To expand on Lightfoot's explanation.. The receiver length stayed the same, but the internal parts were redesigned at serial number 900,000 in order to make room for the 243/308/358 class of cartridges. Prior to serial number 900,000 there isn't room in the magazine to load anything longer than a 250-3000 or 300 Savage cartridge.
But if you have a tang safety 99 whose serial number is over 900,000 or starts with a letter (and all factory tang safety 99's were), then it will be able to handle the length of a 7mm08. Whether it loads and feeds properly is a different question.
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The Savage 99 Pocket Reference”.
All models and variations of 1895’s, 1899’s and 99’s covered.
Also dates, checkering, engraving.. Find at
www.savagelevers.com