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Subsonic HMR ammo


12borejimbo
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That's a bloody good question! If there was subsonic ammunition available for the 17HMR just think about how much better the rifle would be with a sound mod fitted when you could get rid of the sonic crack! Then you could have the ideal bunny bashing rifle!

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OK quick look, obviously not using any decent measurements its has pretty much a trajectory of my 32ft/lb rapid in .22.

 

Energy retention is better though.

 

This is calculated with a 17g bullet at 1100, which is near as dammit (25fps not taking environmental changes into account) the speed of sound.

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What would be the point in a subsonic HMR round? You'd need a hollowpoint to get it to fragment and the copper jacket would probably stay intact anyway...

 

If you want a subsonic .17HMR, get an LR. The bullet will just fly on the same trajectory as a 22lr, as the speed will be the same.

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The definition of sub sonic is something travelling below the speed of sound! :no: Super sonic is faster than the speed of sound. The speed of sound in air at sea level is 343 m/s or 1126.547 ft/s (768.095 mph) at a temperature of 20°C or 68°F

Edited by Blunderbuss
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What a waste of time that would be at only a couple of hundred feet per second faster than a .177 air rifle, bullet wouldn't expand / fragment. The whole point of the HMR is the flatter trajectory slowing it down and creating a gun inferiour in every respect to the .22 is just plain crazy. If you want something quieter use the .22 sub something quieter and safer FAC air. .308 win subsonics are a specialist sniper round for military use and have no relivence to the civilian market (they are also very difficult to come to terms with in use)

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What a waste of time that would be at only a couple of hundred feet per second faster than a .177 air rifle, bullet wouldn't expand / fragment. The whole point of the HMR is the flatter trajectory slowing it down and creating a gun inferiour in every respect to the .22 is just plain crazy. If you want something quieter use the .22 sub something quieter and safer FAC air. .308 win subsonics are a specialist sniper round for military use and have no relivence to the civilian market (they are also very difficult to come to terms with in use)
not to mention,if u download a 308 that low you risk it detonating not burning. sub sonic .17 hmr,do me a favour. wat next light load for solid slug? or maybe a parachute?
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not to mention,if u download a 308 that low you risk it detonating not burning. sub sonic .17 hmr,do me a favour. wat next light load for solid slug? or maybe a parachute?

308 subsonic loads are common use for the military and Lapua actually make a factory subsonic round but its not of any real use to civilians

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What would be the point in a subsonic HMR round? You'd need a hollowpoint to get it to fragment and the copper jacket would probably stay intact anyway...

 

If you want a subsonic .17HMR, get an LR. The bullet will just fly on the same trajectory as a 22lr, as the speed will be the same.

 

 

Not unless they are the same weight and have the same BC, similar up to a point, but a 40g Sub Sonic LR will carry its energy far better than a 17g HMR, and also carry it further!

 

ATB!!

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308 subsonic loads are common use for the military and Lapua actually make a factory subsonic round but its not of any real use to civilians

 

 

A lot of IMSSU shooters used subsonic loads for comfort and longer life of the weapon. Mostly home loads, as a lot of the weapons are wildcat carts. The detonation issue was overcome by filling the top of the case with a synthetic fibre before seating the bullet. This kept the powder against the primer, and it as good as burned to nothing when fired. I can never remember the name of the wool like fibre, but often have thought of loading large cal. subs.

 

A 177hmr in subsonic? A catapult would outperform it!!

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Frankly I see a sub sonic HMR about as useful as a chocolate fireguard!

 

ATB!! :good:

 

I agree, although I know little about BC's etc. I am a scientist of sort, and looking at the details, a .22 fac air will do the same near abouts. Interesting topic though. as others have said, the hmr is made for purpose.

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Not unless they are the same weight and have the same BC, similar up to a point, but a 40g Sub Sonic LR will carry its energy far better than a 17g HMR, and also carry it further!

 

ATB!!

 

The bullets should touch the ground at the same time, but be a small distance apart, but not too far off

Edited by Billy.
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A lot of IMSSU shooters used subsonic loads for comfort and longer life of the weapon. Mostly home loads, as a lot of the weapons are wildcat carts. The detonation issue was overcome by filling the top of the case with a synthetic fibre before seating the bullet. This kept the powder against the primer, and it as good as burned to nothing when fired. I can never remember the name of the wool like fibre, but often have thought of loading large cal. subs.

 

A 177hmr in subsonic? A catapult would outperform it!!

 

IMSSU ? indulge me, is this some form of nancy boy indoor shooting or something? :yes:

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Maybe not pointless for someone who doesn't have FAC air? I find CB Longs very useful in my .22lr and they're the same. It would be good for HMR owners to be able to load a subby for close shots now and again, perhaps if a Pigeon landed in the tree above where they were shooting bunnies? If they made them I'm sure some people would buy them, just not enough to justify the production run.

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