Pressure signs ??

[Guest]

At the range yesterday attempting to break in a Rem Model 7 in 7 mm SAUM. Nosler # 6 manual shows 3 listings for RL19 of 58, 60 and 62 grains for a 140 grain bullet.

My load:
140 gr NBT
58 gr RL 19
Rem brass
Fed GM 210M match primers
OAL 2.82

The case is not full with this load. The bolt closes nicely before firing. First shot and the bolt was a little tight. Second shot and the bolt was tight, a slight extractor mark and there was a little black residue around the gas excape hole on the receiver = too hot for safety. I did not see any whiteness around the base of the cartridge. Tonight I plan to recheck the seating depth in relation to the lands. I will pull the rest of the bullets I have loaded and back off on the powder but I am a bit surprised at this since I started with the lowest load Nosler listed. Any thoughts or comments? Thanks.

 

[JD338]

You need to determine how far from the lands you are. If you are on the lands, this will raise pressures.

JD338

 

[DrMike]

JD338 is right. I would only ask, is this virgin brass? Be sure to check the case length to be sure you're not too long. If you have a tight chamber, that will be critical. I've been caught more than I care to remember on new rifles with chambers cut to tight tolerances.

 

[Antelope_Sniper]

I'm glad you followed the manuel closely and didn't just jump to the max load. :shock:

Alot of us who load older rounds have become acustomed to light lawyer loads in the loading manuels. Since the short mags have only been manufactured in modern bolt action rifle, these constraints are off. This makes it even more important to start low and work up with some of these new hot rod calibers.

BTW, what brand of brass was listed in the Nosler book, was it Remingtion like you used, or something different?

 

[JD338]

I believe Remington is the only maker of 7mm SAUM brass.

JD338

 

[Antelope_Sniper]

I'm inclined to agree with you JD.
To give you an idea how hot some of these new super magnums are, I've seen extractor marks from Remington factory ammo in the 300 RUM.

 

[DrMike]

Tight chambers/close tolerances seem to be a somewhat common feature in all the short magnums.

 

[Guest]

The brass is new. Nosler did use Rem brass with its testing. Didn't get in until after 6 and just finished with supper. Have a little home work to do and then will recheck the distance between the bullet and the lands. Will post results when I get it checked.....may be tomorrow.

Thanks for your thoughts and input.

 

[craiger40]

260fan,

Since you were doing break in i would ask did you clean the rifle right after you bought it. I have bought rifles from stores like Cabela's or what not that have cleaned the rifles several times. Unfortunately the people who cleaned it know as much about guns as they do rocket science, as to say there was a lot of debris and built up oil or grease in the chamber area. if your rifle had not had your touch applied to it, it may have been dirty in the chamber or around the rifling. This dirt would throw of any measurements you might have taken. if that is not possible i agree check the distance to the lands.

Craig,

 

[1Shot]

What was the temp outside when you did your shooting? Did you leave you ammo in a hot auto for a while? Did you leave your ammo box sitting in the hot sun? These all can raise the pressure a great deal.