The planchet was damaged before the strike, the lamination peel on the obverse rim shows a corresponding weakness on the reverse. The obverse rim also show a lack of metal available to push up the rim fully.
Blowhole errors are somewhat common in Canadian small cents, particularly from 1977 to 1981, but this is the first I have seen in a large cent. This one is a nice, problem-free AU coin.
![1896-Large-Cent-Error,-Planchet-Flaw-With-' <a target=]()
Blowhole'" class="userimg" style="image-orientation: from-image !important; max-width:80%;height:auto" name="img" src="uploaded/SPP-Ottawa/20211202_1c_1896_blowhole_rev-ccfopt.jpg" border="0" style='cursor:default' onClick='doimage(this,event)'>
![1896-Large-Cent-Error,-Planchet-Flaw-With-' <a target=]()
Blowhole'" class="userimg" style="image-orientation: from-image !important; max-width:80%;height:auto" name="img" src="uploaded/SPP-Ottawa/20211202_1c_1896_blowhole_obv-ccfopt.jpg" border="0" style='cursor:default' onClick='doimage(this,event)'>
![1896-Large-Cent-Error,-Planchet-Flaw-With-' <a target=]()
Blowhole'" class="userimg" style="image-orientation: from-image !important; max-width:80%;height:auto" name="img" src="uploaded/SPP-Ottawa/20211202_1c_1896_blowhole_rev_zoom-ccfopt.jpg" border="0" style='cursor:default' onClick='doimage(this,event)'>
![1896-Large-Cent-Error,-Planchet-Flaw-With-' <a target=]()
Blowhole'" class="userimg" style="image-orientation: from-image !important; max-width:80%;height:auto" name="img" src="uploaded/SPP-Ottawa/20211202_1c_1896_blowhole_obv_zoom-ccfopt.jpg" border="0" style='cursor:default' onClick='doimage(this,event)'>