Catpop
Member
I'm looking for some input from those with experience in reloading and shooting lead boolits in Marlin microgroove barrels.
Thanks in advance for any input.
Thanks in advance for any input.
Marlin microgroove and lead boolits
- Thread starter Catpop
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I've shot some cast bullets in my Marlin 1894, 357 mag rifle with micro groove rifling. Accuracy is not as good as with jacketed bullets but otherwise I do not remember any issues. I do not drive cast bullets any where near full 357 Magnum levels.
It has bee a while since I shot any cast bullets in the rifle, 20 years or so, so I do not remember how poor the accuracy was except that I do remember the rifle prefers jacketed bullets.
On refection just now, I wonder if gas check bullets might do better.
It has bee a while since I shot any cast bullets in the rifle, 20 years or so, so I do not remember how poor the accuracy was except that I do remember the rifle prefers jacketed bullets.
On refection just now, I wonder if gas check bullets might do better.
NeuseRvrRat
Member
pages upon pages of info on the subject at http://castboolits.gunloads.com/
THR is a great forum, but if it's cast bullet info you're after, that's the place to go.
THR is a great forum, but if it's cast bullet info you're after, that's the place to go.
Lafitte
Member
I have shot leterally thousands of lead bullets in micro groove Marlins. NO problems, just stay with lead bullet loading data and use a bullets that fits the barrel.
Lafitte
Lafitte
ReloaderFred
Member
My wife and I shoot several thousand cast bullets per year our Marlin 1894 .357 rifles, all of which have micro-groove rifling except for my Stainless steel, but it doesn't get shot near as much as our older ones.
Size your bullets to .358", and keep your loads reasonable, and they will work just fine.
Hope this helps.
Fred
Size your bullets to .358", and keep your loads reasonable, and they will work just fine.
Hope this helps.
Fred
cheygriz
member
I've shot several thousand cast, gas check 385 grain bullets from a Marlin 1895. My loads ran 1450-1550 FPS, and I never had an issue.
Carl N. Brown
Member
The Marlin Microgroove barrel was introduced with Marlin .22 rimfire rifles in 1953 with great success. .22 rimfire ammo is lead bulleted ammo. My Marlin Model 60 and Model 39 rifles are super accurate. Centerfire Marlins with Microgroove barrels are also very accurate with jacketed bullets.
But the Microgroove lands with standard centerfire lead bullets do not upset the bullets as much as conventional rifling does to seal the bore diameter, so lead bullets for reloading cartridges for use in Microgroove barrels must be a bit oversize for the caliber.
Added: I suspect gaschecks with lead bullets might have solved the bore fit problem I had in my brief experient handloading lead bullets for my .30-30 Marlin 336W.
But the Microgroove lands with standard centerfire lead bullets do not upset the bullets as much as conventional rifling does to seal the bore diameter, so lead bullets for reloading cartridges for use in Microgroove barrels must be a bit oversize for the caliber.
Added: I suspect gaschecks with lead bullets might have solved the bore fit problem I had in my brief experient handloading lead bullets for my .30-30 Marlin 336W.
FROGO207
Member
I have shot 1500+ Lasercast 170 grain lead FP bullets out of my Marlin 336 RC as well and had superb accuracy with near max lead data with several loads that were listed in the reloading manuals. Better accuracy than in any of my Winchester 94's come to think of it.
Dog Soldier
member
I cast for a Browning Mdl. 92 .44 Mag. these rifles were built around the Winchester Micro Groove barrels. Micro Groove barrels have over sized throats and bores. You will need a bullet .002+ cast hard with a gas check for best accuracy. Ranch Dog Molds used to make bullet molds for Micro Groove barrels. They are different.
ReloaderFred
Member
For .44 Magnum rifles, the SAAMI specifications for bore diameter is .431", whereas the SAAMI specifications for .44 Magnum handguns is .429". Saying a .44 Magnum rifle barrel is "over sized" is incorrect, if it's at .431".
Micro-Groove was a trademarked name for Marlin's rifles, and I may be wrong, but I've never seen a Winchester barrel that was "micro-groove". My Winchester Model 94 in .44 Magnum has standard rifling.
Hope this helps.
Fred
Micro-Groove was a trademarked name for Marlin's rifles, and I may be wrong, but I've never seen a Winchester barrel that was "micro-groove". My Winchester Model 94 in .44 Magnum has standard rifling.
Hope this helps.
Fred
midland man
Member
i'm glad this got posted as I own a marlin 336w jm stamped 30-30 and I was told lead bullets without gas checks will lead the barrel so I was about to buy a Mossberg 30-30 for my cowboy loads as I call them using cast bullets so what oversize bullet mold do I need that will work? maybe I won't need to buy another 30-30 after all! thanks!
Dog Soldier
member
The Winchester Micro Groove was used on all Browning Mdl. 92 Carbines. These rifles require a .432 cast bullet to preform properly. If you own a Browning 92 you would know it does not have cut rifling. Winchester used Micro Groove for the same reason Marlin did. It is a much less expensive process with a higher hourly production. Marlin/Sako Bolt action rifles used Micro Groove barrels and were a market failure. The accuracy was terrible. Marlin and Winchester/Browning have abandoned this process. Many special bullet molds were made for these rifles.
the Black Spot
Member
444 marlin, lee 310 gr mold cast of wheel weights backed by varget powder gets me under an 1.5" at 100 yds(3 shots).
ReloaderFred
Member
I didn't say I owned a Browning Model 92. I own well over a dozen Marlin leveraction rifles in numerous calibers, plus two Winchester 94's, one in .30-30 Winchester and one in .44 Magnum. A .432" diameter cast bullet would be the correct bullet to use in a SAAMI correct .431" barrel, so it's not oversize. Micro-Groove barrels can be made to shoot accurately using cast bullets with the correct bullet.
Hope this helps.
Fred
Dog Soldier
member
Did I mention Winchester Mdl 94 having Micro Groove barrels? No, as far as I know only the Mdl. 92 made by Browning/Winchester use these barrels. SAAMI, like all specs have + and - specs. Any time you are pouring your own lead measure your particular barrel. Being able to correctly match the bullet to the barrel is what it is all about.
gojuice101
Member
The first rifle I started casting for was the Marlin 336 that I gave to my brother. We have shot a lot of cast rounds through that (I don't remember how many, just a lot), and we always checked it afterwards for leading because I'd heard that Micro-Groove has problems with lead. Never found any leading.
I shoot a gas-checked bullet design, but I don't put checks on them. I'm sure if you do use gas checks you won't have any problem at all, but in my experience you don't need them.
I shoot a gas-checked bullet design, but I don't put checks on them. I'm sure if you do use gas checks you won't have any problem at all, but in my experience you don't need them.
OP
OP
Catpop
Member
From what I am gathering from responses to this thread, the micro groove leading issue may be an old wife's tale. I hope so as I'm a dedicated lead boolit user!
Maybe more will chime in with their actual experience in this issue.
Maybe more will chime in with their actual experience in this issue.
Salmoneye
Member
Not sure what's going on, but there is no such thing as a "Winchester Micro Groove", and never has been...Maybe the disconnect is confusion over the difference between cut rifling, and button rifling...No idea...
As to shooting cast through Marlins with Micro-Groove rifling, as noted, use fat bullets...
Many on CastBoolits.com suggest that when loading for Micr-Groove rifling, that you use the fattest bullet that will chamber reliably, no matter what the cartridge being loaded for...
As to shooting cast through Marlins with Micro-Groove rifling, as noted, use fat bullets...
Many on CastBoolits.com suggest that when loading for Micr-Groove rifling, that you use the fattest bullet that will chamber reliably, no matter what the cartridge being loaded for...
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ReloaderFred
Member
Those are my thoughts, too. Like I mentioned above, "Micro-Groove" is/was a Marlin trademarked name for it's form of rifling.
Hope this helps.
Fred
Dog Soldier
member
The Winchester Micro Groove used the same 12 groove .433 bore as did Marlin. Winchester made these barrels during the 1980s. Any knowledgeable American gun collector know this. Read the link from the seller of a Browning/Winchester Mdl. 92. If you do not have a B 92 you are only guessing anyway.
http://www.gunbroker.com/item/590926032
http://www.gunbroker.com/item/590926032
ReloaderFred
Member
So now you're claiming they were made with a .433" diameter bore, instead of the .431" diameter SAAMI spec. bore. You also mentioned that you use a .432" bullet, so which is it? Never mind, I'm done.........
Fred
Fred
LOLBELL
Member
I don't know if a B92 has " Micro Groove " or not, I have one so I'll check it and see. From experience with loading a couple of 336s in 35 Rem I have to shoot "fat" bullets. I cast a 200 RNFP from clip on wheel weights and size to .360. Anything smaller skids on the shallow grooves and leads the bore pretty bad and accuracy is off. Groove diameter one is .3585 and the other is .358
Marlin is the only one who made "Micro Groove" barrels. It was their registered trademark for their barrels with the many lots of shallow grooves, and while another maker may have copied it or made something similar, it isn't a "Micro Groove" barrel. The seller in the GB auction linked to described it honestly.
"The bore looks very similar to a Marlin Micro groove barrel."
The Marlin MG barrels did get a bad rap for shooting lead, deserved or not, but people have been able to shoot lead in them with no problems. Like any gun, it's all about fit, hardness, lube, and people have obviously worked that out.
"The bore looks very similar to a Marlin Micro groove barrel."
The Marlin MG barrels did get a bad rap for shooting lead, deserved or not, but people have been able to shoot lead in them with no problems. Like any gun, it's all about fit, hardness, lube, and people have obviously worked that out.
Dog Soldier
member
No Winchester never used the Micro Groove word. It is used to describe the type of rifling Winchester used which was the same. If you do not have access to a B 92 you Browning how would you know?
Ranch Dog made molds for the Marlin and the Winchester Micro Groove style bores. These over sized throats allowed gas cutting leading problems. The Marlin-Sako 422 Varment King rifle failed due to the micro groove barrels. Throat and bore fouling caused constant accuracy problems.
Ranch Dog made molds for the Marlin and the Winchester Micro Groove style bores. These over sized throats allowed gas cutting leading problems. The Marlin-Sako 422 Varment King rifle failed due to the micro groove barrels. Throat and bore fouling caused constant accuracy problems.
kerreckt
Member
I have shot nothing but cast bullets in my two 1970's era Marlin 336's in 30-30. They both have microgroove barrels. No leading or any negative effects. The bullet must fit the barrel. Mostly, leading is a result of a poor fit between barrel size and projectile size. My bullets are in the 15 BHN range. Microgroove is a Marlin trademark. Others may have made a similar barrel but if it is not Marlin it is not Microgroove.
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