7RUM reloading problems


May 16, 2008
Henderson, NV
First, let me say that I'm a novice at reloading. I've got a custom 7RUM that's only had about 50 rounds through it while breaking the barrel in. When I picked it up from my smith, he told me that he was having issues with some of the factory remington rounds chambering but thought that it was due to the varying neck size on the factory loads. He stated that the rifle has a match grade chamber and that some of the necks on the factory brass were out of tolerance. While breaking in the barrel with factory remington ammo I found that about half of it would chamber fine, and the other half would not. It wasn't a big deal to me as I gave the ammo that wouldn't chamber to my uncle who has a factory 7RUM and it chambered just fine for him.

Now, I bought some bulk 7RUM unfired brass and am running into problems. I FL sized the brass with a forester die, checked overall length and neck dimensions and everything looked fine. However, once I seat the bullets they will not chamber in the rifle. The bolts ends up roughly 1/4 shy of being all the way.

I've got some reloads from the breakin brass that chamber fine, and when I check the dimensions between the two (the once fired vs. the virgin brass) I cannot tell the difference. I was hoping someone on here could possibly tell me what I'm missing. I've got a neck turner so it wouldn't be a big deal to turn some of the brass, but as I stated above when I compare a round that chambers to a round that will not, I don't notice any discrepancies. Thanks.
Did you make sure the resizing die touched the shell holder when you adjusted it first. Sounds like the shoulder needs to be set back a little. Make sure when you are resizing the case it goes all the way in the sizing die ( no space between die bottom and top of shell holder ). Did you try chambering one of the resized empty cases first.
I double checked that the resizing die was touching the shell holder. I loaded up a dummy round without primer and powder and it is the one that will not chamber. I did not try one just after resizing without a bullet seated. I can do that tonight.

The thing that bothers me is that, as stated before, when I measure the difference between a round that will chamber and one that will not, I do not notice a difference that should effect chambering the round. If anything, I've found that the round that doesn't chamber is actually a little smaller in most dimensions which should make it chamber a little easier. The one thing that I didn't check was the taper of the round itself, from the shoulder down to the rim. I know that the o.d. at the shoulder is within spec but I did not really check lower that that. Is there any way that if the taper is out of spec it could be causing the problem?

One other note, when I started running into problems I took a marker and painted the bullet, neck, and shoulder to see if I could potentially see what was causing the problem. I then tried to chamber the round and put a little force on it hoping that it would mark up the paint that I had put on the round. When I removed the round I cannot see anywhere on it where it may have rubbed or anything causing it not to chamber. This just confused me greater. I'm thinking about borrowing my uncles RCBS FL sizer die to see if it makes any difference.

Thanks for any input on this matter.
I would go back to your gunsmith and see if he can figure it out. Sounds to me like it has a tight neck chamber (smaller diameter than saami specifications). If it is a standard neck chamber, there is almost no way that factory ammo wouldn't chamber as it is generally smaller dimensionally than conventionally full length sized reloads. You may have to turn the case necks to a smaller diameter or have him open up the neck to standard diameter. Either way, he needs to be of assistance. I wouldn't think a good gunsmith would send out a rifle that wouldn't chamber factory ammo unless a person specified tight neck chamber. Best of luck.
I initially thought it was the necks as well, but when I check the neck dimensions on a round that would chamber vs. a round that wouldn't chamber I found that the ones the wouldn't were actually a few thous. smaller that the round that chambered. This just confused me even more. Thanks for the help so far.
Downsouth, when you run the shell in the resizing die and the press is all the way up is there a space between the bottom of the die and the top of the shell holder? You might have to adjust for press flexing. Does that make sense?
In that factory new ammo doesn't chamber reliably, I think you're wasting time with looking for an answer in the reloading process. I'm surprised that the rifle was given to you knowing that the problem existed. Either way, your smith is much more capable of getting to the bottom of this and you should give him the opportunity to correct it.

Before visiting the smith I'd be inclined to try some different factory ammo just to see what happens. This may help solve the mystery.
The forster die can be a litttle long in length and may not bumb the shoulder back but actually cause it to move forward. Been there done that. It sounds like you don't have a guage to measure what you are doing to the head space and you really should pick one up from Hornaday or Sinclair. I would try thr RCPS die and see what happens after you measure, the cost of brass today warrents it. I had to send the forster die in to get shorten, no big deal other then time. If the issue is a very tight speced chamber you will be happy in the long run, though with the 7 RUM it's not very long to begin. Dave
One thing he forgot to mention regarding the factory ammo that would not fit... When the gunsmith and I measured the factory ammo the necks size was bigger then specified. The neck is supposed to be .322 and the bullets that would not fit were +.365 up to .380 if I remember correctly.

I have the same gun, with the same barrel, which was built using the same reamer and I have no problems... I think it might be something with the dies but I am no expert either...
Update. I attempted to chamber an empty FL resized case and it chambered perfectly without any resistance. Once I seat a bullet, however, I run into the problem. I marked up the bullet with black paint and it appear that a portion of the bullet is making contact with something within in the chamber before the round can be fully chambered. Only about 1/3 of the circumference right above the neck of the brass is making contact with something. It's difficult to explain but I've got a couple pics if anyone knows how to post them. I've checked the freebore and I know that the bullet is not anywhere near touching the lands. I'm going to send the pics to my smith in the morning to see what he has to say.
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