Effects of off-center sprue in rifle bullets?

[Dutchman]

I bought this mold off of ebay. These older Ideal 266469 are hard to come by as they drop a .268" bullet. I took the chance with this one. It was in very nice, excellent condition. It in fact drops .268" bullets. I have a current mold of this number and they drop .266".

But when I used it the first time....ugh.... one of the sprues was way off to the side. I'm convinced the sprue plate on this mold is not original to the blocks. So as it is I can use it as a single cavity mold or go to the considerable trouble in making a new sprue plate on the milling machine (which I have).

I bought from NOE their push-through sizer for .268" figuring I'd pan lube these for my various Swedish Mausers. I ended up using LLA but still have to attach and crimp the gas checks. I'm sure I used too much LLA but figured in a 29" barrel more was better:-).

Any practical experience in shooting off-center sprue cast bullets?

https://images49.fotki.com/v292/photos/4/28344/9430776/DSCF2065-vi.jpg (https://public.fotki.com/dutchman/crufflerstuff/bullet-casting/dscf2065.html)

https://images46.fotki.com/v521/photos/4/28344/9430776/DSCF4303a-vi.jpg (https://public.fotki.com/dutchman/crufflerstuff/bullet-casting/dscf4303a.html)

[JWFilips]

If you have an accurate bore not much up to 100 yards

[JM7.7x58]

I haven’t shot bullets with off center sprues. But I have shot some 30-06 Lyman 311291 bullets that the base was rounded and not perfectly square. After the gas check was installed I did not see a difference when shooting groups.

I think that you should segregate a batch and see if the shoot differently.

JM

[JWFilips]

Always remember what rifling is supposed to do! Even out irregularities! ( to a point)

[Silvercreek Farmer]

Shoot some and let us know. My hunch is it won't matter.

[ShooterAZ]

I think as long as the gas checks seat flush and squarely you'll probably be OK. I also agree with keeping them separated and test them at first, just to be sure. If I had the capabilities I'd make a new plate, IF your rifles like the boolits!

[garandsrus]

I don’t remember the issue number, but a Handloader magazine from years ago had an article about a guy that intentionally doesn’t completely close the sprue plate. He wants a smaller sprue that is off centered. It seemed to work for him so I would give them a try.

[cupajoe]

It may not make a bit of difference, but if I had the equipment to make a new plate and the knowledge to use it, I would remove the doubt.

[rintinglen]

Unless the rifle is a genuine bug-shooter, you won’t notice a difference. I have a 311-316 that had the stop pin slightly misplaced, so that the sprue cut-offs were unequally off-center. Never made a difference that I could discern when fired from an iron-sighted Browning M-53.
What I would do, just to put my mind at rest, is to cast up a hundred boolits, carefully segregating them, then load 25 centered cut off ones, another 25 with the off-centered ones, and then 25 with no regard as to which was used. I’d fire five, five shot groups with each load and compare the results. My bet is that you will find no significant difference.

[uscra112]

Col. Harrison did an article about this about 50 years ago. Turns out that there's no discernable effect unless there's a void under the sprue.

[Mr Peabody]

I haven't seen it to matter when I had that to deal with.

[30calflash]

You can always orient them in your loading and see if there is a difference.

A few groups should show a pattern if so.

[redhawk0]

I've shot some off center sprue boolits. I've never seen any difference. A full cavity is a full cavity. Where the sprue is located is of no consequence.

redhawk

[dverna]

if you have a gun/load that shoots 3 MOA the effect may be masked...I do not know for sure. If you have a 1 MOA gun/load, it may matter...I do not know.

I support the idea of testing as suggested above and then factoring in your expectations. In my ignorance, I would not purchase a mold that produced bullets like that...but I am ignorant.

It would be informative if those who state "it does not matter", could supply more information. Were reports based on a small bullet or a large bullet? 1200 fps or 2000 fps? With GC or without? Slow twist or rapid twist barrel? My red flag goes up with "blanket" statements.

[MT Gianni]

I believe if there is a void it will probably be under the sprue. I think it would depend on your ability as a caster. I would segregate the first 100 I cast and see what the groups are like.

[earlmck]

I have a 22 hornet that shoots the casties real well. At one time I got obsessed with getting 10 shots in an inch at 100 yards. One of the things I tried was the "not quite closed" sprue plate to minimize the sprue cut-off size (relatively large in a .225 diameter boolit). I tried several different amounts of offset: it made zero difference and I never did quite get 10 in that inch, but came close. I would not worry one little bit about that offset sprue cut-off.

[gwpercle]

If , when cast , the base is smooth , flat and level ... the way a proper base should be ... the offset
hole should make no difference ... in theory .
I honestly believe once a gas check is installed they will all group the same .

If not....built in alibi !

Gary

[Iowa Fox]

Lyman made two different sprue plates. About, I'm guessing, 12 years ago there was a lot of discussion here about it and also the Lyman part numbers. I actually ordered and received one but I had a heck of a time because it was not a current number in their system.

[Gtek]

I would think not enough to notice. On the other hand, I am sure it will bother you much like it would myself until a new plate is made. Is the other mold a 2 cavity?

[GBertolet]

Could you have a out of spec sprue plate, or did the previous owner swap it out for another? If you have other Lyman 2 cavity molds, compare the sprue plates. If all else fails, contact Lyman, and see if a different sprue plate was used on older molds, and try to get one, or even make a replacement yourself. If the bullets shoot OK, and it doesn't bother you, leave it as is.

[megasupermagnum]

I do think it has the potential to really mess with accuracy. The easy test is to load 20 rounds from each cavity, and shoot them. The pictured bullets are not too bad, but I would have to think if any had more of a divot, that much off balance, especially right on the base, is not going to do good things.

[DonHowe]

If the sprue is cut off flush to the base, barring voids, then I don't see the off-center sprue making much difference. If the sprue is proud of the base then it will cause some imbalance although maybe insignicant.

If prepping match bullets I reserve those with off-center spruces for fouling/sighter shots. This may be OCD but my premise is that I want to be confident that errant shots are MY fault and thus improvable.
If plinking is the goal then load and shoot.

[ABJ]

I have tested an off center to a centered sprue in 30-06. Velocity was about 1850 tested at 100 yds. I could not find that it made any difference at all. Just make sure you let the sprue cool enough for a clean cut instead of a tearing that pulls metal away from the base.
Tony

[country gent]

The actual sprue off center shouldn't matter as long as it isn't raised or recessed from the base. This would cause an out of balance condition. As long as the bullets are round and true they should be fine. Shoot some and see.

I new sprue plate can be made with simple hand tools and a drill press. I usually use 0-1 gage stock for these 1/4" thick and the same with as the plate. lay out the out side and cut with a hack saw. Drill a small hole in corners to leave a radius and for the saw to cut into. Clean up edges and break sharp edges with a small file.clamp the plates together and drill the hinge bolt hole. from this location lay out the sprue holes with a small square and scribe. from the blocks. Drill a small pilot hole on each location.then use a countersink to cut to depth. I like to leave a .005-.010 wide band instead of a sharp edge. Turn the counter sink slow with lots of oil. Get close and then turn chuck by hand to finish. Stone and polish faces to remove burrs and flatten