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Thread: HW90 .22 compared to RX2 .22 pellet velocities

  1. #1
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    Nov 2012
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    102

    Default HW90 .22 compared to RX2 .22 pellet velocities

    Kevin,
    I always thought the HW90 and RX2 gas rams were mechanically the same gun. What mechanical differences would there be that would cause the HW90 to have slower pellet velocities than the RX2?

    I noticed in your velocity chart for the .22 HW90, many pellets have a lower velocity than the same pellets in the chart for the .22 RX2? For example, take the FTS. It's 804 fps at muzzle for RX2 and 778 fps for the HW90.

  2. #2
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    Jan 2010
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    Default Re: HW90 .22 compared to RX2 .22 pellet velocities

    T-Bone
    The RX-2 and the HW90 are the SAME actions with different stocks. The only differences have nothing to do with the action per se. Beeman versions set up the action with a laminate stock, a muzzlebrake and a set of 2 piece mounts. They also eliminate the iron sights because most airgunners use scopes. The HW90 is the older version that Beeman used to call the RX-1 years ago. It has iron sights and a beech stock. I have had one for 13 years now in .20 caliber. But the action that goes into the stock is exactly the same.
    So...what causes the difference in velocity. There are all kinds of things that cause differences in velocity for any spring or gas ram rifle. I realize that many shooters assume that gun models are always identical or that pellets always weigh their advertised weight. But I do the Our Take testing on all the guns and I can tell those shooters that the word "identical" never applies to any gun model or pellet type. It simply doesn't exist except as a coincidence. In fact, on our main page, on the right side, is an article that I wrote called the "Our Take Why & How" and in the second paragraph I allude to pellet weight and gun models varying from one to another.
    The reasons for the RX-2 v.s. the HW90 result variance could result from a number of reasons and some never get discussed on forums. One possible reason could be if the charge in the gas ram wasn't quite charged to full power then the velocities will be slightly different than from a gun with a full charge. Or even if the charge levels are the same, if one model has a bore that is slightly smaller then it may be within tolerances but the pellets will fit tighter and consequently there is more drag meaning decreased velocity. However, sometimes that also means better grouping because pellets that fit snugly tend to group better overall. So one gun might have slightly less velocity but possibly could group better. And pellets can vary in head size, skirt size, weight or whatever from one tin to another resulting in slightly lower or higher velocities. And let's not overlook the fact that I shoot these pellets through 2 chronographs and if the pellet goes through the chronographs at different spots it can change the velocity by a few fps also. Our chronographs will reject any shot that is too far off the mark automatically but there can be a few fps difference nevertheless.
    Bottom line is that there are a number of things that can affect velocity differences. The results in the Our Take are average velocities of a string, not the highest velocity per string.
    Do the 26 fps difference you noticed amount to much in reality? Well one gun is shooting the FTS at 548 mph and the other at 530 mph. So from a practical standpoint, in terms of hunting or pest control, the difference won't make any difference at all.
    Kevin
    straightshooters.com

  3. #3
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    Default Re: HW90 .22 compared to RX2 .22 pellet velocities

    26 fps is nothing to sweat about. Same rifles don't have exact same velocities and it could be as simple as the difference in pellets' weights. What you see are average numbers. For springers it is sometimes as simple as different amount of lubes. If you ever chronographed Match grade .22lr ammunition you will easily notice that advertised velocity flactuates...and that is with Match grade ammo. And if your testings are done in the uncontrolled environment, the spread will be even wider.
    Camouflage Ten Times, Shoot Once

  4. #4
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    Nov 2012
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    102

    Default Re: HW90 .22 compared to RX2 .22 pellet velocities

    Kevin,
    Thank you for your detailed explanation. Even with all those theoretical and actual variances, you mention, it still doesn't make sense to me that you would get lower velocities across the board with the HW90. I understand that things could be different from pellet to pellet, tin to tin, gun to gun Chrony to Chrony etc., but after all, with all these variances being equal, then one can assume from the chart that the RX2 is the more powerful rig. Right?

    Both models test different across the board in pellet velocity, with ALL the variances you mention. That being, the HW90 is shooting slower with everything put through it. So wouldn't that also mean that something is different in the gun? If not, why show a velocity chart for both models? Especially if your saying the guns are the same action with only different wood and name. Not trying to beat a dead horse here but something is still amiss. Isn't the reason to show charts on different models, to show differences in performance of those models?? Maybe It's just me, but I'm still not getting your explanation.

    However how many of each model did you test and average? Maybe you only tested two guns and not several, then averaged just the two?? Then the variances would make sense to me. However, I thought you tested several of the same model to get the average.

    Ambush Hunter,
    Nobodys' "Sweating over 26 fps". I'm making a point about the velocity charts on both guns. And their differences across the board. Not the difference in one particular pellet. The example I gave on the FTS pellets was just that…an example, not a complaint or single pellet velocity comparison. I know about the many actual and theoretical variances, Kevin made that real clear already. I'm sure there are many more we haven't touched on. But thanks for the input about grease.
    Last edited by T-bone; 01-03-2013 at 04:29 PM.

  5. #5
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    Default Re: HW90 .22 compared to RX2 .22 pellet velocities

    T-Bone,

    more than likely, it's a simple case of one ram being per-charged slightly more than the other.
    .22 Theoben Eliminator/.20 Beeman R1/.17 HW97/.17 TX200/.22 Daystate Airwolf MCT

  6. #6
    Join Date
    Nov 2012
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    102

    Default Re: HW90 .22 compared to RX2 .22 pellet velocities

    Scott,

    If only one RX2 and one HW90 were used for the velocity tests, then your undercharged ram theory, and ALL other variables WOULD directly affect the velocity outcome.

    I guess what it comes down to is, HOW MANY of each model were tested. If three RX2's were tested and three HW90's and an average done on the velocities, that would probably rule out your undercharged ram theory and the many other incidental variables. This would make the velocity tests more accurate, since it would not be hinged on single gun tests. But that would be a TON of work!

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