CZ .17hmr Q's

kenneths

i'm trading my CZ .22lr against the .17hmr but i am wondering why they make the barrels in different lenght.

i'm going for the CZ silhouette model but it has a choices of 16" & 20" which is the better choice? do i lose range or anything with the shorter barrel.

BTW i will be using a edgar brothers sm11 moderator if it's any difference

Cass

A shorter barrel is usually preferred when hunting as it does not get caught up in the ditches, etc when traversing rougher ground. Also in some sports a shorter barrel is of advantage as it reduces weight so the shooter can carry/hold the rifle up longer without tiring as easily

In relation to performance. The shorter a barrel the less time a bullet spends in it (obviously), and as a result stabilisation of the bullet may suffer, depending on twist rate, as opposed to a longer barrel.

Other factors are decreased overall distance. If a bullet is fired from a shorter barrel it may not have used/gained all the force from the load and muzzle velocity will be down. This is not say so. Its fact. I can fire the exact same grainage bullet from my 32" (.308) rifle as from my 24" (.308) rifle and the MV will be higher from the longer barrelled rifle as the bullet gets the most from the powder load in the round. Same would apply to the CZ. A 20" barreled rifle will give more MV than a 16" one. This could have an effect on accuracy, but i have not done anything along these lines from a testing point of view so cannot comment.

Its really a matter of personal choice. If you're shooting 150 yards or so both rifles will perform as you need, and you can try various rounds to see which gives the better performance through the rifle. Personally i wouldn't go below 20" (if i'm really honest i wouldn't go below 24", but thats just me). After going below a certain length you have to start loosing accuracy, power, speed, etc than you would against a longer barreled rifle.

Hunter21

Sorry to hijack your thread Kenneths, but this question might benefit you too.
I have read that .17 barrels are prone to wearing faster then other barrels most noteably the .22 is this true or just fiction made up by some lad who never cleaned his rifle

Cass

Compared to the .22lr no other barrel comes close to the same level of use. A .22lr can go for tens/hundreds of thousands of rounds.

Your average .17hmr could last between 15,000 - 20,000 rounds. I've read reports of much higher numbers, but there just that reports. I do not know of anyone having a .17 long enough to use that many rounds.

Other calibers vary. For example here are some common calibers and their average life expectancy:

.308 = 3,500
6.5x284 = 800 -1,100 rounds
.220 swift = 2,500
.223 = 3,500 - 5,000


The "hotter" the round, usually, the faster a barrel wears out. Not always the case, but most of the time it holds true. Bullet make also plays a factor. Lead, copper, etc.

kenneths

found this...
so to me it looks like the 16" don't lose much MV over the 20"

http://www.bullberry.com/HMRdata.html

i plan on this scope is it a good choice?? Burris fullfield II 3x9-50 ballistic plex recticule.
http://www.burrisoptics.com/fullfield1.html#3x9x50

Cass

Thats actually quite surprising. A 100fps spread in the first 9 inches then 150fps in the next 3 inches. Bit of a steep drop. I know you are looking at 20" or 16" so anything under the 16" wouldn't matter too much.

A few things i would like clarification on. The site is that of a custom barrel manufacturer and it was those barrel(s) they were using. Also the ammo they were using. 103fps is a fairly large ES. I don't know if it was the shorter barrel or different batch of ammo but as the barrels shortened the ES came to a little more "respectable" 45-50fps.

I was basing my previous post on my testing that i done with my 32", match barrel, against my 24" factory barrel. With 190gr rounds i was looking at 2714fps average with the 32", and 2537fps with the 24".

garv123

kenneths wrote: »

i'm trading my CZ .22lr against the .17hmr but i am wondering why they make the barrels in different lenght.

i'm going for the CZ silhouette model but it has a choices of 16" & 20" which is the better choice? do i lose range or anything with the shorter barrel.

BTW i will be using a edgar brothers sm11 moderator if it's any difference

where did you pic up the mod? i was reading reviews and that got 5/5 compared to the sak getting 3.5/5 it was the lightest(149g) but one of the longest. (6.8") and 2nd cheapest

kenneths

lads i have decided to get this scope
http://www.bsaoptics.com/scope.aspx?productID=343
anyone have reviews?
also can i just order it from UK without hassle???

FISMA

Ezridax wrote: »

Other factors are decreased overall distance. If a bullet is fired from a shorter barrel it may not have used/gained all the force from the load and muzzle velocity will be down. This is not say so. Its fact.

Yep, + 1. Actually, + 2 since this is my board's registered username name-sake.

The physexier (sexier Physics geek) way of saying this is Impluse.

The longer you keep a Force on an object, the greater the acceleration. Greater acceleration in this case means the bullet clears the longer barrel with a higher speed.

I would go with the longer barrel.

kenneths

kenneths wrote: »

lads i have decided to get this scope
http://www.bsaoptics.com/scope.aspx?productID=343
anyone have reviews?
also can i just order it from UK without hassle???

anyone able to answer this question

kenneths

Got the rifle on saturday
so tried to order from uttings and they don't do delivery to ireland anymore.
bit of a pain!!!

so can someone recommend a scope for me that i can get here or delivered easy enough.

Cass

There has been an influx of scopes for sale in the "For Sale/Wanted" section. Have a look there.

Stay clear of BSA. Air gun based scopes and wouldn't trust them. I know you said you're not getting it anyway, but incase you try again.

fathersymes

A very good budget scope would be the Bushnell Banner or Trophy. Plenty of very good reviews from the US where they're used on fullbores without problems.

Here's one from Ebay:

http://cgi.ebay.co.uk/Bushnell-Trophy-3-9x40-Multi-X-Reticle-Matte-/400144693861?pt=UK_SportingGoods_Hunting_ShootingSports_ET&hash=item5d2a7b7a65