21st February 2016, 02:12 PM
Join Date: Jan 2013
Member of: Ford & Oaks
Have been messing with this recently, posted the following on the other side:
So this little project was started by the need for some super low and narrow mounts for my new semi-pup Steyr before the bonfire pi##ers start with the "whats the point" there really isn't one other than I like cutting stuff up
The pup is incredibly comfortable and easy to shoot, problem is the scope is 50mm high and is unchangeable due to cheek weld on action constraints, so with 0.177" running legally this is a bit of a mare, it means the holdovers (I zero at 25 yards) are between 3.1 dots at 8 yards and 1.1 dots at 45 yards, so a lot of scope for error.
So now I am creating the semi-pup where my cheek will be just behind the action, where is the sweet spot for scope height, I suppose it depends what you want really, for me I like to have the spread of dots as small as possible and equal at 8 and 45 yards, this gives me less to remember during a comp - my weakness (apart from no time to shoot) is eyesight and falling apart under pressure
So 0.177" running at 11.4ftlb (all the below numbers off Chair Gun so not exact) this equates to a barrel to scope centre height of 32mm which would give a dot spread of 1.4-1.4, as the distance between the barrel centre line and the top of the action of a Steyr LG is 16mm and the scope is a 30mm tube (15mm radius) this means I would need mounts with a top of action to bottom of scope height of 1mm - not easy - so how low can you go
My current full length set up uses Rick Arden super lows, the mounts to judge all others against, the accuracy of machining is second to none. These are 7mm high, which means my scope is running on a centre height of 38mm which gives a dot spread of 1.9-1.3, pretty good and actually as good as it gets with this scope as the zoom ring is currently 0.5mm above the action - it will not go any lower
But with the semi-pup I think I can get the zoom ring over the breech cut-out so can go lower
So I bought some cheap mounts to cut up (thanks to Simmo for the idea), with the traditional match type mount and M4 clamp screws I think I can get down safely to 6mm, the constraint being the need to leave some material above the screws to flex, this is the weak area of this design so I have tried to improve on Ricks design a little by easing the stresses using a round hole not square corners, I can see some mileage in side cut outs too - like BKL do. I have left 2mm of material to flex. These are fine if you mount once and forget - if you take them on and off a lot they will probably fracture I got these down to 6mm so centre height of 37mm which gives a dot spread of 1.8-1.3, not much change as I struggle to differentiate between 0.1 and 0.2 dots anyway
I also tried a set of Warne type mounts this time with M3 screws (but a lot of thread contact, almost 15mm long) and managed to get these down to 4mm so centre height of 37mm which gives a dot spread of 1.7-1.4, closer together but not the same
With the Steyr this is it I think, the only way to get lower is to get a rifle with a smaller distance between barrel and top of action, or to slow the pellet if I drop to 10.5ftlb the dot spread is 1.6-1.6 - more windage though
The mounts for comparison:
....watch this space for the semi-pup....
From what I can see its almost always the ocular bell or zoom ring that clashes with small objective HFT scopes.
My current competition rifle has 0.5mm clearance, but the new project gun has a 2.5-10x24 NXS on it which has small ocular diameter - which is nice
Working on the "stock" today
...the statements, opinions and comments in the post above are from someone who has never won anything and probably never will, just an enthusiastic air gunner, for those here who only place value in the opinions of winners - move along to the next post ...