US Air­guns

Stephen Archer gets a priv­i­leged in­sight into the de­sign and tech­nol­ogy of the new SIG Air ASP20 ri­fle

Airgun World - - Contents - Stephen Archer is the Pub­lisher of Hard Air Mag­a­zine, the US-based on­line air­gun mag­a­zine. www. hardair­

Stephen Archer is at SIG SAUER in New Hamp­shire, with their new ASP20 ri­fle

So, there we were at the cor­po­rate head­quar­ters of SIG SAUER in New­ing­ton, New Hamp­shire, USA. That’s your il­lus­tri­ous edi­tor, Terry, me, and a num­ber of in­vited air­gun scrib­blers. The date was 25 July 2018 and we were at­tend­ing the of­fi­cial un­veil­ing of the new SIG ASP20. It was the world pre­miere of the com­pany’s new break-bar­rel, gas-ram air ri­fle!

We’ve seen pro­to­types of this new gun be­fore, at the SHOT Show and IWA, but this was the for­mal launch of the fi­nal pro­duc­tion gun. SIG is locked and loaded for the ASP20 and we saw some of the first pro­duc­tion guns com­ing off the line.

These first pro­duc­tion guns are to US spec­i­fi­ca­tion, as you would ex­pect. They give a muz­zle en­ergy of 20 ft.lbs. in .177 cal­i­bre, and 23 ft.lbs. in .22 cal­i­bre. That’s rea­son­ably stan­dard for mag­num gas-ram break-bar­rels on this side of the Pond.


The SIG ASP20 is the first new break-bar­rel air ri­fle to be com­pletely de­signed and man­u­fac­tured in the USA for many years. Cer­tainly, it’s the first this cen­tury, and pos­si­bly the first ever. As Joe Hus­ton, the Gen­eral Man­ager of SIG’s air­gun busi­ness said, ‘This is def­i­nitely the first to be de­signed and built in the USA by a firearms com­pany’.

It has mul­ti­ple new, in­no­va­tive fea­tures that show a com­pletely fresh ap­proach to air ri­fles de­sign. The SIG ASP20 is the first model in the SIG Air pre­ci­sion line. Yes, SIG Air is the new name for SIG SAUER’s air­gun divi­sion.

At this press launch, the com­pany was amaz­ingly open about the new tech­nol­ogy they’ve de­vel­oped for the prod­uct. There’s been a great deal of R&D un­der­taken for the ASP20, and SIG wanted to en­sure that we un­der­stood all of it. The com­pany was not hold­ing back about the new SIG ASP20, and for good rea­son – it’s ob­vi­ously an out­stand­ing new in­tro­duc­tion.


SIG ex­plained that they had de­cided early on, the core de­sign goals for the ASP20. They didn’t want to pro­duce ‘just an­other break­bar­rel. Their aims were for the ASP20 to be su­pe­rior to any other mag­num power, break-bar­rel air ri­fle on the mar­ket, in three key ar­eas; it was to be eas­ier to shoot, con­sis­tently more ac­cu­rate, and more plea­sur­able to shoot than the com­pe­ti­tion.

From a tech­nol­ogy per­spec­tive, this meant a great amount of time and ef­fort de­voted to the de­sign and en­gi­neer­ing of sev­eral key fea­tures, in­clud­ing bar­rel lock-up, cock­ing ef­fort, trig­ger pull and ri­fling.


SIG ex­plained that they were in­tent on

elim­i­nat­ing the bar­rel droop en­demic in break-bar­rel air ri­fles. They also wanted to achieve con­sis­tent lock-up, so SIG en­gi­neers de­vel­oped a pro­pri­etary ‘key­stone’ breech lock de­sign, the ge­om­e­try of which elim­i­nates bar­rel droop, they told us, with matched an­gles be­tween the breech block and fork.

An­other key tech­nol­ogy used in the ASP20 is ‘match drilling’ of the pivot holes through the bar­rel and re­ceiver. This means that the pivot point for the bar­rel/breech in­ter­face was drilled just once through both parts us­ing a jig.

This makes the SIG Air ASP20 air ri­fle dif­fer­ent from other break-bar­rels, which have the parts drilled sep­a­rately then matched to­gether dur­ing as­sem­bly. That ap­proach can re­quire ad­di­tional parts in ex­pen­sive guns, or lead to a poor fit in cheap ones, says SIG. Ei­ther way, it’s clear that the match drilling process is likely to pro­duce su­pe­rior fit and op­er­a­tion for the all-im­por­tant pivot point of the ASP20.


First, SIG bench­marked the cock­ing ef­fort re­quired for other break-bar­rel air ri­fles, both springers and gas-ram guns. As you would ex­pect, they found that the cock­ing force in­creased with the muz­zle en­ergy, but they also found that the claims of some other man­u­fac­tur­ers for cock­ing ef­fort were not matched by the sam­ple guns they tested. It ap­pears that some man­u­fac­tur­ers’ claims for cock­ing ef­fort are lower than they ac­tu­ally are; just like fps claims are usu­ally higher than those ac­tu­ally achieved.


From the data SIG pre­sented to us, you can see im­me­di­ately that the cock­ing force for the 20 ft.lbs. muz­zle en­ergy, SIG Air ASP20 air ri­fle is close to that of mid-power guns – we’re talk­ing US ex­pec­ta­tions here – 12 to 16 ft.lbs. It’s sig­nif­i­cantly less than other mag­num mod­els of 20 ft.lbs. and above.

This re­duced cock­ing force is largely due to the new SIG SAUER Glidelite cock­ing mech­a­nism built into the SIG Air ASP20 air ri­fle. SIG ex­plained that his in­cludes a low-fric­tion bear­ing sur­face for smooth ro­ta­tion of the cock­ing arm and de­creased con­tact pres­sure. In ad­di­tion, there’s a wedge-shaped de­tent. This in­cor­po­rates a dou­ble-spring de­sign that makes it eas­ier to break the bar­rel be­fore cock­ing.


SIG is mak­ing their bar­rels for the SIG Air ASP20 air ri­fle. As the com­pany al­ready man­u­fac­tures ex­cel­lent bar­rels for firearms, this was a very log­i­cal step for the new air­gun, so bar­rels for the ASP20 are be­ing man­u­fac­tured by SIG in New Hamp­shire. They’re made on the same machines used for firearm bar­rels, and they have ri­fling of SIG’s own de­sign.

The com­pany says that this ri­fling has two de­sign goals; one is to min­imise un­nec­es­sary dis­tor­tion of pel­lets and the sec­ond is to cre­ate a highly ef­fec­tive seal on the pel­let skirt.

ASP20 air ri­fle bar­rels are but­ton-ri­fled. They have 12 lands and a twist rate of 1 in 450mm. The bar­rels are air gauged and there’s a bore scope in­spec­tion on ev­ery sin­gle ASP20 bar­rel.

In ad­di­tion, the si­lencer hous­ing is laser welded onto the bar­rel. In to­tal, there are no less than 18 dif­fer­ent laser welds on each ASP20.

Laser weld­ing equip­ment is ex­pen­sive – very ex­pen­sive – but SIG has cho­sen it for the ASP20 to re­move the chance for dis­tor­tion present with con­ven­tional weld­ing, par­tic­u­larly where the Pi­catinny rail is welded to the com­pres­sion tube and other key ar­eas, like si­lencer at­tach­ment.


There’s no doubt about it; a huge amount of time and ef­fort has been put into de­vel­op­ing the trig­ger for the SIG Air ASP20 air ri­fle. It’s called the ‘SIG ASP Match­lite’ trig­ger and it has some unique fea­tures. SIG is ap­ply­ing for two patents in the trig­ger as­sem­bly alone – that’s how unique it is.

The trig­ger blade it­self is based on that of the SIG SSG3000 cen­tre­fire ri­fle. It’s man­u­fac­tured from an ad­vanced ny­lon poly­mer, over-moulded onto a zinc bear­ing sleeve. SIG says that this re­duces weight and fric­tion, as well as pro­vid­ing im­proved bal­ance.


De­sign goals for the Match­lite trig­ger were for it to be safe and pro­vide a clean break. It would also al­low the owner to cus­tomise the feel over a wide range of ad­just­ment. The re­sult is a trig­ger with a man­ual safety op­er­a­ble from each side of the gun. It also has an ad­just­ment mech­a­nism which, to my knowl­edge, is unique on spring-pis­ton and gas-ram air­guns.

The trig­ger of the SIG Air ASP20 air ri­fle is ad­justable in two-ounce in­cre­ments, be­tween 2.5 and 3.5lbs. There are eight dis­tinct set­tings se­lectable us­ing a screw­driver. There’s an un­usu­ally long spring around the trig­ger ad­just­ment strut to pro­vide this range of ad­just­ment ca­pa­bil­ity, and ad­just­ment is made us­ing a ratchet sys­tem with in­di­vid­ual clicks.

Con­trolled by a sin­gle setscrew, these ad­just­ments change not only the trig­ger pull weight, but the pull char­ac­ter­is­tics, too. The ASP20 trig­ger can be ad­justed to

give sin­gle or two-stage op­er­a­tion, or a point be­tween. Im­por­tantly, trig­ger ad­just­ments can be made to the ASP20 with­out the need to re­move the stock, or peer up un­der the trig­ger guard.

An­other key fea­ture – un­like most other trig­gers, the SIG Air ASP20 air ri­fle trig­ger can­not be ad­justed out of its safe tol­er­ance range. A bracket as­sures the min­i­mum sear en­gage­ment re­quired for safe trig­ger func­tion.


SIG SAUER is se­ri­ous about qual­ity, and that means they’re se­ri­ous about test­ing; one rea­son their prod­ucts find such favour with the mil­i­tary around the world. Ron Co­hen, the com­pany’s Pres­i­dent and CEO, him­self a for­mer ac­tive-duty sol­dier, ex­plained that the ASP20 was sub­jected to the same test­ing reg­i­men as SIG’s mil­i­tary firearms. He knows what it means to de­pend on your ri­fle, and he de­mands that SIG users can de­pend on his prod­ucts – in­clud­ing the ASP20.

Now, I don’t sug­gest you try this at home, but here are some of the tests SIG un­der­took on their new air ri­fle:

For ex­am­ple, it has to pass a 72-hour salt­wa­ter spray test and still op­er­ate cor­rectly. They also sub­jected cocked and loaded ASP20s to the SIG test of two min­utes to­tally im­mersed un­der­wa­ter. They had to fire after this test, and they did. We saw the video to prove it!

SIG told us that they had tested the ASP20’s breech/cock­ing de­sign for up to 20,000 – yes, TWENTY THOU­SAND – ac­tu­a­tions to en­sure re­li­a­bil­ity.

That’s just some of what it takes to be ap­proved as a SIG prod­uct ,and I know the edi­tor can’t wait to test the sub-12 ft.lbs. ver­sion of the ASP20 as soon as it reaches the UK.

An over­view of part of one of the SIG SAUER fac­to­ries. The big white boxes are CNC machines. The ASP20 is as­sem­bled un­der the ‘As­sem­bly’ sign, top left.

Ed Schultz, SIG’s Air­gun En­gi­neer­ing Man­ager, ex­plains the Match­lite trig­ger.

John Bright - boss of SIG Air’s UK dis­trib­u­tor, High­land Out­doors, puts in the range time.

The cock­ing lever as­sem­bly is at­tached to the bar­rel be­fore mov­ing down the line.

After the the bar­rel has been fit­ted, it’s time to at­tach the trig­ger pack, then the gas-ram unit.

Here’s a CAD ren­di­tion of the com­plete ASP20 trig­ger pack. Part 1 is the trig­ger weight ad­just­ment as­sem­bly. Part 2 is the trig­ger stage bracket again, it’s green this time.

Cock­ing Force. This chart shows dif­fer­ent cock­ing ef­forts and muz­zle en­er­gies for a num­ber of air ri­fles. You can see how the ASP20 (the star) is su­pe­rior to the oth­ers tested. Data supplied by SIG SAUER.

The ASP20’s de­tent mech­a­nism in­cludes two springs, one in­side the other, to make break­ing the bar­rel eas­ier.

Com­po­nents of the Match­lite trig­ger. That arm on the grey-coloured part (the trig­ger stage bracket) for­ward and down from the blue safety pin, pre­vents un­safe ad­just­ment of the trig­ger.

The fi­nal com­pleted air ri­fle, as it comes off of the line.

The green parts of this CAD ren­di­tion show SIG’s ‘key­stone’ breech lock de­sign.

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