There aren’t many good options for transporting rifles and shotguns on motorcycles. Fortunately, several companies now have bags that fit my parameters: must have two straps, hold at least one broken down, defensive-length long gun, look normal (i.e. not screaming THERE’S A GUN IN HERE or SO TACTICAL!), and be well made (a bag coming apart while you’re riding is a serious safety issue—ask me how I know).
A few things to bear in mind: since these have to be taller than average to accommodate the firearm, the tops of the shoulder straps attach below the top of the pack, which will stick up above your shoulders. This is good—otherwise they’d ride low over your butt and you’d have a hard time sitting—but it affects aerodynamics for me on my bike (a standard, naked/no windscreen or fairing), especially in high wind. Positioning my head to reduce the gap between the back of my helmet and the top of the pack helps. May work differently for you on your bike.
I haven’t used them all personally, but all of these manufacturers have good reputations for making quality products.
Comes with one padded, zippered sleeve that holds a gun with hook-and-loop anchors, and has a small internal storage pouch. The sleeve fits right into the bag, which holds a single sleeve with room left over, two sleeves with no room left over, or one sleeve and a top-to-bottom, hook-and-loop-mounted pouch set with no room left over. (Pro tip: if you get an additional sleeve, get a different color from the first one so you can tell which gun is where without looking inside). Functional but narrow top carry handle.
I’ve used this one for about two years with the extra sleeve. So far, so good: it’s very well made and has held up to everything I’ve thrown at it. This is probably the way to go if you want to carry two guns.
26″ x 11.5″ x 4″, 1940 cubic inches. $200.
Most normal/sporty-looking color combos, beefy-looking rubber-coated top carry handle, external water bottle and mesh pockets on both sides.
28 ¼” x 13 ¼” x 5″. $199.
This has two compartments, one for a broken-down long gun and another for random stuff, including a laptop sleeve. Comes with a removable waist belt and a rain cover that stows in the pack. Doesn’t look from the pictures like it has a top carry handle.
30″ x 13″, 7.5 lbs. / 3.4 kg, 1800 cubic inches / 29 liters. $299.
Traditional hiking backpack look, stowable straps & waist belt, side handles for suitcase-style carry, big top carry handle.
Main Compartment: 30 1/2″ x 13 1/2″ x 6″
Front Pocket: 20″ x 6 1/2″ x 3″
Top Pocket: 2 1/2″ x 9 1/2″ x 8 1/2″
Obviously, make sure you comply with all applicable laws when transporting firearms.
Falling off a motorcycle with any kind of bag strapped to your back may cause additional injury.
Related: Easy Rider: Handgun Carry While Riding a Motorcycle, by Deryck Poole of Echo-5 Training at PDN