The Firearms Forum banner
1 - 20 of 25 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
Hello, i’m very new to reloading and currently struggling with determining how deep to seat my bullet. I have an Aero Precision AR10 in .308 and I’m using Hornady brass and SST 150gr bullets. After using their oal gauge tool I measured the oal several times, getting 2.877” each time. It states in my book the max col is 2.810”. I’m assuming that is probably just a guideline and it might be different for different rifles but this seems too long no?
Tire Hood Automotive tire Bumper Automotive exterior
 

·
Registered
Joined
·
1,979 Posts
Hello, i’m very new to reloading and currently struggling with determining how deep to seat my bullet. I have an Aero Precision AR10 in .308 and I’m using Hornady brass and SST 150gr bullets. After using their oal gauge tool I measured the oal several times, getting 2.877” each time. It states in my book the max col is 2.810”. I’m assuming that is probably just a guideline and it might be different for different rifles but this seems too long no?
The Hornady manual #8 list the .308 150gr SST COL at 2.735. I also have a AP LR-308 and when loading those specific Hornady bullets I am at 2.706 COL.
Hope it helps.
 
  • Like
Reactions: Colby Cargile

·
Registered
Joined
·
565 Posts
Keep in mind if you were to load these to 2.877 or 0.020” less, (2.857”), they still need to fit in your magazine. I always measure the inside of the magazine then take a few thousandths off of that.
The COL measurement of 2.750“ works pretty well in my AR10.
 

·
Registered
Joined
·
1,979 Posts
Keep in mind if you were to load these to 2.877 or 0.020” less, (2.857”), they still need to fit in your magazine. I always measure the inside of the magazine then take a few thousandths off of that.
The COL measurement of 2.750“ works pretty well in my AR10.
I'm not sure sizing your rounds based upon your magazine is the best way to go about it.
 

·
Registered
Joined
·
2 Posts
Hello, i’m very new to reloading and currently struggling with determining how deep to seat my bullet. I have an Aero Precision AR10 in .308 and I’m using Hornady brass and SST 150gr bullets. After using their oal gauge tool I measured the oal several times, getting 2.877” each time. It states in my book the max col is 2.810”. I’m assuming that is probably just a guideline and it might be different for different rifles but this seems too long no?
View attachment 279699
Two different things there, the measurement you are taking is to measure to the lands or jam point of the bullet that measurement is to make sure you don’t stick the bullet into the rifling, the measurement you are referencing is the magazine length in relationship to the coal if you want to feed from a magazine then the max coal is going to be 2.860 if you don’t mind single feeding then your coal can be longer just make sure it’s less then 2.877
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #9 ·
Two different things there, the measurement you are taking is to measure to the lands or jam point of the bullet that measurement is to make sure you don’t stick the bullet into the rifling, the measurement you are referencing is the magazine length in relationship to the coal if you want to feed from a magazine then the max coal is going to be 2.860 if you don’t mind single feeding then your coal can be longer just make sure it’s less then 2.877
Okay that makes sense thank you
 

·
Registered
Joined
·
1,979 Posts
Two different things there, the measurement you are taking is to measure to the lands or jam point of the bullet that measurement is to make sure you don’t stick the bullet into the rifling, the measurement you are referencing is the magazine length in relationship to the coal if you want to feed from a magazine then the max coal is going to be 2.860 if you don’t mind single feeding then your coal can be longer just make sure it’s less then 2.877
That makes no sense at all. The OP asked about the C.O.L (Cartridge Overall Length) and your'e talking C.B.T.O (Cartridge Base To Ogive) dimensions.
Of course you need to insure that your ammunition will feed in your magazine, but to measure a magazine and subtract any amount from that measurement to determine C.O.L. is useless.
The Hornady manual list the C.O.L. for that specific bullet at 2.735 - why would you tell the OP to use the range of 2.860 to 2.877?
 

·
Registered
Joined
·
405 Posts
Two different things there, the measurement you are taking is to measure to the lands or jam point of the bullet that measurement is to make sure you don’t stick the bullet into the rifling, the measurement you are referencing is the magazine length in relationship to the coal if you want to feed from a magazine then the max coal is going to be 2.860 if you don’t mind single feeding then your coal can be longer just make sure it’s less then 2.877
I've read recently, and was aware of it even before I got my AR, you do not want to load into the chamber by hand unless you ride the bolt home! Otherwise you leave yourself open to an out of battery discharge. It has everything to do with the free floating firing pin, and the bolt flying home to a dead stop at the live cartridge! Try it, you'll find a nice scary little "hammer strike" on your primer!
 

·
Super Moderator
Joined
·
47,187 Posts
Well now, my Hornady #10 manual shows the maximum COL of a .308 Winchester as 2.810, now keep in mind that is the MAXIMUM length. Now when you go over to the page that shows the 150 grain SST bullet it shows the COL as 2.735 and with most bullets, according to the design of those bullets even at the same weight, the COL changes a little bit, either up or down.

Colby, look at your manual and go with what it says. If you are just starting out reloading, you should not be concerned or worried about how close to the lands the bullet is seated. I've been loading for 45 or so years and I still don't think or care about how close (or far away) those lands are.
 

·
Registered
Joined
·
405 Posts
Something else that is vague in my mind, imagine that, is my first endeavors to reload for the 5.56, I got out my Hornady case measuring stuff just like you have, and after some reading and general wasting of time it became apparent that the AR's chamber cannot be measured with that method! It might have had something to do with it being a semi auto, or maybe it was because of the gas system!
 

·
Registered
Joined
·
4 Posts
Discussion Starter · #15 ·
Well now, my Hornady #10 manual shows the maximum COL of a .308 Winchester as 2.810, now keep in mind that is the MAXIMUM length. Now when you go over to the page that shows the 150 grain SST bullet it shows the COL as 2.735 and with most bullets, according to the design of those bullets even at the same weight, the COL changes a little bit, either up or down.

Colby, look at your manual and go with what it says. If you are just starting out reloading, you should not be concerned or worried about how close to the lands the bullet is seated. I've been loading for 45 or so years and I still don't think or care about how close (or far away) those lands are.
Sounds good, thank you all very much. I’m only 20 and I don’t really know anyone who loads so that’s how I ended up here haha.
 

·
Registered
Joined
·
10 Posts
I'm new to reloading, so I stand to be corrected. But...

Seems to me that with any given powder load, there is a proper pressure to be generated when fired. Further seems that if the bullet is seated significantly deeper or not as deep, that might affect either the pressure or the way the pressure builds and bring some, uh, unexpected excitement to your day.

Just guessing; according to my wife most likely I am wrong.
 

·
Registered
Joined
·
405 Posts
I'm new to reloading, so I stand to be corrected. But...

Seems to me that with any given powder load, there is a proper pressure to be generated when fired. Further seems that if the bullet is seated significantly deeper or not as deep, that might affect either the pressure or the way the pressure builds and bring some, uh, unexpected excitement to your day.

Just guessing; according to my wife most likely I am wrong.
I’m relatively new to the gig myself, but that is exactly as I understand it!
 
1 - 20 of 25 Posts
Top