I'm trying to get my 250 savage to be more accurate with cast bullets. I've had some good groups, only to try the same thing again and have it all fall apart. I've done a lot of casting over the years, for the most part in the 30 and up range and I've had fair success. I don't believe my problem is in the cast bullets themselves. I weigh up everything to within +/- .1 grains and then segregate them to within a grain. Any external imperfections are tossed back in the pot. I've sized them generally .001 over bore diameter. I have a bore void of copper, etc. I'm not a newbie, but I'm sure a don't know everything either.

One thing I have is a neck expander die for both 30 and 25 caliper, I learned this early on so I didn't damage the sides of the bullets. So I don't have an issue in this department.

One area that I haven't focused on is using a neck sizing die versus the full length die I currently have for my 250 savage. So this is one path I can go down and probably will just to reduce the stress on the case, and now that 250 savage brass is really hard to find. I've also never used a case neck gauge.

Next is the bullet seating itself. My current dies are just the standard Lyman full length sizing die kit. Nothing special about the bullet seating. Wondering if it was worth getting a competition bullet seating die, not sure how these would work with cast bullets being oversized, or is this just a waste of money. Guess the big thing is, how do you know your bullet is straight.

Basically I'm thinking about getting a Redding type S die for neck sizing. And than get a better bullet seating die also. I just want to take any issues of being concentric, etc. out of the equation.

I suspect your powder choice and or powder charge is the culprit.

neck sizing only or FL sizing won't make or break a group.

sounds like you have the loading part down pat.

you could be on the ragged edge of the velocity limits of the bullet you're shooting.

what powder and what charge are you using?

It's a load mentioned in the Ken Waters Pet Loads book.

16 grns of 4198

#257464 lyman bullet weighing in at 87.1 grns (at least if not better then lyman #2 hardness (using Saeco hardness tester).

#257388 lyman bullet is also used, of course this is a Spitzer bullet but I have got it working good at times (not as good as the 257464 but not bad). It weight is around 80.5 grns.

Seems like every other time I try this load it either does good or fails totally.

I'm sizing to .258 and I'm using Hornady gas checks. Rifles being used are 14" twist.

I was thinking since I had a fairly hard bullet it wouldn't give me problems. I purchase the 70/30 allow from Rotometals. I have had my own Tin and Lead that I acquired years ago, so my alloy I mix up is decent.

Perhaps the newer powder I'm using is a hotter batch than what they had back when Ken tried his load. I could back off 0.5 grns and give it a try.

A chronograph is one thing I do not have.

Is the alloy the same, for sure, between the "good" loads and the "bad" ones? What is the throat diameter, and are you sizing the bullets to match that and not the groove diameter? What exactly is the diameter of your expander dies? (Just because it says ".25" on the box doesn't mean it's right for your particular bullets. I like to expand/bell case necks to a mere .001" under bullet diameter- a little tighter for hunting ammo.) Same brass both times? Same headstamp on all lots of brass? Have you checked loaded ammo for concentricity? Is your shooting bench technique consistent? (Exact same positioning on sand bags, etc.) Parallax-free scope, and if not, cheek weld precisely the same each time? Bore condition the same between test lots? Etc., etc., etc.

As you can see, there's a lot to take into consideration when striving for keen accuracy with cast bullets, and anything else for that matter.

I wouldn't presume to answer your problem without knowing/seeing exactly what you're doing every step of the way. I would suggest starting to eliminate as many variables as possible, one at a time, while re-checking accuracy along the way. By not adopting a scientific method-style approach to it you will never know what the fault was should you accidentally solve it.

Alloy has been the same batch for some time now.

The expanding die is .257 (just miced it and it is exactly .257)and the lube sizer die is .258 (not many choices for 25 cal rifles).

The 257464 is a Loverin bullet design so no bore riding nose section, the 257388 is a spitzer with no bore riding section either. Bullets are seated just so they start to engage the rifling.

I have not check the ammo for concentricity. I ordered a Sinclair gauge a few days ago (was on sale). I also have a Lyman turret press, I've had to tighten on the middle nut several years ago, perhaps it's time again. This could be screwing things up in both bullet seating and resizing.

check your scope, make sure it's tight.

I'd also check how you rest the rifle on the bags, be consistent.

yea dropping back a half grain and then another half if needed may do the trick.

I'd take a loaded round and take out the bullet (impact way) and measure it to make sure it's not getting sized down in the seating/crimping operation.

I now have the equipment to measure runout using a Sinclair micrometer. Most of the brass was hit in miss, most of it was out 2-5 thousands, with a lot of them around 4 thousands. The wall thickness of the neck seemed to be OK although I don't have the correct gauge but my regular micrometer seemed to work for now.

Using a bushing neck die did nothing to correct the brass. I removed the expander from my standard full length die and sized them without it. Then I used my expanding die that I use for cast bullets to bell the end (I avoided belling the end although I will eventually need to do this). I let the expander free float and didn't tighten down on the locking nut. This corrected the problem and I was back into most of the brass being within 1 thousands and none greater than 2.

Before I did any of the above I tightened down on the Lyman turret press that I have. When I examined it, it appeared to be tilting some. This may have been causing some of my issues. Trying to fire form the brass didn't appear to help with such light loads used for cast bullets.

Hornady gas checks don't always fit properly on Lyman mould cast bullets.....