[5mmMag]

I suppose it is a little early for this question but here goes. Since the original barrel length of the only rifle made to fire these pills is 24 inches, could we suppose the powder of the original ammo is burnt up later than the .22, which is usually pegged around 16 inches? Do any of you have an old T/C that has chronoed the 5mm from that barrel? I'm wondering if the new ammo will try to duplicate the burn rate of the old or will it be shortened up to accommodate a wider variety of new firearms, ie pistols. Also it may help me determine whether I get the new CZ 5mm in Varmint or American. I would hate to give away velocity if the Varmint is too short.

 

[CraigC]

I think that would be a fair assumption. Also, bear in mind that there are new powders available now that are applicable, Hodgdon's Lil Gun for example that does so well in the HMR.

Everything I've read on the subject points to the .22LR burning all its juice in 12"-14". Maybe a little more for the hyper-velocity loads.

 

[natman]

Both the 17 HMR and 5mm Mag are necked rounds and both are loaded to higher pressures than the 22LR. They will perform best with a longer barrel.

 

[Digital Dan]

Thinkin' here that what was, is no more with 5mm loads. Whatever is put on the market will almost certainly be loaded with Li'l Gun. I'm not a high velocity rimfire nut but I do hope somebody takes the time to build a better rifle for this round than Remington when they introduced it. Marketing suicide that.

 

[whiffelball]

I agree that these new rounds are not loaded with the same powder, and therefore can not compare burn rates with the old ones. Some 22LR, such as CCI's Velocitor, were designed for a 24-28" barrel with slower burning powders to help get maximum velocity. But a lot of the regular high velocity rounds for 22LR work well in the 16-18" range. All rounds will be quieter out of a longer barrel, something else to think about.