If you can handle quarter mil machining, attention to detail, reloading will not tax you. As BMT85 said, to some it is tedious but like him I find the time spent to be rewarding. Actually, any excuse not to have to sit with the Mrs while she watches Pride ad Prejudice for the umpteenth time, or scream at the news on CNN, is its own reward. I got my Alt Rock hipster channel on down in the cave and that's plenty entertaining for me. I've said this before so those who have read it can go get something to drink or give some back.
Reloading is more than just a means to trade your disposable time for a discount on ammo, though it does that well. IMHO, it allows you to fine tune your ammunition to exactly what the rifle or pistol you will be shooting it in, needs to perform to the best of its ability. The savings are the icing on the cake. Reloading often exceeds the performance you get even from factory offerings with the added bonus (not the primary) of it costing less. It will take some time getting your investment back, so don't try selling that angle to the significant other. They keep score!
So, by all means, build up a list of equipment. Many of the items you needs to buy only hurt once. Most of us would be hard pressed to shoot so much that we wear out our reloading equipment, provided we take care of it. Preventive Maintenance is not something you do once a failure occurs from lack of it, but as a machinist, you already know that. Before plunking down your hard earned shekels, get a reloading book and actually read the beginning. There are several sources for them. Read what is going on in there to give you insight into how you're going to control it. Many reloading equipment
roads lead to Rome. How much you want to spend will dictate how much effort you have to put into it. I started out with one of those kits and over time, replaced some of the more rudimentary pieces of equipment that drive the touch labor, with more sophisticated, labor saving devices. Again, as BMT85 already said, the best return in that arena is a dispensing, automatic powder scale, if you intend to weigh every charge. Manual scales work well but take a lot more time to crank them out. When I was reloading pistol ammo, I just used a drum powder measure calibrated with the occasional check on the scale. That's fine for "blammo ammo" that's not running near the top of the safe charge zone. You no doubt already understand the importance of a good set of calipers and mic. I could afford a progressive press, but I prefer a good single stage. My time's not that valuable. Actually, I have two. the original one that came with the kit and a second one mounted alongside it.
Double your pleasure, Double you fun...When the time comes to decide which piece of equipment to add to your setup, members will be falling over one another offering their opinions, so you won't be out there struggling for lack of testimonials. All of this still doesn't address your sudden change in group size but I will dangle one point out there. Everyone has a day at the range, every now and then, where after a few shots of a known good load, its pretty evident that they could be doing something more useful with their time than trying to shoot well. I know I have. I forget whether you said the change in group size has lasted beyond a single session. If not, try again, preferably under better weather conditions. They vary a lot this time of year, what with the season change and all. Up here our club's rifle range is still snow covered and no, 32 degrees in a damp breeze is not Hoot's idea of the beginning of a good range session. its perfect however for the continuation of a good reloading session.
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If your grouping continues to stay opened up. that may be the rule, not the exception and you just had a magic outing the first time. They happen occasionally, just like the go home ones. Unfortunately, the only way to test whether something you added or removed, caused that change, is as others have said, revert back and then change one thing at a time while testing along the way. I know, that's easy for the person(s) not buying the ammo for you to say. The 450b caliber is very forgiving, but if the problem persists, you don't need different ammo, you need to eliminate the variables you changed between the before and the after, assuming the cause lies therein.
Bed time is upon me as I realize I am rambling. 04:30 comes early.
Hoot