Anyone have suggestions as to why my Ruger #1 is very erratic with cast bullets?

I've got a beautiful Ruger #1 in .458 Win Mag (1:14" twist and a bore that measures .460") that I've recently obtained. I love the rifle and am experimenting with various loadings. I had hoped to use cast bullets as they are easier on the bore and cheaper of course. I've tried Cast Performance 460gr WNGC .459" bullets at about 1750 fps. I also tried 540gr J B Young FNGC cast at about the same velocity that are about .458" to .459" and both bullets were erratic - 6" to 10" groups at 35 yards! Some evidence of keyholing too.

With jacketed bullets it seems fine - 550gr Woodleigh Weldcore SN at 1800fps easily does 1.5" at 50 yards with iron sights.

What suggestions do you fellas have? I'd love to make this beast a cast-bullet shooter at modest velocities, but so far I'm baffled. I've been loading various calibers for about 27 years and have never had such wildly erratic performance in rifle or handgun.

I have just received a box of .460" Beartooth 450gr FNGC that I plan to try this week or next. Perhaps it's the .460" bore and improper bullet fit?

Hard cast bullets that are smaller than the groove diameter of the barrel often don't shoot well, and they may lead the barrel a lot from "gas cutting." They should be at least groove diameter, and a few thousandths bigger is fine. You'll have a hard time finding .45 bullets bigger than .460" commercially.

I'm aroused, to hear you have erotic bullets for your rifle. Oh... sorry... that was erratic.

Your bullet size is most likely the culprit. You will need to shoot at least a .460, and maybe a couple thousandths larger to get it cooking good. The .45's WILL shoot.

It may be a problem finding bullets over .460. Check on some BP pages, maybe someone would send you some of each size to try. Best bet? Make a chamber casting, send it to Dan at Mountain Molds, and have him cut one for you. Then I will pretty much guarantee it will shoot well, plus being tailored to profile and weight you want to shoot.

Check on the aimoo cast boolits page, as I believe there was recently someone there with the same problem, and they may be able to get you some bullets to try out.

Another possibility, I believe Buffalo Arms sells incremental bullets for this type of testing, but be prepared to pay big money for them.

What ever size it takes, just figure on buying the proper mold. the commercial suppliers are not all that consistant on hardness or size.

I believe I will stick with my suggestion for Mountain Molds as being the way to go. And his prices are good!

458 Ruger-- A fellow that posted on the old board and now posts at Aimoo Cast room goes by Beagle(he might post here too????) has told of putting aluminum tape between the mold halves and getting a bigger bullet. He states they aren't out of round as I would have suspected nor do they have fins. Several have reported favorable results by "beagling" a mold.

Suggestions have been right on. Small diameter boolits won't shoot worth a hoot. That 14 twist is a might steep for lead boolits, and suggests a 400 grain boolit or heavier shot at low speeds. You want the diameter to be the largest you can stretch into the case and still chamber the round without friction. This would most easily be tested by having a bunch of different diameter boolits on hand to test with, and using a magic marker around the loaded case where the boolit is seated full length. The diameter of the boolit that scratches the case, rubs off some magic marker, is about 2 thousands too much in diameter when the boolits are of soft composition. For hard cast boolits, 1 thousands of total clearance is satisfactory. With that twist, load for no more than 1800 fps. ... felix

I can't argue with the others' advice, but let me add that my Ruger #1 (.243Win.) is very particular about bullet weight (both jacketed and cast), cast bullet design, and OAL of cast bullet loads (shorter is better than longer in my #1). With respect to design, Loverin types (all body, no nose and lots of lube grooves) shoot well in my #1 and most of my other rifles (in other calibers) too. You may want to think about this type. Also, you may want to experiment with velocity and powder combos trying perhaps 1,600 fps to 1,900fps with various propellants. Although you didn't mention it, have you checked both your 'scope mounts and the tension on the forend screw? Years ago C.E. Harris, who worked for Ruger for many years, recommended installing a piece of flat plastic (the type that holds bread and English muffin bags shut) on the base of the forend hanger and then re-installing the forearm, etc. One last suggestion: Many .45-70shooters have had success with the Lee 405gr. hollow base bullet, which generally casts
~.462" from WW + 1% Sn. Maybe it's worth a try in the .458Win as well. ...Maven