I may be out on a limb here, but I THINK they are intended for a .410 shotgun, which SHOULD be less powerful than a 209 primer. Regular 209 primers are a little hot for in-lines and that is why the Triple 7 209 primers.I shoot a CVA Kodiak Pro .50 caliber with 2 standard Triple-Seven pellets. A buddy of mine just gave me 4 boxes of Remington 69 primers (400) and assures me that they will work fine in place of 209s. Is anyone using 69s and do they work well?
These primers are different size then the regular 209 . They fit in the old Rem 410 hulls . You need to watch what you use them in . They if I remember right is smaller then the 209 . So they are a little lose .Hope this will help.