is the only way to keep a barrels lands and grooves consistent from end to end.
There is a Few barrel makers that make .299 and .300 bores for 30 cal and .236 and .237 for 6mm.
Lead slugging a barrel is really the only way to measure your land and grooves
as previously mentioned.
Some barrels are just slower than others.

 

[HSmithTX]

Assuming you bought it used? First thing I would do is clean it down to bare metal. Get it dead clean, and then work up a load.

I would caution you against any kind of lapping or bore polishing. I have one barrel that fouls badly enough that in about 80 rounds it goes from no pressure signs at all to hard bolt lift and flat primers and loosened primer pockets in Hornady brass. The length of the bore is chattered and ugly. The barrel is garbage overall in my opinion, but it shoots very well for 50-60 rounds so I haven't pulled it yet. It also won't group at all until the 5th round after cleaning, after that it stacks bullets. So, nothing to lose right? I went after it with some bore polish, visibly better with the bore scope, the chatter didn't get moved at all but some of the rough edges of the chatter are much less rough. The previous load I had worked up no longer works, it is over pressure and velocity was higher than previously shooting ammo from the same box I loaded before the polishing. It makes sense also, if the barrel is smoother there will be more friction on the bullet increasing pressure and velocity, same as 'breaking in' a barrel and the corresponding 'speed up'. Worked up a load at the previous speed by dropping the powder charge until velocity matched the old load and the pressure signs are gone. Same results though, shoot 5 to get it going, stacks bullets for a while and then the pressure starts coming back. Unless you KNOW what you are doing I would 100% recommend not trying to do anything inside the barrel other than shooting and normal cleaning.

 

[Bruce Treloar]

I have lapped dozens of barrels, accuracy improved but they all tend to copper foul for the next few rounds. I would take the barrel to a competent gunsmith who has experience lapping a chambered and crowned barrels. Barrels with copper fouling won't shoot well . I clean every 10 to 12 shots wanting reliable point of impact after the first shot.