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300 win mag headspace

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 18:08
avery View Drop Down
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I'm getting ready to reload for my Tikka T3 Hunter 300 win mag and there seams to be a lot of varying opinions on how one should set the head space. I've found various post that say to measure the head space of the shoulder as I would do with my 30-06. I know the head space is also measured from the belt instead of the shoulder. I would like to know if there are any members here who have experience with the 300 win mag reloading and what their opinions are, Pros and Cons?

Thanks in advance for you help!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 18:17
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The .300 WM is an excellent cartridge. 

Have you chose a bullet weight? 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 18:39
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I have a bunch of 180 AB for my 30-06 that I will try, I picked up some 190 burger VLD's to try and I have a buddy of mine trying to find me some 200 AB to try as well.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 18:40
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berger* mistype :)
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 18:44
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Just got a text he picked up some 180 barnes tsx and 168 berger vld's to try. Sound like a sore shoulder for me this weekend, funnest sore shoulder ever Yippee
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 18:56
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RL 22 is pretty good place to start, though my Sako preferred IMR 4350.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 19:04
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They do head space off the belt. But that being said it is not good practice to push the shoulder so far back your could stretcht it so much back and forth upon mutilpe firings to cause a ruptured case

I would pay close attention to th shoulder. I have learned this lesson with my 7 mag
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 19:26
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  +1  You don't want to wear out your casings.
 
 Just ignore the belt and resize it as you would a beltless bottlenecked cartridge(like your .30-06) so that it will headspace on the shoulder.  I varying my resizing from having just a slight chambering resistance in some rifles to just below that in others.  In an extreme hunting situation where you could possibly get some debris in the rifle,dust for instance,it would probably be best to have that extra bit of clearence in the shoulder area for dependable chambering.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 19:28
avery View Drop Down
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Cheaptrick, RL-22 will be my powder of choice. The choices of powder in western Canada are very slim right now and I have a decent supply of RL-22 for my 30-06 built up. Will be using federal GM215 primers and I have one 50 bag of federal brass and one bag of norma brass. This was all the brass I could find and wow almost 100 bucks for the norma brass....Whacko

Supertool73, what is your process in reloading for your 7 mag? I assume you would take your fired brass and start with the FL die out 1/4 to 1/2 turn the slowly turn it in checking each time to see how it chambers in your rifle. Then when you have found the sweet spot as you determined it measure from the datum line on the neck to the head of the brass and record so that you can check the brass as you FL size them?

The head space measured from the belt.... will this change as the brass is fired? or will that headspace not change? If that distance does change then when you use the FL die will it actual decrease the length from the head of the brass to the far side of the belt? If thats the measurement i'm checking then is the typical method to just measure with my micro's from the head of the brass to the far side of the belt.

Sorry if I seam ignorant but i'm a little unsure about the belted mags and how the hole thing relates to what i have reloaded in the past my 30-06.

Thank-you
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 19:42
avery View Drop Down
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300S&W, This rifle is brand new but if it preforms well i will be taking it on a 10 day hunting trip at the end of the summer into the Tuchodi Lakes in northern BC. So I will be looking for that extra bit of clearance. If I were to use the same brass a couple times at the range and not FL size then would measuring that particular brass for head space be a pretty accurate measurement to use to find the headspace I'm looking for? What should I be aiming for when it comes to head space, 0.020 or is that to much?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 19:44
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  RL-22 is one of the top favorites with the 180+ bullets.
 
  Headspace shouldn't change. Otherwise those of us who neck size only would have a chambering issue.  Don't concern yourself with that belt once you begin headspacing off the shoulder. The less headspace without chambering difficulties the less stretch on your casings.


Edited by 300S&W - July/03/2013 at 19:49
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 21:08
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Personally I would use H4831 over R22 due to the temp insensitivity of the Hodgdon powders. Weight charges are practically interchangeable between those two powders too. Likely to see more drastic temp changes from working up loads to hunting season being that the OP is from Canada.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/03/2013 at 22:24
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avery, maybe I can help

http://www.saami.org/glossary/display.cfm?letter=H

"HEADSPACE The distance from the face of the closed breech of a firearm to the surface in the chamber on which the cartridge case seats."

What that means is that headspace in a belted case is a measurement from the bolt face to the front of the belt groove in the chamber. That will never change with firing since the case head does not expand. Nor will it ever change with sizing since a sizing die does not size the case head.

However, a belted case can move forward in the chamber to the belt stop and still have a gap between the case shoulder and the chamber shoulder. This is the measurement you should be concerned with.

To illustrate, you can measure this with several tools called "headspace gauges" (a misnomer but true headspace gauges are for gunsmith use). I use the Hornady tool

http://www.midwayusa.com/product/479704/hornady-lock-n-load-headspace-gage-5-bushing-set-with-comparator

You install on your caliper and take a measurement to the datum line on the shoulder (pic shows a rimless beltless case but same-same datum line location)





Now belted cases can have a lot of space in between the new case shoulder and the chamber shoulder. With this tool you can measure that gap. Here is worse case scenario

new case measurement


once fired measurement


That is a gap of .040" which is huge. But remember that the case will not move forward in the chamber that much because forward movement is stopped by the belt. But the case WILL expand to fill the chamber. HOWEVER it will not expand all the way to the shoulder on the first firing. The case may take 3 or 4 firings to fully expand until it fills the chamber and there is contact between the case shoulder and the chamber shoulder.

For example on my 300 win mag the measurements are as follows taken with the Hornady tool

new case - 2.253" (4.253" minus the 2" for the Hornady insert)
once fired - 2.270" neck sized only (shoulder not pushed back)
twice fired - 2.272" neck sized only
3 times fired - 2.2725" when chambered the case is tight (crush fit) so time to push the shoulder back for easy chambering

You can do the same thing without the tool by setting your gun up on the bench when sizing and chambering the cases after sizing. Check for a harder bolt close and adjust your die to just barely relieve the crush fit. A shoulder push back of .001" is plenty and you want to push the shoulder back as little as possible to prevent too much case expansion on every firing (recipe for a case head separation).

So the simple answer is to fire and size (setting your die not to push the shoulder back) until you get a crush fit and then set your die just enough to relieve the crush fit.

Edited by sakomato - July/04/2013 at 09:08
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/04/2013 at 07:29
cheaptrick View Drop Down
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Yet another example of your many excellent pictorials and commentary, Sako.  Salute
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/04/2013 at 09:35
avery View Drop Down
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Thanks Guys Don't have time to digest right now but i will tonight...

Cheers,
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/04/2013 at 23:05
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I've been looking for 200 gr ABs for weeks. All the big online places are out of stock. I found some on one of the auction sites. The guy had more a couple of days ago.. Send me a pm if your interested and ill get you his contact info.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/05/2013 at 07:20
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My 300 winny likes h1000 best. I'm shooting 240gr SMK and 230 Berger Hybrids.  I did load some sizzle rounds once..... 130gr TTSX barnes...... they move!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/05/2013 at 08:36
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ive been using the .300 win mag since 1997, 180gr sierra prohunter and imr 4831, 72.5 gr to be exact. Ive never had any issue with any belted magnums as far as reloading is concerned. I just use my calipers and get my cases under the oal the books list and everything is fine. Maybe im naive, but i really dont see that you need to make any special preparations in going from a belted mag to a standard bottleneck case.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/05/2013 at 10:39
avery View Drop Down
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Sako, have you noticed an increase in accuracy from the unfired brass to the 3 times fired brass? Or is this strictly to make you brass last longer? Also to set up my full length die would marking the neck with a marker and slowly turning the die down until the contact point seams to be where the neck meets the shoulder a good method for setting up my sizing die?
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/05/2013 at 11:25
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Originally posted by avery avery wrote:

Sako, have you noticed an increase in accuracy from the unfired brass to the 3 times fired brass? Or is this strictly to make you brass last longer? Also to set up my full length die would marking the neck with a marker and slowly turning the die down until the contact point seams to be where the neck meets the shoulder a good method for setting up my sizing die?


MAINLY sizing for a slight crush fit is to make the brass last longer and prevent case head separations. Case head separations occur when the brass if forced to repeatedly expand a lot toward the shoulder from setting the shoulder too far back

case head separation


when the case if fired if the case shoulder has to expand a long way to the chamber shoulder, the case will thin at the pressure ring. The pressure ring is where the interior of the case goes from being solid at the case head to the open interior space of the powder column



Most case head separations occur in belted cases because the case manufacturers do not worry about a tight fit at the shoulder and manufacture belted magnums with more shoulder gap than an unbelted case. I have reloaded for a lot of different rifles and calibers and would estimate that the average shoulder gap for a belted case is close to .020" and an unbelted close to .006". So there is no way to get around a lot of initial case body brass stretching on new cases with a belted magnum. BUT once you fire and keep the case close to chamber dimensions then the problem will not be exacerbated.

IME accuracy comes from consistency. It is possible to get a good combination with NEW cases and a certain set of powder/bullet/seating-depth specs. But that will change when you have fire formed the brass, so you will have to fine tune again to get consistency with the expanded brass. Even though the brass has not fully expanded on once fired brass, there is not enough of a difference to be able to tell an accuracy difference from the same load in twice fired, 3 times fired etc brass. So you will see the biggest change from NEW CASES TO ONCE FIRED fired.


Marking the shoulder is not a good way to do it. You are pushing the flat surface (actually slanted) of the interior die shoulder onto the flat surface of the brass and probably won't get much wiping of the mark until you have pushed enough to make the surface move enough to move laterally against each other (too far). Set the rifle up on the bench and the bolt closing force will let you know when the shoulder is being pushed back.

It helps to put witness marks on the die/lock-ring/press because even a small movement will make the case go from a crush fit to a loose fit



Also when you are sizing close to a crush fit, the setting can change during sizing a bunch of cases. There are a lot of linkages on the press and in the die that can move or be compressed with the forces being applied. So after you get it where there is just a little more force necessary to close the bolt than on an empty chamber, size 5 or so and the recheck in you gun.

EDITED - reread and I didn't make sense    

Edited by sakomato - July/09/2013 at 08:39
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/05/2013 at 14:46
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I always size brass as Sakomato illustrates with a slightly firm bolt closure. I don't know if it makes much difference with regards to accuracy, but I firmly believe that "working" the brass as little as possible extends it's life. With regards to the belt.....? Ignore it.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/05/2013 at 16:57
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As usual, excellent explanation and supporting pics, Bob!

Not only is brass life extended by headspacing on the shoulder, but contact between 2 conical surfaces (case shoulder and chamber shoulder) with a slight crush fit has a self-centering affect that theoretically ensures the bullet enters the rifling leade with less yaw vs the sometimes sloppy shoulder to chamber fit when headspacing on the belt. I say "theoretically" because that will naturally vary with chamber and case dimensions. All else being equal, the closer the headspace datum is to the bullet, the better for wringing out all the precision your rifle is capable of.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2013 at 01:58
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Thanks so much guys! Can't Waite till I'm knowledgable enough to help others starting out... I hope to get a chance to get started this weekend on my 300 win, cheers
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2013 at 08:40
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You're welcome

Found a mistake in my last post and EDITED
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: July/09/2013 at 09:14
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Originally posted by avery avery wrote:

Thanks so much guys! Can't Waite till I'm knowledgable enough to help others starting out... I hope to get a chance to get started this weekend on my 300 win, cheers


How do you think the guys here learned all they know...? By asking questions. Nothing like shortening the learning curve by asking others for a little help.
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