Trying to work up some cast loads for my 308, not much success with two prior molds. The Lyman 311413 was sideways at 50yards and the Lee 312-185 gave 6 inch groups.
I'm not new to casting and have had great luck with my 8x57 in the past
I had a Lyman 314299 purchased for a 303 British that dropped bullets a bit small for the 303 with wheelweight alloy at .312 (Lyman told me it was close enough as far as they were concerned )
Even though they are a bit heavier than I preferred for the 308, I decided to size them down to .310 and give them a try.
I also decided that if I could get them to shoot without gas checks I could save 3 cents a shot.
Keep in mind that this mold is designed for use with gas checks.
The gas-checked bullets shot into about 1.5-2 inches at 100 yards for 5 shot groups with no noticeable leading at approximately 1700fps. Not spectacular accuracy but round groups that show promise and it was a bit windy.
Next I attempted the same bullet and load with no gas checks installed. They were an utter failure. Significant smoke likely causes as there is now a smaller diameter base on the bullet filled with lube that is exposed to the burning powder. I could have helped this by wiping off the extra lube. Accuracy was horrible. My 2 inch group opened up to 18 inches. To add insult to injury, 3 of those rounds (what are the odds) managed to find my target frame as well.
In the future think I will just pay the extra 3 cents for this load...

I had a rather similar experience ,use of gas checks as you found, can easily change the group size
I tried 300 grain gas check bullets in my 44 marlin carbine and get amazingly tight groups in the 1"-1.5" range off a good bench rest at 100 yards, with several powders, but the same bullet used without gas checks produced groups in the 7" range
http://handloads.com/loaddata/default.asp?Caliber=44%20Magnum&Weight=All&type=Handgun

but thats not always the case
on my 45/70 gas check slugs produced 2" 100 yard groups and non-gas checked bullets of the same 405 grain weight over 45 grains of RL7 and very similar design produce the same groups, at least in that rifle with those loads

http://www.handloads.com/loaddata/d...mp;Weight=405&type=rifle&Source=

Knock 5-600 fps or so off of that load and I'll bet they shoot a heckuva lot better. Probably not as good as with the GC's, but still plenty good plinking accuracy. 1700fps in a .30 caliber without a gas check, even with a design not intended for a GC, is pushing it way into the territory of "probably not".

You might be right but I don't have a need for a 308 at 1100fps. I wanted a lower recoil practice load but not that low.
It would be tempting to try a plain base design in the 1500-1700 range to see what it could do.

Who cares what velocity it is if it's only a plinking/practice load. The bullet only has to make it as far as the paper, doesn't matter if it takes an 1/8th of a second to get there or a 1/4 second. I probably shoot 10 such low velocity loads for every 1600fps and higher load out of all my .30 rifles. A lot less powder gets burned (not an insignificant thing in this day and age), less recoil, less noise. Heck, when shooting "cat sneeze" loads the most expensive component is the primer- making them cheaper than shooting .22's these days. What's not to like?

I too have shot "cat sneeze" loads, have enjoyed them and can appreciate their use. That is just not what I'm looking for in this case.
I am looking for a moderate velocity, moderate recoil 308 load that might even hit close to the point of impact of my full-power loads.
The purpose is to allow me more cost-effective and more comfortable longer practice sessions while still providing the sensation and effects of a centerfire rifle. It is also to let my small-framed daughter become more proficient with centerfire rifles without introducing detrimental effects like flinching too early.
I am not trying to replicate, replace or simulate a 22 rimfire, althought there is nothing wrong with that if it is your goal.
Thanks.

Gotcha.