OAL question?

[Lucky Scott]

I have been loading 140 gr. nosler ballistic tip bullets for my 7mm rem mag. I measured the gun with one of the OAL gauges that you put a shell and a bullet in it to see and it told me to go a little long with the noslers. I have been loading them 3.340 even though the books say 2.90 is max. I am about 20 thou off the lands. They shoot great, very accurate with no problems.
Here is my question. Maybe 200 rounds fired that way.
I have some other bullets and measured the gun with them with the OAL gauge.
The gauge said the nosler 150 gr. are the same OAL as the 140 gr., the Sierra gameking 160 gr. should be 3.310 and the Speer 175 gr. should be 3.40

So I loaded a test cartridge, (no powder or primer) of each using my RCBS single stage press and with the die at the same setting. It gave me
nosler 150 gr. the same as the 140 gr.
The Sierra 160 gr. was 2.82
The Speer 175 gr. 2.90

To me it looks like I am well on the safe side, with more than a 20 thou jump. It also put the Speer and the Sierra at the recommended 2.90 max that is in all the reloading books.
According to the OAL gauge I could go longer.

What do the CalGunners say? Am I Good to Go? Is this,
nosler 150 gr. the same as the 140 gr.
The Sierra 160 gr. 2.82
The Speer 175 gr. 2.90, a safe OAL length to load up some rounds and try it?

[BLR81]

For starters, the SAAMI max length for the 7mm Rem Mag is 3.290 and my Lee manual has 3.250-3.280 for the 140gr Jacketed Bullet depending on the powder for safe pressures. But it's not unusual for chambers to be longer, especially older weapons that have been shot alot. The SAAMI spec is a recommendation, and not a law.

If your 3.340 shows no pressure signs and shoots well, I wouldn't worry. As far as the other bullets go, you can't use the same die setting. Each manufactures design is different. Your seating die stem is hollow like a straw to allow the tip to enter so it's not damaged. The seating die stem doesn't touch on the ogive but some where between the ogive and the tip.

If the angle of the bullet from the ogive to the tip were the same with all manufacturers and all bullets, the seating stem would touch the bullet at the same place and seat it the same amount, but they don't. Some will touch sooner and seat deeper and some will touch closer to the ogive and seat shallower.

Sometimes when the brass hardens from reforming, the bullet will seat harder and when you force the bullet into the die it will compress the brass and you COAL will vary because of the ring in the brass caused by the brass being damaged before the bullet starts to seat.

You need to get a micrometer style seating adjuster for your die, so you can adjust the die to seat to the length you measured with your COAL guage. I have one for all my Hornady and Redding dies.

One seating depth does not fill all.

[Bastard]

like BLR said - if there are no pressure signs, I would just keep shooting.

also I would recommend measuring bullet ogive vs COAL.

[Lucky Scott]

The 7mm Rem Mag is a belted cartridge, does that make a difference with measuring ogive?

[Witch Hunter]

Does not matter, belted or not. Measure to the ogive with each bullet you shoot. That gives you the same measurement to work from.

[stevied]

Oal isn't nearly as important as measuring to the ogive. When I load sgk for my 7.5 swiss, the oal is below the recommended measurements because of the tight k31 chamber and the shape of the game kings. Keep an eye on the primer for pressure and you should be good. You can always pick up a comparator to give you a more accurate measurement.

[Witch Hunter]

To answer your original question, COL is a matter of each gun, not a SAAMI spec. Your ammo length will be governed more so by your magazine length, unless you want to single load it. Once you determine the maximum length for each bullet that you want to load, make sure it will fit your magazine. You can use that length or start about .020 off. As always start low and work up looking for pressure signs. Be careful, once you get close to the lands pressure can spike quickly. If your rifle like that length and it fits your mag, you are good to go.

[Lucky Scott]

I always try to load at least 20 thou off the lands, sometimes more. My accuracy and grouping is fairly good at this point, but I might look for more accuracy later when I start shooting longer distances. For right now, I am just trying to load safe and consistent. If I give up a little accuracy for safety, I am fine with that.
Even my long Nosler rounds seem to work fine in my magazine. However, I am planning on changing my bullets to a sierra match king in the near future. I like to eventually pick one bullet and then just stick with that. But I picked up a few different types and am trying them out to see what the gun likes. The Nosler seem to work fine, but the match king seem to be the bullet most target shooters like.

I still have a lot to learn about reloading and am trying to learn and be safe
at the same time.

I am measuring OAL, and still need to learn more about ogive measurements.
I was surprised when the other bullets loaded so much different with the die set at the same setting as the Nosler bullet. I guess the shape of the bullets differ so much that the die seats them different.
I was not trying to load them without changing the die setting, but was surprised to see how close I was before adjusting the die. I will adjust the die a little to get it just right.

[LynnJr]

Most seating dies use a funnel shaped cup to press the bullet into the case.This works but has several drawbacks to it.

If the tips of the bullets have jagged edges your over all length will vary do to the contact being at the longest point of the jagged edge.

If you use bullets with different ogive shapes like round nose or flat nose versus spitzer or VLD your over all lengths will be all over the place even if you maintained your original 0.020 off of the lands.

When you look at your over all lengths above notice that they are all over the map.

Target shooters use seating dies with a hollow stem that fits much further down on the bullets ogive or side of the bullet rather than pressing against the meplat or tip of the bullet.The bullets meplat or tip must never touch any part of the hollow seater stem itself for this to work.

Using that method gives you one length rather a bunch of lengths to achieve the same 0.020 off of the lands you were after.

If your shooting your 7mm Rem mag with 130 140 168 or 175's and you want to be 0.020 off the lands you wouldn't adjust the seating die at all when using a seater die with a hollow sleeve in it but you must if it has a regular type cup in it..

Round nose or flat nosed bullets would have a short over all length while Spitzer or VLD type bullets would have a very long over all length even though all rounds would be the same 0.020 off of the lands.

[Witch Hunter]

Nice looking hot rod by the way....