Far from the lands...

[azar]

I'm just starting to work up a load in my 7mm Remington Mangum with a Hornady 154g Interbond. This particular bullet is long, and has a fairly long ogive (almost 1/2 the bullet). This is probably what gives it a B.C. of .530 but it does pose a (potential) issue.

Using the Sinclair OAL gauge with this bullet I get a measurement that my overal length would need to be 3.390" from base to tip to just touch the lands. That's 0.100" over the SAAMI max length for this cartridge. So, for this particular bullet I'm quite a bit off the lands. So, any expert opinions on what I should choose for my O.A.L.? If my magazine will hold a round at the max of 3.290" do I use that? Or do I give myself a little breathing room (for bullet variances) and load it to 3.280" or just use the published Hornady O.A.L?

Ideas? Thoughts?

 

[GooseGestapo]

Most manuals recommend that you seat to the maximum that will function/feed through your magazine. Sometimes this will still allow you to seat the bullet out to touch the lead, many times not however.

If seating the bullet to touch or "jam" into the lead (lands junction in throat), be sure to back off on your starting load to that recommended in the Hornady manuals. Without a "jump" into the lands, pressures will rise perhaps as much as 5,000cup/psi.

You may not have to seat the bullet into the lands to get good accuracy. Several of my rifles prefer the Hornady bullets .030-.050 off the lands to give good accuracy. One in particular is my Remington Mod7 in 7mm08. But, it has a short magazine, and a very short throat/lead.

The only 7mmRemMag that I've loaded for was a Savage M110. It had a short throat and a Sierra bullet couldn't be seated longer than 3.250". Accuracy was very good however. I just seated the Hornady 139gr BTSP's to the cannulure. Still do with my 7mm08.

You'll just have to experiment and figure it out for YOUR rifle.

 

[USSR]

Got a Model 700, huh?

So, any expert opinions on what I should choose for my O.A.L.? If my magazine will hold a round at the max of 3.290" do I use that? Or do I give myself a little breathing room (for bullet variances) and load it to 3.280" or just use the published Hornady O.A.L?

Here is what I do. You need to keep one caliber of the bullet (.284") inside the neck (not counting the boattail), so measure your bullet from where the boattail ends at the full diameter part of the bullet, up .284" towards the bullet tip, and mark it. Now, seat your bullet so that the mark is flush with the case neck. That's your OAL.

Don

 

[Walkalong]

You need to keep one caliber of the bullet (.284") inside the neck (not counting the boattail)

+1

Other than that you can seat it at any length your mag will allow that gives you the "jump" to the lands you want.

Many stock rifles won't allow you to get as close to the lands as one would like.

That does not mean it can't shoot very well though. Many bullet/rifle/action combos with a lot of jump to the lands shoot very well indeed, as long as the bullet, barrel, and shooter are up to the task.

 

[moooose102]

personally, i keep my oal to a .020" short of touching the lands (when i can). i dont like the idea of a big spike in pressure.

 

[Walkalong]

When folks work up loads with their O.A.L. set, there is no "spike in pressure".

 

[azar]

USSR said

Got a Model 700, huh?...You need to keep one caliber of the bullet (.284") inside the neck (not counting the boattail)...

Actually it's a Ruger M77 Mark II, but same issue. Anyway, I understand that you always want to keep at least 1 caliber (0.284" in this case) in the neck but that's not really the issue. If I kept just 1 caliber in the case with freshly trimmed-to-spec brass that would give me an O.A.L. of 3.586" (0.296" over listed max C.O.A.L for the 7mm Rem Mag and 0.196" into the lands in my gun)!! So, keeping at least 1 caliber in the neck is a non-issue.

The listed max length for the 7mm Remington Magnum is 3.290", but with this particular bullet in my gun that would put me 0.100" away from the lands. I can't get any closer than that without exceeding book listed max C.O.A.L. and was just wondering mainly what recommendations people have (if any). I think Walkalong and GooseGestapo's answers were probably the only ones that can be given.

Walkalong said:

Many stock rifles won't allow you to get as close to the lands as one would like.

That does not mean it can't shoot very well though.

GooseGestapo said:

You'll just have to experiment and figure it out for YOUR rifle.

I'm just loading these to the cartridge max of 3.290" as that's also the C.O.A.L Hornady used. Now I'll just have to double check that they will fit in the magazine.

Thanks for the input guys.

 

[USSR]

The listed max length for the 7mm Remington Magnum is 3.290", but with this particular bullet in my gun that would put me 0.100" away from the lands. I can't get any closer than that without exceeding book listed max C.O.A.L. and was just wondering mainly what recommendations people have (if any).

azar,

There is no SAAMI listed max length for loaded cartridges, as OAL will vary according to the bullet being used. The OAL listed in the reloading manual is simply the OAL that they used. Load the bullet out further to bring you closer to the lands and don't worry about the OAL. As long as you are not into the lands and it mag feeds, it's fine.

Don

 

[azar]

Ha ha. This is why you don't read reloading manuals before 6:00AM!

For some reason I read Hornady's 7th edition data that said Max c.o.a.l of 3.290" and thought it was part of the caliber specs. Like the 2.500" max case length and 2.490" trim-to-length, etc.

Dang, I've already seated all 25 reloads to 3.290". Oh well, I guess I can still take the best grouping and then play with the c.o.a.l later.

Thanks.