chamber size, COAL

[Kman]

So I have been reloading according to my loading manuals for .308 and .300 blackout. Now I have my chamber size for a rem 700 .308 and a model 7 .300BO I need to do a ladder starting at .005 off the lands and work downward until I see where accuracy is optimal. The published coal is much shorter than where I'm starting my ladder. All I've read tells me that the extra space in a case can cause pressure issues. I'm planning on using the low end on the powder charge. Before I load anything I would like input if you have done this before. I would love to be able to load rifle specific ammunition for better consistency.

 

[jeep78]

"All I've read tells me that the extra space in a case can cause pressure issues."

Yes and no.

As you seat the bullet deeper in the case, pressure goes up - not down.

That is is you are staying with published loads and starting loads.

Some reports indicate massive reduction in starting load can result in detonation of the charge instead of normal ignition and burning, and can cause a KB. This may be what you are referring to as "increase in pressure due to seating the bullet further out",

And "of" vs "off" really means 2 different things WRT something as technical as loading ammo. I think I read your post properly.

 

[woodstock]

I always stay in published guidelines, but usually go with just under max length as long as it chambers well in my firearm, and with med low powder charge for target stuff, as long as its reliable and accurate. If it isnt, I adjust from there.
Im not going for super accurate though, appears you may be.

 

[jeep78]

As you are custom fitting the ammo to a specific gun, it is good practice to mark the rounds so you know what it is.

Some use a sharpie and draw a design on the headstamp/primer area. Record your mark, the loading and rifle in your notebook.

Today you may only have 1 rifle that caliber, in 10 years ?? It save having to pull cartridges down in the future, as ammo has a way of getting out if their marked boxes.

 

[Greybeard]

Perhaps I am reading this incorrectly, just my thoughts,
Bullet depth, the deeper you seat the bullet the more you increase the pressure, as with some powders they don't like no space or compressed loads. However I agree, you don't want to jam the bullet into your lands in the barrel.

Coal, this is normally the shortest you want to load, or seat your bullet. If your going shorter than col accuracy would suck and bad things could happen.

I would load a dummy round perhaps .020 longer than coal, smoke the bullet with candle wax and gently load your round. Extract the round and look for the worn off smoke ( rubbed off by your lands) measure coal. Then load several, +.000/-.005 and see what works.
The closer you are to the lands the less squabble you have and adjust your power. Start min and increase +.2 grains until your happy.

Always use case gage, on shoulder ammo (go no go) period....
Just my thoughts.

 

[Kman]

And "of" vs "off" really means 2 different things WRT something as technical as loading ammo. I think I read your post properly.[/QUOTE]
Fixed it, was running out the door when I put the post up.

 

[Kman]

Perhaps I am reading this incorrectly, just my thoughts,
Bullet depth, the deeper you seat the bullet the more you increase the pressure, as with some powders they don't like no space or compressed loads. However I agree, you don't want to jam the bullet into your lands in the barrel.

Coal, this is normally the shortest you want to load, or seat your bullet. If your going shorter than col accuracy would suck and bad things could happen.

I would load a dummy round perhaps .020 longer than coal, smoke the bullet with candle wax and gently load your round. Extract the round and look for the worn off smoke ( rubbed off by your lands) measure coal. Then load several, +.000/-.005 and see what works.
The closer you are to the lands the less squabble you have and adjust your power. Start min and increase +.2 grains until your happy.

Always use case gage, on shoulder ammo (go no go) period....
Just my thoughts.

I'm planning on doing almost exactly that. Coming off the lands .005 and working down to published COAL. I wasn't sure what difference using the published minimum powder load would have when I was seating beyond the published coal. SO far I gather I should be fine. I'll be using a chrono and will check for pressure signs.

 

[Kman]

I always stay in published guidelines, but usually go with just under max length as long as it chambers well in my firearm, and with med low powder charge for target stuff, as long as its reliable and accurate. If it isnt, I adjust from there.
Im not going for super accurate though, appears you may be.

I'm just tinkering, but I would like to have the smallest possible group at 100 yards from my reloads. I guess it's just another step in educating myself about reloading.

 

[1006]

Most of the time the best accuracy is achieved loading with a longer COAL. I load mine right up to the rifling lands in my Ruger Rifles. The accuracy is best with the long COAL. In fact, I find my desired COAL for each type bullet by partially sizing the neck of an unloaded, clean case, inserting a bullet just a small amount into the case, and then seating the bullet by loading it into the gun and forcing the bolt closed. It should go in pretty easily, if not you have sized the neck too much, you want just enough neck tension to prevent the bullet from sticking in the barrel when you open the bolt. Then I take this unloaded parially seated bullet to the press, lower the handle, raise the cartridge, and twist the seating die down until it makes contact with the bullet at its current seating depth. Then, I lock the die in place, remove the unloaded cartridge, and turn the seating stem 1/8 further into the die.

It seems to work pretty well for me. You can then setup your ladder test by increasing the seating depth in small increments.

I also usually start with close to the max recommended load and work down, as the reduced pressure resulting from the increased space in the case will add to my safety margin.

I keep saying "I" because it works for me. Your results may vary.

There are sometimes that your COAL will be limited by your magazine space and/or by the bullet length.

Examples: Some guns have to be loaded as single shots to accommodate a long bullet, because they will not fit in the magazine. Some long skinny pointy type bullets will cause this.

Some bullets like a 55 grain in a 243 may be too short to load into the lands-there just is not enough bullet left to fit securely into the case neck when loaded too long.

Good Luck, check the facts, read some books, have fun, be safe, ect

 

[Kman]

Most of the time the best accuracy is achieved loading with a longer COAL. I load mine right up to the rifling lands in my Ruger Rifles. The accuracy is best with the long COAL. In fact, I find my desired COAL for each type bullet by partially sizing the neck of an unloaded, clean case, inserting a bullet just a small amount into the case, and then seating the bullet by loading it into the gun and forcing the bolt closed. Then I take this unloaded parially seated bullet to the press, lower the handle, raise the cartridge, and twist the seating die down until it makes contact with the bullet at its current seating depth. Then, I lock the die in place, remove the unloaded cartridge, and turn the seating stem 1/8 further into the die.

It seems to work pretty well for me. You can then setup your ladder test by increasing the seating depth in small increments.

I also usually start with close to the max recommended load and work down, as the reduced pressure resulting from the increased space in the case will add to my safety margin.

I keep saying "I" because it works for me. Your results may vary.

There are sometimes that your COAL will be limited by your magazine space and/or by the bullet length.

Examples: Some guns have to be loaded as single shots to accommodate a long bullet, because they will not fit in the magazine. Some long skinny pointy type bullets will cause this.

Some bullets like a 55 grain in a 243 may be too short to load into the lands-there just is not enough bullet left to fit securely into the case neck when loaded too long.

Good Luck, check the facts, read some books, have fun, be safe, ect

It has been fun and thanks for the suggestions.