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Jul
17

Blast Shields


Over time, the high-zoot gear for IPSC/USPSA competition has evolved pretty significantly, from the original gold standard 1911 in .45, to what we see today with a modern high capacity .355-ish caliber gun that holds 30 rounds and incorporates a red dot sight, a compensator, and – possibly – barrel ports. Such evolution is not without it’s challenges, of course. With the current, lower power factor, one of the hot ticket setups is a shorter, Commander length slide on the gun – and if you also use barrel ports with this kind of setup, you can easily get into an issue where the front lens of your scope is impacted directly by the gasses coming out of the ports, leading to a broken scope. Enter the blast shield!


Blast shields come in several flavors, but all of them perform essentially the same function – block gasses and debris from the ports and/or compensator from reaching the front lens of the scope. They’re also predominantly made from aluminum to minimize weight. Some, such as the Kidd Blast Deflector you see featured in this post, can be added directly to the scope itself (assuming you’re using a C-More of some flavor). Others are implemented as a part of the scope mount, either as a permanent protuberance of the mount itself or as an optional add-on at the front of the mount. From a functional standpoint, they pretty much all seem to do their intended job, and there’s not a huge weight difference between them.

On some configurations, like my Brazos Custom Gunworks Pro Sx (with four Poppleholes™), you really don’t have much choice – leave a blast shield off, and you stand a real risk of scarring or shattering the lens of the scope over time. While the expense of fixing the scope is not dramatic (about $60, at last check), potentially zero-ing a stage at a major match is a different story. Not to mention that sometimes the lens just loosens up first, and you have a wildly wandering zero before the lens either gets blown out of the scope or cracks. No bueno.


On 5″ guns with no holes, though, a blast shield probably isn’t necessary, though some people still prefer them. To me, with a 5″ gun, I’m seeking to leave out any unnecessary weight. Even with ports spaced almost an inch back on the slide, I never had a problem running a 5″ gun without a shield. In fact, the picture at the top of the post is the gun I’m thinking of, and you can see that the gas column out of the ports goes up and wraps around the top of the scope, but it doesn’t impact directly into it. Back those ports up an inch toward the scope, though, and it’s another story entirely!

The downside? Well, weight, obviously – to the tune of an ounce to an ounce and a half, right in an area you’d rather not have a lot of weight added. You can tell a noticeable difference in the handling and feel of the gun, but not something that dramatically affects how the gun handles. It just feels a little more top heavy.

Also, if it’s really required, the shield will get chewed up over time. Realize that you’ve got hot gasses at high pressure being uncorked right underneath this thing. Those gasses, plus any particles of unburned powder that make it out the ports are going to smack into that shield at high velocity. Over time, the aluminum takes some damage, as you can see from the photos. This is the one argument I know of for using a separate or add-on shield, vs. using a one piece mount/shield combo. It would take a large number of rounds to make the shield on the combo mounts ineffective, but then you’re shelling out for a whole new mount, rather than just the relatively inexpensive shield. The edges the wear creates are sharp! Be careful! You can use an appropriate file, or a gunsmith’s friend Dremel to carefully clean them up periodically, if you like.

If you’ve got an add-on unit (either one that attaches to the scope, or one that attaches to the mount), you’ll want to periodically check the tightness of the screws attaching the blast shield to the scope or mount. These things do take an impact every time you fire the gun, and that can cause screws to back out over time.

One other point – the damage to the blast shield should clearly illustrate why you want to keep any body parts you want to keep away from those ports and compensators! Skin and bone is a lot softer than aluminum and steel ;-)

About the author

DaveRe

USPSA Grand Master, NRA Instructor, http://re-gun.com/about/

Permanent link to this article: http://re-gun.com/2011/07/blast-shields/

2 pings

  1. DR Performance says:

    By request, some info on Blast Shields for Open division guns: http://bit.ly/qbLCyo

  2. xre says:

    By request, some info on Blast Shields for Open division guns: http://bit.ly/qbLCyo

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