I was wondering if you already have a win mag, be it 264, 300 mag whatever if its a simple matter of just reaming the chamber to ultra mag?? the bolt face on the ultra is .534 and the win mag is .532, is there enough play in the bolt face on a regular mag to accept the .002 larger ultra mag case, heck that probably could vary from lot to lot of brass.

also what changes if any would a regular magnum remington 700 action need to feed the ultra cases if any??

First, the bolt faces for each are the same, despite some sources showing different diameters for the rims.

Yes, unless a regular belted magnum chamber is grossly oversized, it will clean up with an Ultramag reamer.

I suspect that no change is necessary to the feed rails, but simply placing a few Ultramag cartridges in the magazine and test-feeding them through the action will tell the tale. On an action with a somewhat narrow box like a Rem 700 that holds only three belted magnum rounds, it will likely hold only two Ultramag rounds without some modification to the box, follower, and/or rails.

An ulta mag reamer should clean up a standard belted mag chamber. The big problem is clearing out the belt area of the existing chamber. You will want to mike the particular chamber, and, the particular reamer to know for sure. As far as bolt face goes, there is room in the Remington 700 magnum bolt face for the ultra mag case without modification. You will need to replace the standard magnum mag box with the ultra mag box to give the shoulder of the wider case some breathing room.

quote:

Originally posted by Westpac:
An ulta mag reamer should clean up a standard belted mag chamber. The big problem is clearing out the belt area of the existing chamber. You will want to mike the particular chamber, and, the particular reamer to know for sure. As far as bolt face goes, there is room in the Remington 700 magnum bolt face for the ultra mag case without modification. You will need to replace the standard magnum mag box with the ultra mag box to give the shoulder of the wider case some breathing room.

as usual your posts are a big help, I have a 264 win mag thats never given me the speed I want at least combined with accuracy, I am thinking about having it reamed out to 6.5 ultra, thus shit canning the belt of the 264 win mag, I know this would make a pretty intense barrel burner, however I can always run it a bit slower, and the gun never sees more than 3 shots down the tube at once,

so if I decided to do this, do I need a specific 6.5 ultra reamer or would a 7mm ultra or 300 ultra reamer that a smith might happen to have on hand achieve what I want??

The feed rails need to be opened up .015" from WM configuration to Ultra mag.
A windowed mag box is also required for the Ultra.

Decide which Ultra case you want to wildcat,set the 264 Bbl back & the belt will clean up from the WM chambering.

quote:

Originally posted by cummins cowboy:
do I need a specific 6.5 ultra reamer or would a 7mm ultra or 300 ultra reamer that a smith might happen to have on hand achieve what I want??

It would be pretty hard to stuff a 7mm or a 30 cal reamer in a 6.5 hole. I won't say it can't be done because there is someone out there who will try it just to prove a point. In fact, I may have seen an attempt at doing something similar to that in the past. If you are in this business long enough, you quit flinching when that sort of stuff rolls into the shop.

Minimum base diameter of the Ultra Mag chambers is .551"; max belt recess diameter of std. belted mag chambers is .547". Therefore, an Ultra Mag reamer--in the correct bore size--will clean up the belt recess, as well as the body and shoulder of the chamber.

Dave Manson

quote:

Originally posted by DManson:
Minimum base diameter of the Ultra Mag chambers is .551"; max belt recess diameter of std. belted mag chambers is .547". Therefore, an Ultra Mag reamer--in the correct bore size--will clean up the belt recess, as well as the body and shoulder of the chamber.

Dave Manson

Correct -- in theory. Factory chambers for belted magnums are notoriously oversized. Factories try to get the most chambers out of a given reamer before it wears out, so they start with one that fudges on SAAMI specs. If you have a chamber that was among the first cut with a brand new reamer, you can expect it to be pretty "loose".

That said, however, even if the belt recess did not clean up completely, so what? This falls in the web area of the Ultramag brass which is normally unsupported by the chamber walls, anyway. Even if the "ghost" of a belt recess remained in the chamber the Ultramag case would never know it.

Hello Stonecreek:

I don't carry any brief for factory rifles, but I'll take issue with the statement that,
"factory chambers for belted magnums are notoriously oversized".

Over the 29 years I've been in the firearms tooling business, I've made chambering reamers for, or quoted tooling to prints from virtually all of the first and second-tier manufacturers.
I haven't made reamers for all calibers for all of them, but have made or seen a representative cross-section of manufacturing specs from most.

Occasionally a manufacturer would specify chamber dimensions different from SAAMI for handgun calibers, but I don't ever remember other-than-SAAMI specs for rifle calibers. The manufacturer might specify tolerances closer than SAAMI limits, or might ask that a dimension be held to the high or low, but actual chamber reamer dimensions for rifle calibers never exceeded SAAMI specs on the tooling I made, or in the prints I reviewed. This not to say that an occasional manufacturing screw-up, or QC mistake won't put a rifle with an oversize chamber in the customer's hands, but that it wouldn't be by design of the maker and is likely infrequent.

I haven't seen every print from every manufacturer over the past 30 years, but I'd place the blame for sloppy cartridge-to-chamber fit primarily on the ammunition.

SAAMI sets maximum dimensions for cartridges
and minimum dimensions for chambers, as well as allowable deviations (tolerance) from these dimensions. Cartridges are allowed to be as much as .008" smaller in diameter than max; chambers are allowed to be as much as .002" larger in diameter than min. With at least .001" specified as clearance between max. cartridge and min. chamber, there can be as much as .011" diametral difference between min. cartridge and a max chamber. This, I believe, is the cause of bulges at the base of fired cases--there's a lot more variation in ammunition than in chamber dimensions.

Considering all the factors involved, I think major rifle makers offer pretty good value.
Mass-produced firearms aren't custom guns and can't be expected to be made to the same standards. They provide you and me and cousin Bubba a lot of bang for our increasingly scarce bucks and open up shooting to a lot of folks who will never be able to afford a custom rifle.

Dave Manson

Per the www.ammoguide.com rebarrel/rechamber tool:

Dmanson,

Thanks for the response. It's always good to hear directly from someone who has worked in the trade.

I still maintain that factory chambers for belted magnums are "notoriously oversized". This may be a result of the SAAMI standards themselves being somewhat loose for belted magnums.

By the way, do you have any idea how many chambers a reamer is good for at the factory before it has worn below SAAMI minimums?

Homebrewer: The ammoguide.com is way off base on this one. The bolt faces for both belted magnums and Ultramags are identical.

Of course they are correct that you cannont "rechamber" your .264 to .300 Ultramag. Well, you could do it, but squeezing a .308 bullet down a .264" groove would be a little tight.

Hello Stonecreek:

I'd love to be able to provide a "typical" chambering reamer lifespan, but there are too many variables in the techniques used by the majors to do so with any confidence.

Reamer material (HSS or Carbide), coating(TiN or TiCN), manufacturing process (rough and finish, or rough, finish and headspace, or ?) and the caliber being chambered all affect tool life. Some manufacturers run a final reamer for one or two shifts--never mind how many chambers it's done or its condition--others change tooling as necessary.

I CAN tell you from experience with the reamers I've made, that a high-speed steel finish reamer, properly heat-treated and ground and used with good technique, should cut 40-50 complete chambers before requiring sharpening. By "complete", I mean from a barrel blank, with no rougher. TiCN-coating of the reamer will approximately double its life--again, with the caveats mentioned above.

Dave Manson

DManson,

THANKS, quite interesting.

Any idea how many sharpenings can a reamer take before its dimensions are reduced below spec?

Hello Stonecreek:

Usually once without losing too much size. There are all sorts of considerations in this statement--condition of the dull tool, level of precision desired, manner of sharpening, etc--that make it difficult to predict with any certainty. Basically, "it depends".

Dave Manson

quote:

Well, you could do it, but squeezing a .308 bullet down a .264" groove would be a little tight.

I am guessing a rebore or rebarrel is part of the exercise...