Drooper 101
Tim McMurry – Mac1 Airguns
30 minutes
=30"@ 100yds
=15"@ 50yds
=10"@ 33yds
=7.5"@ 25yds
=3"@ 10yds
=1.5" @ 5yds
=.030" @ 4"
This is how low most (75%) airguns shoot at 10 yards if the optics are centered with straight mounts. Airguns typically shoot three and a half inches low at 10 yards when in a perfect world they would shoot about 3/4" low at 10 and right on at the apogee.
If you install a 30 minute drooper which brings the centered scope view back to POI that is also the approximate point of impact at 50 yards (medium mount/800fps gun). When I mounted springers in the early days with weaver tip offs (choice of 1) we had to dent the scope tube tightening the rings to get the scope not to slide in the rings. We would have to shim, glue and tweek. It was a complete pain.
Basically mounting anything with the standard 3/8" dovetail has always been kinda a joke. But especially on a supermagnum springer. The original application(.22 rimfire) did not have near the demands of today's airgun magnums. But we are stuck with the 3/8" dovetail which in our case will vary from 10.5mm-12.5mm with some non-standard 13-13.5MM out there to torment us further.
We are a lot better off nowadays the way I see it but there are still some issues to deal with when it comes to mounting hardware. Manufacturers will always claim their product serves all but reality says otherwise. True R&D and testing is virtually non-existent in this cottage industry. The exception is the American made BKL which is now a mount you can special order with droop. Factory direct. http://www.bkltech.com/faq/. They also sell risers that have 16 (4 thou per inch) or 28 minutes (7 thou per inch) of droop.
Some scopes have very limited adjustment range which forces you to nail your droop or you can't get on target. Bushnell Elites come to mind in this context. The basic goal at Mac1 is to satisfy the heavy users with supermagnums. It will be overbuilt for all other applications but overkill is OK. Sportsmatch and BKL are my favorite.
We can droop anything in 1" or 30MM for a $25 charge if the mounts are Aluminum. $40 for steel mounts. Windage corrections are usually limited to half the droop correction.
Magnum Springers kick. More power is more kick in most cases. (Need super strong Mounts). They are long range guns that can hunt to 75 yards. (Need high Mag scopes with big lenses) They generally shoot in bigger bores where trajectory is more extreme.
The high mag big objective scopes are heavy, rarely have much adjustability and have to use high rings to clear receiver. So they need strong high rings with droop compensation. Barrel to receiver alignments are generally in droop or straight at best. The
most recent guns from HW are less droopy at around twenty minutes. Also we see some guns with positive barrel angle (usually guns meant to be scoped only) so droop is not required. US FT and the LD MKI are guns that fall into this category. They have droop built in to the frame. These are the exception rather than the rule.
Even if the barrel was inline with the receiver the minutes required to use it at 60 yards would be about 30 minutes with average weight .22 Cal. going 800FPS. In fact pretty much everything needs 30 minutes to use the scope mid adjustment as the manufacturer intended. Some scopes will adjust that far off center adjust but the adjustment repeatability will often be compromised.
Some guns need more and some less. The lower scope needs less. The barrel drooping gun needs more.
What really amazes me is the proliferation of adjustable mounts that simply will not hold zero in the long haul on a magnum springer. The worst of them are the ones that use the scope tube as structure. These are OK on recoilless guns but on supermagnums they are a waste of time and money.
The Beeman Sportsmatch seem to have the most promise in an adjustable and B-Square also does a decent job.
Dual scope stops or Loctite 640 does a decent job when mounting split rings but the ultimate will be a one piece. You can also use Locktite 640 between rings and tube for the best split ring set-up.
I decided to get the rings to share the stopping load by connecting them with a tie rod. The rear ring has a solid adjustable stop screw that you screw down into a receiver stop hole. The rod connecting the front of the rear ring with the back of the front ring is oil blued steel and allows both rings to share stopping load through the guns stop hole. The mounts are called HTRD. High Tie Rod Drooper. They are machined with 20-50 minutes of droop as off the shelf items. Custom droop/ring spread and/or custom windage corrections are available for most 1" & 30MM rings.
Split drooper mounts are recut with specific ring spread (4") that you can deviate from slightly (1/2" + or -) but you don't want to tweek scope tube so it is best to lap them in with a solid 1" bar when deviating from standard spread. We can do split rings also w/ custom ring spread, windage and droop for mounting non recoiling guns. If the standard 4" ring spread doesn't suit your application we need to cut a special set for your gun.
When mounting a scope on a PCP, like the Career, it shoots so hard you would think the gun doesn't need droop but guns capable of 100 yard groups actually need droop as much or more than your basic 50 yard guns. Most need a scope that can be used mid adjustment at much farther distances than anything else because it has the farthest capabilities for hunting that I have seen.
Any scope twisted to within a couple of clicks of the end of its adjustment cannot repeat adjustments as effectively as it could mid adjustment. When you have a gun that can hit a 2" circle at 100 yards why squander its potential by using straight mounts and a scope wound all the way out.
The problem has always been determining how much droop you need. There are certain procedures you need to go thru with straight mounts to determine the specification for your particular gun.
Mount the scope with straight rings.
Center the scope adjustments (count total clicks and divide by two). This can be done by putting the scope mid clicks or by actually putting it in V-blocks and finding true optical center via spinning it and adjusting till eccentricity of crosshairs is gone.
Mount scope in straight rings and shoot it at 10 yards. How low or high & left or right does the gun hit compared to where you aimed? That info allows us to make mounts specific for your gun or select from stock a mount appropriate for your application.
This is the way to do it as far as I'm concerned.
Mounting scopes can be a real pain to the novice and even the informed can get stumped. Experience has led me here. The alternative is bending your barrel into the scopes view. It saves a lot of time, dollars, aggravation, and hassle to do it right the
first time.
For each application we want to know which mount, scope and gun are going together so be sure you give us all the info so we can help you make an informed choice.
Do your droop check twice to verify. Once you make custom mounts they will serve the specific gun forever, but it is a case of garbage in garbage out, so no guessing. We will not take custom droop mounts back if you screwed up.
Gravity sucks and it doesn't look like that will change in the foreseeable future.
We've come a long way with mount quality but without the experience of 1000's of scoping jobs the choices just add to the confusion.
Thanks for the business.
Tim