Throat Erosion

No, this is not the start of a porn story. I just found out about throat erosion or throat wear. When you have a new barrel on your rifle you need to measure where a bullet “gets stuck” when you stick it in the throat of the chamber. That gives you a measurment to seat your bullets when making ammo.When you shoot a lot of rounds through the barrel, over time the throat wears down. Which means the bullet will have to be measured again because most likely it needs to move forward down the throat for a fresh spot just after the worn spot. Make sense? It took a couple of explanations and demonstrations for me to understand.

I am now going to try new bullets by Sierra. This will add more details. Bullets are not all the same! Even if you have a 155 grain bullet from three different manufacturers, they will all be different. It can be very slight but one might be skinnier or taper in different spots than others. The photo with bullets and ammo shown are  from left to right, Nosler, Berger and Sierra brands. The cases are all Lapua. Each bullet had a different measurement when we tested them in chamber. Huge differences! That is because each bullet is shaped differently. The second photo is of the  measuring device and the bullet comparator (red thing attached). This tool tells you what measurement you will need when making the ammo. There was another tool called the Stoney Point Gauge that stuck the bullet up in to the throat of the gun to the point it gets “stuck” in the fresh unworn part. Phew!

We now have measurements for all 3 bullets if I choose to shoot all 3 in tests. I am going to use Sierra this time for my State Championships in a couple of weeks!

“Shoot Like A Girl! If You Can……”

About 30calgal

Member of the Unites States Rifle Team. 2011 NRA National Civilian Record Holder of 300 Yards. 2011 B.C. Rifle Champion (First American woman and second woman ever to win this in 127 years) and more. Starting the fast and exciting world of 3 Gun or Multi-Gun Competition.
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