7mm-08 O A L question

[tecumseh]

I made up a dummy round last night for my 7mm-08 with a 139 gr Hornady BTSP Interlock, I barely seated the bullet and chambered it and the O A L measured 2.866, it chambers and ejects with no trouble at all and fits the magazine with no trouble. Is seating it another .050 and starting with low powder charges the way to go as far as pressure issues go? The max O A L in the manual is 2.800.

 

[SJB358]

I’d start right there. With the Hornady they aren’t usually too fussy about seating depths. I’d take the length if the rifle is giving it to you.

 

[mjcmichigan]

You are ok. Shortening the jump can tighten your groups.

I’ll add, loading on the lands is territory to be careful. SAAMI spec establishes minimum standard chamber specs. Gun makers will exceed those so ammo chambers. Ammo makers will be close to or under those.

Get out a couple boxes of factory ammo and your caliper. You’ll be surprised by the variability.

I haven’t loaded th 7mm08, but in my 3006, it generally like 0.02” inch jump on Hornady Interlocks.


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[desertcj]

What do you mean when you say that you barely seated it at 2.866" and it chambers no problem? How did you arrive at that length? I work up loads at .005" off the lands to find max powder charge and will adjust the length shorter from there if needed.

 

[tecumseh]

What do you mean when you say that you barely seated it at 2.866" and it chambers no problem? How did you arrive at that length? I work up loads at .005" off the lands to find max powder charge and will adjust the length shorter from there if needed.

I seated the bullet into the neck just enough to hold the bullet and and chambered it to get a measurement. I hope that makes sense.

 

[EastTNHunter]

I have always started with the longest length that my rifle will accept (chamber or magazine, whichever is the limiting factor), then took around .010 off of that. Develop a load, then adjust length accordingly. Stay off the lands unless is a bullet designed for that and you really know what you’re doing...

My rifle likes less jump, while others have found that their rifles like more jump.

 

[desertcj]

What do you mean when you say that you barely seated it at 2.866" and it chambers no problem? How did you arrive at that length? I work up loads at .005" off the lands to find max powder charge and will adjust the length shorter from there if needed.

I seated the bullet into the neck just enough to hold the bullet and and chambered it to get a measurement. I hope that makes sense.

It sounds like you used a sized case to do that? You probably jammed the bullet into the lands because of the force required to seat the bullet deeper into a sized neck. You should use a case that will barely hold onto a bullet with the neck.

 

[tecumseh]

What do you mean when you say that you barely seated it at 2.866" and it chambers no problem? How did you arrive at that length? I work up loads at .005" off the lands to find max powder charge and will adjust the length shorter from there if needed.

I seated the bullet into the neck just enough to hold the bullet and and chambered it to get a measurement. I hope that makes sense.

It sounds like you used a sized case to do that? You probably jammed the bullet into the lands because of the force required to seat the bullet deeper into a sized neck. You should use a case that will barely hold onto a bullet with the neck.

That’s what I did. I’ll find a used case with a loser neck and do it over. It was recommended to me to use a sized case.

 

[Songdog]

When finding the lands, I resize a small portion of the neck, maybe .1” ...

I’ve found this works much better, and provides more consistent reading than using either s fully sized case or one that’s fired and unsized.

When using one that’s fired and unsized.... you can get some erroneous readings. The bullet will actually stick slightly in the lands, and will make it look like it’s farther than it is.

A Black Sharpie is your best friend when trying to find max COAL.

 

[tecumseh]

I’ve got a Hornady O A L gauge, I sent off to Midsouth Shooters Supply for the modifiedcade I need and the bullet comparator set. This should make the job much easier.

 

[Songdog]

I have one of those Hornady thingys laying around. I used to use it.... but anymore I just set-up a dummy round for each bullet at max COAL, and use it to set-up the dies.