Update on sizing conventional wisdom

[Harry O]

I loaded up some cartridges for my sporterized Krag and shot them yesterday. The groove diameter was slugged at 0.309" so I used 0.310" cast bullets for some time. It shot pretty good. The bullet that worked best was a Lee 303B with the bore-riding front at 0.300" and the rear at 0.314" as-cast. The chamber is rather large (like many military rifles) and I found that I could load an unsized 0.314" bullet and it would still chamber. It is snug, but not a problem. So, I loaded up 20 unsized ones to shoot.

The weather here was snowing with the temperature below zero. I had to fire them at an indoor range (25 yards maximum), so I have not really tried it for accuracy. Almost anything looks good at that range (including this test). However, I did verify that there was no leading or shaving with the bullets used. In fact, if anything, the barrel was cleaner than when I shoot the 0.310" ones. As soon as the weather gets better, I will take it to the outdoor range and check it at 100 yards.

If that checks out, I intend to start using that the largest bullet that can chamber on pretty much everything. The old 0.001" over groove size doesn't seem to do as well. With the two other tests I ran (one is a pistol and one in a revolver), that seems like the way to go.

[felix]

That's the only way to go, Harry! Bigger the better. Let the gun do the sizing. It pays dividends to play with diameter only in a real BR gun, where a thousands smaller can be better because of typical loading practices for those machines. Hotter loads than normal, for example, which bumps the rears up with those kinds of loads. Besides that, with these kinds of guns and loads, we don't want any left over lube from the previous rounds playing games with the current round being fired. Because these extra-carefully made boolits can and will be sized down somewhat by this left over lube. ... felix

[sundog]

Harry, I am currently working with the 314299 mainly because the 311299 works so darn good. Looking back in my notes several years I found some reference to the 314299 working really good, so here I am full circle. This time, however, I'm air cooling the 314s, sizing in a .312 which actually is .313, heat treating (man, they're hard!), running back thru the same die to GC and lube, and loading to fill the throat in a 03A3. Nose is lightly engraving and boolit base is at base of neck - best of both worlds. I've bumped up the velocity also, and added dacron wad. Hope to test over the weekend, but early test shows promise. Even though we're forecast for crappy wx, my club has an all wx shooting bldg out to 200 yards. Nice and warm and dry and comfy inside with good benches, slide shooting windows, and a rock solid loading bench on the back wall. What more could a feller ask for? If I get this done, I'll report back. sundog

[Buckshot]

..............Sizing to fit the throat is a kind of a given but not always. Sometimes other bore forms biased more toward wide lands may not show up as well. The leade may have something to do with that too, but lead displacement can be an issue.

................Buckshot