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Discussion Starter #1
My 336ss has a 91xxxxxx serial number putting it towards the end of Marlin's North Haven production. It has a virtually non-existent throat and the leade angle is very sharp. This has caused some problems including bits of lead getting forced back into the chamber around the case mouths as pictured here. Also, I have to deep-seat boolits from RD's TLC311-165-RF to 2.420", well past the crimp groove (something RD and I have discussed at length).



I'm gonna take her in to a gunsmith today to have the chamber casting made and see if they have the right reamer on hand. Anyone else have experience doing this themselves or with a professional? I really want to sweeten my rifle up well beyond factory norms and this seemed like as good a place as any to start.

~ Jech
 

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The problem with doing a reaming of the throat by hand is doing it concentrically. Since the chamber neck allows the reamer to be canted, it is possible to cut a crooked throat in the rifle. Visualize the rifling reamed completely away on one side and then some, while the other still has rifling lands remaining.

Quite possible!

To eliminate some of this canting, it is possible to insert a case with a hole drilled in the back to admit the reamer's extension handle. Keep the rim on so the case can be withdrawn from the chamber. If the reamer body is too large, you can only do this with a cartridge that has the entire back end, including the rim, removed completely.

Since it is possible to ream the throat considerably longer, be careful of what you want accomplished. If you simply want the leade set back sufficiently to allow proper chambering with cast bullets crimped in their crimp grooves, not a lot of material needs to be removed. To some degree the nonexistent throat on your rifle, such that it starts the rifling immediately ahead of the chamber, is compatible with the typical RN softpoints used in the 30-30 that generally have little bearing surface forward of the cannelure. Such short to no throating is compatible with the typical jacketed bullet used and suffices to do the job as cut by the factory.

A concentric throat, not cut overlarge (ask about the finished dimensions of the reamer and the chamber) is a great benefit to cast bullet shooting. Subsequent to this throating, if the throat is of any appreciable length at all, size bullets to fit the completed throat.

Since a concentric throat is so valuable, and a poorly cut one such a disaster, it may be well worth the peace of mind to have a competent gunsmith do it for you. You may not have access to the equipment he has that will insure it is done correctly.

Or, you could shoot the hell out of it with jacketed bullets and let the throat naturally lengthen......but it will take a lot of shooting to accomplish that job. Throating it will certainly save time, and you may be happier with your results with cast.
 

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Discussion Starter #3
Although, I'm investigating what it takes to get into a gunsmith trade schools, I have no applicable experience and will have this work performed by a local certified smith.

My intent for this rifle is to have it exclusively shoot Ranch Dog's TLC311-165-RF at 1.5moa or better at 100yds. I love casting my own boolits and thus far, no one anywhere has provided me any substantial justification as to why I should shoot anything other profile. It makes sense to have a chamber cast made and take in a few dummy rounds showing how I have to seat them now as well how they are supposed to be seated.

I understand not every shop will have every size of reamer on hand and that often, it may be helpful to provide my own, use it on my rifle, share with a few friends then resell it on eBay etc. I see models made by Clymer and Manson Precision on Brownells, are either of these model I'm after?

Thanks ~ Jech
 

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Discussion Starter #4
Good grief!

Just got back from visiting the gunsmith and he said it was gonna take him a MONTH to get a stinking chamber casting made! To put this in perspective, the town I live in barely has 16,000 people in it...a very rural community.

Time to find a retired smith who still has a lathe and some time to burn...
 
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