Weihrauch HW77K part 4
If you are following this 4 part series of Weihrauch HW77K air rifles, you will now be expecting some information on the 25 calibre models. Presently at the time of writing this, Weihrauch do not make any calibres larger than .25 in both their ‘springers’ and their PCPs.
The HW77K range of springers in .22 calibre account for the majority of sales at Gun Room with .177 cal a distant 2nd and both the .20 and .25 calibre sales virtually non-existent. This has been bought about by the fact that until I ordered in some in late 2014, .25 cal has never been imported into Australia to my knowledge and only a handful of .20 units a few years ago.
The HW77K .25 calibre out of the box.
I have tested the .25 straight from the box and with the energy output just above that of a Weihrauch HW77K .22 air rifle you need to ask if it is worth the hassle getting the larger calibre? Well if you are hunting, then I believe the 25 cal is the better springer with the heavier pellets because it stands to reason that the kill zone will be larger and the wound channel greater. This effectively will result in more ‘kills’ for the same placement than smaller calibres.
In my opinion the effective hunting range of a 25 cal HW77K is probably short of 50 metres and more likely 40 metres in an un-tuned state [it will shoot further but we are looking here at 2-3 inch (50-75mm) drop limit below a 25 metre zero]. By fitting a V-Mach Tuning Kit and adding the maximum shims possible (prior to spring lock), the air rifle should perform well and reach out 50 metres effectively with selected pellets.
22 Calibre v’s .25 Calibre Weihrauch.
When discussing the maximum ranges of the .22 and .25 air rifles here, it stands to reason the .22 will reach out further due to the increased speed, the larger range of pellet types to chose from, lighter pellets and the likelihood of finding pellets with a better ballistic co-efficiency. However, the .25 cal HW77K and HW77 are primarily hunting air rifles and when used within their effective range are a more effective calibre at bringing down larger prey.
When we compare the HW77K in .22 cal to its larger .25 brother, what counts in hunting apart from accuracy, is the energy that either one delivers. Having recently ‘max’d up’ the power of a .22 HW77 where I increased the power from 16.8 Ft Lbs. to 19.8 Ft Lbs. by adding shims to the V-Mach spring. This was an increase of 26% more power when using heavy pellets like the H&N Baracuda but it came at a cost of accuracy.
For this article I have fitted a V-Mach Tuning Kit to a brand new .25 cal Weihrauch HW77K air rifle after taking the initial Chronograph readings and the following chart lays out the results quite simply. You will immediately notice that the lighter H&N Field Target Trophy pellets showed a more significant increase in FPS and Energy which is to be expected with only a small amount of increased spring pressure.
However, this increase in FPS/Energy is at the expense of the Standard Deviation and Extreme Spread that increased markedly, resulting in poorer grouping.
You will also notice that the heavier pellets excelled with the increase in spring pressure, while not contributing much in the way of increased FPS/Energy, all 3 heavier pellets showed a decrease in the Stand Deviation and Extreme Spread. They showed better groups as a result.
So to recap on what you would expect to achieve by fitting a V-Mach kit and ‘maxing’ the number of shims in it in a .25 calibre Weihrauch HW77K is this:
- Higher speeds and more energy from lighter pellets.
- Quite possibly at the expense of grouping so a larger range of pellets should be tested if you are seeking maximum energy with lighter .25 cal pellets while still grouping fairly well.
- Marginally higher speeds and energy increases from heavier pellets.
- Testing has shown better grouping in this scenario, however, this is not set in stone as there are heavier pellets with poor ballistic coefficients that could well provide poorer groups as a result and vice versa.
- In this .25 calibre Weihrauch HW77K a hunter would benefit from the heavier pellets providing better accuracy over the lighter Field Target Trophy pellets. As we all know, air rifle tuning is fraught with compromises as there is no ‘one fix for all’ due to variances in pellet architecture, ballistic coefficients, speeds, barrels, you the shooters just to name a few. All too often a gain in one department quite often results in a loss in another.
- At the end of the day, this Weihrauch HW77K in 25 calibre would make an ideal hunting rifle for larger game such as foxes out to around 40 metres is my guess. The larger diameter pellets with the significant weight increase over the .22 calibre pellets will in the end give you a larger wound channel resulting in a higher kill ratio.
Tuning air rifles for more Power.
You need to understand this when tuning, and that is accuracy quite often comes at the expense of power, that’s right, decrease the power and you increase the accuracy in more cases than not. So if you are tuning for someone who intends to hunt with the air rifle, then I tune it for accuracy first, see what the best group the air rifle is capable of and with which pellets. I then look at the Energy and if it is too low in my opinion, I shim up the spring to increase the energy and that usually comes at the cost of accuracy.
With the HW77K in 25 calibre, we are not talking about hitting match heads at 50 metres here but something along the lines of Rabbits or Minor birds, so you need to be realistic. If you want to shoot match heads at 50 metres than I suggest you get a PCP air rifle where you do not have recoil and precision shooting is available out to 100 metres and more.
Tuning your Weihrauch HW77K air rifle is not restricted to just a V-Mach tuning kit, but encompasses such things a fitting a Race Brake, working on the Rekord Trigger Group to make it crisper, lightening the trigger pull, adjusting the butt pad and length of pull, fitting and adjusting the best scope you can afford and even fitting a customized trigger as below. It amounts to an accumulation of minor adjustments and added accessories, mainly after market parts.
Summary of the Weihrauch HW77K.
The HW77, HW77K and HW97K air rifles all have the same internals just different length barrels and varying calibres. So whatever calibre Weihrauch HW77K you intend to shoot, it is powered by exactly the same spring and seal and so pellet placement varies dramatically between pellet types and calibres ‘straight out of the box’.
Given what I know about Weihrauch HW77K ‘springers’ and that is pellet selection is crucial as there are too many variables; follow this up with tuning the rifle with a dedicated tuning kit like V-Mach and providing you have the patience to chronograph the results and vary them with shims, you will end up with a great air rifle, regardless of calibre.
Author: Ian McIntosh