.300 Win. Mag. Throating

[.300winmag]

Right now I've got a 28" 1-9" twist Hart barrel at my gunsmiths that is going to replace my current barrel on my .300 Win. Mag. I've put about 1,500 rounds on my current barrel in the matter of 3 years. It still shoots great, but I want to have another barrel ready for when my current barrel goes. What I've been going back and fourth about it having my new barrel throated slightly longer to better accommodate the 215 grain Berger Hybrid. I plan on using this as my primary bullet for hunting and for 1,000+ yard shooting. The reason I'm having such a hard time deciding to go with a longer throat or not is I have about 1,000 190 grain Sierra Matchkings that I'll use for paper punching and for the local tactical matches that only go out to 1,000 yards. I want to be able to shoot the 190's as well as the 215's with good accuracy and precision and am not sure if the longer throat will be detramental to the 190's performance.

In my current barrel, I went with a standard throat and have run the 210 Berger, 190 Sierra, 200 AccuBond, 215 Berger and 230 Berger with excellent performance from all. The long throat on the new barrel would give me a touch more case capacity and theoretically, give me slightly more performance. My question for you folks is should I go with the longer throat, or go with what I know has worked in the past?

 

[IdahoCTD]

Throat it for the 190 Sierra's and it probably wont be far off for the 215's because of their more aggressive profile and shorter bearing surface.

 

[Desert Fox]

Is this going to be magazine feed or single shot?

 

[Thebear_78]

if your slaved to the original box magazine length then just throat it normal. If your going to put an extended magazine box like a wyatt then I would throat it for the COL that will fit in the extended box magazine.

 

[.300winmag]

I have a Wyatt's extended magazine in it, so I can seat bullets roughly 3.800" OAL is not an issue.

 

[SJB358]

I would seat for the shortest bullet your going to use.. I imagine you'll do fine with the 215's and your loads are shooting pretty awesome from all I have seen..

 

[Guy Miner]

This said it all for me:

"In my current barrel, I went with a standard throat and have run the 210 Berger, 190 Sierra, 200 AccuBond, 215 Berger and 230 Berger with excellent performance from all."

A lot to be said for retaining that same performance & capability.

Guy

 

[woods]

A longer throat means a larger combustion chamber like a Weatherby caliber/chamber. You can compensate for it by loading more powder. It will reduce velocities substantially on factory ammo. All of which may not be a concern.

IMO to get the most out of the bullets you want to shoot, load a dummy case (no powder no primer) and seat the Berger 215 where the bearing surface at the base (not including boat tail) is at the neck/shoulder junction. Then tell the smith to set the lands to where you are .020" off at that OAL. The throat will recede minimally with shooting and you should be able to stay within .040" off the lands through the life cycle of the barrel. On the shorter bullets you will be further off the lands but not by that much.

Or like SJB said throat it to the shortest bullet and the amount you will protrude into the powder capacity with the longer bullets will be minimal.

 

[.300winmag]

A longer throat means a larger combustion chamber like a Weatherby caliber/chamber. You can compensate for it by loading more powder. It will reduce velocities substantially on factory ammo. All of which may not be a concern.

IMO to get the most out of the bullets you want to shoot, load a dummy case (no powder no primer) and seat the Berger 215 where the bearing surface at the base (not including boat tail) is at the neck/shoulder junction. Then tell the smith to set the lands to where you are .020" off at that OAL. The throat will recede minimally with shooting and you should be able to stay within .040" off the lands through the life cycle of the barrel. On the shorter bullets you will be further off the lands but not by that much.

Or like SJB said throat it to the shortest bullet and the amount you will protrude into the powder capacity with the longer bullets will be minimal.

Right now that's exactly what I've done. I've loaded the dummy round exactly like you described and the smith has had it for a month now. Great minds think alike. But, I had my smith put a note in my order to give me a call before he throats the new barrel, just in case something in my head has changed my mind. I love having rifles built, but my mind goes wild with ideas and options, sometimes it just seems like too much. I'd rather have these types of rifle issues to deal with than any of the many other world issues though!

 

[woods]

Are you going to get a specific neck?

If you figure a neck thickness of .013" per side and a .003" clearance in the neck

.308"+.013"+.013"+.003"=.337"

or if you figure .012" which means you probably would have to do a complete outside turn

.308"+.012"+.012"+.003"=.335"

I've used a lot of 300 win mag brass and it seems like the average thickness of new brass is .013" to .015"

Perhaps someone else could pitch in on that

 

[.300winmag]

I'm going with a standard neck, I don't want to have to turn my necks. I have a good smith and don't feel turning necks will benefit me enough to justify it. I honestly don't know what dimensions the neck is on his reamer but it worked well for me in the past.