Tight chambered 300 RUM fix needed

[xtratoy]

I have one of the first 300 RUM model 700 rifles that was available in this area when they introduced the round in 1999-2000. I got the gun fro the original purchaser and he never fired the rifle. That is the history of the rifle. My problem is that when I got it I purchased several hundred once fired cases. and a set set of Hornady Custom Grade Dies. After full length resizing the brass still would not chamber. I cursed the dies and slowly ground the shellholder so that the shell would go further into the die and be sized more. I finally found where I could get the brass resized to where it would chamber with minimal bolt pressure and reloaded some rounds to try it out. The fired brass chambers easier that the sized brass due to to fire forming in the chamber. Now my problem started once again. When I reside the brass trying to adjust the dies for minimal case resizing but resize the neck my brass was difficult to rechamber again. I am talking some serious pushing on the bolt. I finally broke down and bought a box of Remington Premier Ammo and guess what I can barely get the bolt closed on factory ammo. I was going to but a RCBS FL sizing die but after trying factory ammo I am not sure that this will cure the problem. What do you think about smoking-sooting an empty case and trying to find where the tight spot is and then trying to polish the chamber in that area ( spin a once fire case case with some super fine abrasive ) to fix the problem? Or do I need to find , borrow or rent a 300 RUM finish reamer and relieve the chamber a little. It doesn't seem like it will take much material removal to end up with a chamber that will close on a case like it should . Has anyone polished up a tight chamber like this with positive results?

 

[J E Custom]

I have one of the first 300 RUM model 700 rifles that was available in this area when they introduced the round in 1999-2000. I got the gun fro the original purchaser and he never fired the rifle. That is the history of the rifle. My problem is that when I got it I purchased several hundred once fired cases. and a set set of Hornady Custom Grade Dies. After full length resizing the brass still would not chamber. I cursed the dies and slowly ground the shellholder so that the shell would go further into the die and be sized more. I finally found where I could get the brass resized to where it would chamber with minimal bolt pressure and reloaded some rounds to try it out. The fired brass chambers easier that the sized brass due to to fire forming in the chamber. Now my problem started once again. When I reside the brass trying to adjust the dies for minimal case resizing but resize the neck my brass was difficult to rechamber again. I am talking some serious pushing on the bolt. I finally broke down and bought a box of Remington Premier Ammo and guess what I can barely get the bolt closed on factory ammo. I was going to but a RCBS FL sizing die but after trying factory ammo I am not sure that this will cure the problem. What do you think about smoking-sooting an empty case and trying to find where the tight spot is and then trying to polish the chamber in that area ( spin a once fire case case with some super fine abrasive ) to fix the problem? Or do I need to find , borrow or rent a 300 RUM finish reamer and relieve the chamber a little. It doesn't seem like it will take much material removal to end up with a chamber that will close on a case like it should . Has anyone polished up a tight chamber like this with positive results?

Polishing a chamber is risky with the chance of more problems.

The best thing to do would be to find/buy a SAMME spec. finish reamer and a head space gauge.

This will assure you that the neck and the shoulder are right and also open the body.

Also the Hornady dies should have worked without grind the shell holder.

With the chamber already there hand reaming is possible if you are careful (Don't use a drill
because it will cut to much to fast). You can get a hand tool that will drive the reamer through
the action once it has been removed from the stock.

It would be best if you have a gun smith do it unless you feel ok with it. If so clean the chamber,
clean and oil the reamer, and clean every time you remove the reamer to check head space
before re inserting the reamer in the chamber.

Be carefull and it will turn out ok.

J E CUSTOM

 

[IdahoCTD]

Another option is to send it back to Remington and see if they will fix it or replace it.

 

[Rustystud]

You have indicated it is a tight chamber. Is it not headspaced correctly or is it tight in the throat, neck, shoulder, or web. Is the chamber out of co-axial alignment with the bolt? Your options are 1. to send it to Remington for repair or replacement, 2. send it to a good gunsmith, 3. repair it yourself if qualified. No offence intended after reading your question and previously tried solutions I would advise on option 1 or 2.
Nat Lambeth

 

[ken snyder]

Under sized chambers are extremely rare and inadequate head spacing is as well. Die Manufacturers make their dies on the small side unless ordered differently. The problem is almost a guaranteed die set up problem along with trim length and c.o.a l. If the chamber is smooth the only thing you are going to do with a hone is waste your time or ruin the chamber.

 

[xtratoy]

Thanks to all for the info. The hone or polish was to be a last ditch effort . I really didn't want to and haven't done it. I am trying to locate a local reloader to borrow some different dies to see if my dies are just not working for my rifles chamber. If I can't locate anyone willing to let me resize a couple of my brass I will bite the bullet and purchase a different set of dies. Lee or RCBS?????? Anyone have any experience with Lee 300 RUM dies?

 

[IdahoCTD]

If you can barely close the bolt on factory ammo something is wrong with the chamber not your dies. Have you tried calling Remington and telling them their own ammo won't chamber without considerable effort? They would probably want the rifle back to look at it.

 

[Rustystud]

Thoroughly inspect the chamber, counter bore, tenon, bolt lugs, front and face for trash ie: brass, unburned powder etc. Check it with a SAAMI go gauge. If the bolt closes on the Go Gauge you have rulled out headspace issues. Then take a felt tip marker and mark up the outside of a case completely and let it dry. Then carefully insert it into the chamber and attempt to close the bolt. Then remove the case carefully. Look for places on the case where the marker has been rubbed off.
This test may identify a tight spot. Most chambers require a little polishing but it must be done in a lathe otherwise you risk damaging the chamber.
Good Luck
Nat Lambeth

 

[ken snyder]

Honestly at this point there is not anything other than speculation. No one has it in their hands that can give a look and identify the concern. Just plain take it to a gun smith and have him identify the problem it could be something so simple that you will slap yourself in the head and say " why didn't I see that " or actually require some machine work. The Forum is a great place but how can an auto mechanic indentify whats wrong with your car by describing the noise it is making while talking to him on the phone! Drop it off at a Smith