GC or flat base for rifle?

[mpmarty]

Heck and tarnation!! My micro-groove barrel eats plain base boolits just fine in my 45/70 at velocities around 1500fps which is all I want or need. No leading and accuracy is fine since I mounted a 1.5 X 6 scope to compensate for my seventy year old eyes.

[turbo1889]

Bret,
Teach me. I'm not a PhD in GCs. How does a GC design make things easier?
This is not a challenge, it's a request for education.

The part of a boolit that experiences the highest stress loads is the very bottom base and especially the bottom perimeter edge around the bottom driving band. It has the high pressure gasses like a cutting torch trying to leak around the bottom edge and a massive torque load as well. From an engineering point of view the gas check is a case of nearly pure elegant simplicity; it puts a harder stronger metal that is more resistant to gas cutting exactly where it is needed most and no-where else. You may have heard the joke about engineers that the glass is neither half full nor half empty but rather the glass is twice as large as it needs to be to do its job. The gas check is the glass that is the right size for a certain class of loads that go above and beyond what a plain base boolit is able to withstand but where a full length jacket is unnecessary.

Just like a jacketed boolit is more forgiving to how it is loaded then cast boolits in general. A gas checked cast boolit is more forgiving then a plain base boolit do to its copper clad bottom. Which isn't so much a matter of the bottom of the boolit being protected by a copper base as having a copper ring for the bottom driving band. In fact so long as one can securely attach it to the base of a boolit so that it does not come off the boolit in the bore a copper ring or washer works just as well as a gas check. There were even a few molds made back in the day that were designed to use zinc washers on their base instead of a regular gas check.

For the particular combination under discussion namely the 44-mag cartridge in a long gun firearm I personally don't think you need either a gas checked boolit or a jacketed boolit since with the proper choice of powders and casting alloy you can get everything performance wise out of that combination with a plain base boolit that you can with a gas checked boolit or a jacketed bullet. That is my personal opinion, however, with a gas checked boolit you won't need to be as picky about your load. Of course if one follows that logic to its conclusion a jacketed bullet would be the best choice since it one can be even less picky about the load used then.



As to micro groove barrels; I personally have had no luck with them with either plain base or gas checked and would seriously consider not buying a gun with either micro groove or polygonal rifling or if I did switch out the barrel for the correct type of rifling ASAP. Others mileage may vary.

[1Shirt]

I don't get all excited about theories, formulas, etc. I cast hard, water drop everything for conveniende, cast/size and lube large to insure proper fit, and have had no problem with 44 or 357 from rifle w/plain base. If it works, I tend not to try to fix it. If it shoots well, and doesn't lead, think I it is satisfactory. I like GC blts, and I like the Thompsons as well, but I like the proper sized plain base just as well from a cost standpoint and convenience factor. More or less the KISS principle. Just my opinion.
1Shirt!