Speer changes diameter of 6.5 bullet


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reloaderralph
May 26, 2010, 08:10 PM
The .264 Winchester Magnum has a reputation of quick barrel burn out and rapid throat errosion. Speer reloading manuals 1 thru 12 showed the 6.5 bullets having .263" diameter. The bullets actually measured .263.5" diameter; and were "easier" on barrels when loaded at or near maximum pressure. Speer manual 13 shows their bullets as now being .264" diameter. I measured the diameter of a speer 140 gr. Hot-Cor bullet stock No. 1441 and found that they now measure a true .264" diameter. Why has Speer now decided after nearly 40 years to increase the bullet diameter size of a hot rod cartridge with an already finicky reputation; thus, possibly increasing pressures, barrel fouling and velocity loss?

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JimKirk
May 26, 2010, 08:55 PM
Could it be that all the other major bullet makers have been using .264 for many years with their bullets? All that I checked still do.

Jimmy K

NCsmitty
May 26, 2010, 09:10 PM
The bullets actually measured .263.5" diameter

I'll have to take your word on the .263 dimension, but all the 6.5 bullets that I have checked in the last few years measure .264 on the button.
I sincerely doubt that .0005 more bullet diameter can give a barely measurable difference in a 264 WinMag or any 6.5 caliber for that matter.
Just load'em and shoot'em.



NCsmitty

R.W.Dale
May 26, 2010, 09:49 PM
I've found it to not be uncommon for jacketed rifle bullets to mic slightly undersized anyway.

I seriously doubt .0005" is gonna blow your face off

Ol` Joe
May 26, 2010, 11:45 PM
Winchester originally used a two diameter bullet in the 264 factory ammo to help it reach the claimed velocities and keep pressure down. The area ahead of the cannelure was .263" and the rear a full .264. This helped reduce bearing surface and lengthen jump to the lands. Nosler also made bullets like this at one time if I recall right, and Sierra had a slight taper to their 140 gr 6.5 bullet from .264" at the base to ~.263" or slightly less at the foreward end of the shank.

I don`t know for sure but, I suspect the reason for the change to a full .264 shank is more as an effort to improve accuracy of the bullet then anything else. All the 6.5mm bullets I`ve used for a long time now have been .264 diameter.

MichaelK
May 27, 2010, 12:39 PM
Hi Ralph
I suspect that an increase in the diameter might be related to the influx of so many war-surplus M96 Swedish mausers a few years back. I myself got two when they were only 80$. In general, military surplus is noted for having "looser" tolerances than commercially made rifles.

By the way, listing a measurement as .263.5" is incorrect. There should always be only one decimal point. It is correct to type .2635". For machinists though; it would be correct to say 263 and five tenths thousandths.

pete f
May 27, 2010, 01:01 PM
Its not just the swedes, but there have been 20 times more .260 rems, 6.5 creedmores, 6.5 grendels sold lately than all the .264 winmags ever sold. Its just the real world, you have to make what works for the masses, not the niche, now if this is as big a deal as you wish it was, someone like berger or J4 will show up with a .263 as a short run bullet.

But frankly, the .264 winmag is dead, no one is chambering for it that I know about, and after 25 years of working in and around the gun business, I have seen 2 rifles and sold 3 boxes of ammo for that chambering. Its dead, gone, passed on, expired, kicked the bucket, gone to meet its maker, etc.

azar
May 27, 2010, 05:29 PM
Pete,

I understand what you are saying. Lyman #49 lists a whopping ONE load for it. However, no caliber truly dies as long as there is a single factory chambering or a handloader willing to reload for it. Just saying... ;)

jon_in_wv
May 28, 2010, 12:22 PM
I would be amazed they can actually mass produce a bullet with less than .0005" variance from bullet to bullet.

DILLONHELP
May 28, 2010, 01:18 PM
The SAAMI dimensions for the minimum and maximum diameters for these bullets are
.262-.265". Anything within these two dimensions is acceptable.

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