The HW90 uses Theoben gas strut technology while the R9 is powered by a standard coil spring. In answer to your question, the R9 and HW90 are two completely different animals. I agree, that write up pretty much touched on all issues concerning the HW90. I would hope that those discouraged by high cocking effort and low power take a second look. It's long enough to reach through the hole from the other side of the receiver.Ĭonclusion - I love my HW90. To deburr the inside of the receiver holes, I use a swiveling deburring tool, and put it into a pin vise, see photo. The inertia piston deserves a closer look. I ordered a Vortek piston seal, and may retest later. It may be possible to reduce weight to 7.5 pounds. It’s got me thinking about fabricating a aluminum stock. The bare gun without a stock, iron sights or inertia piston weighs only 6.4 pounds. I found recoil to be comfortable, even at 26 bar. I did these tests without the stock, holding the receiver with gloves. People say that gas-ram magnum springers have harsh recoil. At that level you get maximum power, and cocking effort is very reasonable. IMHO, the sweet spot appears to be 18 bar. Ideally all HW90’s should be sold with the understanding that they need to be tuned. I think the factory sets them all at 26, and expects people to tune them down themselves. The 26 bar limit is just an engineering maximum. Cocking effort and recoil also seemed about the same. I removed the inertia weight and checked velocity. The power vs bar curve appears the same for both. Any higher made it harder to cock and dropped power dramatically. I found the highest power (21fpe) is about 19 bar, not at 26 bar. It’s easy to creep down to the target level. Doing so drops ram pressure about 1/4 of a bar. Each time you depress the head, it empties its small internal plenum, and takes a new reading. You take a reading by depressing the head.
You just screw it into the schrader port in the back of the gun. The Weihrauch pressure gauge is ideally suited for the job. You start high, and work your way down to the target pressure. But it’ll get you pretty close to 26 bar in about 10 pumps. The Hill pump’s gauge is meant for much higher pressure levels and doesn’t have fine resolution for this job. You screw the two adapters together, and they connect the Hill pump and the schrader port.
Available from Best Fittings in UK.Ī quick release to 1/8 BSPP adapter. To charge the piston I used a Hill Mark IV pump, and two adapters.Ī Schrader to 1/8 BSPP adapter. I used the Weihrauch HW90 pressure gauge.
#HW90 GAS RAM PRESSURE SERIES#
I ran a series of tests, measuring the velocity at different ram bar pressure levels. Receiver and barrel assy without inertia piston, sights or stock = 2911 grams Gun overall = 4275 grams, or 9 lbs 7 ouncesīeech stock = 1224 grams, or 2 lb 11.2 oz. I didn’t actually measure the cocking effort but it was very high. Funny, Weihrauch’s site says 4 kg, or 8.8 lbs. I measured the overall gun weight at 4275 grams, or about 9.4 lbs. I really like the distinctive checkering. I also ordered a Weihrauch HW90 pressure gauge and a. I decided to bite the pellet, buy one, and figure out what’s going on. There have been several posts about low power, hard cocking, weight and general tuning questions.
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