Primer pockets

[survivalshop]

  The older brass I'm using for my Annealing testing was used to test work up loads for my 20" 308 & is , on the most part , at the end of its service life . Which is why I'm using it for testing . I had to think of a way to sort the brass for any defects & I thought of the the primer pockets , along with the usual stuff   & any too short , under my 2.0045" length , these are already sized & de-primed with a SB sizing die & all met the length min. & most need trimming , but I won't do that till I re-size them with my Redding bushing type FL sizing die , after the Annealing .

 

   Since this brass was used for work up loads , some were loaded a little hot . I was working up loads for WC 846 , a military pull down powder & there are no loading manuals for it .So I had to think of some ways to test the primer pocket for the proper spec's to hold the primer in there .  Heres what I did , I first checked them for fitment with my Primer Pocket Swaging tool head & all the brass (WW& FC ) being commercial , are always loose compared to Milspec brass, even after swaging the primer pocket. So, I had to think of another way , I took a LR CCI primer & tried to force it into the Primer pocket by hand . 

 

  Well only half of the 71 rd's. passed the test. If I couldn't force the primer into the pocket any more than just the beginning of the pocket , it passed . if I could seat it even half way, it failed . Not sure If I will get any popped primers with these loads when done , but I had to test them some way . The loose Primer pocket , condemns all my brass to the scrap heap. 

 

Some of the tools used.

 

A seated primer ,by hand.

 

A primer seated half way by hand

 

And finally , what I wanted to see , a primer I could not force into the pocket by hand.

 

We will see if this process of sorting Primer Pockets works out .

 

 

  

[.308LiteHunter]

So something in your post caught my attention. I didn't realize that there was a minimum length to check for. I have some that I have trimmed farther than what I wanted when I was first learning to trim, some even a little less than 2.000 but all have fired fine.

I use these for paper punching mostly but have also used them successfully for hunting. Is the minimum that you listed just what you go by, or should I start sticking to that minimum as well?

[survivalshop]

  I trim my 308's to 2.005", + or - 0.0005 so they can be 2.0045 to 2.0055" , Just what I use for my trim to length spec's. . I have loaded & shot brass shorter ,but I like to keep things as close as recommended & all my manuals give a trim to length of 2.005" , so I stay on it for consistency reasons .

   You can use cases shorter , I just don't .

Edited May 7, 2014 by survivalshop

[.308LiteHunter]

Ok, I keep mine as close to 2.005 as possible now, but just wanted to make sure I could keep shooting those shorter cases, I'm still learning...

[392heminut]

You can keep shooting the shorter cases. The biggest problem I can see with trimming cases too short would be the shorter neck not having enough tension to keep the bullet from being set back an an auto loading rifle. If that hasn't been an issue then I wouldn't worry about it.

[survivalshop]

   That would be real short , I would worry more about case head separation , then bullet set back . The brass when fired will conform to the chamber , some call it flowing into the chamber , if too short , that brass that moved or flowed into the void left behind of a too short case will have to come from some where & that place will be the thickest part of the case , not where you want to lose material . That would have to be an extreme case though.

  I tested some 5.56 hand loads that I trimmed the case to the SAMMI spec's of 1.760" & some to the trim length of 1.750" , to see how they Chrongraphed & shot , I will see if I can find it here .

  <laughs> And you thought this was a Primer Pocket thread .

 

Posted 16 September 2012 - 05:12 PM

What do you trim your .223 brass to ? I just loaded up some 62 gr. Barns TSX bullets & made some of them to case length spec's of 1.760" & some trimmed to trim length spec of 1.750 " from my older Lyman 45 th edition hand book & the trimmed loads out shined the case length spec ones , big time on the target & grouping .

All charges were weighed on my new Pact electronic scale & all were compared with like charges .All were same name brass & close to same weights , as I always choose , all had Remington Bench rest primers , all same COL.

Rifle -AR ,24 "  ultra match HB., 5.56 chamber, S/S . 

Results of Chronograph.

23.5 grs. WC 846 ( trimmed to 1.750")
Avg. vol. -2994 fps
ES ------- 10 fps.
SD ------- 5  fps.

23.5 grs. WC 846 ( trimmed to 1.760" if needed )
Avg. vol. -3000 fps.
ES --------18 fps.
SD--------- 9 fps.

24 grs. WC 846  ( trimmed to 1.750" )
Avg. vol. -3020 fps
ES ------- 5 fps.
SD ------- 2 fps.

24 grs. WC 846 ( trimmed to 1.760' if needed )
Avg. fps --3044  fps.
ES -------- 47 fps.
SD -------- 20 fps.

All the trimmed to 1.750" printed one hole groups @ 100yrds & the ones that are at case length specs of 1.760 " were spread out a little , still good groups but the 1.750 " were real good .

It may be that this chamber likes the one case length better than the other , but now I have to test in other calibers & barrel lengths , because in all my years of reloading , I have never done a test like this . I have always trimmed to the trim to length spec's from this manual .
Any one else trim as I do ? 

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Edited May 7, 2014 by survivalshop

[392heminut]

Brass flow is caused by too much shoulder setback when resizing. I don't believe that the length of the case neck would contribute much (if any) to that problem. I've got a bunch of .223 brass that got trimmed to 1.745 that I've been shooting with no problems at all. Don't ask how I got them that short! ::)

[Toolndie7]

  I trim my 308's to 2.005", + or - 0.0005 so they can be 2.0045 to 2.0055"

 

Just curious, what are you using to measure your length?

[survivalshop]

Digital caliper & I just don't take a measurement in one place. Yes there are more precise measuring tools, I just don't see a need for them .Once my LE Wilson trimmer is set , they all & I mean all, come out the same . 

 

Brass will flow into the entire chamber area upon firing & contract when pressure subsides , for extraction , of course . It won't stop at the shoulder . I did say it would be an extreme case . Enlarged primer pockets are part of that stretching or flowing .

 

Once a case has been fire formed to a chamber , the stretching is minimized , of course , unless to make a very hot loads . 

 

Too bad I use my cases for multiple rifles , tis why I used SB sizing dies for so long. I'm beginning to think as far as the brass is concerned , it reduces the working life of them , is why I went to a new FL sizing die. Still trying to see if accuracy is changed .

[N Jensen]

Of all the cases I have reloaded, I find that Federal cases are the worst. The primmer pockets get big fast and may only last two reloads before the primmer will fall back out or fall out after being ejected from the chamber. Lake City Brass being the hardest, last the longest even when loaded very hot. Winchester and Remington brass are about the same, will last a good number of reloads even under hot reloads. However they do eventually wear out and just like in the opening thread. can get the primmer started with a little hand/thumb pressure.

I never worried to much on a bolt gun as long as I felt some resistance in seating the primmer. With a semi auto I'm a little more picky and want to feel more resistance. When you pick up the brass and the primmer isn't there, you know next time to reject cases that the primers seat easily.

Brass grows under two conditions, hot loads and resizing the case. Hot loads, high gas pressure and at the same time, the brass gets very hot so it flows in the direction of gas movement. The harder the brass less movement. Resizing, pulling the brass neck over the pair shape expander ball works to stretch the brass as well. I believe RCBS came up with a die that eliminates brass stretching during the resizing operation.

Adjusting the resizing die correctly, bushing dies and turning the necks are 3 ways to make the brass last longer. Much to often the resizing die is adj for to much push back. Need to buy some case measuring tools and set the die for .001 to .002 push back for bolt guns and .002 to .004 for semi auto. Because of bolt flex under HP rounds, those case will measure a little longer than lightly load rounds. Same for the semi auto guns, more pressure, the case will stretch more. Adj the resizing die to accommodate the hottest load to make sure it will fit the chamber next time.

If you buy 7.62 machine gun surplus brass at a gun show you will have problems. Usually the machine gun brass is twice as big as a normal chamber gun. You might have to resize it twice just to fit the normal chamber of your rifle, and will have a case failure within two or three reloading's. Bring a case gauge and measure them before buying them.

I always trim the cases to the minimum amount recommended, but if I do it wrong and there a few thousand shorter I don't worry about it.

It can blow up a rifle when you let the case grow and grow and never trim them. I know a guy blow up his M1A using a multi stage press and never checked is length of the case. The bullet was pinched into the chamber between the case and the chamber.

I think over the years of shooting I have seen 2ea AR 15 blow up, about 10 M1A's blow up, more than several Garands/M1A's have slam fires.

Since we talking about primers, 210M are the easiest primer to get a gun to slam fir on. Remember the firing pin is free floating and continues moving fwd before the bolt can rotate and lock. This goes for the AR 15 and DPMS LR guns. DO NOT PUT THE ROUND INTO THE CHAMBER AND LET THE BOLT FLY FWD TO SEAT THE BULLET INTO THE LANDS OF THE BARREL. You will regret it. If it can happen on a M1A it can happen with an AR style action as well. I seen this mistake a lot!

[gnatshooter]

Remember the firing pin is free floating and continues moving fwd before the bolt can rotate and lock. This goes for the AR 15 and DPMS LR guns. DO NOT PUT THE ROUND INTO THE CHAMBER AND LET THE BOLT FLY FWD TO SEAT THE BULLET INTO THE LANDS OF THE BARREL. You will regret it. If it can happen on a M1A it can happen with an AR style action as well. I seen this mistake a lot!

 

I have to wonder if a heavy buffer would make it safer to let the bolt fly forward to seat the round.

 

Letting it fly is something you'd do between magazines when the BCG locks back on the empty mag, right? The option -- pushing the bolt release while holding back on the charging handle -- would seem to be pretty awkward. Unless there's another way, or I'm not understanding this right.

[unforgiven]

That's why the barrel is pointed in a safe direction when closing the bolt.

[gnatshooter]

That's why the barrel is pointed in a safe direction when closing the bolt.

 

If this is a real issue I would have reconsidered my decision to get my DPMS LR-308T.

 

When I swap mags on my pistol I expect it to strip a round and seat it when I press the slide release, and I'm used to that being reliable.

 

Now I'm really bumming.

[survivalshop]

  I have been reloading once fired 308 Machine gun shot brass for more years then I can remember & never had a problem , as long as they pass my pre inspection before I reload them. As was said you have to be careful .

  I'm on five reloading's on the present test batch of LC brass for my 175gr. loads , but we will see after this week , I will test the Primer pockets.

  I have followed the instructions on all my die sets( not saying they work for every one or chamber ), but if I don't have cam over on my single stage press for sizing , they don't fit in the chambers . RCBS , Redding , doesn't matter . Always wanted a Case Gage , just seems to be not needed . 

Edited May 7, 2014 by survivalshop

[392heminut]

  I have been reloading once fired 308 Machine gun shot brass for more years then I can remember & never had a problem

Same here! ALL of my 308 brass is milsurp fired from a machinegun, about 3k rounds of it!

[392heminut]

I have to wonder if a heavy buffer would make it safer to let the bolt fly forward to seat the round.

 

Letting it fly is something you'd do between magazines when the BCG locks back on the empty mag, right? The option -- pushing the bolt release while holding back on the charging handle -- would seem to be pretty awkward. Unless there's another way, or I'm not understanding this right.

Gnatshooter, he was talking about letting the bolt fly on a round that's already in the chamber. Letting it fly when stripping the next round from the magazine is not a problem. the friction of stripping the round from the magazine slows the bolt's momentum down considerably.

[gnatshooter]

Gnatshooter, he was talking about letting the bolt fly on a round that's already in the chamber. Letting it fly when stripping the next round from the magazine is not a problem. the friction of stripping the round from the magazine slows the bolt's momentum down considerably.

 

OK thanks, now I can sleep tonight. Guns are only supposed to be dangerous when you want them to be dangerous.

[N Jensen]

There were guys who would drop the mag on a M1A and insert the round into the chamber and let the bolt go fwd/fly. It was not good, every so often a slam fire would occur.

 

On my LR, I leave the mag in during single fire and place the round loosely ahead of the bolt and release it. One can still see a small mark/scratch on the primer. The mag slows the bolt down. I use rem 9 1/2 primers instead of 210M in my LR. Just seen to many slam fires.

 

I'm just saying one needs to be conscious of the fact that bad things do happen at times.  

 

I still won't buy machine gun brass, it doesn't last from what I have seen.

[survivalshop]

  If I was participating in shooting match's @ 1K , I would be buying much better brass also  <thumbsup> . Would probably be doing a lot of things different with reloading  & actually have been changing some of my practices & adding new procedures , Annealing being one of them .

 

  Old dog new tricks , I guess us old reloaders need to learn new ways & procedures . You can never stop learning.

Edited May 8, 2014 by survivalshop