Chuffed at my Bloop Tube!

Today was a good day for a range trip.  Sunny and quite calm.  I wanted to spend all my effort on playing with the bloop tube, so all groups are 10 shots of Eley Target.  I know Target isn’t the highest dollar ammo out there, but I’ve tried almost all the Eley and Lapua offerings, and this shoots well in my gun.  Right now in America, we’re in a situation where we take what we can get.  Also, all the groups are off a rest and rabbit ear bag, so my personal wobbling isn’t really much of the equation.  The last detail of note is that I was using 50 Meter targets at 50 yards, so the targets were about 5 meters too close.  One deals with the hand one is given.

First out of the gate, I shoot a couple groups with my standard setup.  This uses the 20mm of sight riser I’ve grown accustomed to.  The groups were “meh” at 18mm and 20mm center-to-center of worst holes.  Like so:

 

I put on the bloop tube.  Everything fitted up nicely.    The aimpoint moved significantly.  This is to be expected as the design kept the sight at the same height from bore center, so it “flattened” out the triangle between the sight line and the bore when it moved forward.  I needed a total of 75 clicks left and 40 clicks up, to get somewhat recentered.  Interestingly, I forgot to tighten the nose screw for the first group. This configuration shot a nice 15mm group.  All groups after this were done with the screw tightened and I did shoot another  15, as well as some 19’s, so I’m assuming no effect on group size unless I do more rigorous testing.  Tightening the screw  did move the aim point up about 5 bullet diameters.

The next test was to remove and replace the tube and see how the point of aim changed.  Zoinks!  Jinkies!  The group moved 70 mm straight to the left.  I didn’t repeat the test any.  I know for certain that if I use this in a match I’ll be doing a thorough re-zeroing.

 

The above 2 targets  are only different in that the tube was removed and replaced.

One other item popped up that I’ll need to address.  The front aperture appears smaller as you move it forward.  This decreases the band of light around the bull.  I'm on my maximum insert now, so I'll need to get my hands on some more discs or a different front sight.  I’m leaning toward the sight because the huge bubble level blocks a lot of the circle that aligns to the rear sight, just a visual thing.

So am I pleased?  Taking 18-20 mm groups down to 15-19 mm groups is nothing to sneeze at.  If fixing the aperture problem can help a bit more, I’d say I’m very pleased.  Or, as the British say, “chuffed as a fart.”

Bloop Tube for the Ural 5-1. Why practice when one can accessorize?

While my sight risers for the Ural 5-1 make me a lot more comfortable and correct my head alignment, they don’t seem to do much for my scores.  At least they haven’t gone down.  I’m now in search of the next great accessory to send me to the top of the scoreboard.  Of course, a bloop tube is what I need.

I started perusing commercial bloop tubes and I kept running into the same problem.  Either they were designed for a specific rifle, so I was out of luck, or they needed a good straight muzzle shank to clamp onto.  Now, a lot of Anschutz muzzles just have two small grooves, so I can see how that works, but the Ural has a big dovetail fitting.  I looked at removing the fitting, but I was pretty sure I’d ruin the flat black (Teflon?) coating on the barrel.  So the only solution was a custom fabricated clamp that reached around the sight clamp.  There’s a decent chunk of muzzle exposed in front of the dovetail fitting giving me  a solid index.  I just needed to extend the clamp back to firmly hold behind the fitting.

This shows the standard muzzle and sight.  The boss around the muzzle seems about as permanent as it can get without scratching up the finish.

I started drawing up what I wanted, with a plan to machine it out of aluminum.  I had tried various muzzle weights to see if I could get some barrel tuning out of them, but I could only find configurations that made things worse.  Either I’ve been doing it wrong, or the Russians knew what they were doing in the first place.  This led me to plan on making the tube as light as possible.  Because of this, and the coolness factor, I planned on a carbon fiber tube with aluminum end fittings.  Finally, after my successful experience with the 3D printed sight risers, I decided to build the end fittings from plastic instead of aluminum.  If they turned out to be too flexible, I had aluminum to fall back on.

Here's the final solution.  Everything fit up nicely.  The tube slid snugly into the caps and bonded up cleanly.  Just under the rear cap is a boss I tapped for a plastic screw.  This gives a little preload to hold things rigid, though it seems it isn't really required.

Component prices came out pretty reasonable. 

The carbon fiber tube, part number 5287T13, was $26.22 from McMaster.com. 

The epoxy to bond it, part number 1813A243, was $16.34, though JB-Weld would have worked.

The aluminum shaft clamp, 9520T14, was $14.10.

The 3D printed nose and rear cap were $29.07 and $40.82 respectively from Shapeways.com.

Grand total: $126.45.

Commercial bloops run $100-$200 and wouldn’t fit anyway, so I’m happy.  I’ll be happier if it shoots well.

There are a few issues.  The clamp model from McMaster wasn’t 100% accurate, so I made the fastener head clearance a little tight.  Nothing some grinding couldn’t cure.  The thing is plastic after all, so I’m expecting the sight zero won’t be that reliable after removing and replacing the tube.  I like to show up for a match with the gun ready to go, and just take a few practice shots to verify.  With this tube, I will either need to go through a zeroing ritual every match, or build an extra-long case so I can carry the rifle with the tube installed.  I’ll eventually be doing a series of remove-replace tests on the bench rest to verify this, but I can’t imagine it will repeat very well.

Range report to follow.