The 17 HMR at 300 Yards

[Matt304]

About a week ago I decided to launch some 17 HMRs a little farther than usual. It was dead calm so I thought it would be fun. Don't try this with any wind.

This is at 303 yards on the rangefinder.

I believe I was cranked 14.5MOA up from a 100 yard zero.

10 shots were fired. 3 went above the paper. Bullets were just making it through the 5/8" OSB and some were laying on the ground with noses broken off.

I find it interesting that these little bullets can remain in somewhat of a group at such distance.

It was a Marlin 917, 17 grain Remington ammo, and the velocity average was about 2575FPS. The extreme spread was around 70FPS if I recall correctly. I wish there was a way to sort the ammo a little better.

Squares are exactly 1x1".

 

[t george]

good shootin! i dont have alot of trigger time with the 17 hmr but i do with the Mach 2 and it is a very fun round to play around with.

 

[rangerruck]

sort by two ways; rim thickness, and OA LENGTH. this will shrink your groups considerably.
also replace the return spring, with a bic pen clicker spring, or cut 1 coil off of yours.
then take rifle out of stock, thorougly rough out the stock channel, very well, and reaseal with varnish or Minwax. the marlin really likes an open stock channel.
considering that group; you are shooting sub moa at 300 yds, with freakin 17 hmr dude, how
awesome is that???

 

[Matt304]

sort by two ways; rim thickness, and OA LENGTH. this will shrink your groups considerably.

Thanks for the tip, rangerruck.

I looked at some of those rim thickness gauges and wondered if it would help the HMR. Maybe I should go ahead and try one. I'll also get a .17 cal insert for my comparator to measure base to ogive on them and see if that helps.

 

[rmuzz]

Nice target!

Was just wondering though if the farthest upper right hole looked a bit sideways to anyone else though. What is the .17hmr bullet doing velocity wise at that range do you think? Every time Ive tried doing reading on long range shooting with plain ole' .22lr I hear past xxx yards it drops through sound barrier and keyholes more often, and other areodynamic complicated stuff I didnt quite get. Does the the .17hmr do that too at a certain point? It sound like it cools off quite a bit there by the time it reached your OSB board, but is there wierd stuff going on ballistically at that range or am I looking too far past the fact that its cool that those little bullets group as well as that at an extreme range? Any ways, cool thanks for post that pic.

 

[50caliber123]

I hear the reason subsonic .22LR is used in match guns is to prevent keyholing as supersonic ammunition becomes unstable as it slows to subsonic speeds.

 

[Matt304]

rmuzz,

Basically, think of a shock wave as a traveling object moving at a constant speed, since it is a vibration of the air. If you stand still, the wave moves away from you. If you were to accelerate faster and faster towards it, you would catch up to the wave, and eventually pass it.

Now think of this in reverse. The bullet is moving out ahead of the pressure waves it is making, since those waves travel at the speed of sound. They are also quite strong. As the bullet slows down, the waves start catching back up to the bullet, and when it crosses the speed of sound, it meets up with the erratic pressure zone that was dragging behind it. This pressure tends to bump the bullet around in unpredictable ways at times, and is what causes some projectiles to turn sideways when they pass the sound barrier.

I have looked at the hole a few times now and I think it is starting to keyhole because of the way the paper is also ripped. It may be hard to tell, but the 2nd hole on the top row also appears to be slightly keyholed when closely examining.

Using the group drop MOA and FPS data to get a rough BC prediction, I get 975FPS at 300 yards, or mach .88.

 

[rmuzz]

Cool, thank you for the explanation! Sorry to take it off topic, but well it was relavent I guess. Post another target if you sort your ammo or make changes to tighten that up any, its interesting finding threads like this amongst the endless AR/AK debates. I have a spot on my wish list for a .17hmr, so I've been reading some on what rifles are out there and what the round itself is capable of.... just keeps getting more unbelievably good

 

[Tim the student]

Man, that is awesome! Makes me want one more now.

 

[rangerruck]

if you find a fast lot# of ammo, try to chrony it, and see if you can find some as close to 2700 fps as possible, this way, you will stay supersonic at 300.
Another problem that the 22 round suffers from, is unique to the 22round, it is even diff from 22 cal bullets that are center fire. Because of the relative flat meplat on a 22, and it's gently but regularly curving face up to the ogive, and because the front air pressure speed seems to stay constant, while the bullet slows down very fast- the front air pressure wave hits the front of the 22 round, and then bounces down the face/ogive of the round, like a dude dribbling a basketball. It will smack down on the round several times, before it quits smacking back down into the bullet, and then , just to finish it off, if you are shooting a flat base bullet, the last of the air pressure wave, as it goes on by, grabs the back of the flat base, to give it a little tug of war match, just one last time. this doesn't happen , that we know of, with any other bullet.
and it is really bad with a 22 mag; a 22 mag will lose fully half of it's speed, from the muzzle, out to 100 yds.

 

[Matt304]

So far I have only chrono'd 2 boxes of ammo, and both were somewhat similar FPS (CCI and Rem). Now the accuracy between them is always similar results, with the smaller Rem group sizes about half of the CCI. I have a few 5 shot groups with the Rem ammo at 100 yards that measure 0.2".

There were some ammo tests where a few types of HMR ammo was around 2650FPS. I'll have to try a few more brands. The local F&F chain only sells those two brands, and I don't get out much looking for ammo as HMR is the only factory ammo I buy anymore.

I remember reading about a guy in Shooting Times who was developing the HMR back before it was the HMR. He was using primed 22WMR brass necked down, and getting the 20gr bullets to 2700FPS! So you can see this case has more potential than we get to experience.

What I thought about doing a little while back was reloading the HMR. Before everyone jumps at how dangerous it sounds, all you would really need to do would be to put a clear plexiglass box over the reloading press with a hinged side door. Then get a custom shell holder that supports the full base, and a custom sizing die. HMR bullets could be pulled, then iron the neck crimp out with an expander, size neck, and put new bullets and powder back in. If one were ever to go off, the plexiglass box would contain the blast. But I have heard it's no problem to do with a light hand.

 

[sscoyote]

Actually i've considered going to a 14-17HMR. There are some that are "reloading" the rimfires.

That is a nice group u got there. Try readjusting the BC and MV of the load until the 300 yd. trajectory reads maybe 1.25 MOA less, recalibrate the turrets and/or the reticle based on the new trajectory curve, then set a pop can up there and nail it on the 1st shot...maybe??

What optic r u using?

 

[jbech123]

a 22 mag will lose fully half of it's speed, from the muzzle, out to 100 yds

Don't think so. Makes the rest of your post kinda suspect as well.

http://www.federalpremium.com/products/compare/rimfire_compare.aspx

 

[Matt304]

Try readjusting the BC and MV of the load until the 300 yd. trajectory reads maybe 1.25 MOA less, recalibrate the turrets and/or the reticle based on the new trajectory curve, then set a pop can up there and nail it on the 1st shot...maybe??

What optic r u using?

I'm not exactly sure what you are trying to say about the 1.25MOA thing.

Odds are limited that you will ever hit a popcan on the first try at 300 yards. New conditions in each shooting session move the HMR to a completely different zero, even at 100. A 2mph wind change would likely cause it to miss the paper completely at 300. It's really not a 300 yard target cartridge by any means, only about 5% of the time around here when conditions are perfect with no wind.

The scope used was a Millett LRS on 25x.

 

[rangerruck]

jbech, yes, they will or darn close, federal, like most ammo boxes, are generous with their findings , to impress you. unless you are using accutip bullets, most all of your 22 mag rounds, will be below sound barrier at 100 yds; a slow moving , or standard 22 round, will be moving at about 800 fps at 100 yds, even though they started out at just over 1000 fps, to stay under the speed of sound.
the 22 mag sheers off speed, like a drunk chick vomiting out the rear window of your car! it is that ugly, violent, and noticeable.

check the bullet drop of a 33 grain vmax accutip bullet here, it is almost as bad as a 22lr.
http://www.varmintal.com/17hmr.htm
then check some speed drop here
http://www.chuckhawks.com/rimfire_ballistics_table.htm
some of these are typo's , but you can see some of the 22 mags are really shedding some speed.
then compare that speed loss, to standard velocity 22lr, or 22 short , or 22 long, at 100 yds.
couple more 22 mag velocity numbers here;
http://www.chuckhawks.com/compared_17HMR_22WMR.htm

that's why a 22 mag, after about 100 to 120 yds, drops like a cement block.

 

[jester_s1]

All bullets lose alot of speed during the transonic portion of their trip to the target. That was the point of the 17HMR. Start out well ahead of the sound barrier to cover more ground before losing it all during the transonic zone.

 

[Matt304]

The transonic region has a small curve where drag is a higher, but there is not a drastic spike if drawing on a graph. Something moving at 1300FPS still has more drag than something at mach 1.0. I have an aerodynamic simulation program which I will post a photo of a graph generated from it below in the attachment. It shows drag through the transonic region. The body used in the sim is similar in design to a pointed bullet.

Shape also provides more value into the square function of drag, of course. So an incorrect shape may yeild a square of increased drag as the velocity increases over a shape which is very pointed. This is why flat nosed bullets lose BC as they go faster, and why pointed bullets lose BC as they go slower. So when you try to push a blunt object faster, I.E. 22 rimfire bullet, things get worse instead of better at higher speeds--as far as velocity retention is concerned.

Yes, I can attest that manufacturer BCs are often exaggerated. Even the HMR lists BC of 0.123, where I find it to be closer to 0.11.

Now if this is somehow turning into a 22WMR vs 17HMR debate, which it was not intended to be, there could be a solution. Shoot a target at 300 yards with your 22WMR and show the results.

 

[Dr. Tad Hussein Winslow]

If Chuck Hawks is right, that the BC of these 17 gr bullets is around .123, then at 300 yards, it's still going 1,071 fps, with 43 ft-lbs of energy, and will reach the target in 0.568 of a second. "Total drop" is 47.98".

 

[Ned Kelly]

I shot a 3 shot- 2 and a half inch group with the .17 hmr once several years back. Its neat but I wonder what you could kill at that range?

 

[sscoyote]

Matt, the 1.25 MOA adjustment will bring the trajectory reference with the optic more in line with what your true trajectory is giving you. Certainly the air density changes will cause a slight change in trajectory, but the point is it will be better than guessing, wouldn't u agree?

As far as hitting the coke can on the 1st shot, of course that's gonna be lucky, but u'll be closer than anyone else probably with a little less luck factor involved in the attempt. I have seen shots accomplished that were more spectacular than that--here's one example--

A couple years ago i was out hunting with a buddies son. He brought his 22 Marlin with him. The rig had a 3-9x Simmons on top with plex reticle. The rig was sighted in for 75 yds. +/-. When i looked at the reticle it appeared to measure (subtend) 6 MOA from x-hair to lower plex post tip @ 9x. I told the kid, who was actually no avg. shot, that if he cranked the power down to 3x it would be about 18 MOA and that would be close to a 300 yd. zero. So while walking through a prairie dog town back to the truck we decided to give it a try. There was no wind that day, and while the kid got set up off a priairie dog mound, i lasered a couple dogs at 290-something. Can't remember exactly. So the kid takes a shot at 1 of the dogs and hits low. He readjusts the zero higher and nails the dog on the 2nd shot. The dog rolls off the back of the mound, and runs back up but hesitates a second on top. Kid shoots and nails him again. The dog rolls off the back of the mound. His buddy comes out to check things out and the kid nails that 1 too in a couple more shots. We walked up to the mound and sure enuf there's 2 dead adult PD's on the back side of it. Now the whole idea here is would this kid have had a chance of hitting those dogs if he hadn't at least attempted to apply a system in the field--the odds would've been a lot less no doubt about it. And like u (shooting at 300 yds. with a rimfire) he had an inquiring mind.

 

[Matt304]

sscoyote,

I realize my zero was 1.25MOA high for 300 yards. I just shot a group, drove down to the target and those were all below the paper, so I cranked it up some, fired 10 shots and then came back to yank the target. My prediction of the BC is based on a 100 yard zero, FPS, and amount in MOA (minus the 1.25) I had to come up in zero.

I will try this again on another day when the wind is dead, and fire a series of targets instead of just one.

 

[sscoyote]

I see, of course. Be interesting to see if the zero changes at all.