ANGSTADT ARMS’ UDP-9i

IN­TE­GRALLY SUP­PRESSED WITH A KG­made SUP­PRES­SOR, THE SHOOTER-AD­JUSTABLE GAS PORTS CAN TURN SONIC 9MM LOADS SUB­SONIC AND GET RID OF “FIRST-ROUND POP.”

Gun World - - Contents - By Andy Mas­si­m­il­ian

In­te­grally sup­pressed with a KG­made sup­pres­sor, the shooter-ad­justable gas ports can turn sonic 9mm loads sub­sonic and get rid of “first-round pop.”

Angstadt Arms might not be a fa­mil­iar name in the firearms world, but in just a few short years, this com­pany has carved out a re­spectable rep­u­ta­tion for mak­ing spe­cial­ized AR-15-style weapons that use Glock mag­a­zines.

When the com­pany re­leased the UDP-9 ri­fle at the 2013 SHOT Show, it was one of only a few AR-style plat­forms that used Glock mags. Three years later, many more play­ers have stepped into the Glock mag AR niche, so Rich Angstadt upped the ante by team­ing with Kyle Grob of KG­made sup­pres­sors to pro­duce the in­te­grally sup­pressed 9mm UDP-9i.

Al­though in­te­gral sup­pres­sors are hardly new, the AngstadtGrob firearms set them­selves apart from the herd with a unique and in­ven­tive de­sign that al­lows the user to re­duce bul­let ve­loc­ity by ad­just­ing 15 bar­rel ports to di­vert gas from the bar­rel into the sup­pres­sor. The user-ad­justable port­ing is unique ... but so are Grob’s other de­sign fea­tures (see the “Sup­pres­sor De­tails” sec­tion on page 57).

Why re­duce ve­loc­ity on a 9mm? To elim­i­nate the sonic crack pro­duced by 115-grain FMJ ammo and al­low shoot­ers to use this much-less-ex­pen­sive and far-more-avail­able ammo in­stead of hav­ing to buy nat­u­rally sub­sonic, 147-grain car­tridges. There’s also the ben­e­fit of tun­ing 147-grain loads to lower ve­loc­i­ties with even less sound sig­na­ture, al­though the power and lim­ited range make them strictly a spe­cialty use round. (For those who want an ul­tra-quiet 9mm fac­tory load, try the 165-grain HUSH from Free­dom Mu­ni­tions. My test­ing shows the HUSH has the per­for­mance of a .38 Spe­cial when shot from a 16-inch bar­rel.)

The HK MP5SD al­ways comes to mind when think­ing of in­te­grally sup­pressed 9mms, but it lacks ad­justable bar­rel ports, thus re­duc­ing the ve­loc­ity of 147-grain loads to be­ing marginally ef­fec­tive—or worse. With the UDP-9i, you have the choice of bleed­ing off gas or re­tain­ing full power.

The UDP-9i is avail­able in pis­tol (UDP-9iP), car­bine (UDP-9iC) and ri­fle (UDP-9iR) con­fig­u­ra­tions and is sold as a com­plete firearm or as a sup­pressed up­per re­ceiver (com­pat­i­ble with Colt 9mm and most ded­i­cated Glock lower re­ceivers). The pis­tol and car­bine (ac­tu­ally an SBR—Short Bar­rel Ri­fle) ver­sions have a 6-inch bar­rel fol­lowed by a 5.9-inch baf­fle core. The ri­fle uses an 8-inch bar­rel and 8.1-inch baf­fle sec­tion.

Be­cause of the added ve­loc­ity of the longer bar­rel and the ad­di­tional sup­pres­sion af­forded by a longer baf­fle stack, I se­lected the ri­fle ver­sion to test for this ar­ti­cle.

GUN DE­TAILS

Angstadt Arms’ UDP-9 se­ries is blow­back op­er­ated; and, ex­cept for lack­ing a for­ward as­sist and an ejec­tion port dust cover, it is pat­terned like the AR-15. It has sim­i­lar dis­as­sem­bly, con­trols and op­er­a­tion—in­clud­ing the bolt lock­ing open af­ter last-round func­tion (this func­tion is not uni­ver­sal among Glock AR-type weapons).

In­ter­change­able parts be­tween the UDP-9 and the AR-15 in­clude the ham­mer/trig­ger groups, charg­ing han­dle, butt­stock and grip. This makes them con­fig­urable with AR-15 parts. None is more use­ful to me than LAW Tac­ti­cal’s fold­ing stock adapter, which al­lows the butt­stock to be folded side­ways, mak­ing the ri­fle far more com­pact than oth­er­wise.

The LAW adapter fits both AR-15s and AR-10s and mounts be­tween the re­ceiver and the buf­fer tube. It is rugged, well made from stain­less steel, and it al­lows the folded stock to be in­stantly swung into the fir­ing po­si­tion for im­me­di­ate de­ploy­ment. (fir­ing a sin­gle shot with the stock folded is pos­si­ble—but not rec­om­mended). Us­ing LAW Tac­ti­cal’s fold­ing stock adapter on the UDP-9i ri­fle re­duces its over­all length to 24 inches when folded and 20 inches on the SBR ver­sion, mak­ing these firearms dis­creetly stow­able in unas­sum­ing carry cases or back­packs.

The sup­pres­sor does add some weight com­pared to the un­sup­pressed UDP-9, but it is com­pa­ra­ble to other 9mm carbines—6.5 pounds for the ri­fle ver­sion and slightly less than 6 pounds for the SBR.

The up­per and lower re­ceivers are milled from a 7075-T6 alu­minum bil­let and fit tightly with­out any gaps or wob­ble. Stan­dard fin­ish is black hard­coat an­odiz­ing, with Cer­akote op­tional. The 12.5-inch-long hand­guard is from Odin works and has a top rail and key­mod on three sides.

The UDP-9i uses a heat-treated ex­trac­tor and ejec­tor for nec­es­sary dura­bil­ity in these high-stress ar­eas. The in­ter­nal parts are typ­i­cal with the in­dus­try stan­dard AR-15, but the fit and tight­ness of Angstadt’s assem­bly are un­sur­passed. The trig­ger on my sample has a 7-pound pull weight, mea­sured us­ing a Ly­man elec­tronic scale, but it has no takeup or over­travel, mak­ing it a de­cent trig­ger, de­spite be­ing on the heav­ier side.

Stocks are far bet­ter than MIL-SPEC A2 style and use the col­lapsi­ble Mag­pul MOE and Mag­pul K2 grip. This grip is more

ver­ti­cal than most de­signs; it places the shooter’s hand at a more-nat­u­ral an­gle when us­ing a shorter length stock. It also has a com­part­ment for stow­ing an extra bat­tery for your re­flex sight—not a small mat­ter when you are out in the field, away from home. The stock is ad­justable for length of pull to fit body ar­mor and for bet­ter stowage, but its more sub­tle value comes from the rub­ber buttplate, which keeps the ri­fle from skid­ding out when leaned against a ve­hi­cle or wall.

The in­te­grally sup­pressed UDP-9i uses a heav­ier-weight AR-10 buf­fer spring; the stan­dard model does not. Those who only buy the sup­pressed up­per re­ceiver with the in­tent of mount­ing it on their lower will need to change the re­coil spring for best per­for­mance.

SUP­PRES­SOR DE­TAILS

The KG­made sup­pres­sor pro­vides sig­nif­i­cantly greater vol­ume for con­tain­ing gas than a de­tach­able sup­pres­sor. Clever en­gi­neer­ing is ev­i­dent in its use of two con­tain­ment ar­eas for the ex­pand­ing gas rather than sim­ply build­ing a mono­core sup­pres­sor and pin­ning it to a short­ened bar­rel, which is typ­i­cal of in­te­gral sup­pres­sors. The pri­mary ex­pan­sion cham­ber sur­rounds the bar­rel, fol­lowed by a sealed baf­fle stack that is at­tached to the muz­zle.

Here’s how it works. Gas is vented into the pri­mary cham­ber in two ways: by re­mov­ing the screws on the bar­rel ports and through vent holes in the rear of the baf­fle stack. A ti­ta­nium sleeve cov­ers the en­tire unit, com­pletely seal­ing in the gas The Stream­light TLR-2HL mounts and dis­mounts quickly for easy move­ment from pis­tol to ri­fle. At 800 lu­mens, it eas­ily throws enough light to iden­tify tar­gets at (and be­yond) typ­i­cal en­gage­ment dis­tances of the UDP-9i.

The LAW Tac­ti­cal fold­ing stock adapter in its open po­si­tion. Note the bolt car­rier

ex­ten­sion, which comes with the LAW kit, and the latch that holds it in place when

the stock is folded. The in­te­gral SBR sup­pres­sor with the shroud re­moved.

Note the bar­rel ports, each of which can be used fully closed or fully open with the set screw re­moved. In­ter­me­di­ate screw set­tings don’t work, be­cause they loosen un­der use. Also note the ports at the rear of the sealed baf­fle stack that di­rect gas into the bar­rel area, as well as the su­perb work­man­ship ev­i­dent in re­mov­ing the welds from the baf­fle stack. (Photo: KG­made) that is vented into the pri­mary area. Sound re­duc­tion is achieved by the ac­tion of both the baf­fled sec­tion and from vent­ing some of the gas from the baf­fled sec­tion rear­ward into the pri­mary cham­ber. This gives con­sid­er­able vol­ume for the gas to ex­pand and cool; and KG­made states that “first-round pop” is elim­i­nated by this de­sign.

The baf­fle stack is made with eight sym­met­ri­cally ar­ranged M-type baf­fles made of hard­ened 17-4 stain­less steel. They are cir­cum­fer­en­tially welded to­gether and then pinned and welded to the muz­zle. It’s a durable de­sign for heavy fir­ing sched­ules and full-auto use. KG­made ma­chines its M baf­fles from a solid bar rather than us­ing less-ex­pen­sive stamp­ings.

Bul­let ve­loc­ity is ad­justed by re­mov­ing hex head screws that cover 15 1/8-inch-di­am­e­ter ports just ahead of the cham­ber. Gas is si­phoned off into the pri­mary sup­pres­sor cham­ber sur­round­ing the bar­rel by fully re­mov­ing one or all of these screws. KG­made states that vent­ing every port will drop the ve­loc­ity of 115-grain FMJ range ammo by 125 fps from 1,200 fps down to 1,075 fps—slightly un­der the 1,110-fps thresh­old for the speed of sound at sea level.

US­ING LAW TAC­TI­CAL’S FOLD­ING STOCK ADAPTER ON THE UDP-9i RI­FLE RE­DUCES ITS OVER­ALL LENGTH TO 24 INCHES WHEN FOLDED AND 20 INCHES ON THE SBR VER­SION, MAK­ING

THESE FIREARMS DIS­CREETLY STOW­ABLE IN UNAS­SUM­ING CARRY CASES OR BACK­PACKS.

Ac­cess­ing the bar­rel ports is not quick, but it is needed only in­fre­quently. First, re­move six hex-head screws that at­tach the hand­guard and pull it off. Un­screw the sup­pres­sor’s end cap by hand and pull the sup­pres­sor shroud for­ward, off the bar­rel/sup­pres­sor assem­bly. An O-ring seals in the gas at the cham­ber end of the shroud, and extra rings are pro­vided.

SUP­PRES­SOR MAIN­TE­NANCE

Be­cause the baf­fles are in­ac­ces­si­ble, don’t shoot un­jack­eted or un­plated lead bul­lets—be­cause lead ac­cu­mu­lates in the blast baf­fle. FMJ bul­lets with ex­posed lead bases also de­posit lead, but at a lesser rate. Jack­eted bul­lets with en­cap­su­lated bases, such as the Winch­ester Win­clean, are best for this ap­pli­ca­tion. KG­made rec­om­mends soak­ing the bar­rel and baf­fle unit in Kano Kroil pen­e­trat­ing oil and then us­ing an ul­tra­sonic cleaner af­ter 2,500 rounds, as well as less-ex­ten­sive clean­ing through the bore with a rod and patch af­ter every 500 rounds. Be care­ful not to get clean­ing patches caught in­side the baf­fle stack, be­cause re­trieval will be dif­fi­cult.

RANGE TIME

Ac­cu­racy was tested at 50 yards shoot­ing from a Caldwell Rock BR bench rest and us­ing a Leopold Mark 4, which has the magnification and im­age clar­ity to ring out a gun’s ac­cu­racy (al­though it’s ob­vi­ously not what you would use on a 9mm ri­fle).

The tests showed that the UDP-9i fa­vors heav­ier-weight loads, with best/av­er­age five-shot groups of 1 inch/1.4 inches—turned in with SIG Sauer 147-grain JHP loads and 1 inch/1.6 inches from Winch­ester Win­clean 147-grain BEB. These groups were not easy to shoot, due to the stan­dard, 7-pound trig­ger and tac­ti­cal stock (rather than tar­get-style stock). How­ever, they were re­peat­able and not just a fluke. Of course, drop-in AR-15 trig­gers with lighter weights can be in­stalled.

The UDP-9i was re­li­able, and the bolt locked open with the sup­plied Glock mag, but it was in­con­sis­tent when us­ing other mags—both Glock OEM or af­ter­mar­ket. This is caused by the mag­a­zines’ di­men­sional and spring ten­sion vari­a­tions. I found that one par­tic­u­lar 30-round Glock mag worked if it was pulled slightly rear­ward. That put more con­tact be­tween the mag fol­lower and the con­nec­tor bar; but an­other 30-round Glock mag worked fine.

Rem­ing­ton UMC and Winch­ester USA 115-grain FMJ loads, which pro­duce su­per­sonic ve­loc­ity with the ports in place, dropped to sub­sonic ve­loc­ity af­ter re­mov­ing them—thus val­i­dat­ing KG­made’s tests.

This sup­pres­sor of­fers lots of flex­i­bil­ity and will surely be ap­pre­ci­ated by those who like to tin­ker with ve­loc­ity- and sound-re­duc­tion pa­ram­e­ters. Be sure to chrono­graph your loads. In ad­di­tion, don’t as­sume the ac­cu­racy will be iden­ti­cal once you ad­just the port­ing.

It’s al­ways in­ter­est­ing to see how dif­fer­ent bar­rel lengths im­pact ve­loc­ity, so I in­for­mally com­pared ve­loc­i­ties of 10 dif­fer­ent loads—from the UDP-9 SBR, with its 7-inch bar­rel and

bird­cage flash hider, to the UDP-9iR ri­fle, with its 8-inch bar­rel and 8.1-inch sup­pres­sor baf­fle stack. The re­sults showed that the ad­di­tional 1 inch of extra bar­rel and 8.1 inches of added baf­fle gave an av­er­age in­creased ve­loc­ity of 57 fps.

How­ever, there was a wide range, de­pend­ing on the load. Winch­ester 147-grain PDX and At­lanta Arms Ammo 115-grain Elite showed only a 24 fps in­crease, while Free­dom Mu­ni­tions 165-grain HUSH and Rem­ing­ton UMC 115 grain had dra­matic in­creases of 142 fps and 89 fps, re­spec­tively. These re­sults once again demon­strate how im­por­tant chrono­graph­ing is to un­der­stand­ing the per­for­mance you ac­tu­ally achieve with a given load in a given firearm, rather than re­ly­ing on guess­work.

JUN­GLE WALK AT NIGHT

The UDP-9i is a very adapt­able short-range tac­ti­cal weapon. Its abil­ity to squelch sound and flash sig­na­tures makes it an ob­vi­ous choice for LE/MIL use and home de­fense (with the proper loads). How­ever, this ri­fle is also ideal for closerange erad­i­ca­tion of small noc­tur­nal varmints (such as rats, rac­coons and opos­sums) that plague agri­cul­ture op­er­a­tions.

... THE ANGSTADTGROB FIREARMS SET THEM­SELVES APART FROM THE HERD

WITH A UNIQUE AND IN­VEN­TIVE DE­SIGN THAT AL­LOWS THE USER TO RE­DUCE BUL­LET VE­LOC­ITY BY AD­JUST­ING 15 BAR­REL PORTS TO DI­VERT GAS FROM THE BAR­REL

INTO THE SUP­PRES­SOR.

Night­time op­er­a­tions re­quire lights or an NVG, but be­cause the lat­ter is far too pricey, I mounted a Stream­light TLR-2HL light/ laser de­vice and con­ducted a jun­gle walk in the woods late at night. Pa­per tar­gets were set along a trail at 15 to 50 yards into the woods, both par­tially oc­cluded or in the open.

THE UDP-9i IS A VERY ADAPT­ABLE

SHORT-RANGE TAC­TI­CAL WEAPON.

ITS ABIL­ITY TO SQUELCH SOUND

AND FLASH SIG­NA­TURES MAKES IT AN OB­VI­OUS CHOICE FOR LE/ MIL USE AND HOME DE­FENSE (WITH THE

PROPER LOADS).

The TLR-2HL is a highly ver­sa­tile unit with which I have prior ex­pe­ri­ence. At 800 lu­mens on the “high” set­ting, and with a red laser, it eas­ily il­lu­mi­nates and pin­points tar­gets at the en­gage­ment dis­tances typ­i­cal when us­ing a 9mm ri­fle. Yet, it is com­pact enough to fit onto a pis­tol. I like its switch­ing and mount­ing sys­tems. These switches are ac­ti­vated with the in­dex fin­ger when used on a pis­tol or with an ex­tended switch cord for eas­ier use when mounted on a ri­fle. A small tog­gle switch al­lows you to in­stantly change from “light” to “laser” to both, while a rocker switch gives “mo­men­tary” or “con­stant on.” This unit can be quickly mounted and dis­mounted with­out tools to 1913 rails and Glock-style rails, mak­ing it easy to re­move for hand­held use.

I found that this light worked very well at il­lu­mi­nat­ing any of the tar­gets within 50 yards—and it would have worked had I

set them at 100 yards. The beam was even, with­out a hot spot. Mount­ing un­der the bar­rel at the for­ward end of the rail, rather than on the side, works best, be­cause the laser is eas­ier to sight-in, and you only need to ad­just el­e­va­tion to pin­point more-dis­tant tar­gets. The beam gets some­what oc­cluded by the end of sup­pres­sor shroud, which ex­tends in front of it by sev­eral inches, but that’s un­avoid­able.

Fi­nally, this unit weighs only 4.8 ounces, so it didn’t no­tice­ably di­min­ish the ri­fle’s han­dling char­ac­ter­is­tics, even when mounted far for­ward.

FROM AG­GRES­SORS TO RAC­COONS

The UDP-9i is a ver­sa­tile plat­form well suited to sport shoot­ers, home de­fend­ers and LE/MIL, alike, and its abil­ity to mount on a va­ri­ety of ded­i­cated Glock mag­a­zine-com­pat­i­ble AR-15-style low­ers is a real ben­e­fit. Ac­cu­rate with heav­ier weight loads, this ri­fle is also re­li­able and very ef­fec­tive at sound re­duc­tion. The port­ing sys­tem works as ad­ver­tised: No first-round pop was no­ticed, and the shooter has the op­tion of us­ing economy ammo to achieve sub­sonic ve­loc­ity.

Adding the LAW Tac­ti­cal folder adds an im­por­tant el­e­ment of con­ceal­ment and dis­crete carry, while a light/laser, holo­graph sight and a sling make it mis­sion ready to help solve most CQB prob­lems—from crim­i­nal ag­gres­sors to ra­bid rac­coons. GW

I

A con­nec­tor links the mag­a­zine fol­lower

to the bolt catch. Angstadt’s con­nec­tor is in­ten­tion­ally made to be light­weight and loose fit­ting, be­cause mag­a­zine spring ten­sion is at its least when empty,

and the fol­lower needs to press the con­nec­tor up­ward to make the bolt catch

work. Chang­ing to the Wolf extra-power spring will im­prove

re­li­a­bil­ity.

Two bolts—one with the ex­ten­sion needed for the LAW Tac­ti­cal folder (left) and one with­out. Note that the key is staked prop­erly. In ad­di­tion, the car­rier will work on fully au­to­matic

low­ers.

The large “win­ter trig­ger guard” makes ac­cess­ing the trig­ger

easy when the shooter wears a thick

glove.

The stan­dard stock and grip are from

Mag­pul and far bet­ter than MIL-SPEC com­po­nents. The

grip’s stowage com­part­ment holds bat­ter­ies for optics.

The LAW Tac­ti­cal fold­ing adapter is very rugged and firmly locks into place. Note the small latch but­ton at right.

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