How much oversize?

[SkookumJeff]

I often read advice to cast a boolit .002 larger than bore diameter for Marlin MG rifling.

What if I don't want to slug my barrel and I choose to cast/load/shoot oversize cast boolits without checking? I'm going to cast/load/shoot a .432 diameter boolit in my 444 Marlin. Should be fine.

'Should' be.

But what if the barrel is smaller than I believe it is? How much oversize in boolit diameter can I reasonably go before I start having to worry about safety or accidentally plugging a bore? Has anyone done any testing by intentionally pushing oversize boolits down a barrel?

[RobS]

If you are not slugging then leading and accuracy will be your factors in figuring things out. Slugging the barrel simply takes the guess work out. As for a 444 Marlin and their general groove diameter I can't tell you, but if it's like all firearms it can change from one to the other.

[felix]

Oversize is never a problem provided you can insert the cartridge into the gun's chamber without friction. Use magic marker. ... felix

[Three-Fifty-Seven]

I load .4328 in my Marlin 1894 44 mag . . . pull a boolit after it is loaded and check and see if you case is swaging down the boolit while being seated . . . if it will chamber it is fine.:Fire:

[Bret4207]

What Felix said. If it'll fit in the chamber and you're using a load with enough "oomph" you won't stick it.

[1Shirt]

Yep, what Felix and Bret said! I load .432 in both 44 mag and 444 and both are MG. No problems, and no leading at above recommended vols.
1Shirt!:coffeecom

[sqlbullet]

As a general rule, slugging and measuring are activities I undertake when I am trying to solve a problem. But, I don't undertake them unless I have a problem to solve, or am bored.

Now, I get bored alot, so I have slugged the bores on most of my guns. But, I didn't need that info to develop what I shoot.

As far as 'plugging' the bore or pressure issues...as long as you can chamber the round it only takes a little pressure to size a lead bullet down. Put 10,000 psi behind it and it will get smaller easy. The 47,000 PSI your 444 Marlin makes is not going to be contained by a lead plug.

Now, obstruct you bore with one slug, then load another, and things will get exciting in a big hurry.

[peerlesscowboy]

Like the others have said, as long as it will chamber freely..........the bigger the better. FWIW I'm running Ly31141's that "mike" .312" in .30-30, that's .004" over groove diameter.

John C. Saubak

[SkookumJeff]

Thanks everyone, I appreciate the info, just what I was hoping to hear.

[Bret4207]

As a general rule, slugging and measuring are activities I undertake when I am trying to solve a problem. But, I don't undertake them unless I have a problem to solve, or am bored.

Now, I get bored alot, so I have slugged the bores on most of my guns. But, I didn't need that info to develop what I shoot.

As far as 'plugging' the bore or pressure issues...as long as you can chamber the round it only takes a little pressure to size a lead bullet down. Put 10,000 psi behind it and it will get smaller easy. The 47,000 PSI your 444 Marlin makes is not going to be contained by a lead plug.

Now, obstruct you bore with one slug, then load another, and things will get exciting in a big hurry.

HAR! And I thought was the only one. Add that to the "don't fix it if it ain't broke" column.

[Char-Gar]

Ditto to Felix and Bret. Too many folks make this harder than it is.

[onondaga]

It wasn't anywhere as tough or complicated as i thought after I watched this video by member Cowboy5780, Give it a look, you will be surprised:

http://www.youtube.com/user/Iraqveteran8888#play/uploads/13/ErFaJlUVs1Y

Gary

[45 2.1]

It wasn't anywhere as tough or complicated as i thought after I watched this video by member Cowboy5780, Give it a look, you will be surprised:

http://www.youtube.com/user/Iraqveteran8888#play/uploads/13/ErFaJlUVs1Y

Gary

Its not really the groove dimension of the barrel that you want (unless its a revolver, and that to compare to the cylinder throat diameters), but the throat diameter and profile from the case mouth to the full rifling point.

[mdi]

When I get a new truck, I record the tire sizes, and the type/viscosity of oil. When I get a new gun I slug the barrel/cylinder throats. I just wanna know for future work, and correct operation...