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240 Weatherby reloads
CapnMidnight
Member Posts: 8,038 ✭✭
I have two neighbors that have these rifels. They are loading 100gr Nosler partitions over Imr 4350 & IMR 4831, I've checked case lenth, powder charges, that is all fine. The problem is that neither of these guns will print much under 3" at 100yds. I shot both of them again today, it whas dismal. I finaly convinced them to shorten overal lenth from 3.112 to 3.o62 which is what the #48 Lyman calls for. I'm not shure this is the only problem, does anyone have any experiance loading for one of these? One is a MK-V, the other is an 03A3 custom built. Thanks for looking.
W.D.
W.D.
Comments
It's tough to say as most of the Weatherby's I've loaded for and shot haven't been spectacular until I got my .257 WBY. Shoots around 1/2" with the right bullets...that don't come apart.
One of the things with the Weatherby is to find out with a longer barrel if you are making the bullet come apart with a given load. The load won't be too hot for the case and rifle...it will be too hot for the bullet! I shot Nosler 85 gr. BT's in my .257 and they shot 1/2". My Sierra 90 gr. GK's shot 14"...yes one foot 2" groups... Found out the Sierra's were coming apart with the extra speed of the WBY. The cases showed no signs of overpressure. Back down a ways from max load if you have a long barrel and then see what you get.
The other thing I noted...and this was said to me beforehand....seat the bullets deep and let them get a run at the lands. I naturally seated the bullets out as far as I could get them and accuracy suffered. Seated them way in....accuracy improved, immensely! Whaddya know... some ol' timer was right!
As you may have noted I haven't specifically loaded for the .240 WBY but have loaded WBY's. -Hope these points may help.
I now seat them to SAAMI specs. for the cartridge. and fling a 75 or 85gr barnes hp. and throw a factory crimp on there. and the groups have tightened up significantly. still a bit to be desired but getting there.
Wby's are just finiky and take alot of time and effort to dial in.
I know what you mean. It just happened that I tripped into the good load for my rifle. I was loading for a friends .257 before I got mine and was trying 110 Accubonds. I don't remember what caused me to do it but I finally pushed the bullets way in so they would 'make the jump' and they shot a tight group. I was like HUH???{much head scratching and thinking of chicken rifle voodoo}. but it worked and so I did it. I switched down to 85's because that weight is what I shot with my .257 Roberts with so much success. Anyway, him growing up in SD he understood light fast bullets as a lot of guys out there use that. 59 gr. of VV N150 behind an 85 gr. Nosler BT for 3720{@40 deg}.
I always thought RW did that just for velocity. I'm thinking now it's because more of the bullet is centered by the case and not how accuracy guys normally think and that is the bullet is centered by the rifle before firing. -Anyhow, that's my stab in the dark
W.D.
W.D.
The freebore allows the bullet to cant before entering the rifling. By seating them deeper, you have grabbed more bearing surface allowing a straighter exit from the case neck. However,..you can also have the barrel set back and have the freebore length shortened with a match reamer. Just remember, factory loads may be too hot for the new chamber.
There isn't a lot you can do about their problem if they choose not to follow a process of working up a good load and using a logical method of evaluation.
The first thing to be done should be to look for problems that exist and contribute to poor accuracy. Scopes, mounts, bedding, crown, etc. There is a long list of ills that can occur with a rifle before you even get a chance to work up loads. If you are satisfied that there are no other outside factors that are a problem then you can start working on potential loads. But there are a couple of things that would be helpful to take into consideration.
You need to know what the dimensions are for each chamber. The factory rifle should be standard but you can't always depend on that. The '03 could be anything simply because it would have been done as a 'custom' either by a gunsmith, barrel maker or basement cobbler. The reamer variations are endless so you need to do a cast of the chamber, leade and throat. Be sure to cast a small length of the bore and groove so you can see if the chamber is concentric with the bore. A non-concentric chamber will be the ruination of any form of accuracy. While you're at it, carefully measure the land and groove diameters of the barrels by slugging them with some dead soft lead. It could be that the diameters are off a little and that doesn't help with accuracy.
Measure everything carefully, hopefully with a micrometer and NOT just a set of calipers. It is important to know what the diameter of the leade is. The leade is often referred to as 'freebore'. This is the cylindrical area right in front of the chamber neck following the transition angle. The leade should be somewhere between 2 ten thousandths (0.0002") and 5 ten thousandths (0.0005") larger in diameter than the bullet's primary shank diameter. It is this diameter that is critical to accuracy not how long the leade is. If the leade is larger than that in diameter it contributes to inaccuracy.
Bullets have a pressure ring located at the base of the bullet or at the junction of the shank and the boat tail. It is the result of the manufacturing process. This pressure ring can be between 0.0003" and 0.0006" larger in diameter than the primary shank diameter. The leade diameter should be as close to the diameter of the bullet as possible, allowing the pressure ring to slightly seal the leade and help keep the bullet stable as it heads toward the throat and the rifling.
You really need to stress the process of load development with your friends. As a review, read these articles and let them read them too.
http://www.frfrogspad.com/loaddev.htm
http://www.reloadingroom.com/page15.html
Best.
ADDED:
I guess I should include that I am the exception to having problems working up loads for Weatherby cartridges. I shoot three rifles chambered for the .240 Weatherby, one of which I use for 1,000 yard competition, one is for prairie dogs and the last is for hunting. All have long barrels, two have fast 1:8" twists and all are extremely accurate.
I used a custom reamer that I spec'd out with the reamer maker's help so it is a bit different from the factory specs and other custom designs. My Match load uses Re-25 with 107 gr. Berger VLD's (new), the hunting load is Re-25 with 115 gr. Berger VLD's and the prairie dog load is AA-XMR-3100 with 87 gr. VMAX. All loads are full cases of powder and all run very near the top end of the pressure curve.
Best.