Swedish Mauser Freebore

v35

Being that Swedish 6.5 chambers were cut for 156 grain R.N.bullets,the 140 grain and lighter bullets have to make a good jump to engage the rifling. This amounts to a freebore for more modern ogive style bullets.
Has anyone discussed this issue with regard to accuracy, pressure and accelerated throat wear?

jonk

Regarding accuracy, I have loaded some with 100gr FMJHP. They were as accurate as Swedish surplus. It seems to be hard to load for these and get anything but great accuracy.

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leeblackman

There souldn't be that much difference in the length, there is standardized tolerances that assure this. So there shouldn't be enough difference in gap between different wieght bullets loaded in the same cartridge to make a noticeable difference. The real difference will be found in how the length of the bullet and the twist in your barrel effects accuracy.

In otherwords the lighter bullets should stick out of the case the same amount as the heavier bullets. If they don't something is wrong.

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leeblackman

Another thing I should mention is that chambers aren't cut for different bullet weights, only for different cartridges. Who ever told you this doesn't know what they are talking about.

Only the rifling is cut for different bullet weights, because heavier bullets are longer than lighter bullets, therefore you will need more twist for a lighter bullet.



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v35

Lee, The throats were cut for the old 156gr roundnose bullet. The profile of the original bullet has the bore diameter much further forward. In order to seat ogival bullets just short of the rifling they may be too long for the magazine. In my rifle the cannelures will be out of the case by about 1/8".

MIKE WISKEY

LEE, YOU BETTER GO BACK TO THE BOOKS. THERE IS A BIG DIFFERENCE IN OVER ALL LENGHT ON THE 6.5x55 WHEN LOADED WITH 100 GN. BULLETS V.160 GN. THE 100 GN WILL HAVE ALMOST 1/2" FREE BORE. THIS IS NOT NECESSARILY BAD, WEATHERBY USES THIS TO KEEP PRESSURE DOWN. THROAT EROSION PROBABLY WILL BE LESS AS THE PRESSURE WILL BE LESS (BULLETS DON'T ERODE THE THROAT PRESSURE/HEAT DOES). AS FOR TWIST RATES; HEAVYER (LONGER) BULLETS NEED MORE TWIST THAN LIGHTER (SHORTER) BULLETS. MOST OF THE SWEDISH MAUSERS SHOOT EXTREAMLY WELL FOR MILITARY RIFLES DO TO THE QUALITY OF THE BARRELS.

MIKE WISKEY

LEE, YOU BETTER GO BACK TO THE BOOKS. THERE IS A BIG DIFFERENCE IN OVER ALL LENGHT ON THE 6.5x55 WHEN LOADED WITH 100 GN. BULLETS V.160 GN. THE 100 GN WILL HAVE ALMOST 1/2" FREE BORE. THIS IS NOT NECESSARILY BAD, WEATHERBY USES THIS TO KEEP PRESSURE DOWN. THROAT EROSION PROBABLY WILL BE LESS AS THE PRESSURE WILL BE LESS (BULLETS DON'T ERODE THE THROAT PRESSURE/HEAT DOES). AS FOR TWIST RATES; HEAVYER (LONGER) BULLETS NEED MORE TWIST THAN LIGHTER (SHORTER) BULLETS. MOST OF THE SWEDISH MAUSERS SHOOT EXTREAMLY WELL FOR MILITARY RIFLES DO TO THE QUALITY OF THE BARRELS.

v35

Jonk- Were those surplus 156 grainers ? I would think a proper comparison would be to compare accuracy performance of lighter bullets to that of the original bullet.
When the 30-06 was adopted, the Army had their Springfield 1903 barrels brought back two threads and rechambered for the shorter 150 grain bullet (from the 220 grain bullet of the original 30-03 cartridge).
Now that all of Sweden's '96 mausers are probably here in the U.S., I wonder that the issue hasn't been widely discussed.
The US Army used a breechbore gage for determining serviceability of barrels. It measured how far forward rifling had worn. Sweden measured the diameter of the throated area.