Measuring .308 cartridge overall lentgh
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All handloading data posted on Full-Bore UK from 23/2/2021 must reference the published pressure tested data it was sourced from, posts without such verification will be removed.
Any existing data without such a reference should be treated as suspect and not used.
Use reloading information posted here at your own risk. This forum (http://www.full-bore.co.uk) is not responsible for any property damage or personal injury as a consequence of using reloading data posted here, the information is individual members findings and observations only. Always verify the load data and be absolutely sure your firearm can handle the load, especially older ones. If in doubt start low and work your way up.
Re: Measuring .308 cartridge overall lentgh
Thanks guys I will have a measure up to night and see what the numbers come out at.
Re: Measuring .308 cartridge overall lentgh
Not sure if this makes any sense. First off I weighed 5 bullets they weighed
1=167.5grains
2=167.5grains
3=167.5grains
4=167.4grains
5=167.4grains
They are supposed to be 168grains don't know if these weights are acceptable or not for 168grain Sierra match kings.
Cartridge OAL=
1=2.8195
2=2.8215
3=2.8215
4=2.8215
Comparator OAL(COAL)
1=2.2360
2=2.2335
3=2.2330
4=2.2320
5=2.2360
Don't know if any of this makes sense the numbers are not consistent. These numbers are with the bullet jammed in the rifling. What does this tell me what do I do next.
The rifle is a heavy barrelled varmit type jobby it has a 25.6" barrel.
Hope you don't mind I have recreated your spread sheet.
1=167.5grains
2=167.5grains
3=167.5grains
4=167.4grains
5=167.4grains
They are supposed to be 168grains don't know if these weights are acceptable or not for 168grain Sierra match kings.
Cartridge OAL=
1=2.8195
2=2.8215
3=2.8215
4=2.8215
Comparator OAL(COAL)
1=2.2360
2=2.2335
3=2.2330
4=2.2320
5=2.2360
Don't know if any of this makes sense the numbers are not consistent. These numbers are with the bullet jammed in the rifling. What does this tell me what do I do next.
The rifle is a heavy barrelled varmit type jobby it has a 25.6" barrel.
Hope you don't mind I have recreated your spread sheet.
-
The Cupcake Kid
Re: Measuring .308 cartridge overall lentgh
Firstly, the bullet weights:
To begin with, how accurate and repeatable are your your scales? It really doesn't matter too much if '168gn' bullets all weigh 167gn or 169gn or 166.3gn on your scales, as long as they all weigh the same (within an acceptable tolerance).
Assuming you have accurate scales, a variation of 0.1gn is not the end of the world in my opinion, but...
...you may get differing opinions from other people on how important consistent bullet weight is. If you think it's going to make a noticeable difference then you'll have to weigh and sort your bullets into different batches and shoot those batched bullets together.
My advice is always to try these things yourself and then decide if it's worth your while sorting everything into different weights and lengths.
Secondly, your OALs and COALs:
You didn't say whether you had a comparator which allows you to measure the COAL directly from the stoney point gauge, but even if you do, it is almost impossible to get the same measurement every time when you're doing this. This is because the point at which the bullet's ogive touches the lands within the barrel is very difficult to determine, especially when you're doing it through 'feel' when pushing the bullet into the barrel using the gauge's plastic rod.
This is why you need to do it several times and take the average (eliminating any obviously wrong readings). So don't feel bad you haven't been able to get a measurement which is repeatable every time you do it. We all have that problem!
Just keep trying and see if you can get a feel for when the bullet just touches the lands. Don't be too firm, or the bullet will start engaging in the rifling and you could be jamming it in 20 or 30 thou' yourself.
Hope all that helps and please feel free to create a spreadsheet or anything else we might suggest if it helps you get the result you're after!
To begin with, how accurate and repeatable are your your scales? It really doesn't matter too much if '168gn' bullets all weigh 167gn or 169gn or 166.3gn on your scales, as long as they all weigh the same (within an acceptable tolerance).
Assuming you have accurate scales, a variation of 0.1gn is not the end of the world in my opinion, but...
...you may get differing opinions from other people on how important consistent bullet weight is. If you think it's going to make a noticeable difference then you'll have to weigh and sort your bullets into different batches and shoot those batched bullets together.
My advice is always to try these things yourself and then decide if it's worth your while sorting everything into different weights and lengths.
Secondly, your OALs and COALs:
You didn't say whether you had a comparator which allows you to measure the COAL directly from the stoney point gauge, but even if you do, it is almost impossible to get the same measurement every time when you're doing this. This is because the point at which the bullet's ogive touches the lands within the barrel is very difficult to determine, especially when you're doing it through 'feel' when pushing the bullet into the barrel using the gauge's plastic rod.
This is why you need to do it several times and take the average (eliminating any obviously wrong readings). So don't feel bad you haven't been able to get a measurement which is repeatable every time you do it. We all have that problem!
Just keep trying and see if you can get a feel for when the bullet just touches the lands. Don't be too firm, or the bullet will start engaging in the rifling and you could be jamming it in 20 or 30 thou' yourself.
Hope all that helps and please feel free to create a spreadsheet or anything else we might suggest if it helps you get the result you're after!
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