300 Win mag brass swell

ROJO20

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Joined
Sep 10, 2024
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Location
Arizona
I have a Remington 700 long range chambered in 300 win mag. I mounted a scope on it bought some factory ammo for it and took it to the range. The factory ammo I bought for it were the Barnes 180gr TTSX. I shot two rounds through it with the bolt sticking on both shots. I stopped shooting and noticed that the brass is rubbing just above the belt. Anyone have any advice as to why this would happen? Is it an issue with the Barnes bullets or an issue with the gun? I did reach out to Barnes, and I sent them several pictures and lot number of the ammunition but have not heard anything back.
 

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Yeah I cleaned the barrel after. It was a little dirty but didn't seem out of the ordinary. That's a good idea I will measure it. The rifle is not new, it was strange to me. I did take it out today and it shot a few federal premium scirocco ii perfectly fine. Must have been the Barnes bullets?
 
As mentioned. Some barrels take more rounds to brake in. You may have to shoot a few rounds then clean real well and repeat. Most barrels need a minimum of 25 and up to 100 rounds for it to settle in.
I let the barrel tell me. Pure copper, depending on the type can create more pressure then the Cup and Core.
Hope this helps. đź‘Ť
 
Any chance you have a bore scope? Might tell you if there is a burr in the chamber, carbon ring, etc...

Odd that another ammo doesn't have the same issue.

K.E.C makes a good point, might be the harder mono bullet. Might also be due to guilding metal not playing nice with the mono bullet. Perhaps clean to bare metal and try again.
 
My Seekins 300 WM has about 500 rounds on the barrel. It was showing some signs of pressure. Velocity for a load with 215 Bergers was running around 2965 fps. I bought a Teslong flexible bore scope and some Bore Tech C4 and some Iosso paste off of Midway thinking I might be dealing with a carbon ring. I cleaned it really good and the pressure spike went away and velocity dropped to the normal 2915-2920 FPS. It may have been your Barnes ammo, but carbon rings can cause havoc as well!

Before and after cleaning pics attached showing carbon buildup.
 

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