7mm RUM reloading difficulties

[HillCountry54]

So heres the deal...

I just started trying to reload rounds for my 7mm RUM. I ran across this problem of messing up the case when I load the bullet in.

I am using RCBS Dies. I resize the case, the shell will feed fine, but as soon as the bullet goes in, I cant lock the bolt down, or its really hard to do.

This doesn't happen every round but Id say 3/5 times it will.

Now its not the bullets, theyre the right size, and if I take the shell that didn't work, take the bullet out, resize the case, and it will work again.

So my assumption is that when I am pressing the bullet into the case there is enough friction in pressing the bullet that its deforming the case.

So my question is, is there a lubricant for the bullet for cases such as this? Is there something I've missed? I know the neck is clean and deburred, so the friction is the only thing I can find to blame it on, but I have never experienced this before.

Any help is greatly apprectiated!

 

[arthurj]

You probably know a lot more about reloading than me, and have probably considered what I will suggest, but you don't have a chamber that's on the tight side do you? Are the cases trimmed? Is it a factory gun or custom? I'm not the right one to diagnose this problem but just throwing a few things out there.

 

[winmagman]

Have you measured the outside neck diameter of a round that chambers and one that won't? Is there a difference, if so how much? Also check the neck thickness, some cases may have thicker necks and when the bullet is seated in a thicker necked case it might expand enough to be tight in a tighter chamber. Neck turning might be in order.

Chris

 

[HillCountry54]

Well the gun is a Sendero SF. The brass I am reloading is from factoy Remington rounds that I have fired already. Fired once.

I didn't have any problems with locking the bolts with the factory ammo. And I've shot about 80 rounds through the gun since I purchased it new.

Also, I have not measured the neck width, but right now I believe its unlikely because if you take the 5 that I loaded and you have 3 that dont want to fit right...

Unload those rounds resize and reload, and the ones that dont fit now, may be the ones that fit not 5 min before.

Thanks for the suggestions, and when I get the chance, I will measure the necks.

 

[winmagman]

HC
Are you seating these to fit the mag. or are you trying to get close to the lands? Wondering about overall length if trying to stay near the lands.

 

[HillCountry54]

[ QUOTE ]
HC
Are you seating these to fit the mag. or are you trying to get close to the lands? Wondering about overall length if trying to stay near the lands.

[/ QUOTE ]

Ive tried lengths from I believe 3.6 to 3.9

The length seems to have no effect on the problem. I am mainly trying to make this work with the factory lenght for now...

 

[Mysticplayer]

If the case length and neck diameter check out, try measuring the base on the case in front of the extractor groove and at the shoulder. Believe it or not, FL sizing dies don't always size enough. The RUM is a high pressure rd and brass can grow very quickly. If the dies don't bump the shoulder enough or squeeze the base, it doesn't go in.

The fact that some brass does and others don't leads me to believe it's a die issue. Sometimes taking just a bit of the bottom of the die is enough to bump the shoulder and make the brass chamber.

Nothing wrong, just a stacking of tolerances.

However, having a OAL with that much variance and not crash into the lands is not a good thing. With a throat that long, accuracy is not likely to be in the tiny arena.


Jerry

 

[ricka0]

I had exactly the same problem with a set of RCBS dies. Visual inspection after resizing showed it was not bumping the should back at all, despite being 1/4 turn past bottom. I tried chambering a bunch of the brass before I put the bullets in and verified the problem before I reloaded them. I posted the question and got the same answers (all wrong). I put blue ink on the neck and could see that's where it was hitting. Grabbed a set of LEE dies and no problems. I'm sending them back to RCBS. Turns out other folks have had that problem.

 

[Fiftydriver]

HillCountry54,

Lets walk though this and figure out where the problem is occuring.

Step one, take a fired case and chamber it in your rifle. If you are running normal pressures the fired case should chamber even if it takes a bit of pressure on the bolt to lock her down. If the bolt will simply not close on a fired case you are WAY over pressure and need to back your loads off. If it chambers move to step two.

Step two, size the case in your usual manor, clean off any excess lube and again chamber in the rifle. IT should chamber at least as easily as the unsized fired case and usually even easier depending on the load level used.

If it will not chamber something is wrong with your sizing die which I doubt but it may be, just rule it out. If it does chamber then move onto step 3.

Step 3.

With no primer or powder in the case, seat a bullet to the same length just as you would with a finished loaded round. Chamber the round and see what happens.

If it does not chamber there are a couple things that can cause this.

A. The seating length for the bullet is to long and it is contacting the origins of the rifling and not allowing the round to fully chamber so the bolt can lock down.

B. The die is turned down to far in the press and its built in crimping shoulder in the die is trying to crimp the case mouth into the bullet. If there is no crimping groove this generally results in a slightly bulged shoulder which maked it nearly impossible to chamber in the rifle.

I would suspect this may be the problem. To check this, take a sized case that is know to chamber easily in the rifle, out it in the shellholder in your press, raise the ram to its highest point and then screw the seating die down until it just contact the case. Turn it back 1/16 of a rotation and seat the bullet to the proper OAL you want by adjusting the seating stem adjuster, not by turning the entire die down in the press.

Go through the steps one at a time and figure out at what point the case is being deformed out of spec. Then correct the problem.

Have a good evening,

Kirby Allen(50)

 

[HillCountry54]

Thanks for all the great info guys. Ill be out of town for a few days, but I'll get back and let yall know the progress I make.

Thanks again! /ubbthreads/images/graemlins/cool.gif

 

[Wild_Bill]

Have you debures and chamfered the inside of the necks the factory's flare the necks and then crimp them so the cases do not need a chamfer. This can cause a dimple or fold in the neck when seating bullets as it can shave off fine shavings and stop the round feeding into the chamber it seems to me this could be a contributing factor. Try a bigger chamfer als are you crimping with the seeting die if you are you can be bulging the cases if the die is not exactly right if you are going to crimp get a Lee collet crimping die to crimp in a seperate opperation and back the seater off and try again.

Cheers Bill
australia

 

[HillCountry54]

Just to let everyone know, we found out the problem. Thanks for all your input!

Seems as though, when trying to press the bullet into the brass, the bullet was hitting the edge of the die, more than the peice that you screw in from the top of the die.

This was causing it to go in partially crooked I think and warp the brass. Instead of the shoulder being staight, it ended up looking bowed more.

So with different brass and loading the bullet correctly, we fixed that problem.

Also, after I realized that the rounds we loaded the first time were not going to work...we tried to unload them. We have a hammer for this usually, but due to the extreme size of the round, it wasn't working, so plyers had to be used.

The teeth in the plyers ended up indenting the bullet, and ended up also causing trouble when locking down the bolt. However, after filing some on the bullet to "de burr" it, the new round goes in great.

As of now Im using an overall length of 3.7" with 104.5 grains of BFG50 Powder. Hollow point 140 grain bullet. /ubbthreads/images/graemlins/cool.gif

 

[olcrip]

You are most likely pushing the shoulder back when you seat your bullet. Back your seating die out and try again. After you seat your bullet check the diameter at the base of the shoulder. It sounds like you might be callapsing the shoulder and it won't chamber. Without the bullet it chambers after you resize again. Pull the bullet and try chambering the case without resizing. If you are colapsing the shoulder it won't go in without resizing. /ubbthreads/images/graemlins/wink.gif

 

[HillCountry54]

Yup, thats what we did.

and after shooting those new hot loads! /ubbthreads/images/graemlins/shocked.gif

WOW, after about 30 rounds...my shoulder sure is soar! /ubbthreads/images/graemlins/wink.gif