throat length on new Rem. 700

[papafox]

I have a question about throat length and what's acceptable and/or safe.

This summer I bought a new Remington 700 CDL in 7mm Rem Mag. After breaking in the barrel with a couple of boxes of cheap Federal ammo I went to make some of my own loads. Before seating my first bullet I measured the OAL with my Stoney Point OAL gauge. Using a Sierra Game King 140 grain bullet I was surprised to see how short the OAL was.

SAAMI max OAL for the 7mm is listed as 3.290. Sierra's load data suggests an OAL of 3.240 with the 140 grain SGK. But the OAL when I just contacted the lands for the Sierra bullet in my rifle was 3.235. That's 0.055 shorter in my rifle than the SAAMI spec!

I double checked myself by making a dummy round at the SAAMI spec (3.290). It wouldn't chamber. When I forced it, it went in but when I ejected the round, the OAL was now 40 thousandths shorter. The bullet had just pushed further back into the case.

If I make up almost any load from any recognized load manual to the OAL listed in the manual I will have the bullet seated well into the lands.

Even my factory ammo, Federal Powershocks (made with a Speer Grand Slam, I think) is only 40 thousands off the lands. Factory rounds are usually very short.

I sent the rifle back to Remington under warantee. They sent it back (3 months later) saying, "chamber dimensions are within SAAMI specs", and didn't change anything but polish the chamber and test fire it. With all the fear of lawsuits, I was really surprised Remington would say this.

Should I be concerned about this short throat? I certainly can just make my cartridges shorter. Obviously, I won't have any problem loading the bullet right off the lands while still fitting the magazine. And maybe my short throat is a good thing since throat erosion won't be an issue for a much longer time.

The reasons to be concerned, I guess, are that I might some day put in some factory ammo that isn't as conservative as my current Federal ammo and it might be sitting on the lands when chambered creating a high pressure. Also, will this limit my case capacity significantly or create higher pressures?

Should I be concerned? Are there any major downsides to a short throat? Should I consider myself lucky to have such a short throat?

Thanks for any insight.

 

[Bullet]

I believe that different bullets will give different measurements (from the base of the case to the tip of the bullet) to the lands due to bullet shape. You need to measure to the lands with a bullet comparator.

I double checked myself by making a dummy round at the SAAMI spec (3.290). It wouldn't chamber. When I forced it, it went in but when I ejected the round, the OAL was now 40 thousandths shorter. The bullet had just pushed further back into the case.

SAAMI max OAL for the 7mm is listed as 3.290. Sierra's load data suggests an OAL of 3.240 with the 140 grain SGK

3.290 - .040 = 3.250. You’re wanting an OAL of 3.240 with the 140gr SGK. Looks like your .010 off the lands.
Just to make sure make a dummy cartridge at 3.240 with the 140 grain SGK. Then chamber it and see if you see any marks from the lands (you might color your bullet with a marker to make seeing the marks from the lands easier).
If you see marks from the lands using your 140gr SGK at an OAL of 3.240 something is wrong.

 

[papafox]

Bullet,

When I forced the SAAMI length cartridge into the chamber I think the bullet was still wedged about 15 thousandths into the lands. So the final length when I ejected it wouldnt really be a OAL to the lands.

Aren't all rifles supposed to chamber ANY round made to it's caliber's SAAMI Max OAL? I thought that was the whole point of the SAAMI spec.

 

[Bullet]

I sent the rifle back to Remington under warantee. They sent it back (3 months later) saying, "chamber dimensions are within SAAMI specs", and didn't change anything but polish the chamber and test fire it. With all the fear of lawsuits, I was really surprised Remington would say this.

Aren't all rifles supposed to chamber ANY round made to it's caliber's SAAMI Max OAL? I thought that was the whole point of the SAAMI spec.

I sure thought if your rifle is within SAAMI specs it should chamber any ammo made to spec MAX OAL of 3.290. Since Remington said it was within spec I thought somehow your measurements were off. But if your measurements are right your throat is very short.

Definitions from SAAMI -

CHAMBER
1. In a rifle, shotgun or pistol, the rearmost part of the barrel that has been formed to accept a specific cartridge or shell when inserted

CHAMBER LEADE
The conical part of the bore between the chamber and the rifling. Also called Throat or Ball Seat.

LEADE (LEAD)
That section of the bore of a rifled gun barrel located immediately ahead of the chamber in which the rifling is conically removed to provide clearance for the seated bullet. Also called Throat or Ball Seat.

Maybe Remington doesn’t consider the throat part of the chamber and didn’t check it.
I don’t load for 7mm Rem Mag but in my older Sierra manual it says for 7mm Rem Mag “Great care should be exercised in loading for this cartridge, since there appear to be many variations in chamber and throat dimensions.” Since I don’t load for this I should probably not comment and let someone more familiar with 7mm REM Mag answer, but I would be interested hearing the replies.

 

[USSR]

papafox,

You're complaining because your Remington has a short throat? Most Remingtons have the throat FAR beyond what can be possibly reached in a normally loaded round. Count your blessings and load it to the dimensions that your Stoney Point AOL Guage tells you.

Don