Centra Duplex

I got one of these (direct from MEC, but you can get them from Intershoot.co.uk now) a while ago to try out.

Centra Duplex parts unpacked...

Looked great, but had a few problems – for a start, my rearsight got a little complicated:

All we need now is a kitchen sink...

Okay, so some of that got stripped off, but even after that, it was still a bit… busy:

Centra Duplex in match configuration

Now, I have a fairly pronounced cant on the rifle, so that introduced another problem – the duplex is only anchored at the top and I don’t know if it’s my one alone or the design, but when you cant it, the iris doesn’t hang vertically, it moves slightly to one side and makes a mess of your sight picture, so you’re fiddling with its adjustment a fair bit to try to get everything aligned. And speaking of which, the sight picture itself gets a bit more complicated as well:

Centra Duplex Sight Picture

The problem is that the gap between the rear iris ring on the outside and the middle ring of the duplex is just as critical as the centering of the foresight ring in the rear iris, and unless the duplex is perfectly centered in the rear iris – and locked solidly in place – then you get a sight picture like the one above, and if you’re mid-match and fixating on the target, you don’t notice the small drift offcenter of the duplex in the rear iris.

Now I know these can work; I saw one or two being used to good effect in Intershoot and in RIAC by the Dutch team (it’s hard to see but look at the rearsight of Peter, second from the left in the photo):


But for me, the Duplex is now sitting in the pile of Bits I Bought Because They Were A Good Idea At The Time But They Haven’t Worked Out So Far But Maybe With A Bit Of Work They Will Later On…

Practice match

So the plan for this evening was to shoot a practice 60-shot match. With the UCD Open coming up on the 17th, I thought practice matches for the next few sessions would be a good idea. So I got to the range about 1830h and got kit prepped and ready, and started my prep time at 1900h. And straight into sweating and feeling like I was in a straitjacket and having issues with flexibility of the jacket and so on. Not a great start. It wasn’t helped by the sighters – that first shot was well out in to the white and gave me something to look at for the rest of the match:

Sighters
Sighters

The reason the sights were so far out was a purely mechanical one that I spotted on Friday and which Paul confirmed – if you’re putting on the MEC rearsight and just slide it on the rail and tighten the clamp, it clamps like so:

MEC Free rearsight clamped without pressure
MEC Free rearsight clamped without pressure

The weight of the rearsight is all behind the clamp, and you can see it’s making it lean back a little. Tightening the clamp won’t bring it down onto the rail at the nose of the sights, and you can’t consistently replicate the angle it finally comes to with the rail if you just tighten the clamp. So you’d be sighting in every time you put on the rearsight. Friday saw me zeroed in with the rearsight at an angle like this. Today, instead, I did what I’d planned to, and applied pressure at the nose of the rearsight to hold it down to the rail, and then clamped it in place:

MEC Free rearsight clamped with pressure on the nose
MEC Free rearsight clamped with pressure on the nose

The difference may not look like much, but it’s there and visible and rather critical – that much of a change takes you from an inner ten to an outer two, right out in the white of the card. It took seventy-odd clicks to get back to the inner ten…

Once the sighters were done, I was now looking at being behind on my time plan (which is 10 min for sighters, 90 seconds per match shot, and 5 mins in reserve), and of course, that’s stress, and I’m still watching to fine-tune sights. I didn’t handle the mental game well for the first string as a result and it was awful:

String 1
String 1

Too high, and too much wobble. By this point, I’m still sweating and fighting the jacket; but the thing about a horrible start is that your mind decides that the match is now lost (which, to be fair, it is) so it might as well relax – exactly the thing you’ve been trying to get it to do for the last ten shots…

String 2
String 2

And immediately things start to improve. Yes, it’s not perfect or even average yet, but it’s getting better. Odd fliers out to the right hand side though. So I put the head down and get on with the shooting, figuring that I want to walk away as it’s so bad, but I need the physical acclimatisation if nothing else…

String 3
String 3
String 3 closeup
String 3 closeup

And feck. That’s really quite good. Dammit. Sights are a bit low and left, and I have one flier at six o’clock, but that’s a nice group apart from that (and by this time, I’m actually back in the flow with a solid-feeling platform in my position and my temperature and breathing are back to normal). So I tweak the sights a bit and go back to it…

String 4
String 4
String 4 closeup
String 4 closeup

Mother-loving son of a ….

That wouldhave been my first tun in air rifle.

Gah. Okay, head back down, on with it, time’s pressing now…

String 5
String 5
String 5 closeup
String 5 closeup

Oh sweet suffering cats. I know the last shot was a complete flier, but why am I drifting to the right here? Some sort of sight picture problem perhaps. On with it, time’s ticking…

String 6
String 6
String 6 closeup
String 6 closeup

And feck. Finished two minutes after the time limit, so shots 9 and 10 of that string wouldn’t count – not that that last shot did me any favours – though I knew the moment it broke that it was bad; the trigger just broke before I was ready for it. No idea where the other flier came from though.

Still. 560 with an 88 (and a 98 with an 8) is not bad. The scores histogram shows 32×10, 18×9, 9×8 and 1×7; compared to the last good match I had (the DURC Open back in November before all the new changes), that’s pretty okay (that one was 29×10, 26×9, 5×8). Tidy up the start and watch the sights adjustments, and that would be a pretty decent score. And that’s after a long day in the office too.

A few more practice matches needed, but Sunday is looking good so far…

Mirror, mirror…

When I was shooting a lot of smallbore, I had a small mirror attachment on the back of my rearsight iris as an alignment aid. It worked quite well, so I thought I’d try it on the Tiny iris on the Free rearsight. Trouble was, the Tiny wasn’t compatible with the rearsight mirror I had and the mirrors I’d seen on the Tiny had to be built into the iris itself; and there are just too many tiny parts in the Tiny (har, har) to do the work myself. However, Centra now have an alternative push-on mirror as well. So a few emails with their sales guys later (thanks Johann!) and I had a package on my desk:

It arrives!

One monumental amount of packaging later, and there’s my new mirror:

So much packaging for such a small item!

Mirror

So this evening, after some dry-firing and some live-firing to warm up, I attached the mirror to the rearsight:

Mirror attached

Mirror in place

The idea is pretty simple. Here’s the rearsight normally;

Rearsight w/o mirror

And with the mirror in place, you now have another concentric aperture behind the rearsight iris:

Rearsight w/mirror

And the idea is that when you look through that aperture with your eye properly aligned, your pupil (which you can see in the reflection) will be eclipsed by the aperture and your iris surrounds it, the way that the camera lens is eclipsed by it here:

Shooters eye view through mirror and rearsight

Unfortunately, when I tried using it tonight, it didn’t work as well as it had in the past. I couldn’t arrange my head behind the mirror so that I was looking through the aperture at the same time my pupil was eclipsed. Either I had the eclipse and no sight alignment, or I had sight alignment and my pupil was off in the top right of the mirror looking back at itself (which is more than a little disturbing 😀 ). I tried ten shots with the mirror and ten without anyway, just to see what the groups would look like:

10 shots without mirror
10 shots without mirror

 

10 shots with mirror
10 shots with mirror

 

Mirror group on right, no-mirror group on left
Mirror group on right, no-mirror group on left

Leaving aside the score as the sights were slightly off anyway, the no-mirror group seems to be the smaller of the two – it would all fit within the eight ring bar one shot which clips it – the mirror group clips it on both sides with multiple shots. Without the eclipsing of the pupil, I’m getting an asymmetric sight picture and my sight alignment seems to be off a bit as a result. It’s not by much, but it’s enough. It’s a bit disappointing really, but I’m not throwing it in the bin just yet – I won’t experiment too much with it until after the UCD match on the 17th, but I’ll try it out again at some point, to be sure it’s not just tiredness mucking up the shooting.