Ah, yes, the mysterious SAAMI no throat .264 specs. I'm not at all sure why Winchester did this, but suffice it to say that NO .264 should be used without fixing the throat to seat normal (not "two diameter") bullets out to around 3.4" or even 3.5".

Downwind makes an excellent point that I had not considered, which is that the loading manuals HAVE to load to limits for the "no throat" .264's circulating out there.

Should you obtain a .264 with a SAMMI throat, the first thing you should do is take it directly to a competent gunsmith to do a little judicious reaming on the throat.

By the way, I have some factory WW 140's. They only chronograph about 2800 fps from a 26" zero-thoat Sako barrel. Certainly velocities vary from lot to lot in factory ammunition, but I've never seen any .264 that was even close to velocity spec.

It's worth while for any member of the 264 cult to get a copy of John Barness's Handloader article.It's not strain gaged,but it is good methodology.

When I get ny hands on some .595BC VLD hunting bullets,I'm going to do some more load development.There are some new 140Accubond out as well, so Hornady won't be too long in adding a 140IB to their 129IB.

quote:

Originally posted by Stonecreek:
Ah, yes, the mysterious SAAMI no throat .264 specs. I'm not at all sure why Winchester did this, but suffice it to say that NO .264 should be used without fixing the throat to seat normal (not "two diameter") bullets out to around 3.4" or even 3.5".

I think another issue was the 24" barrel length popular back in the day. Winchester made some in 26" but most were shorter. Ruger even made a bunch of 264Ws with 22" barrels. Talk about LOUD!

That fact and the SAMMI throat may also have contributed to the early powder choices.

quote:

I think another issue was the 24" barrel length popular back in the day. Winchester made some in 26" but most were shorter. Ruger even made a bunch of 264Ws with 22" barrels. Talk about LOUD!

The vast majority of .264 barrels were 24". Winchester's pre-64 "Westerner" M70 was the most popular in its line and had a 26" bbl. The M70 Featherweight had a 22" barrel, but was not as popular. Post '64 Winchesters came with a 24incher. Rem 700's had a 24-incher. Sako made most of its in 620mm (24.4"), but also produced a few in 26-inch. All of the Rugers were, to my knowledge, 24". Most Brownings were inexplicably made 22", but a precious few escaped the factory with a more reasonable 24" barrel. Savage made a few on its 110 action and they had 24" barrels. I think at one time Steyr Mannlicher, FI's Musketeer, and a few others were chambered in .264, but I can't recall their barrel lengths. Oh, yes, the BSA-actioned Herter's U-9's all had 22" barrels.

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Should you obtain a .264 with a SAMMI throat, the first thing you should do is take it directly to a competent gunsmith to do a little judicious reaming on the throat.

As my .264 is being re-barreled, what do you recommend be done with the throat. Are you saying it should be lengthened to allow seating the bullet "way out there" to accomodate more slow powder?

Thanks!

If you know what bullet you will be using most, you can have the smith set the throat to the OAL of the cartridge with that bullet seated to the base of the neck. That is what I did with my 6.5x55. The only caution is to not make it too short, or it will need another trip to lengthen it. (Been there, done that. When factory 140s will not chamber because you had the length set for the 125 Partition, it sucks.) The other alternative is to have them set it at factory OAL.

R: The standard SAAMI chamber has essentially zero leade, meaning that the full diameter of the bullet (.264") can be no further forward than the mouth of the case. In the case of the original Winchester "two-diameter" 140 grain bullet, it had a short base section that was .264" diameter and a long "nose" section that was .256" or so that rested on the tops of the barrel lands. In order to use a conventional bullet of ANY length, you need to have at least some leade in your chamber. My loads with Nosler Partitions in my revised chamber are around 3.4 or 3.425" in length (seated to just short of the lands). I would recommend lengthening the leade in your .264 chamber to allow seating at least as long as your magazine (if your magazine is the "standard" 3 3/8 inch variety), or allowing you to seat to as long as 3.5" if your magazine is "magnum" length.

It is possible that the chambering reamer your gunsmith is using already has a "non-standard" leade built into it which you'll find adequate.

quote:

It is possible that the chambering reamer your gunsmith is using already has a "non-standard" leade built into it which you'll find adequate.

I think it is. Loading for the first barrel he did, I was able to seat bullets past the mouth of the case for their full diameter.

ANSI/SAAMI Performance Standards books


These books and more have been released on the SAAMI web site as downloads.

The below ANSI/SAAMI Performance Standards books detail the voluntary industry performance standards for pressure and velocity of ammunition for use by commercial manufacturers. Each book includes detailed specifications and drawings.

ANSI/SAAMI Centerfire Pistol & Revolver Item #205 Z.299.3 1993

ANSI/SAAMI Centerfire Rifle Item #206 Z.299.4 1992

ANSI/SAAMI Rimfire Item #208 Z.299.1 1992

ANSI/SAAMI Shotshell Item #209 Z.299.2 1992

All Four on CD-ROM Item #210

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http://www.saami.org/Publications/

Glenn