View Full Version : Reaming Chamber with barrel installed

January 8, 2005, 08:52 AM
OK, I am embarking on another DIY Mauser project (Frankenmauser part deux)...And I wanna convert it to 8mm-06 AI...But I don't have barrel removal tools etc. (one of the reasons for caliber choice), so I wanna know if its possible to ream the chamber with the barrel attached to the action. Figure it'll also save alot of time checking headspace, as I can do it as I ream. Can this be done? This is very low-dollar project, strict budget, but I've managed to "scrounge" cheaply the parts I need. (Frankenmauser 1 cost total of $180 w/ new 6-24x scope installed.) Its a beat up ZV-24 if that makes any difference.

sleeping dog
January 8, 2005, 10:21 AM
Can you put that longer round into the magazine so the bolt can pick it up? If it won't fit, then the '06 conversion may be more work than it's worth. Maybe test it with some blank 30-06 with the bullets inserted to the 8mm-06 OAL.

If the '06 round doesn't fit, then maybe some kind of chamber insert could convert it to a 8mm-08 (based on .308 case)?

If budget is a concern, maybe just get some brass & dies for the original 8mm round.


January 8, 2005, 11:01 AM
Since Frankenmauser 1 is in original 8x57, I wanna do something different. 8mm-06 has about 25% more powder capacity(than 8x57). With handloads, can acheive near 300 win mag peformance with less powder and recoil.

sleeping dog
January 8, 2005, 12:37 PM
Understood. Bigger case, bigger bang. But, I was mainly wondering if the magazine can hold the 8mm-06 round. You're changing from 8x57 to 8x63, (or 8x64, can't remember), and in a mauser, the bolt should strip the round from the mag.


January 8, 2005, 01:19 PM
When you ream the chamber, you will need to use a headspace gauge. Unless you have done several barrel changes and reamed the chamber each time, I wouldn't try to headspace one without the barrel attatched to the reciever. You might go too far with the reamer or not enough and need to finish with the reciever on anyway. Just go slow and work carefully and remove the reamer every few turns to blow off the chips and blow out the chamber from the bore end and make sure to use plenty of oil on the reamer. Check it every few turns until you get it close to closing on the go gauge. I then check mine every complete turn of the handle just to keep from cutting too much or getting a chip that messes things up when you're close to a finished chamber. Good luck to you.

James K
January 8, 2005, 10:35 PM
Hi, Dfaugh,

It is normal gunsmith practice to finish chamber a barrel after it is installed. You have to use a reamer extension, which will run about $15 from Brownells. Some other tools will work, but it is best to use the right tool for the job. You can also use a pull through reamer, which is turned from the muzzle as the bolt forces it into the chamber.

Note that unless you have some experience, reaming a chamber is a very good way to really ruin a rifle barrel.

Sleeping Dog is saying that the standard Model 98 magazine is too short to take a .30-'06 or 8mm-'06 of normal OAL. Not only do the magazine well and the feed ramp require work, but the guide rails in the receiver almost certainly will need to be reshaped for the different base-to-shoulder length of the .30-'06 or 8mm-'06. This is tedious work, involving trial and error, but it needs to be done if feeding is to be smooth.

I will note that there is little an 8mm-'06 will do that a standard 8 x 57 will not do if properly loaded, but one does need a "project", so good luck.


Harry Bonar
January 18, 2005, 02:53 PM
Dear Sir:
In this country the 8x57JS (S-bore .324) is only loaded to about 36,000 CUP.
In Europe it's loaded to 49,500-50,000 cup. Turkish ammo is the hottest.
I'd think twice about going to 8MMx06 because you'll gain almost nothing over a properly loaded 8x57JS!
Have your headspace checked - the Germans didn't pay too much attention to that (I've seen them with.025 headspace.) If you want a "sporting rifle" have the bbl. set back,if necessary, and have correct headspace set.
However, the vz24 was perhaps the best of the 98s. It may be fine as is.
You could get a Clymer reamer and use an extension and go ahead with the 8MMx06 idea! You must go slow and even with an extension; I don't like them!
Now, if your headspace closes on the "no-go" guage but not on the "field-guage" you could possibly fore Rem. factory ammo and then upon reloading fit to your chamber, but I wouldn't do that!
Get the A-Square Shooters Manual - it's the best to explain alot!!