300-378 Wby factory ammo, blown primer stuck bolt

[dig]

At the range today sighting in a friends 300-378 Weatherby Mag. It's a stock Mark 5 action and stock, no custom work. Using Weatherby Factory ammo 180 grn Nosler AB. First shot bolt is stiff, like pry on it stiff. Second shot bolt stuck, I open up with mallet and primer is blown, both show major extractor marks. Rifle is in great shape barrel is clean, no obstructions etc. . . Needless to say I am done shooting it. Ammo is about 4 years old I am told, temp was hot 105 but ammo not left in sun, came out of truck. What are he possible issues, yes I will have it looked at of course.

 

[Fiftydriver]

Get some fresh ammo and try it again. Make sure you wear protection. If it happens again, send the rifle to Wby and let them fix the problem. Likely the ammo may have been allowed to heat and cool, heat and cool over the past 4 years. This can cause the powder to start degrading which speeds up the powders burn rate.

Also, if the ammo was bouncing around in a truck for some amount of time, this vibration can also cause the powder to break down and burn rate to increase causing pressure spikes.

First thing to do, get fresh ammo and see what the rifle does.

 

[dig]

Thank you, that was along my thoughts, ammo ridding in the vehicle for several years in this az heat breaking down. I always wear glasses at the bench this just reinforced it scary! One other thought could there be a bend in the barrel? Neither shot hit 2' x 3' piece of paper at 100, I checked with a crude down the tube bore sighting prior to pulling trigger. Looked high, ran through the chrono at 3590' which seams very hot from a stock tube. He is buying fresh factory ammo to try prior to me starting to load.

 

[Lefty7mmstw]

Thank you, that was along my thoughts, ammo ridding in the vehicle for several years in this az heat breaking down. I always wear glasses at the bench this just reinforced it scary! One other thought could there be a bend in the barrel? Neither shot hit 2' x 3' piece of paper at 100, I checked with a crude down the tube bore sighting prior to pulling trigger. Looked high, ran through the chrono at 3590' which seams very hot from a stock tube. He is buying fresh factory ammo to try prior to me starting to load.

3590-- I've shot along side guys with that round and they struggled to get 3400 fps with a 180 in an accumark. Yep, it's a bit hot indeed.

 

[Fiftydriver]

A bent barrel will do nothing to increase pressure as long as its not bent to the point that it STOPS the path of the bullet. IF that was the case, your barrel would look something like this >. A barrel that looks like ( will not cause any pressure spikes but getting point of impact and point of aim to match up may be a trick!!!

That is VERY high velocity, get a new lot of brass and recheck.