I've been shooting the Swedish Mauser since 1964 or 65. It was a m/1894-14 carbine dated 1932 and with the highest known serial number I've seen or heard 113150. Having fun with this carbine is what led me to buy a Carl Gustaf m/38 in 1969 for the high price of $65. The bolt handle had been forged but nothing else was done to it.
Starting in 1969 I began handloading 6.5x55 mostly with Winchester or Hornady 100 gr jacketed to around 3,000 fps. It was very fast and very flat shooting and would kill coyote deader than dead. In the ensuing years I've loaded every bullet available from 77 gr Norma soft point to Hornady 160 gr RN. I'm very fond of the Hornady 160 gr RN.
Cast bullet loading in 6.5x55 didn't start until about 20 yrs ago with purchased .266" Loverin 266469. It wasn't spectacular or encouraging. What improved my efforts in this caliber was this forum. Knowledge improved performance.
First off not every Swedish Mauser has a barrel that will provide outstanding accuracy. And its the barrel that determines, to a great degree, how that rifle will respond when fed cast bullets.
I have owned 30 or so Swedish Mausers. From m/96 with new condition barrels to a particular 1902 Gustaf m/96 that has NO rifling left, completely shot out. How is it that such a rifle escaped Swedish military maintenance? Easy answer to that.
When all the Swedes were imported into the U.S. and elsewhere, most of those rifles came out of military stores. Many of those rifles were rebuilt prior to storage to include new barrels and new stocks. They are generally tight and crisp rifles and will make you happy. But many rifles came from the various Swedish shooting clubs, FSR, and those rifles escaped military inspection and maintenance. Some of them were shot to death, literally.
Somewhere in between shot-to-death and like-new will be your rifle. How do you assess the condition of your rifle's barrel? Slugging the barrel will give you the numbers, bore and groove. Pin gauges will tell that land diameter at the muzzle but the real inspection comes from your eyes.
I separate a 29" barrel into 3 sections, the 10" at the breech, then the middle 10" and then the muzzle end 9". Many Swede m/96 will have very worn barrels to the point that the lands are very rounded in the breech end and some barrels will show only a hint of rifling in the breech end. I have a couple rifles like that.
This rifle was outfitted with a Tasco 3x28 handgun scope. On the outside its a very decent rifle. But the bore is very worn at the breech end. Shooting .266" Loverin 266469 with a light charge of Unique. That's a 1" group, the best it would do. I've not worked further with this rifle because of the poor bore. But later this summer I'm going to shoot it with Lyman 266673 .266" and Ideal 266469 .268". Powder change will remain on the light side to maximize accuracy potential. Instead of optical sights I'm going to install the diopter target sights as they offer an advantage over optical sights in a way I can't really explain but it has to do with error and math.
http://dutchman.rebooty.com/foto_study.html
A different rifle, an Oberdorf m/96 dated 1900 that I call my FrankenSwede because I put it together from parts. The bore looks VG but the shooting was VP (very poor). And this was with a 7x long eye relief scope on the rifle. At 50 yds that's not a group its a pattern.
Shot with my m/38 Carl Gustaf with 6-18x44 Tasco target scope. This is what a Swedish Mauser can do if you start to put together the right ingredients.
This is how you eliminate error when testing handloads. This is the 1915 Carl Gustaf m/38 I bought in 1969.