Guide Gun Throat?

[Spokerider]

Has anyone slugged the throat of a newer Marlin Guide gun? I'm wondering if the GG has a "long" throat, "wide" throat, or non-existant throat? I'd like to eventually design and order a mould from Mountainman Moulds, so I've been reading his FAQ's on mould design. Apparently, the throat of the gun has a lot to do with the design of the nose length, ogive, meplat of the bullet. The distance between the case mouth and where the rifling starts as well as the anlgle of the throat also plays a part in cast bullet design. Typically, what does the Marlin GG have?
I don't have my GG as of yet, but it'll be here soon. How does one slug the throat, and what will I need to do this?

Thanks.

[BABore]

I slugged and checked the throat on my Marlin 1895M 450 Marlin on its first barrel. Using an egg sinker, it slugged at 0.4585. This was after approx. 1,000 rounds of jacketed. I tried to upset a pure lead slug over a casefull of lead, but kept locking up the action with my pounding. I ended up seating a bullet backwards and incrementally seating it deeper until the action would close. My throat was 0.206". As the original barrel is history, I have to start all over again. After I lap the bore, I'm going to slug then have a chamber cast done. Only the upset method or a chamber cast will tell you if you have one of the infamous toilet bowl throats.

On my first barrel I had real good accuracy with J.B. Youngs 420 gr WFNGC Crater Lite. It has a full dia. nose with a 78% metaplat. The start of the ogive must have been perfect for my throat. I tried some samples of his Crater Lite II which is a bore rider with a 0.08 front band. It didn't shoot near as accurate.

You may want to post your question over on www.MarlinOwners.com or at Mountain Molds forum as well. MO has a lot of big bore users, so you'll get a large sampling of throat dimensions.

[felix]

BAB, that throat length of 206 is exactly what my marlin 41 mag cowboy measures with a 413 brass wadcutter made with very slightly rounded edges. With a like wadcutter at 411 the length goes to 245 exactly. ... felix

[Dutch4122]

Marlin 1895GS, brand new barrel that was only test fired at the factory. Throat measured .091" with a jacketed slug seated backwards. Bore slugged at .4575."

Hope this helps.:)