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Remington 673 Guide Gun Chamber Size Question
famous wolf
Member Posts: 125 ✭✭
I have a question about the Remington 673 chambered in 6.5 Rem. Mag. What I am concerned about is whether or not the chamber on this model will accomodate longer length bullets than the factory ammo (which is a 120 grain PSP). From what I understand when Remington chambered this round in the Model 700 back in the 1970s the chamber would not accomodate bullets longer than the short action (.308) overall length. This caused problems when trying to load heavier bullets such as 140 and 160 grains since the longer bullets had to be seated farther down in the case and into the powder space - thus limiting powder room. As such performance suffered with anything larger than the 120 grain bullet. Does anyone know if Remington corrected this problem in the 673? Will the 673 chamber allow longer bullets w/o suffering lost powder space to seat the bullets?
Comments
That's an interesting way to word your description and question.
First of all, there are standardized lengths for cartridges and they are not set by the manufacturer but by the standards groups such as SAAMI and CIP. Those that fall into the 'Short Action' category such as the 6.5 Rem. Mag., usually have an OAL of 2.800" +/- 0.050" which is accommodated both in the SA magazine and in the chamber.
In the past, Remington factory chambers have had longer than standard throats to allow for seating bullets out and reducing pressure excursions but it's the magazine length that curtails the overall loaded length. So, in essence, Remington and the other manufacturers didn't have a problem, they were conforming to the industry standards.
The solution to your 'problem' is to get a Wyatt extended magazine box for your Remington SA and then have the throat extended if necessary. The best method to use is to seat the bullet out to length you desire and measure it. Realize though that even the extended magazine boxes have limits. Cast the chamber and measure it accurately so you can establish an OAL to compare to the length you want to achieve. If this doesn't make sense, have a gunsmith assist with this part and the magazine box installation.
There will be some small feeding issues but they are easily cleaned up by someone who understands the feeding geometry.
The greatest solution is to buy a Mauser intermediate action and let yourself go wild with overall lengths.
Best.
Thank you for your response. I assume my ignorance on this subject came through loud and clear. In some ways I guess I understand what you are saying, but in other ways I do not. In a nutshell I guess I still have some questions:
(1) I guess the 673 (as is) can't accomodate longer bullets w/o the modifications you describe. Correct?
(2) Is it normal to have to do this (the modifications you suggest) for other calibers?
(2) Why would they make it so that you could only realize the full potential of a 120 grain bullet?
(3) Why don't other chamberings have this problem - such as a .308 for which you can load all sorts of bullets and not have this issue?
Thanks in advance for your insight.
It wasn't my intention to appear to be mean.
(1) I guess the 673 (as is) can't accomodate longer bullets w/o the modifications you describe. Correct?
Yes, correct, without intruding into the case capacity.
(2) Is it normal to have to do this (the modifications you suggest) for other calibers?
Not necessarily. It depends on the cartridge and to a certain extent, the caliber. It also hinges on your needs for the longer, heavier bullets in any caliber.
(3) Why would they make it so that you could only realize the full potential of a 120 grain bullet?
You can realize the greater potential but you are reduced to using the rifle as a single shot.
Usually it has to do with a marketing plan/advertising/competition and not functional reality. We've seen this in several other instances including the more current WSM cartridges.
(4) Why don't other chamberings have this problem - such as a .308 for which you can load all sorts of bullets and not have this issue?
The difference is a little more difficult to explain without getting into a bunch of esoteric math and physics. Suffice it to say that the 6.5mm bullets are longer for their diameter than the .308 bullets. It also has to do with the design of the bullet. Soft point, flat base bullets are shorter than the hollowpoint Match bullets. Speer and Hornady soft points don't take up as much room in the case as the Sierra SPBT or any of the Match-type hollowpoint bullets.
If some of this isn't clear, post again and we'll take another whack at it.
Best.
No, no, no....I didn't take your initialize response as "mean". On the contrary very, very helpful.
So, to follow up:
(1) In order to be able to use a multitude of bullet sizes, while maintaining maximum powder capacity, I will have to perform the modifications to the magazine (extend) and extend the throat? How much trouble is that? If I bought this gun I would plan to have a new, longer barrel installed (24") - how would that play into the modification of the magazine and throat? Cost??
(2) Can you further explain the whole magazine and throat extension process?
(3) If I don't make any modifications I have to ensure that any bullet is a maximum of 2.8" in total length. Correct?
(4) I don't handload, so assume I decide to purchase custom ammunition still using a 120 grain bullet, but of a different design than that of the factory ammo. Given the potential for a bullet with a higher BC such as a Nosler Ballistic Tip to be longer I would need to ensure that the maker keep it to 2.8", potentially ensuring that the bullet would be set further into the case thus diminishing case capacity and therefore performance. Correct?
Again, thanks for your insight. So far, very helpful
Thanks!
O.K., stick with me on this as it could get a little long...
I broke your 1st question into 2-parts since it will make more sense.
(1) In order to be able to use a multitude of bullet sizes, while maintaining maximum powder capacity, I will have to perform the modifications to the magazine (extend) and extend the throat? How much trouble is that?
Correct. Yes, since one goes with the other. Longer bullets seated out to maintain powder capacity requires a longer magazine box and throat.
It's not a terrible amount of trouble but it takes some time and effort to get it right. The box gets a little touch up, the bottom of the action and the feed ramp gets a little touch up and the throat can be lengthened without removing the barrel if the gunsmith is supremely careful and knows what he's doing. I remove the barrel and dial it in, in my lathe. Maybe not necessary but I get a great look at the throat and how straight the chamber is.
(2)If I bought this gun I would plan to have a new, longer barrel installed (24") - how would that play into the modification of the magazine and throat? Cost??
Here's why I separated the questions.
I wouldn't bother to buy a new rifle, re-barrel and then fix the box and throat. It seems like this could be a little more expense and bother when compared to getting something that will work correctly from the start.
I suggest looking at the Montana Rifleman actions which are available with the extended work done right from the start. It is a good action for a project such as yours and will probably break even with getting an M673 then doing all of the required work. Montana Rifleman also makes barrels so you could have all the work done at one spot, at one time. That leave you with picking out a new stock and you're ready to go shoot.
http://www.montanarifleman.com/
(3) Can you further explain the whole magazine and throat extension process?
If you examine the little photograph of the box:
You purchase this magazine box and there are a couple of small machining steps required to get it to fit the cut out in the bottom of the action where the factory box is located. The feed ramp will need to be shortened to allow the cartridge to feed and contoured to feed the longer cartridge correctly.
http://www.wyattsoutdoor.com/mag.html
http://www.brownells.com/aspx/NS/store/ProductDetail.aspx?p=1405&title=EXTENDED MAGAZINE BOX
The throat is cut deeper with a 'throating' reamer available from the same makers as the original chamber reamers.
Throat Reamer
Chamber Reamer
Cutaway Chamber with Notations
Two Different Throat Angles
(4) If I don't make any modifications I have to ensure that any bullet is a maximum of 2.8" in total length. Correct?
No. You need to have the total cartridge length (case + seated bullet) to be 2.800" or magazine length with a little room to move and feed.
(5) I don't handload, so assume I decide to purchase custom ammunition still using a 120 grain bullet, but of a different design than that of the factory ammo. Given the potential for a bullet with a higher BC such as a Nosler Ballistic Tip to be longer I would need to ensure that the maker keep it to 2.8", potentially ensuring that the bullet would be set further into the case thus diminishing case capacity and therefore performance. Correct?
Correct. If you leave the rifle set up as it comes from the factory, the overall length of the cartridge will need to be magazine length of 2.800 +/- inches.
I hope I read all of this right and the answers make sense.
Best.
Welcone to the forums herre on Gunbroker!
I see you have already found some of the best advice and direction that can be found anywhere.
I see you don't handload, but if you know someone that does try this if they will do it for you.
There is nothing saying that at present your 673 can not shoot the longer bullets. Have you tried making a dummy round(s) with the 140 and 160 grain bullets? Try that by seating one out so the base of the bullet just barely engages the case mouth without crimping, then close the bolt and cam it down. That should let you know where your lands start. Most often than not though, it is the magazine length on the Remingtons that are the limiting factor. The Browning A-Bolts are worse yet. It seems we have thest problems with the short fat cases that have short necks...what were them engineers/wildcatters thinking...but I love it.
Best