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Observation Regarding Underwood 155gr

Discussion in 'The 10 Ring' started by G29SFWTF, Sep 11, 2012.

  1. G29SFWTF


    Aug 3, 2012
    Currently I prefer 135 grain 1600fps JHP from Underwood for a defensive round. For the range I recently bought some Underwood 155gr Total Metal Jacket 1500fps for no other reason than it's the cheapest box of full power 10mm that I know of.

    The 135gr recoil is very manageable and this bullet is only 20 grains larger than that so I loaded it up for the first time the other day not expecting much kick and the first shot felt like someone was trying to knock the gun out of my hand with a baseball bat. Maybe it also felt stronger because I wasn't expecting it but still I had to double check the box to be sure I hadn't been sent the wrong ammo.

    I went home made a list of the specs for each UW round and discovered the 155gr was just as stout on paper as it feels when shooting.

    gr..... fps .....PF..... ft.lbs.

    200 1250 250,000 694 ft. lbs.

    180 1300 234,000 676 ft. lbs.

    165 1400 231,000 718 ft. lbs.

    155 1500 232,000 775 ft. lbs.

    135 1600 216,000 767 ft. lbs.

    In fact it's #1 in muzzle energy, #2 in velocity and comparable in power factor to the 165 and 180 grain. Maybe this is a question for Kevin Underwood but do these numbers suggest the 155 has a high, maybe the highest powder to bullet weight ratio of Underwood's 10mm line?

    Regardless it seems the 155 might be a good choice for those wanting the highest velocity possible but more penetration than a 135gr could offer (assuming JHP not TMJ for defensive). Particularly because you can get the 155 in a bonded bullet but not the 135.

    As far as accuracy, at 10 yards I was able to keep almost all shots in the white vital area with slow, deliberate aiming; using one of those ATF targets with no clearly defined bullseye.

    I don't think I'm skilled enough to rapid fire this round yet unless maybe at 3 yards or so.

    Gun: glock29sf, KKM barrel, 23lb spring

    Here is a youtube user who posted a google doc with real world test results from various 10mm. Look at what round is #1.
    Last edited: Sep 11, 2012
  2. SDGlock23

    SDGlock23 Glockoholic

    I'm not really sure what you're asking specifically, but the 155gr does seem like the best choice for those who want speed and a bullet that will hold together. I would think the 155gr would kick more than the 135gr, sure there's a 100fps difference (which isn't much IMHO) but a 20gr jump in bullet weight offsets that and I could see where it would kick more.

  3. G29SFWTF


    Aug 3, 2012
    I guess I was just surprised that the 155 has the most muzzle energy of all the UW 10mm line and though I don't reload, as I understand it when bullet weight goes up then amount of powder must go down so that bad things don't happen. But from the specs it doesn't look like the performance scales uniformly. So I wondered if the 155gr is kind of a sweet spot that allows for the highest powder to bullet weight ratio and therefore giving the most ME.
  4. nickE10mm

    nickE10mm F.S.F.O.S.

    Apr 13, 2004
    Wichita, KS
    Well, keep in mind that the "Muzzle Energy" that you refer to is simply a function of Mass and Velocity (squared)... which means that Velocity contributes more to the higher energy numbers than does mass.

    In addition, ME is only part of the equation as to how "effective" a load is. Momentum and striking surface, displacement and penetration are also functions of the big picture.

    So, while the 155 / 165 is very much Muzzle Energy sweet-spot in 10mm, that doesn't necessarily mean that 155gr loads are the "best" due to the ME number for a given task... since we need bullets to do different things for different purposes.

    :) Clear as mud
  5. drsjr1969

    drsjr1969 "10mm ammo" FB

    Mar 3, 2011
    Check this out about 155 gr.

    [ame=""]10MM AUTO and 44 MAG vs Grizzly skull plate - YouTube[/ame]
  6. cowboy1964


    Sep 4, 2009
    There is a lot to be said for practicing with a load that gives the same recoil and feel as your carry ammo.
  7. G29SFWTF


    Aug 3, 2012
    Yep makes sense. For what I value in a 10mm SD round the 135 and 155 are the most attractive and the properties of the 155gr at full power are very interesting.
  8. G29SFWTF


    Aug 3, 2012
    Nice video. I don't know what a grizzly skull plate is but I'll be sure not to hide behind one when 155gr TMJ's are flying around.

    Have you ever shot 155gr at AR500 steel? I have some target plates which I have not yet shot at with a 10mm but now I wonder if it might ding the surface.
  9. drsjr1969

    drsjr1969 "10mm ammo" FB

    Mar 3, 2011
    I don't know the metal makeup of the plates I shoot at. I come across scrap very rarely so I'm happy just to find something big enough to shoot multiple times.
  10. cadjak


    Mar 16, 2005
    I don't know what I think about the Underwood 155gr. I tested some using wet phone books as test media. It went through about 22 inches and then took a chunk out of the tree they were resting against. I compared it to some Doubletap 200gr hardcast, which also penetrated the phone books, and then burried itself into the tree. The Underwood lost about 15% of it's weight. The piece that I recovered weighed 132gr.

    These are entrance holes. The larger one, on the left, is from the UW 155GR the smaller one from the Doubletap 200gr hardcast.

    Fired at a distance of 30 feet.
    Glock 30 w/KKM 10mm conversion barrel and 23Lb spring.
    Last edited: Sep 13, 2012