Throating Results?

[southpa]

i get that as most are for 1 specific bullet, but when you throat just far enough that groups start getting worse, then what. for those that run close to lands unlike those that jump them there, then what. like some people that have a 30cal w/215's using a purpose designed reamer although they've used it before, but's a no-go in this barrel

I don't understand. Throat far enough that groups get worse? Just because you like a jump or jamb doesn't mean you cannot throat your chamber to do both.

This is kinda a funny coincidence since were in the middle of fire season.
Study done with bullets causing fire

https://research.fs.usda.gov/treesearch/43918

That's a terribly written article IMO. But not surprising what I think was found.

 

[Varmint Hunter]

Another potential benefit of extending a throat is that (depending on the bullet used) you might be able to keep the bullet bearing surface above the infamous donut.

I just loaded some Berger bullets in Lapua 6.5PRC cases. The bullets all seated without issue. I never even considered that the cases might have donuts. Then I seated a few 140 Accubonds that I intended to use as fouling ammo. The Accubonds hit a wall on the way down. I took a closer look and realized that the bearing surface was where a donut would develop. I continued to push the bullets in further but they went in with a bit of a snap. Looking at the Berger bullets, I noticed that the bearing surface was slightly above the donut area. Ideally, you only want a boat to rest in the area where donuts form.

 

[JAYgs8163]

"Another potential benefit of extending a throat is that (depending on the bullet used) you might be able to keep the bullet bearing surface above the infamous donut."

I had my 270 WSM chamber done with a total Freebore of .200 and it's ideal for the 170 Berger and similar bullets. It accomplished this perfectly and is running at 2960-2975FPS with great accuracy.

 

[K.E.C. Darkside]

It's a new build, that was the plan from the start, but I just wonder if there really is any gain??

If this is a new build.
Have a reamer made for what you want. You mentioned the 165nlra, make a dummy round using that bullet to Your specific and have a reamer made. That should accommodate the copper bullets as well.
Just a thought.

 

[JAYgs8163]

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[southpa]

Doesn't give a price.

 

[frostop]

Another potential benefit of extending a throat is that (depending on the bullet used) you might be able to keep the bullet bearing surface above the infamous donut.

I just loaded some Berger bullets in Lapua 6.5PRC cases. The bullets all seated without issue. I never even considered that the cases might have donuts. Then I seated a few 140 Accubonds that I intended to use as fouling ammo. The Accubonds hit a wall on the way down. I took a closer look and realized that the bearing surface was where a donut would develop. I continued to push the bullets in further but they went in with a bit of a snap. Looking at the Berger bullets, I noticed that the bearing surface was slightly above the donut area. Ideally, you only want a boat to rest in the area where donuts form.

Can you explain this "Donut" , What is it your referring to??

If this is a new build.
Have a reamer made for what you want. You mentioned the 165nlra, make a dummy round using that bullet to Your specific and have a reamer made. That should accommodate the copper bullets as well.
Just a thought.

It is a new build, but I didn't want to buy a custom reamer-wanted to be able to use it again as a standard 270wsm.
The rifle has been built with the standard reamer and I will likely have it throated

 

[Varmint Hunter]

Can you explain this "Donut" , What is it your referring to??

Repeated firing and reloading of brass can cause brass to flow from the shoulder to the base of the neck. The displaced brass can cause a constriction at the base of the neck. It can be reamed out but most shooters prefer to load bullets that avoid the "donut" altogether. Loading bullets out farther can eliminate the interference problem, providing that there is sufficient room in the throat to do so.

 

[frostop]

So what can I expect from doing this?
I've done the work and have run a pressure string though the rifle, 65.4-67.2 grains of Retumbo behind 165ABLR
I didn't see any pressure signs on the cases but the bolt had a little resistance when opening pretty much all the way through the string-brass had two firings on it through a different rifle.
Only saw 2890fps

My pet load on the other rifle was 67gr of Retumbo, Ruger M77 MKII Short Action

 

[Shane Lindsey]

So what can I expect from doing this?
I've done the work and have run a pressure string though the rifle, 65.4-67.2 grains of Retumbo behind 165ABLR
I didn't see any pressure signs on the cases but the bolt had a little resistance when opening pretty much all the way through the string-brass had two firings on it through a different rifle.
Only saw 2890fps

My pet load on the other rifle was 67gr of Retumbo, Ruger M77 MKII Short Action

Have you cycled the 2x fired brass in your rifle without having them loaded? If fireformed to another chamber, then trying to feed them into yours, may cause it to be tight. That tight feeling may be present before you fire.

To really test, pull the firing pin. Size a case and try it. Also try without sizing a case so you can feel the difference. If the sized case is easy to unload, I would say gently work up to pressure. Ejector print, click at the top of the bolt throw, then back off.

 

[frostop]

Yeah, cases are full length resized and they load and unload "unfired" easily.