Measuring Overall Cartridge Length (newbie alert)

[Elliott]

So, one thing I've learnt so far is that bullets vary in their length quite a bit but there's really two readings to think about:

1. Cartridge overall length for magazine fit
2. Ogive measurement for seating depth

How do you you chaps know the correct seating depths when you're handloading and where do I start? Do I need to buy another specialist bit of kit to measure the ogive in relation to the lands and them work back bit by bit?

[tacfoley]

So, one thing I've learnt so far is that bullets vary in their length quite a bit but there's really two readings to think about:

1. Cartridge overall length for magazine fit
2. Ogive measurement for seating depth

How do you you chaps know the correct seating depths when you're handloading and where do I start? Do I need to buy another specialist bit of kit to measure the ogive in relation to the lands and them work back bit by bit?

Cheap method - uses a fired cartridge case and a bullet that you can use again.

1. Take your once-fire case and neck size it.

2. With a fine-blade hacksaw, cut three or four slits in the neck down as far as the shoulder.

3. Insert the bullet - it should be held fairly tightly by the neck, in spite of the slits, which act as a spring-loaded 'retainer'. Insert it just far enough to be held without falling out.

4. Use a felt-tipped marker to mark the bullet all round.

5. Insert the complete item into the breech and close the bolt.

6. As the bullet touches the rifling, that will push the bullet into the case.

7. Carefully open the action, and drop the case with the bullet in it gently into your waiting hand.

8. You now have a dummy cartridge that exactly fits into YOUR breech and 'just' touches the rifling. Exactly WHERE it touches the rifling will be indicated by rifling marks in the felt-tip marking, if you see what I mean.

9. Using the calipers we told you to buy a couple of months ago, carefully measure the OVERALL LENGTH of the COMPLETE CARTRIDGE. Let us say that it is 2.75"

10. Whatever that measurement is, begin reloading a series of cartridge, using the same style of bullets, at 0.010" shorter than 2.75". You are now making a finished cartridge that is 0.010" SHORT of the lands of the rifling, for a start, and see how you get on. Some rifles like a bigger 'jump', but remember that being actually in contact with the the rtifling at the moment of ignition meansa that the pressure will peak virtually instantly - having even the slightest 'jump' will reduce that effect by a small amount, possibly resulting in an increase in accuracy. You can increase the amount of shortness by 0.005" at a time until you get the resaults you want. My Krico 650SS likes a 'ten 'thou jump' with Lapua Scenars, but shooting VLD Bergers I have to make allowances as the ogive is so long that the bullet would have nigh-on disappeared up thr barrel by the time it touched the rifling.

Remember, too, that this will be different of every type of bullet, as has been noted here many times. The longer the ogive, the more the bullet needs to be set out of the case in order to touch the lands - the opposite is therefore true - old-style, short ogive bullets will need careful finagling.

Expensive method. Buy a Stoney Point cartridge length gauge, or whatever it's called now, for about £50 - 60, that does exactly the same thing, but looks really spiffy.

You choose.

tac in Port Orford Oregon, about to go to a HUGE bar-b-q.

[223AI]

To start off with I just loaded to book length, with the a-max in my remmy 0.223loaded to saami spec I was shooting very tight groups. Another option that often gets recommended is to use a factory round that the rifle likes and use that to set the seating die, then use that as a starting point. Obviously the ogive is going to vary from one bullet type to another but if its a point to start from.

Is mag length particularly restrictive on your Tikka? As its a 1:12 you're not going to be loading heavy long bullets so i can't imagine you're going to have an issue, until you buy a hornet at least!!

[BigDuncs]

Cheap method - uses a fired cartridge case and a bullet that you can use again.

1. Take your once-fire case and neck size it.

2. With a fine-blade hacksaw, cut three or four slits in the neck down as far as the shoulder.

etc
etc

Expensive method. Buy a Stoney Point cartridge length gauge, or whatever it's called now, for about £50 - 60, that does exactly the same thing, but looks really spiffy.

You choose.

tac in Port Orford Oregon, about to go to a HUGE bar-b-q.

Very useful. Thanks.

[sidesy]

you can do it with a cleaning rod too........

1. insert as above with bullet inserted so its T I G H T (not primed obvs) and slowly close bolt .....make a mark on rod where its position is with end of barrel.

2. take cartridge out and close bolt. Reinsert rod and make a mark on cleaning road again.

3. measure......


also you may see that BT bullets vary (tips not the same length) quite a lot with measuring COL so the i measure to the ogive now using a stoney point gauge.

[bewsh]

or......

ignore this fascination with loading a "gnat's chuff off the lands"...

load all rounds "at least a calibre depth" so that they are under book maximum OAL

fine tune the best charge level groups either side of the length to get the best groups

most rifles will produce just as accurate rounds with some "jump" as they will almost touching the lands


I load for .22hornet, .222, .243, .270, .308 and .300WM......couldn't tell you where the lands are on any of them!
FWIW the .308 I just sold shot in the 0.1-0.2MOA range

[223AI]

or......

ignore this fascination with loading a "gnat's chuff off the lands"...

load all rounds "at least a calibre depth" so that they are under book maximum OAL

fine tune the best charge level groups either side of the length to get the best groups

most rifles will produce just as accurate rounds with some "jump" as they will almost touching the lands


I load for .22hornet, .222, .243, .270, .308 and .300WM......couldn't tell you where the lands are on any of them!
FWIW the .308 I just sold shot in the 0.1-0.2MOA range

Funnily enough Ed the load data for the 168 gr SMK that you gave me for that very 0.308 at "40 thou off the dummy round" worked on near as damn it book length for .308!!

Taking her out to 1000 yards with the BBS boys Sunday, I'll let you know how I get on!!

As KennyC said to me recently the touble with loading to the lands is the lands are always moving away from you!!

[jackal1]

or......

ignore this fascination with loading a "gnat's chuff off the lands"...

load all rounds "at least a calibre depth" so that they are under book maximum OAL

fine tune the best charge level groups either side of the length to get the best groups

most rifles will produce just as accurate rounds with some "jump" as they will almost touching the lands


I load for .22hornet, .222, .243, .270, .308 and .300WM......couldn't tell you where the lands are on any of them!
FWIW the .308 I just sold shot in the 0.1-0.2MOA range

Good advice there, i recently did a load for my and a mates .243s using some hollow point bullets i couldn't find a figure for. On the advice of someone who reloads a lot i set the bullets into the case's 6mm deep and tried them. They are deadly accurate in both rifles, my mate neck shot a Roe buck at 360yds with his no problem at all.

[BigGun1]

[QUOTE=tacfoley;6721438]Cheap method - uses a fired cartridge case and a bullet that you can use again.

1. Take your once-fire case and neck size it.

2. With a fine-blade hacksaw, cut three or four slits in the neck down as far as the shoulder.

3. Insert the bullet - it should be held fairly tightly by the neck, in spite of the slits, which act as a spring-loaded 'retainer'. Insert it just far enough to be held without falling out.

etc, etc, etc

QUOTE]

Bang on how I do - But Tac described it better than I could manage

[tacfoley]

But Tac described it better than I could manage

Sir, you are too kind to a poor old fart what tries his best...

tac

[Elliott]

Cheap method - uses a fired cartridge case and a bullet that you can use again.

1. Take your once-fire case and neck size it.

2. With a fine-blade hacksaw, cut three or four slits in the neck down as far as the shoulder.

3. Insert the bullet - it should be held fairly tightly by the neck, in spite of the slits, which act as a spring-loaded 'retainer'. Insert it just far enough to be held without falling out.

4. Use a felt-tipped marker to mark the bullet all round.

5. Insert the complete item into the breech and close the bolt.

6. As the bullet touches the rifling, that will push the bullet into the case.

7. Carefully open the action, and drop the case with the bullet in it gently into your waiting hand.

8. You now have a dummy cartridge that exactly fits into YOUR breech and 'just' touches the rifling. Exactly WHERE it touches the rifling will be indicated by rifling marks in the felt-tip marking, if you see what I mean.

9. Using the calipers we told you to buy a couple of months ago, carefully measure the OVERALL LENGTH of the COMPLETE CARTRIDGE. Let us say that it is 2.75"

10. Whatever that measurement is, begin reloading a series of cartridge, using the same style of bullets, at 0.010" shorter than 2.75". You are now making a finished cartridge that is 0.010" SHORT of the lands of the rifling, for a start, and see how you get on. Some rifles like a bigger 'jump', but remember that being actually in contact with the the rtifling at the moment of ignition meansa that the pressure will peak virtually instantly - having even the slightest 'jump' will reduce that effect by a small amount, possibly resulting in an increase in accuracy. You can increase the amount of shortness by 0.005" at a time until you get the resaults you want. My Krico 650SS likes a 'ten 'thou jump' with Lapua Scenars, but shooting VLD Bergers I have to make allowances as the ogive is so long that the bullet would have nigh-on disappeared up thr barrel by the time it touched the rifling.

Remember, too, that this will be different of every type of bullet, as has been noted here many times. The longer the ogive, the more the bullet needs to be set out of the case in order to touch the lands - the opposite is therefore true - old-style, short ogive bullets will need careful finagling.

Expensive method. Buy a Stoney Point cartridge length gauge, or whatever it's called now, for about £50 - 60, that does exactly the same thing, but looks really spiffy.

You choose.

tac in Port Orford Oregon, about to go to a HUGE bar-b-q.

What a cracking idea! I'll certainly be giving that a try. Thanks very much for taking the time to explain the method. Picking up my FL Hornady dies tomorrow and bought some digital calipers off a couple of weeks ago