Years ago Jack O'Connor wrote that 31.5 grains of 3031 under a 170 grain jacketed bullet was max for the 30-30. That load flattens the snot out or primers as does 31 grains. I have always considered 30 grains to be my max.
Addendum: A look back at my records tells me that in 2000, SAEC0 325 over 28.5 grains of 3031 fired by a Remington 9.5 primer gave me consistent 1.5" one hundred yard groups from my Marlin 336A ( a half mag, rifle version) with a Weaver K 2.5 scope. Sizing was .311.
SAECO 325 is a fat version of their 170 grain 30-30 bullet, sold as a 303 Brit bullet, but just right in the nose for the Marlin MG. It was the first real success I had with cast in the Marlin MG barrels.
I think this was before Ranch Dog came out with his bullets for the big groove Marlin MG rifles. It was after this that I speced the 311407 Mod which has also proved to be a good MG 30 cal bullet.
The Micro Groove barrels are problem children due to their size but with the proper bullet they will do quite well with cast bullets.
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Don't accept no for an answer from that other Marlin re cast bullets. It may be metal fouling, but most likely is bore size. The Marlins are all over the map in that regard. I have a 1960 Texan that runs .310 (groove) and .305 (lands) both way large and could not find any bullet that would work. I finally had Mountain Molds make me one with a tapered nose and a .313 body. It shoots to perfection, but no off the shelf mold would work. That bullet also won't chamber in any other 30 cal rifle I own.
It is war and don't let that rifle win!!!!
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As reducing the trigger pull a smidge, get some 1600 grit emery paper from where auto body and paint supplies are sold. Using some needle files to back up the paper, polish the hammer notch and sear plus any other surfaces that show drag. That will take care of the problem. without removing any metal or changing any angles.
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And another thing. The Marlin 30-30s have a 1-10 twist whereas the Winchester and Savage has 1-12 twist. This makes the Marlin just a smidge more cast bullet ornery and the longer heavier designs are the way to go as long as they will work through the magazine and chamber with no issues.
Oh yes, I have a Japchester 1885 Traditional Hunter in 30-30. It has a 26" half round/octogen barrel, a tang sight and a very good trigger. It also has a 1-12 barrel. To round out the fleet, there in a Winchester 94 carbine and a Savage bolt both in 30-30. Again they have 1-12 twist barrels.
My first centerfire rifle in 1956 was a 1911 vintage Winchester 94 takedown rifle in 30 WCF. It got me started in handloading and centerfire rifle shooting. It was the best teacher I ever had.
