Discussion in 'Handloading and Reloading' started by wdill, Aug 7, 2022.
Yes, may be the brass. A good read here & a die.https://www.larrywillis.com/
But first- Compare the head to datum measurement first. The fl sized brass, should be smaller then fired brass, when measured case head to shoulder.
A comparator is used. Head space is on the belt, but the shoulder needs checking.
The OAL should not be to long. Dont want the bullets contacting the rifling.
Small base dies for the 7mm mag are also available. They are often used when reloading for a semi-auto. Might be an easy way to solve your issue.
Remove primer. Case mouth needs to be round & square. Example-
Nice trick, I have some 41 Magnum cases that should work. Trim the mouth on the case trimmer and measure. Will have to get to the range and fire the factory ammo so I have some fired cases to compare to. If I am thinking correctly then that will tell me if the shoulder is not getting sized correctly or I may need the small base dies.
Probably just need to turn the sizer down a hair more. There are lots of ways to check shoulder position, from free, to cheap to reasonable to expensive.
Store bought (Sinclair)
I agree with 243winxb that it's probably the shoulder not being pushed back far enough. Run the problem ones back through the sizing die, make sure you stop for 5-10 sec before lowering the ram. Also lube can play a big difference in sizing. If your using a thick film lube you can gain a extra 1/1000 which is probably all you need. Worst case you may need to adj your die body down another 0.001". Forget about the SB dies, your working on a belted case so it does not apply. Besides after 40+ yrs of hand loading I've never needed them.
I've used the old school method of measuring shoulder position for decades. It's just for reference to indicate shoulder position. Works fine, measure a before and after and you have your answer.
Your trim length is fine, nothing to worry a about there. Anything between max and trim to length is good. You only get into problem when too long. I normally trim to Spec length.
I will give running them through a sizer again a shot, but it feel like I am bottomed out. There is still about a 100th between the bottom of the die and the shell holder. How much pressure does it take to push the shoulder back? Yes, I am using a very thin film lube.
I'm no expert, but I always run the shell holder up until it firmly touches the die.
Is there something wrong with doing it that way?
In most cases the shell holder bottoms out on the die. May need to tweek it a little. Thin film works (Imperial Sizing wax). Some times a thick film will get you a little bit more.
That's the way I do it too, but in this case the ram stops before the die makes it to the shell holder. I don't want to apply too much force and crush the case.
I'm not understanding, wdill. Why can't you just screw the die down further into the press?
When I resize straight-walled cases, I run the ram all the way up, screw the die in until it touches the shell holder, back the ram down, and finally screw the die down another 1/16 of a turn or so - that takes all of the play out of the press, and ensures my strait-walled cases are full-length resized.
Now I know the 7mm Rem Mag is not a straight-walled case. In fact, it's a belted magnum - like several of the belted magnums I load for. And in that case, you should pay a lot of attention to what Blue68f100 said:
If you keep setting the shoulders back on belted magnum cases, so that they continue to headspace on their belts instead of on their shoulders like most bottlenecked rifle cartridge cases, you're setting yourself up for early case head separation.
However, if you don't set the shoulders back just a little, there will be a little resistance when you close your rifle's bolt. How much resistance you want to tolerate is up to you. Getting it where you want it will require some experimentation.
When it comes to belted magnum bottle-necked rifle cartridge cases, n2omike, what Blue68f100 said is what's "wrong" with always screwing the sizing die down until it firmly touches the shell holder - you're setting the case shoulders back too far every time you resize them.
On the other hand, with straight-walled cases, like handgun cases, I set my sizing die up exactly like you do - I screw it into the press until it's firmly against the shell holder.
Edited to add: I don't screw any carbide die in until it is "firmly" against the shell holder - I don't want to bust the carbide ring out of an expensive die.
Remington made a semi-auto 7mm Mag that is finicky with reloads. Many end up having to use the small base dies to get them to work reliably. These guns may be why factory ammo is more loose fitting. Just a guess. I loaded some for a guy with one of these guns, and through my research decided to pick up a small base sizing die. Was able to find a single die on Ebay. Haven't heard any complaints.
No flame here due to the fact I've never really had a case head separation (I've just read about them) with a bottle-necked rifle cartridge case (belted or otherwise), so I can't really say I "believe" in them either.
However, when it comes to belted magnum, bottle-necked rifle cartridge cases, early case head separations DO make sense to me because if you allow the cases to continue headspacing on their belts instead of on their shoulders, you're overworking the brass.
That said, I DON'T do the "internal pick inspection" on every piece of bottle-necked rifle cartridge brass every time. I only do it when it looks like the case might have an issue - like when a bright little ring appears in front of the case head. Do you do the "internal pick" inspection on every case?
has said, when using their press, make sure the shell holder contacts the bottom of the full length die, at the TOP of the stroke.
Unless measuring with a comparitor.
Edit/Add The competition shell holders may be needed if the shoulder bump is not close to the same each case. Takes flex out of the press. The head to datum is inceased by .002" with each shell holder.https://www.redding-reloading.com/online-catalog/35-competition-shellholder-sets
Lube- RCBS 2 applied with a pad.
I don't shoot semiautomatic anything other than 9mm. I also have strict control of shoulder bump on the 308 and 223 I do shoot with .001 bump. Is it fair to avoid situations that generate requirements???? I do own a mini14 that my dad grabbed and took to his house two weeks after I bought it. When I start loading for that I will have to, and considering the cost of components I may likely not shoot it. Between 357, 45c 30-30, and 45-70 lever guns and my 223 and 308 target guns I'm probably never going to have that as part of my process.
A good read on how to avoid case head separation when sizing bottle necked rifle cases.
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