I have a custom built 458 win mag built on a 1917 action with a new 26" barrel. load is 440gr Cast performance bullet @ approx. 2100 f/sec. scope is a leupold 2-7X varII. mounts are weaver. this rifle is shooting all over the place. erratic groups in the 7"range. no consistancy in the group. barrel is floated. trigger is original 1917 but at around 3.5lbs and crisp.

possible problems: 1. bullets are recessed deep into the case making an overall short round nowhere near the lands. need to set bullets out more or just go with the 500gr hornady. 2. bad scope? 3. mounts loose (they do not move or jiggle, feels solid on the rifle.).
other than putting a different scope on the rifle, is there another way of determining if it is bad while on the rifle?
can bullets which are not near the lands shoot this poorly?
I feel if the gun did not like these bullets that accuracy would not be great but not as bad as erratic 7"groups.

oh, and was shooting the rifle off the bench well supported. and I am not scared of the recoil (unless the scope hits me in the head but this set-up has never hit me because the scope has plenty of eye relief.

I need HELP.

A few things come to mind...cast bullets are notorious for only shooting well in a certain velocity range and perhaps you are driving them too fst...also, the twist for your rifle might not be suitable for the bullets used.

The first thing I would try are some factory loads to see how they shoot..if you are having the same problem I would go back to the 'smith who built the rifle and have him check everything out...one other thing on these big-boomers, try shooting at 50 yards until you begin to get an approximation of the performance you want...the sighting is easier and you don't have so far to walk to change targets. Good luck.

If I recall corectly, the 458 Win chamber usually has a long leade. With cast bullets that is bad. If the bullet gets a running start and smacks into the rifling it will skid for a while. I would try some factory ammo. Clean the bore well first, I bet it is well leaded.

I have had the suspicion that a 458 Win would make a really good paper patch rifle. Never had the time to mess with it though.

the load data for the cast bullets was given to me by Cast performance specifically for the 458 win mag. I assumed that it would be fine.
I have loaded 3 other bullets less deep into the case. I determined how far I have to go to the lands by putting a bullet backward into the chamber until it just touched to lands. this gave me a distance of 3.13" from bolt head to lands. I loaded 3 shells so they would be about .15" from the lands compared to .4" origninally. we'll see. I will also pick up some factory 500gr round nose to see how they perform.
it's enought to make a grown man cry. someday I am confident it will be fine.

by the way,,,this rifle has only been shot about 40 times. is there some type of break in period?

Hey Dr.John, Shooting "Lead" can be absolutely wonderful to down right awful.

But, without exaggeration, it would take an entire book or two, to list all of the "potential problem areas". Make sure you keep good accurate records of "exactly" what you have tried, so you can make slight modifications later on.

It would be a considerable advantage for you to get a couple of the old books that deal strickly with shooting Lead. A good place to look for them is through "Rifle" and "Handloader" magazines[Wolfe Publishing (520)445-7810]. The Gun Shows here in the Carolinas generally have 2-3 Book Vendors too.

Lead is well worth the trouble, but it normally takes a good bit more effort than Jacketed Bullets.

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Good hunting and clean 1-shot kills, Hot Core

Dr. John, have you shot any jacketed bullets? If so, how did they group? If so, did you CLEAN THE BARREL thoroughly before changing to cast bullets? Is your barrel staying lead-free when shooting?? If your barrel is leading, it will never shoot a group while doing that. (2100 feet per second is not too fast for a relatively hard lead bullet. I shoot mine at about 16 Brinell [soft enough to expand] at 2200 out of a 45/70 with good accuracy.} Cast bullets can be driven up to 2600-2700 if hard enough. Maybe you need to bed the barrel instead of letting it remain free-floated. Try some upward pressure at the end of the forend, about 20 pounds or so may dampen barrel vibrations. You may end up having to completely glass-bed the barrel. I had to do that on a Springfield .308 Norma Magnum (GI barrel contour unchanged) before it settled down to 1.25" groups. Good luck!!

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Larry

Are there any factory ammo for your .458 at the local stores? If I was you, I would follow the advise listed above, and finally, I would thoroughly clean the bore, and shoot a few factory rounds to see what happens.

I know that .458 factory ammo is very expensive, but you could always shop around for some factory "cheap" ammo just to test the rifle. If everything fails, I would also remove the scope and use the iron sights to see what happens (this would be my last step).

[This message has been edited by Ray, Alaska (edited 02-25-2002).]