How much variation in shoulder from chamber to chamber?

[shortgrass]

Ahhhhhhh! A new Savage . That explains alot!

 

[okie man]

I have no problem with using oncefired brass in a new gun. Chances are it's bigger than your chamber. It's then you can size size it to fit tight in your chamber , measure it and set bump. I'd hate to have to run 100 or more rounds down a barrel burner just to get those cases ready for load development

 

[MagnumManiac]

I have 4 hunting rifles in 300WM, 3 of them run smaller than 1, which means that brass fits in 3 but none of that 1 fits the other 3.
I run SEPERATE batches of brass for each.
I also have 3 barrels in 300WM for F-class, they are cut within .001" of each other, BUT run different batches of brass too, even loads differ in these 3 barrels.

I would buy a batch of 100 to start with in a new rifle, then add to this as funds allow.
I do this with every new purchase, even if the same cartridge.

Cheers.

 

[misterc01]

After I shoot a new factory round, I keep one case to use as reference. ANY new-to-me once-fired brass not from my rifle is full length resized and loaded to match factory ammo. Gives me a starting point for comparison purposes. Works for me. Anyone see any holes in that approach?

 

[Jeffpatton00]

Exactly !!!!

The only real way to find out everything about a chamber is to fire a new case in it.

Older cases fired in another may not exactly fit your chamber and give you false readings. Once you fire the new case, you can try it for fit and size it just enough to chamber well or not at all.

J E CUSTOM

I'd like to ask a follow-up question on this, I hope it's not naive, but I'm confused about this. There's always a lot of back and forth about neck sizing vs FL sizing and many say that FL sizing is the way to go, so what's the benefit of starting with once-fired cases when reloading? When we bump shoulders in a FL die, aren't we FL sizing the cases, at least to some degree? And if that's true, then we're conforming at least the upper end of the case to the die. If there is a value in starting with once-fired cases, then I'd venture a guess that shoulder-bumping doesn't reach the base and there's some accuracy benefit for the case to remain expanded to the chamber's dimensions - is that the deal?

 

[J E Custom]

I'd like to ask a follow-up question on this, I hope it's not naive, but I'm confused about this. There's always a lot of back and forth about neck sizing vs FL sizing and many say that FL sizing is the way to go, so what's the benefit of starting with once-fired cases when reloading? When we bump shoulders in a FL die, aren't we FL sizing the cases, at least to some degree? And if that's true, then we're conforming at least the upper end of the case to the die. If there is a value in starting with once-fired cases, then I'd venture a guess that shoulder-bumping doesn't reach the base and there's some accuracy benefit for the case to remain expanded to the chamber's dimensions - is that the deal?

New brass is the best way to start reloading with, fired brass is harder and doesn't form as well and may be close enough that spring back may occur and the actual size may not be representative of the actual chamber dimensions. I always start with new brass and it is designated to that firearm only. I also neck turn for uniformity on new brass so it fire forms concentric (If it is thicker on one side, it will offset the bullet center buy that amount when fired).

I try not to size cases any more than necessary to chamber because the more you bump or size, the more you work harden the brass because it will return to the chamber size every time it fires. There are many ways to size cases and many reasons to do certain things, so each has to use the method best suited for their type of shooting.

Normally if you have to bump the shoulders, you are running high pressure loads that are stretching the action and compressing the bolt enough to allow the case to expand beyond the head space and Not return. some even load hard enough to get bolt lug set back (Not good).

In my opinion and based on the results I have seen, the better the case fits the chamber, and the more the loaded ammo is concentric,the better the accuracy. In long range hunting, one shot is the norm and precision means everything. If shooting matches or multiple targets rapidly then more sizing may be necessary for function.

You will get many opinions on sizing so you will have to decide which you will use.
I believe that good is not enough, best is only the benchmark for trying to do even better.

J E CUSTOM

 

[keithcandler]

JE custom is right on the money.

New rifle = New brass

Here is a good thing to remember. Brass has a memory of what it was fired in. You size it down, it expands back out over time.

OP talks of shoulder to base of case measurement. Many dies will have to push the shoulder back further than .006 in order to get the web sized to the dia that the new barrel likes. SURPRISE!!!

 

[dreamhunt]

I am interested in this too. I had found that in my loads if I bump between .001-.002" then the POI is the same.
Once I bumped .005" on a few rounds by mistake. The two shots grouped but at a different POI. I would like to see what others have found.

 

[keithcandler]

I always got best accuracy out of my various 7 Mags using a full length sizer. Neck sizing was helter skelter. The standard Forster neck sizer will bump shoulders, for those that are interested.

When adjusting your full length sizer, move it down in 1/16th turns or just barely move it. You will go from a point where the bolt is not closing easy, to a point to where it closes with resistance, then closes easy. You are working down the dimension at the web.

You have to remember that brass springs back. Using brass fired from other chambers invites problems as the brass springs back to the dimension that it was originally fired in. I have had loaded ammo that was purchased from a source that does testing, have the bullets fall back inside the case they expanded so much. Brass shot in huge chambers are a real problem. For this reason, with my brass fired from another rifle, I keep my ammo fresh, meaning that I will load what I think I may need for that season, then shoot it up and start fresh with the next season, 20-30 rounds max.

A guy is real smart to start off with new brass for a new barrel. I and family members have had to learn this several times with various problems arising from picking up range brass or buying once fired brass.

I shot registered Benchrest for a long time. Issues like this brass issue just drives us crazy.

Many of the responses to this would only apply with a custom reamer and custom dies made off the reamer print. Guys repeat what they have heard in good faith of trying to help others out.

It is not smart to try and save money by trying to shoot old brass in a new custom barrel. Now if you are going to one sloppy factory chamber to another sloppy factory chamber, you have some lee way. Factory reamers when they are new cut larger chambers, as they get worn, they cut smaller chambers...you take your chances...been down this road also.

Redding makes a body die, and while it is not intended to do so, I have full length sized my cases with a body die with loaded ammo.

If you can take a Cerro safe chamber cast of your chamber, and use a .0001 Mic, you can get some accurate measurements off the web dia on your brass. You need to size .002 below this dia and .003 is better.

Chambers are not always cut concentric, meaning some are slightly egg shaped. The most accurate factory 7 Mag that I had, had an egg shaped chamber. I full length sized that brass and never had a problem, Browning A bolt, Stainless stalker.

 

[gator378]

Any of you have base-to-shoulder data on a couple (or more) rifles for the same cartridge? What kind of variation is normal?

Got a 7mm Mag coming, and want to load a few rounds for "w000h000, I got it" as well as break in.

I have a couple hundred once fired brass from an older Remington 700, and am hoping to get a handle on how far back to bump the shoulder, without being excessive, so the first 20-30 reloads will function properly.

I have a rule, that I shoot a new gun the day I get it, so I need to have a couple dozen rounds loaded before I get the rifle in hand. Obviously, once I have a few down the pipe, I'll measure its headspace, and size accordingly.

What's do you think the typical variation among rifles is? 0.002", 0.004", 0.010"?

Enough I had to redo about 100 rounds of 300 Weatherby because I had a old one and a new one. about 0.0004 difference in chambers. Never make that mistake again. I got a bunch on once fired brass in 2506. will not fit my 2506. Fortunately just full length resizing solved that problem

 

[shortgrass]

Sizing cartridge cases without a belt and sizing cases with a belt are 2 different scenarios. FL sizing of belted cases never reduce the diameter just above the belt. The only sizing system I have found that does is the collet sizing die made by Accurate Technologies. That die is only $100, but it does reduce the diameter just above the belt back to proper size. May not make much difference to a Savage.

 

[keithcandler]

RCBS makes a small base sizer, that will work. I use it on my 7 STW cases that are shot in a match chamber. Dies made will not size down far enough.

 

[bigedp51]

I buy bulk once fired 5.56 and 7.62 Lake City brass fired in a multitude of chambers. So to compensate for brass spring back I pause at the top of the ram stroke for 4 or 5 seconds. This reduces the brass spring back and makes the shoulder location more constant after sizing.

 

[okie man]

Here's one thing I noticed on a new 100 lot of Winchester 308 brass I worked with a while back. I ran them all through a full length die, trimmed to a consistent length, uniform primer pocket and loaded them.
After I fired them I checked the length from case head to shoulder datum. They all were very close using a Hornady comparator.
Then I checked the overall case length to see how much they grew and they varied quite a bit!
My guess is the cases long enough to get bumped back to a consistent length grew less than ones a little short and the shoulder and neck moved forward when fired and changed the overall case length.
Once all of them were properly sized and trimmed, I loaded and shot them again. The same measurements were taken as before, this time the cases grew much less on average in overall length.
Accuracy and sd and es were better second time around also.
Unless you're buying super premium brass with super tight tolerance I don't see how starting with once fired brass that's at least blown out to a consistent size is worse than starting with brass that's not and burning up barrel life achieving the same thing.