Factory ammo length

[sam39]

I have measured 17 rounds of my sako 223 ammo (had enough at 17 and my wife said I should be talking to her as it's Valentine's Day)

 

Average length is 54.44 mm

 

Most very close to the av but 2 stand out a 54.22mm and a 54.61mm.

 

Q when you re load i presume you avoid this sort of variation? I know there are other factors with re loading but how big a factor is length. What do you chaps think to the above variations vs home loading?

[sam39]

Is it worth measuring all and having 3 batches 1/ normal 2/ short 3/long I suppose if I shoot enough of then I will find out.

 

May be I should just start re loading and be done with it

[simonl]

That's +/- 8 thou.

 

How far off the lands are they? My understanding is that there will be plenty of other things that'll have more effect on accuracy than this, provided you're not touching.

 

Also.. how are you measuring? To the ogive?

[onehole]

Sam,,,,!!!! good factory ammo in a good rifle will get you into 1 MOA,,,,,Don't waste your time measuring and dithering around factory ammo ,,,,it is what it is and some can be very very good,,,,make your own never look back,,,,,,,O

[simonl]

oops! Didn't spot the 'factory' in the title

[sam39]

Onehole response as expected I have had poor weather up here ( so poor I have taken to measuring ammo)

and not shot since but my friend did chrono my gin and completed a detailed drop chart. I plant to have some more practice time to see what I can do with the sako ammo. All part of the journey.

[sam39]

Simon

 

I have not mesured the lands. Just using the best factory ammo I have tested. I measure full length bullet and case

 

As I thought it seems this is not worth while. Sounds like it will do harm but no good so a waste of time.

[sam39]

Thank you both for your help. Onehole souls have been a smiley face after " response as expectedly " !

 

Cheers sam

[bradders]

Metric gobbledegook

Speak Inglese man

[sam39]

Sorry

 

average 2.143

short 2.134

long 2.150

[gbal]

Sam,the central concept is 'standardisation' .Chambers,and loaded ammo are made to specified dimensions-with of course some tolerance-so that for example,any commercial 223 ammo willfiresafelyin any commercial 223 chamber. The US system is SAAMI,and the European system is CIP. (there are differnces in what they include-eg US is more velocity inclined,CIP more pressure) but they agree-thankfully-on the dimensions of ammo and chamber within specified tolerances).

Some commercial ammo brands are probably made better than other brands -but that reflects more the components etc,rather than physical dimensions. ASadvised,don't get too concerned about slight vatiations even in the same batch of commercial ammo.

YOu do need as a reloader to keep an eye on brass length (base to rim-the length) as brass stretches on firing,and may well after several firings begin to exceed the maximum length for that chamber-then it's a fairly simple job to trim it back to standard size -otherwise pressure problems are very likely-the brass is too tight a fit for the chamber...not good.

The COAL (cartridge overall length) is the length from the base(primer) to the tip ofa loaded bullet-it's relevance is mainly that magazines have a maximum lenght they can accomadate-if too long.mmo will need to be single loaded.Why too long,well improved bullet design has tended to result in heavier but also longer bullets,maybe slimmed (that's the 'ogive' shape).The advantage is improved BC (slip through air better,and trajectory etc improves..shoot "flatter' is the popular term.) The critical issue is at what length the bullet 'shank"-thick cylindrical part contacts the rifling/lands,as that marks a pressure increase point.Reloaders aso fine tune a load by varying bullet seating so that it is just touching the lands ,or a known distance off ('Jump")-this is a matter of thousands of an inch-eg "10thou off"..but it varies,and each rifle /bullet combination tends to haave a 'best accuracy' 'jump'-differnceds are not huge,but matter ffor ultimate accuracy.

The better measure for this is CBTo-cartridge base to ogive-ie the point potential contact if jump was reduced to zero-basiically,OAL isn't helpful at all,as the tapered bit of the bullet is into the bore but not in contact-the critical measure is the potential contact point on the ogive.... but that is not an essentiaal for beginning loading-though not difficult-it's a good die adjust issue,and good measuring-and testing.

Good factory ammo with top components and good quality control can and does give sub 1/2 moa performance (Norma Blabck Diamond 6BR eg; Federal do a good match 308 load etc-----these will be way better than almost all military surplus and suchlike-by design...but priced accordingly. Nor is reloading typically 'less than half cost'-essentially you save the brass price,and spend time,as well as a fair bit of equipment costs;unless you compromise on quality.....and loose out on accuracy... :-)

 

OK,sorry the Q?A OL is considerable,but best to sort these things out early,aand focus on what interests you and is achievable.

for a great many shooting purposes utimate accuracy is simply not needed-even if possible-and there is a price to pay in equipment to approach it. Dn't let that deter you-many find the concept 'good enough,easily' for purpose makes sense.Reloading has to be an interest in itself,and of course need rifle etc that has the potential to show it-many factory rifles do not,but work fine.

(note -two reloaders might measure COAL (or CBTO) with their micrometers and be out a thou or two-individual sensitivity!

 

Bryan Litz has a good account of this on Berger Bullets site if you want authoritative advice.

Enjoy

gbal

[sam39]

gbal,

 

Thank you for taking the time to explain that. Several acronyms explained and the relationship between case, bullet, chamber and lands may need re reading but is already clearer than it was!

 

I do not think i HAVE to reload. My 223 i think is probably good enough re accuracy (re vital kill zone radius say 2in and a long crow (for me) being 200 yards and my last 7.... 3 shot groups av 0.64in 100yards worst group was 0.85) but i will quantify and try an repeat this over the next few months them move out to 150 and 200 yards to see what i can do. Also when you take into account the rest you have in the field and wind at 200 yards factory vs home load may be the least of your worries??

 

As for reloading i am just interested in it full stop. Not to save money but to gain confidence in my ammo but also have a regular supply, supply has not been as issue so far but could be in the future.

 

Also the welcome advice on here is basically get off your ass get the kit and get reloading if you want the best from your rifle.

 

Thanks

Sam

[gbal]

Sam,pleasure-we have all been there or thereabouts.

 

What you say about your current shooting is very pragmatic-and yes,field shooting may not offer the good shooting positions/rests of testing,but it's better to have a little in reserve for the 1 3/4 inch crow!). Given factors 'in the field'-thankfully quite a lot don't affect 200y shooting much,but plenty do-wind reading and accurate ranging is way ahead of fine tuned ammo.On the other hand,fine tuning equipment can be bought,as can a laser rangefinder,and used-with satisfaction-in some comfort,and 'at leisure'. Accuracy and precision are never handicaps.

Wind reading skill is much harder won-and out in the elements (well,a bit a breeze anyhow)-but has far larger potential returns-unless you shoot larger crows at shorter distances...then the potential is only a fair bit more! :-)

Good shooting.

g