Thread: .17 HMR blow up

Originally Posted by Sharki

Better than blood or aqueous humour ( eye fluid)

spontaneous incontinence ??

While on the subject, I had a brand new Anschutz .22..fired a few old CAC rounds through it, heard a dull pop, fired another round: there was a loud CRACK and it felt like someone had thrown a handful of sand in my face. It was fragments of the front end of the bolt. If I hadn't been wearing sunglasses, I would have lost an eye. I always wear glasses at the range now. The photos attached are of a .22 barrel which had been dropped in the mud then fired, and the second is of a D/B shottie inadvertently loaded with a double charge. The shooter lost 2 fingers.

"Current standards (SAAMI) show the pressures in PSI. For the 22 Long Rifle and Magnum (and the 17's), the allowable pressure is 24,000 PSI."

Guy Neill
CCI-Speer Technical Services
866-286-7436


Interesting topic.
I had just assumed 17HMR was way more pressure than 22LR - that would result in the problems discussed here.
Not so. As the above quote from CCI rep.

I recently had to make the call for buying a new possum-rabbit gun.
I was very tempted to get a 17HMR, but in the end went with the proven 22LR (CZ457 Varmint) which has the quick-change barrel option, if required (22LR 22MAG 17HMR)
(.22LR CCI stingers come out of the barrel at 1550 fps) - If I was after some more exiting velocity.

Anyhow, I am really glad to have read this thread. I won't be getting a 17HMR in a hurry.
I am going to stick to my original plan, keep the CZ in .22LR for close subsonic work, and keep looking out for that rare beast, a .17 Hornet, and smack that ball right out of the park.
Cheers.

Hi bobbydazzler
As far as pest control ammo goes ! It's great in the fact it fragments very well.No bouncing the round or ricochets in my experience, the 20gn not so, I haven't tried the 15.5gn. I may try it for the built up areas.
If you read the thread, it's old ammo and humidity seems to be the main factors.
I have a handful of. 22lr and a. 22 magnun they are hardly used in the areas I shoot. I have heard the 22lr ricochet off sandhill County and that's no good on the life style blocks I shoot. I fired 30 odd last night and not one split case.
The A17 ammo is 100ft faster than the standard 17hmr and pressure is around 26,000 psi For he standard 17hmr ammo.
KH

@bobbydazzler Quick FYI I saw this listing you may be interested in: Weihrauch HW60J Sporter 17 Hornet Rifle https://www.trademe.co.nz/4498281817

I own 4 HW60J ( New model code HW66CH - Classic Hunter comes factory threaded with no iron sight) 2 X 22LR, 1 X 22 Hornet, 1 X 2222 Remington. I swear by them for accuracy, excellent engineering and fit. I bought the Hornet through r Reloading Supplies, they were $500 cheaper than the big green store. Marston are the importers and will happily advise you of who has stock in NZ and when the next shipment of the CH model is due. Good luck.

I'm reloading my 22 Hornet for less than .17 HMR rimfire and I'm not having the case problems the .17 HMR shooters are experiencing.

Hugh Shields Controlled Rabbit Culling Wellington - Kapiti

Hi Hugh Shields
The 17 hornet is a flat shooter for sure and of course the cases are annealed so not the likely hood of the same problem.
The 17hmr at night I hardly push it passed 150yrds, I find that is the comfort zone for me.
After that I use the 223 with 40gn vmax if the area is good for it and I have a K hornet that I am yet to really play with using 35 v max.
A little off the topic, however certain area's are good for a longer ranger at night, the flavors are many.
The night and the rest, all have their limitations and weight has a limit for me these last few years.
KH

On the change barrel cz rifles if there is any bulge on the head of a fired case I
Have given the barrel shoulder a skim in the lathe to tighten up the headspace
To more minimum specs
but all of the 17 rifles I have had through the door
90% have let go due to hornady Winchester or browning ammo

Cci or federal is better but have seen squibs from all manufacturers
If the stuck projectile is 5” back from the muzzle can usually
Get the projectile out and save the barrel and retain accuracy
Got a Sako quad barrel from a customer that was saved the first time
Using grease and 1/2x20 adapter but the second time it was stuffed

While showing a friend who’s a retired, clever tooling engineer, the head space shims for my CZ 457 we ended up in a world of head space & projectile seating issues with different 22 lr ammo which explains why certain ammo suits in an individual gun.
With the humble 22lr, low pressures, it is preferable for the projectile to touch or press into the lands for concentricity/accuracy. Obviously not so great for a hunting set up, as the shot must always be fire once chambered. There was no 22lr ammo that achieved this in my CZ sporter so we talked about machining the barrel to achieve this.

Next subject revolved around the 22 HMR mentioned, for the price of the ammo, I was non plus ed about the accuracy. Having seen spilt necks etc & the for mentioned horror stories in this article.

Thought s are any & any Gun Smiths, I would love you to chime in, would be most appreciated.

The HMR is still head spaced off the rim.
Head space was 4 thou. Head space on case rim to chamber shoulder is about 20thou. With such a thin brass case expecting the shoulder to grow that much is expecting too much, with the high pressures of the HMR. The free bore of bullet to rifling is about 90 thou so this is used to reduce pressure, but to the detriment of accuracy. With these dimensions, the HMR is rather undone, for an ammunition / chamber, I wouldn’t expect this from a designed round?

I'm not a gunsmith, and I don't have all the answers to your questions. But a couple of points: a .22 chamber cut to engrave the bullet on chambering does not prevent you from unloading a fired round provided you have a rifle with decent extraction. 30 thou. (0.76mm) engraving is a good figure from my limited experience - best measured as the distance an unfired cartridge sits above the breech face with pushed in with light finger pressure vs. seated fully home. My Ruger 77/22 is setup as a hunting rifle and has zero problems with extracting live rounds from such a chamber.

The other point is I don't think you've got your HMR dimensions quite right. The .17HMR headspace should be in the range 50-56 thou (0.050" - 0.056") as per SAAMI, not 4 thou. Or are you talking about a 4 thou difference between the rifle headspace and the rim thickness of a loaded round? I'm not too sure about "Head space on case rim to chamber shoulder is about 20thou" either, but I can tell you that when trying to stop .17m2 ammunition splitting I had that barrel's chamber shortened to minimise shoulder clearance. Didn't help any I could see - the cases split anyway. Probably not too surprising given that they sometimes split just sitting in the box.

Anyway, my .17HMR is comfortably and repeatably sub-MOA at 100m. I haven't really shot enough targets to tell you just how far under 1MOA it averages, but that's pretty good from my perspective.

EDIT: Sorry, best you be careful with the above. I forgot that the 30 thou engraving was what I used for a 'Bentz' chambered barrel with a shallow leade angle. The standard 'sporter' chamber commonly used on factory rifles has a much steeper leade of 5deg, and that length of engraving could be too much. My bad.

Must point out HMR measurements for a Marlin. Which appearently shot the old ammo the best.