Mark Camoccio concludes his trial of the classic Air Arms S400
The two-stage, semi-match trigger that Air Arms fit to the S400 and its derivatives, is the latest version, which features Nick Jenkinson’s 3-sear design as standard. OK, it’s a relatively simple unit, with far fewer components than that of a full-blown, ultrasophisticated match trigger. However, it is a true two-stage design, whereby the first stage does actually start to move the sears apart, instead of a pseudo design, where the blade moves initially just on a pivot, having no affect on the mechanism. Indeed, with some careful adjustment, this trigger can be set reasonably light, with a highly acceptable and predictable release possible.
As mentioned, with no regulator fitted, the S400 needs to be charged carefully to the prescribed fill pressure. Air Arms still specify that pressure as 190bar, but in my experience, a fill pressure of between 165bar and 170bar is more likely to return a consistent band of shots. It’s a knock-open valve at the end of the day, which means the greater the pressure inside the cylinder, the more resistance against the hammer initially as it tries to open the valve. As cylinder pressure decreases, so the hammer will open the valve more easily. Over the whole charge, a power curve of sorts will be seen, but get your initial fill pressure right and you’ll get a good number of consistent shots within a fairly tight velocity band – what’s commonly known as ‘the sweet spot’. For the record, I charged my test gun to 180bar.
Charging the S400 is via the front valve, accessed by just unscrewing the fluted valve cover, and sliding on the airline over the ‘ T’ bar valve. This has to be the safest design of valve because that ‘ T’ bar design allows the high pressure cable effectively to be locked in place for the duration. There’s an in-line 20 micron air filter at work here too, to keep dirt from the internals.
I’ve owned and shot a variety of S400s over the years, so I’m familiar with how they perform and what to expect, and the test model was no great surprise. The factory-set trigger did arrive with a slightly heavier pull than I had in mind, so a judicious tweak with some Allen keys later, and I was in a position to assess the accuracy of this particular specimen. I still find the silky grey ‘satin’ bolt handle very appealing, but the bolt set-up does occasionally comes in for criticism in some quarters. I
concede that it could do with a bit more resistance on closure, but be precise in your approach, and it won’t let you down. Over the chronograph, from the 180bar I had selected, I clocked 80 shots within 19fps, which for an unregulated gun is very impressive. You can get plenty more shots, but I was after maximum consistency so stopped there.
A quick zero at 25 yards to get the scope in the right area, and then back to my normal zero distance of 35yards – which is also a fair initial test of quality machinery! Using Air Arms Diabolo Field ammunition, groups of sub-3/8 inch were easy to come by. Moving out to 45yards, sub-half-inch clusters were the norm with this particular example – a good return with any rifle.
As with any PCP, we need to be aware of how many shots we’ve used up before a recharge is necessary, and here, Air Arms make it easy to keep an eye on residual cylinder pressure with that perfectly placed manometer, recessed on the underside of the fore end.
As previously mentioned, Air Arms produce a carbine version of this model with a shorter cylinder and barrel, but for the additional shot count and negligible weight differential, I’d plump for the longer Classic spec’ every time. In short, the S400 really is the great all-rounder – all things to all people! As mentioned, the S400 was originally designed as a hunting rifle, and therefore sports an appropriately light, sleek profile. Take to the field – its natural environment, after all – and the combination of slick handling, sensible weight, and blistering accuracy makes it the perfect tool for the job. It’s whisperquiet, too, with that silencer in place.
Give in to the lure of hunter field target shooting, and this model allows you to be competitive from the start, but that smart fore end just might need some beefing up. Easy customisation is often part of the enjoyment for many shooters, though, and this model certainly lends itself to simple modification, such as the adding of a hamster block or stock raiser of some sort.
Adding a regulator further down the line is a must for some shooters, too – more for peace of mind – and again, the straightforward S400 lends itself perfectly to that.
As with most walks of life, airgun manufacturers have to be seen to be bringing out new models periodically, yet look at what the S400 offers and you might begin to appreciate just why this airgun classic remains so highly regarded, by new and experienced shooters alike.
Hunting or competition? You decide
Class doesn’t have to cost a fortune
That classic bolt is still there
Surely, the safest filling valve on the market
The perfect place for the vital gauge