OAL

[Col]

guys, when loading for my 223 and 308`s there is usually a discrepency in the cartridge OAL. Whilst this discrepency is not very large I am a very finicky person,and try to get better consistency with all matters of reloading, I weight each load using a powder throw and trickler, trim all cases exactly the same length etc. then to get sometimes a spread of maybe 6 or 8 thou annoys me. I realise these discrepencies are within reason but I like them all the same.
The question I would like answered is, if a 308 for instance is 5 thou long and I decide to push them in a little further to the length I desire would this alter the pressure enough to cause my velocity to change enough to change my POA, I fully understand that to get true consistency the AOL length should be measure from the ogive but is this absolutely neccesary or should I just except the few thou difference

[kennyc]

you need to measure to the ogive if you want an exact repeatable measurement, have you tried measuring the bullets before loading them into the case? you could then get an average length and add/subtract each measurement from the average to get a consistent OAL when you load it. sounds like a lot of faffing around to me though

[John25]

Col,

From the ogive, however if your boolits are good quality, they will give you a consistent oal.

for .308 you need, for best results to be e few thou. short of the lands. Thus, your oal will be differnt from mine. Other calibres benefit from loading into the lands (I don't know about .223 because I haven't reloaded that for donkeys years)

As your thoat wears you will need to alter your oal, only constant measuring (and good cleaning) will tell you what that current length is. At the start of the season, I load to 'long' and finally size just before the shoot.

There are, as I'm sure you know, despite your claims of 'innocence' many other factors; case neck tension (crimp or no crimp) case thickness, brass hardness; I could go on but you should do all you can with your current equipment, eliminate all the variables you can and then look for another step which will help.

Hope this helps, I'm sure you will get lots more positive responses which will encourage you to stay. We all love to tell others what works for us, it is not a quick fix 'though, as I said on the other topic, forty years and still learning!

It's when she says 'Oh no, not more reloading kit!

Best of luck

[tikkathreebarrels]

Having your loads to an excessive cartridge overall length may cause problems when chambering a round - the bolt won't close. Even worse, if you've wedged the bullet into the lands you could pull it out of the case neck if you decide to extract it from the chamber. Should your overall length vary? Well if you're measuring from the tip and not the ogive quite possibly. Could it cause pressure - and therefore POA issues? Possibly if you're pushing a tight fit round into your chamber or the converse might apply, if you're seating the bullet deeper into the case, possibly to the point of having a compressed load.
What make of seating die are you using and are you certain that it's not moving in the press?

[DaveT]

Agree the above comments... Buy a Hornady OAL gauge set and get used to using it (Max OAL to 'kissing the lands' for your specific chamber and then knowing for sure where your bullet sits within that measure...Jump or Jam) ...... nothing but grief & uncertainty in trying to measure head-to-tip.

Whilst you are there get the Headspace gauges as well then you are covered for brass 'setback' during resizing.

[John25]

There are better measuring tools than the Hornay which is designed for 'all in' calibres.

Get a calibre specific one,, I have one made for me by Dolphin Guns which is much more accurate.

But, having said that, you gets what you pays for. I am biased because Mik and Peter of Dolphin are mates so I'm declaring an interest.

All I can say is that, after talking to Mik, trying and subsequently buying one of their guages, my reloading has become more consistent and my scores have improved.

(The nut behind the butt is still causing problems!)

[DaveT]

Agree but pricey!

[ovenpaa]

As has been suggested, it is important to measure from the Ogive. I build my own OAL gauges as the Hornady one is quite flimsy and they do fail over time, once the bullet has been set to length in the chamber using the OAL gauge I measure the OAL length across a point on the ogive which approximates to the point the bullet would start to touch the rifling. Repeat this 5 times or so and you should get a good average, build a couple of rounds to this length using a comparator to measure and then use the came comparator to measure from then on. You should not see any more than .001" variation in length and it should be less.

I can post some pictures if that helps any?

[John25]

Measure, measure, shoot, record, measure, keep notes, shoot, measure.......

It never stops, if one method alone was best, one man would keep it to himself and always win - but he never does which is why we keep striving.

Yes, Dolphins measuring kit is expensive, if there were a cheaper alternative, I would hope to have it already.

Someone I know, who proports to be an 'armourer' actually poo-poos the whole set up!

Like I said, you pays yer money.

:cheers:

[tikkathreebarrels]

I use one of these
http://www.sinclairintl.com/.aspx/pid=3 ... omparators
which, when used consistently, gives good data.