17 HMR Ammo issue

[Edinburgh Rifles]

On 10/09/2017 at 17:37, Walker570 said:

The response on the Shooters Forum so far from a pro gunsmith is that the splits are a result of oversize chambers and he mentions some chambers being .009 oversize.

The cases are brittle by nature but from what I can understand, fired in a correct size chamber, the excessive splitting as shown the photo above should not occur.

That is the reason I suggested taking a chamber cast.

I must have been lucky in that both of the CZs I have owned have had properly sized chambers.

cobblers - its plain to see they are split or scored before firing

By definition rimfire cases headspace off the rim.

If they only split AFTER firing this problem wouldnt be a problem as they are not reloaded

only when water ingress causes a misfire, hangfire or squib is the issue really obvious

Otherwise people saying they have never had one maybe havent looked. I have yet to find a box of any manufacturer that doesnt produce a split before or after firing

 

Annealing is not viable for a rimfire round costing pennies

It is not a process that can be inserted as that would drive cost up even more.  Nothing to stop the manufacturer from annealing the WMR case before priming....except money

The brass is wafer thin, its a poorly designed case forming process using metal alloy not suited to such reforming

the HM2 has splits in them too but doesnt seem to have the volume of issues, primarily due to the reduced number of people using them and the much smaller volume of ammo used I would imagine.

That said I have never had a misfire or issue with the HM2 but have had several with the HMR both barrels in a Sako Quad

Edited November 12, 2017 by Edinburgh Rifles

[Walker570]

Well, two diverse judgements, Who am I to argue with either