.300 Ultra over all length

Joined
Nov 2, 2009
Messages
7
building a .300 ultra. The magazine box in the action I am looking at is 3.65". I am thinking that this may be a little short.

What overall lengthe are you having the most sucess with when loading 210 or 180 VLD Berger?

I just dont want to limit my self with a short mag box.

Thanks in advance.
 

jmden

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Joined
Nov 2, 2003
Messages
2,773
Location
Washington State
Get the Seekins Precision 3.9" box or the 4.010" Wyatts box. I'm running 3.83" OAL with a 210g Berger -.010 and the bearing surface/boattail junction is just barely below the case neck/shoulder junction.

You can always single feed. Many do.

Have fun with the new build!
 
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MontanaRifleman

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Joined
May 21, 2008
Messages
6,194
Location
South of Canada and North of Wyoming
building a .300 ultra. The magazine box in the action I am looking at is 3.65". I am thinking that this may be a little short.

What overall lengthe are you having the most sucess with when loading 210 or 180 VLD Berger?

I just dont want to limit my self with a short mag box.

Thanks in advance.
If you want to seat your bullets close to or up to the lands they will be too long for the mag box. The way I deal with that is to just put one round down and one in the chamber. The tip of the bullet of the round that is down is above the mag wall and will fit, but it only gives you a 2 shot configuration. For most LR hunting, that is more than enough. Your other option is to get a Wyats box.

I've only tried 210 Bergers in my Sendero 300 RUM. The base of the bearing surface is just above the junction of the neck and shoulder with a COAL of 6.860, about .010 off the lands. I'm not sure how long the 185's are but you might need to sit them back a little farther from the lands to get a good bite on the neck.

Some guys just seat them to fit in the mag box and they shoot fine. I like them close to the lands.

Mark
 
Joined
Nov 2, 2009
Messages
7
Thanks for the info. I posted on another page a question about Montana actions, but no one replied. Maybe this is a more appropriate forum.

Do these longer mag boxes mount standard to most actioins? Or should I be looking for a new mag box / action combo?


I am very new to this, but everyone is so keyed on making extending the bullet closer to the lands. Why not bring the lands closer to the bullet? Just a question that I have never heard asked....

thanks again.

carter
 

jmden

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Joined
Nov 2, 2003
Messages
2,773
Location
Washington State
Thanks for the info. I posted on another page a question about Montana actions, but no one replied. Maybe this is a more appropriate forum.

Do these longer mag boxes mount standard to most actioins? Or should I be looking for a new mag box / action combo?


I am very new to this, but everyone is so keyed on making extending the bullet closer to the lands. Why not bring the lands closer to the bullet? Just a question that I have never heard asked....

thanks again.

carter

Not sure what boxes that action will allow. Most aftermarket boxes are made for the Rem 700. I'd go with that action if you want to be able to take advantage of these long boxes. The MT action may be a 700 clone in which it may take those boxes. Check with the manufacturer I guess. Good luck.
 
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MontanaRifleman

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May 21, 2008
Messages
6,194
Location
South of Canada and North of Wyoming
If you're talking about the Montana Rifle Caompany actions, I haven't seemd mentioned in these forums hardly at all. It seems not many use them.

You could chamber to bring your lands back, but that's something I wouldn't do to avoid seating my bullet deeper in the case and taking up case space. When I size my cases, I partial size the necks and leave a small donut at the base of the neck to align the neck/bullet into the throat. If I was going to get a barrel chambered, I would chamber the throat for the bullet I wanted to use so that the base of the baering surface of the bullet was even with the neck at the *top* of the donut. This gives me more case space and allows for a little more capasity for more powder. Something like the principle of an "improved" cartridge. You dont gain a whole lot but it seems to help a little. It's up to you and what your prioritues are.

I think most Wyatt extended mag boxes require a little work to the receiver. You should contact them about the action you want to use to see if they can match it and what it would take to install.

Mark
 
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archdlx

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Joined
Nov 26, 2007
Messages
89
Location
East Central Alberta
yeahbuddy..waytoolongname ;)

I picked up a Wyatts from Brownells....WYATT'S OUTDOOR : EXTENDED MAGAZINE BOX - World's Largest Supplier of Firearm Accessories, Gun Parts and Gunsmithing Tools
"I" have to remove some metal from the bottom of the recv'r. Not sure if I have the 'NADS' as grandson calls them, to pull it off. Not even sure if a dremel will do it. But a local-Calgary- smith has his own Seekins type mag I am contemlating.
Keep getting torn between a carriable 300Rum, or a rifle to packed in my eberlestock to site and set up.

Good luck on your build!

Later....
 

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