Jump to content

Bullet seating - is this OK and depth repeatability.


Recommended Posts

 

It seems bonkers to state a tip-based OAL in a reloading manual for obvious reasons and those mentioned above - why do they do it?

 

 

 

simple

Mag length.

 

most rifles are limited not by Leade or chamber dimensions (even more prevalent with VLD Secant ogive longer bullets) but they are limited by mag length

The chamber leade is often much bigger than necessary on factory rifles to accommodate any and all factory ammo

 

My 300wm is basically a single shot when I shoot 208gr AMax at the length I want to shoot them at

the 180gr Corelokt is at max mag length which is a tip to head measurement, possible they may be more accurate when seated longer but I need a mag feeding round

 

it doesnt matter how close you are to the lands

the ONLY thing that matters is repeatable accuracy and that ONLY requires a repeatable method of OAL measurement. it doesn't matter where you measure it from...so long as it is repeatable and accurate

 

For that purpose a tip measurement on a BT round is not that inaccurate

on a soft point it can be

 

I couldnt tell you where the lands are on half my rifles

can tell you that some ONLy perform with a jump that could be measured in millimetre rather than thou!

Edited by Bewsher500
Link to comment
Share on other sites

White lion is meant to be top notch in the next village down ( harlaston) or travel to Hopwas near me and the Tame otter . Perfect food .

 

 

Lead wasp i know you traveled a fair distance but try to keep it regular ;)

Very kind of you to say so - I've enjoyed every trip, everybody has been great company. I was pretty faarked by the time I'd driven home tho'!

Edited by LeadWasp
Link to comment
Share on other sites

simple

Mag length.

 

most rifles are limited not by Leade or chamber dimensions (even more prevalent with VLD Secant ogive longer bullets) but they are limited by mag length

The chamber leade is often much bigger than necessary on factory rifles to accommodate any and all factory ammo

 

My 300wm is basically a single shot when I shoot 208gr AMax at the length I want to shoot them at

the 180gr Corelokt is at max mag length which is a tip to head measurement, possible they may be more accurate when seated longer but I need a mag feeding round

 

it doesnt matter how close you are to the lands

the ONLY thing that matters is repeatable accuracy and that ONLY requires a repeatable method of OAL measurement. it doesn't matter where you measure it from...so long as it is repeatable and accurate

 

For that purpose a tip measurement on a BT round is not that inaccurate

on a soft point it can be

 

I couldnt tell you where the lands are on half my rifles

can tell you that some ONLy perform with a jump that could be measured in millimetre rather than thou!

Hi Bewsher - but does seating depth affect pressure and safety? This is about my last concern/worry....I understand I need to try to get roughly a 'calibre' of seating depth but on some of the bullets this looks very close to the top of the powder. I had one load of IMR 4831 that was well up the shoulders.

Edited by LeadWasp
Link to comment
Share on other sites

seating depth will affect pressure if its a compressed load with the wrong powder, though a compressed load doesn't mean its guaranteed to be dangerous if that makes sense. A reloading manual will give you a bullet max length with each powder and weight combination, this isn't bonkers as most won't have O give measuring equipment and the tolerances between bullet length differences and sizes given won't be big enough to make the load dangerous, you will be loading up from 10% below max anyhow and you should know when you start to get near the limits. Its always a good idea to use a powder that fills the case the most for a safe load for two reasons, 1) you will know by the over spill that you have double measured, 2) to small a amount of powder can equally be as dangerous.

For me, and not saying this is the same for all but I found that after a few years experience you get a feel for how things are going.

Link to comment
Share on other sites

Hi Bewsher - but does seating depth affect pressure and safety? This is about my last concern/worry....I understand I need to try to get roughly a 'calibre' of seating depth but on some of the bullets this looks very close to the top of the powder. I had one load of IMR 4831 that was well up the shoulders.

 

As above yes

but most powders recommended for a particular application will take that into account

 

I run compressed loads on a number of loads I have without issue

 

52/60gr in .222 - N133 (powder is at the slower range for calibre/cartridge)

100gr in .270 - N160 (bullet is very light for application and requires higher charge weights)

.208gr in 300WM - 78gr H1000 (bullet is huge, neck is short and OAL is relatively short)

 

nothing to be concerned about in just being compressed.

in fact I would rather have a compressed load of a slow powder that is compressed than a fast one I can overun and have REAL pressure concerns

Link to comment
Share on other sites

OK so I think I'm starting to get this.

 

Most of the rounds I've made up so far have not had a lot of bearing surface in the neck - certainly not a calibre's worth....when I made the first batches in 75, 100 and 100 gr I was trying to meet the minimum COL stated in Lee's manual (as this was the only length clue given) yet was concerned that there wasn't a lot of bullet in the neck. However we did have some corking results with 110gr Hornady's as Dougy will attest! However the 100's wouldn't chamber so I'll need to seat them a little deeper and will do this in the ways that everyone has explained above.

 

To stop me worrying about blowing my head off, if I find a happy medium between seating a boat tailed bullet a calibre or so into the neck as the rule of thumb suggests AND having enough jump etc to chamber the round then provided the load isn't compressed even if the tail is a bit into the shoulder of the case it won't be a dangerous thing?

Link to comment
Share on other sites

I will see if I can borrow my mates oal guage he has for his 257 bob. When I see you next at Catton we will have a play and sort out your max oal with your most accurate bullets.

PS

I will show you how to sort out the oal with one of your shot case's.

Edited by Dougy
Link to comment
Share on other sites

Thanks Dougy - much appreciated. I know I'm fretting but I know that for anything that detonates confinement raises the shock stakes. I'm not too sure about deflagrants (cartridge powders) but I'm assuming the same - hence my concerns about how deep is too deep given that I only have tip COL's given in the Lee manual for e.g. 100 grain generic jacketed bullet.

Edited by LeadWasp
Link to comment
Share on other sites

Well I was wrong the 95's seated at 20 thou off my lands do not go past the shoulder, very close to but not past, not that it matters....

 

Surely if your worry is that your compressing the powder to much then you'd be better to measure to the lands and back off a touch to create max case volume? ( or use less powder)

 

Or am I not seeing your problem?

Edited by Paul223
Link to comment
Share on other sites

Using varget in the .223 I had to tap the case to get the powder to settle and not to spill and then yeah a nice crunch on seating the bullet, was good from the point of view that the case could not be overfilled but also that no powder in the neck meant something was wrong, sadly h380 only fills 4/5th's of the .243 case so I have to take a peak

Link to comment
Share on other sites

You will get higher pressure spike from a bullet sitting in the lands than you will from a moderately compressed load

 

only your rifle and brass will be able to tell you how much is too much

only your rifle will be able to tell you what it likes when it comes to OAL.....accuracy is the only indicator

 

personally if the bearing surface is not clear of the neck inside on a .223 I would be concerned I was not going to get a decent concentricity of the bullet in the case

roll the cases in an engineer's V block with a micrometer on the bullet ogive if you are remotely interested

Link to comment
Share on other sites

Thanks to all of you guys - much appreciated!

 

Paul - It's not that I have a specific problem, I'm just trying to learn what is right and what is wrong so any good information helps the learning process.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...