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Lets talk cartridge OAL (Overall Length)

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I usually use OAL from the manuals.

I’m using Sierra 155 gr. and the Sierra manual lists an OAL of 2.775“. BTW my Hornady manuals all list 2.800 for their 155 gr. bullets. I checked the chambers of my M1 .308 barreled by Fulton and M1A James River/Rockola both Criterian barrels and get a max OAL bolt face to lands of 2.860” +/- a few thousands measurement error.

So this means the free space in my handloads is a whopping .085 thousands. Reading up I see that that ideally around .035 or so is a good number provide the ammunition fits the magazines.

My reloads usually shoot 2 1/2” groups with irons. Is there much to be gained by experimenting with OAL other than wasting ammo?.
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I usually use OAL from the manuals.

I’m using Sierra 155 gr. and the Sierra manual lists an OAL of 2.775“. BTW my Hornady manuals all list 2.800 for their 155 gr. bullets. I checked the chambers of my M1 .308 barreled by Fulton and M1A James River/Rockola both Criterian barrels and get a max OAL bolt face to lands of 2.860” +/- a few thousands measurement error.

So this means the free space in my handloads is a whopping .085 thousands. Reading up I see that that ideally around .035 or so is a good number provide the ammunition fits the magazines.

My reloads usually shoot 2 1/2” groups with irons. Is there much to be gained by experimenting with OAL other than wasting ammo?.
Free bore can be a topic that pertains a lot to psychology more than practicality. I have been in discussions with my Palma friends about this. They have used the Palma 95' reamer with free bore past .080 and a bit shorter than that. I cannot recall exact numbers. It seemed that a little more free bore maybe was an advantage, but they shoot well with lesser free bore distance too. I think there are many sub moa m14's around with a comparable free bore to what you measured. I suspect there is no magic number for the best free bore.
 

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The first reloads for a newly acquired Rem 700 in .308 were based on manuals showing OAL.

I always load a dummy round in such cases, and learned the dummy round wouldn't chamber; too long.

I went through a trial-and-error exercise seating the bullet deeper until it chambered and fit in the magazine.

Given it is projectile dependent, in this case a SMK 168 gr, OAL is 2.785. But that's for my M700 and YMMV.
 

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Gents,

I usually settle on a OAL of 2.81" to 2.83" for my M-14's. I use the same for my bolt guns and have had excellent results. Sometimes I wonder if we don't get to wrapped around the axle about AOL.
My bullets are 175 gr Lapau Scenar's or SMK's. Think that I'm the week link, not my ammo...

Wes
 

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That free space does matter. Some of my guns like a larger free space. Most like it tight like 10 thousands of an inch as long as it fits in the magazine. My bolt guns really like it tight. For M1A I have mostly just stayed with 2.80". With semi-autos I think you can run afoul of loading/ejection messing with really long loads but that is my speculation from years of playing with bullet depth in 9mm and 45 ACP.
 

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I once got into quite a snit with Ruger over this. I had found one of the more rare Model 77's in 7x64 Brenneke, supposedly meant for the Euro market but a number of them either never made it or were returned home.
It was built to CIP specs and had quite a lot of throat which I had always thought to be a bad thing. I went round and round with the techie at Ruger on the blower about it, and he finally asked if I had shot the rifle.
Well, un no not yet. He said well shoot it first before whining! So I did. It shot great with a long jump for all bullets.
Like so many things, it all depends, mostly on individual guns. Some shoot better tight, others long. No magic formula except experimenting.
I dont get too wrapped up in it especially for a semi, as long as the bullets are off the lands a tad when I pull the trigger.
I did call the Ruger guy back and told him he was right.
 

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Gents,

I usually settle on a OAL of 2.81" to 2.83" for my M-14's. I use the same for my bolt guns and have had excellent results. Sometimes I wonder if we don't get to wrapped around the axle about AOL.
My bullets are 175 gr Lapau Scenar's or SMK's. Think that I'm the week link, not my ammo...

Wes
Same here. Took the words out of my mouth. 308 seems to be a pretty forgiving cartridge in that regard. Unless it's a VLD then all bets are off. CWO
 

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I load for my M-14s to 2.81 no matter what bullet I am using as long as they don't go under the manual's suggested OAL, which is there as a minimum length to prevent over pressures in your cartridge.
 

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CBTO " cartridge base to ogive " measurement is probably the most effective and useful when setting up ones dies to produce home grown ammo. A few simple tools make the chore a breeze and take most of the guess work and questions out of the equation. Because of the difference in dimensions of bullets it becomes almost a necessity for precision ammo. The published COL has it's place when used as a minimum only measurement. Getting more technical in loading only enhances the effectiveness of producing the best of the best. Understanding what you are doing makes it a whole lot more fun and way safer that just " getting it close enough" to function. Whatta Hobby!



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Having shot Palma matches for a number of years found that the so called "bullet jump" from case mouth to rifling did make a difference for me and my particular rifle. Have used the so called "standard" bullet of 155gr SMK to the 175 and the 190 gr, all SMK. I found that the jump varied by bullet weight and seated accordingly. Found that using the 155 bullet and a chamber with long jump to reach the rifling, you had to be careful with how much of the bullet was actually being held by the case mouth being a shorter bullet compared to the other two weights. Common approach in those days was to have some 1/3 rd. of the bullet diameter in the case mouth and found that using the SMK 190 bullet that was not a problem. From my experience the ideal distance for the jump was 10 thousand or slightly less to gain good performance with the 190's. Was warned that the 190 in 308 would be subsonic at those extended ranges but I did not find that to be true regarding accuracy. Just my experience.
 

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Yes, every rifle can be different and may require particular attention. Without taking the time and experimenting with different bullet jump in your rifle achieving max precision is simply a game of chance. Care should be used not to seat bullets below the safety min COL published in your loading books. Taking time to do a ladder of loads and jump can make the difference of an alright cartridge to an exceptional one. Running good chronograph data and seeking the lowest sd has it benefits. Whatta Hobby!


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CBTO " cartridge base to ogive " measurement is probably the most effective and useful when setting up ones dies to produce home grown ammo. A few simple tools make the chore a breeze and take most of the guess work and questions out of the equation. Because of the difference in dimensions of bullets it becomes almost a necessity for precision ammo. The published COL has it's place when used as a minimum only measurement. Getting more technical in loading only enhances the effectiveness of producing the best of the best. Understanding what you are doing makes it a whole lot more fun and way safer that just " getting it close enough" to function. Whatta Hobby!



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Years ago when I first got into service rifle competition, I would read all I could on COAL and working off the Ogive. Well, when I went to the rapid stage I had problems out the ying yang. Call me stupid, but I could not understand that the mag decided the overall length. Once I got that little ah-ha thought figured out, I now measure the mags that I use for rapid and mark them.. When I reach out past 600 yds I will single feed and get better groups.
The only reason I post this is because we have many new people that are getting into reloading for these types of weapons and come to this forum for guidance. I've had Pm's from some that ask these type of questions, and made the same silly mistakes I did 40 years ago.. I don't mind talking about my mistakes if I can help someone else out..

Ya'll have a Happy Thanksgiving and,

Carry On !!
 

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Years ago when I first got into service rifle competition, I would read all I could on COAL and working off the Ogive. Well, when I went to the rapid stage I had problems out the ying yang. Call me stupid, but I could not understand that the mag decided the overall length. Once I got that little ah-ha thought figured out, I now measure the mags that I use for rapid and mark them.. When I reach out past 600 yds I will single feed and get better groups.
The only reason I post this is because we have many new people that are getting into reloading for these types of weapons and come to this forum for guidance. I've had Pm's from some that ask these type of questions, and made the same silly mistakes I did 40 years ago.. I don't mind talking about my mistakes if I can help someone else out..

Ya'll have a Happy Thanksgiving and,

Carry On !!
This is part of the reason why loading .308 cartridges for my Rem 700 I use 2.785" and my M14 variants uses 2.800". I load the max length that a) will chamber and b) will fit in the magazine.

The Rem 700 uses a polymer mag with thicker walls and even if 2.800" would chamber in my rifle (it won't) my recollection is that the round was too long for the magazine.

I'm new to reloading the .308 so take this as just my experience, not gospel.
 

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Years ago when I first got into service rifle competition, I would read all I could on COAL and working off the Ogive. Well, when I went to the rapid stage I had problems out the ying yang. Call me stupid, but I could not understand that the mag decided the overall length. Once I got that little ah-ha thought figured out, I now measure the mags that I use for rapid and mark them.. When I reach out past 600 yds I will single feed and get better groups.
The only reason I post this is because we have many new people that are getting into reloading for these types of weapons and come to this forum for guidance. I've had Pm's from some that ask these type of questions, and made the same silly mistakes I did 40 years ago.. I don't mind talking about my mistakes if I can help someone else out..

Ya'll have a Happy Thanksgiving and,

Carry On !!
You got that right. That is exactly why threads like this are posted and openly talked about. We all make mistakes, that's for sure. Nice if we can save others from the same boo boos. Loading manuals have their place, but practical experience makes it all make sense. Whatta Hobby!
 

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Discussion Starter · #16 ·
Art. thats a nice set up you have for setting OAL.

I used a .30 cal. cleaning rod with a brass patch tip I cut off and filed square.

I held a straight edge blade across the mouth of the flash hider to make a guide against which I marked the lengths on the rod. Blade gives a clean edge to the marks.

Mrs held the bullet in chamber with a short wooden dowel.

Removing bullet, I marked length to bolt face. Then I used points on my dial caliper to measure btw the marks. Not perfect but I made 8 checks using this method erasing the marks and it was repeatable +/- around .003
 

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Art. thats a nice set up you have for setting OAL.

I used a .30 cal. cleaning rod with a brass patch tip I cut off and filed square.

I held a straight edge blade across the mouth of the flash hider to make a guide against which I marked the lengths on the rod. Blade gives a clean edge to the marks.

Mrs held the bullet in chamber with a short wooden dowel.

Removing bullet, I marked length to bolt face. Then I used points on my dial caliper to measure btw the marks. Not perfect but I made 8 checks using this method erasing the marks and it was repeatable +/- around .003
So many ways of accomplishing the same goal. I also have the RCBS precision mic which works very well too. Whatta Hobby!
 

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Art. thats a nice set up you have for setting OAL.

I used a .30 cal. cleaning rod with a brass patch tip I cut off and filed square.

I held a straight edge blade across the mouth of the flash hider to make a guide against which I marked the lengths on the rod. Blade gives a clean edge to the marks.

Mrs held the bullet in chamber with a short wooden dowel.

Removing bullet, I marked length to bolt face. Then I used points on my dial caliper to measure btw the marks. Not perfect but I made 8 checks using this method erasing the marks and it was repeatable +/- around .003
Another way I used years ago, was to take a fired case and deform the neck just a little. Then take a bullet that you want to use and color it with a black marker. Place in the chamber and close the bolt.. Remove the case, most likley the bullet will be stuck in the land and grooves. Take the cleaning rod and push it out.
Then push the bullet back into the case to the point that the marker is removed from the deformed case. Take your caliper and read the COAL. Or use a comparator to measure the ogive. Then subtract 0.010 from there and find the node the gun likes moving the bullet in or out..

Carry On !!
 

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I tend to load a little longer in a bolt gun because it is not so violent to move the projectile in the case mouth. I like to seat bullets to the boat tail and the bottom of the case neck in autos to get max neck holding power. Some projectiles you can fudge some you can’t. Most SMK bullets are jump tolerant!
 

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I tend to load a little longer in a bolt gun because it is not so violent to move the projectile in the case mouth. I like to seat bullets to the boat tail and the bottom of the case neck in autos to get max neck holding power. Some projectiles you can fudge some you can’t. Most SMK bullets are jump tolerant!
Are you saying that some cartridges you load to less than published COL? Are you concerned with over pressure? Whatta Hobby!
 
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