Need help! Loose Primer Pockets...

[300WSM]

Try Winchester primers. I use a RCBS handheld priming tool so i have a better feel of seating the primer.....I use all three brands and I can tell you Winchester primers always feel to have the most friction when seating.


I haven't put a caliper to all three but I can tell you based on feel of seating them all that Winchester has the most resistance going in.

 

[jockperkins]

Thanks for the responses. I use the Winchester Primers and they are larger in diameter than some of the other brands -- but still the same problem. I will try fireforming some Remington brass without placing the bullet into the lands and see if the primer pockets will hold better than what I have been experiencing with the Nosler cases...

 

[JD338]

Jock,

With the 280 Rem brass, there should be a slight crush feel when you close the bolt. The case head spaces off the neck/shoulder junction (datum line) so you do not need to seat the bullet into the lands.

JD338

 

[Guy Miner]

Jock - I don't know beans about the .280 AI, I just use a 7mm Rem mag when I want to shoot a 7mm bullet fast...

But that's one heck of a buck! Congratulations. Looks like your little buddy is happy about the buck too.

Hopefully you'll get this figured out. The only brass I've lost primers after one firing was some .308 Win brass by Lapua after a 600 yard match on a warm day. Ugh. Hated tossing those cases, but they were toast - after one firing. Doggone it.

Guy

 

[jockperkins]

JD338. Thanks. Yes, my brass is set to slightly crush on the datum line for proper head space. Thanks for the rest of the info. Hopefully this works for me. Have you tried the Nosler brass with the load we are describing -- and if so, have you experienced the same?

 

[jockperkins]

Guy,

Thanks! I hope I get it figured out as well.

Jock

 

[onesonek]

I am full length resizing each time and bumping the shoulder back 0.001. Neck sizing only works for a short period of time before "springback" lengthens the headspace beyond chamber length making it difficult to close the bolt. I know how this works and I don't do it...

Well,,I don't know from everything you are describing. I never push the shoulder back on anything, and do not have that springback issue with chambering. I will bump that shoulder every other firing or 3rd, but not push it back. But if you are finding that,,,I wouldn't bump it back that far,,,barely touching it will do. The idea is to have everything as snug as possible and still function. Personally I like zero tolerance on length, and no more than +.002" on either side from my sized case body. I just make sure each round chambers after loading. If you feel you must push the shoulder back .0002-3" would be plenty in my thoughts.
But with what sounds like a large chamber to sizing die dimension, what you are doing is allowing the gas to partially push the primer out before the case can grab the chamber walls with that .001" bump. This also allows pressure to build in the primer pocket opening it up some before it slams into the bolt face. This action or hammering can also open the pocket even more. The short of it is as I see it, you want the shoulder snug in your chamber, touching the shoulder face in the chamber,,,,,regardless of body clearance. But the case head is getting over worked with the .001" shoulder bump. Not say you don't have bad brass, but I would certainly do something different on that sizing situation, even if it meant sending your sizing die out and have it opened up some so your case body isn't worked so much. But I think I would first go to a neck die or partial size not shoving that shoulder back. And again for what its worth, I primarily load for break or falling block actions, and don't have that springback headspace lengthing issue going on. Most advise full length sizing these actions, but I been partial sizing not bumping the shoulder back at all for years without issue.


I also just went out and weighed some of my virgin 280 Remington brass (parent case) and it is heavier on average than the Nosler that I have been using -- by 8 grains. I am going to fireform some but still waiting for an answer as to whether I should do this with the bullet seated into the lands?

If you got that much play in your chamber, it's the only way I would consider fireforming, otherwise you are inviting early casehead seperation,,,,specially if bumping that shoulder back .001" from the start.

Not happy with Nosler brass so far -- at least on the 280AI. It is accurate but good for 1-2 loadings. I don't have this problem with other brass.

 

[jockperkins]

Dave,

Interesting that you find neck sizing adequate over many loadings. I have numerous friends who find it works for loading two or three rounds before difficulty with springback (and I have found the same). For that reason, I had a custom die made for the Ackley that closely matches the size of my chamber (based off fireformed cases from the chamber). Now I full length resize each time and control the neck tension with bushings from Redding.

Also, how can I get virgin 280 brass that will slightly crush the datum line when loaded for fireforming to avoid case head separation?

For all of you: Googling " primer pockets with Nosler brass" brings up many results and postings from folks like me with the same problem.

 

[onesonek]

As I said Jock, I partial size, not really FL or neck sizing. This only partially sizes the body and returns neck tension. I do screw the FL die down to bump the shoulder every 2nd or 3rd firing, but not enough to to shove it back under chamber dimensions.

"Also, how can I get virgin 280 brass that will slightly crush the datum line when loaded for fireforming to avoid case head separation? "

You would have to size it up to .30 cal and then back down, but partial or short stroke it on the down size, as I see it. If the virgin brass isn't aleady slightly crushing. Maybe others have other ways or thoughts.
But it is much easier to load a bullet out slight to engage the lands to the firing pin strike can move an undersized case forward.

"I had a custom die made for the Ackley that closely matches the size of my chamber (based off fireformed cases from the chamber)."

also,,,how did you fireform the brass for the custom die make?

You may very well have a bad batch of brass Jock,,, but that .001" shoulder bump aint helping anything as I see it. Fine for a dangerous game rounds in my mind, but when top accuracy and brass life is concerned,,,not a good thing imo.

 

[onesonek]

Again, I would still start with at least 3 new brass, ,,,fireform with a bullet seated to bump the lands hard with a modest mid level pressure load. Check if the primer feels tight after that, if not then I would believe the brass to be bad. If the primer pocket is tight, then partial size as not to bump the shoulder back. This can be done by backing the die a 1/4 turn off the shellholder. Fire another set at the same mid level load. If they are still tight all is good, if not, again it looks like a brass issue. Otherwise partial size and load your top load again for the 3rd loading, if they are open a loose,,then its a pressure problem.

 

[jockperkins]

Dave,

Perhaps I do not fully understand what you are trying to say here. The custom die that I had made performs a partial sizing so as not to reduce the case size past regular SAAMI spec. I did this to achieve the best fit to chamber and still perform a full length resize without overworking the brass -- the sizing is partial at best. The 0.001 bump puts it right at the headspace length with a very slight crush at the datum. I do this with all of my rifles and from what I know about benchrest shooters, they do the same. Most folks bump it back a lot farther. I have a headspace gauge that I use frequently to set dies for folks who are bumping back too far (0.004 -0.005). I use this to help them achieve better accuracy.

I had the die made by Jim Carstensen who took 10 of rounds that had been fireformed from my chamber (1x). He reamed the die and converted the top of the die to hold bushings for neck sizings. Carstensen is a bench rest shooter/machinist and this is a fairly regular practice (using such dies) for this application.

I think I understand what you are saying when it comes to taking the virgin brass and upsizing it with a mandrel to 30 caliber and then reducing the neck to 7mm only partially resizing the neck. This would create a "false" shoulder to hold the casing in place against the front of the chamber to avoid case separation.

 

[onesonek]

Dave,

Perhaps I do not fully understand what you are trying to say here. The custom die that I had made performs a partial sizing so as not to reduce the case size past regular SAAMI spec.
Well, I'm not sure I totally understand either. This is the part that really seems a bit off,,,,, " The chamber is not that tight. The neck expands ten thousands when fired and the body does as well. I have head space guages, I have miced the body -- literally looked at everything. If I compare the virgin brass -- it is much smaller than my chamber -- so much so that it can be viewed with the naked eye when compared with a fireformed case."
The virgin AI brass should be close to spec I would think anyhow.
.010" expansion is alot to me, and so I'm not sure SAAMI spec means much of anything. All I care about is the finished chamber. And your chamber is much larger then I'm use to seeing. Again, it don't matter if the reamer was in spec, it is how the guy using it does the work. I have seen such chambers that were straight, but the guy running the reamer had some wobble in it, which made for a sloppy fit with SAAMI spec'd dies. What I'm getting at for the most part is, if your original fireformed brass wasnt crush fit or fireformed right, then the dies could or would be off too. So again SAAMI spec goes out the window,,,it's your chamber that matters, not spec anything other than your chamber dimension specs. Now if the dies were made to properly fireformed brass as you say, just barely sizing the brass leaving a slight crush at the datum, then all should be ok. But it is still either a brass or pressure issue then. At this point with out gun in hand, I wouldn't bet on either. Not until I could cast your chamber and die.


I did this to achieve the best fit to chamber and still perform a full length resize without overworking the brass -- the sizing is partial at best. The 0.001 bump puts it right at the headspace length with a very slight crush at the datum. I do this with all of my rifles and from what I know about benchrest shooters, they do the same. Most folks bump it back a lot farther. I have a headspace gauge that I use frequently to set dies for folks who are bumping back too far (0.004 -0.005). I use this to help them achieve better accuracy.

I had the die made by Jim Carstensen who took 10 of rounds that had been fireformed from my chamber (1x). He reamed the die and converted the top of the die to hold bushings for neck sizings. Carstensen is a bench rest shooter/machinist and this is a fairly regular practice (using such dies) for this application.
I have heard of Jim, and believe he would do it right, along with good work.

I think I understand what you are saying when it comes to taking the virgin brass and upsizing it with a mandrel to 30 caliber and then reducing the neck to 7mm only partially resizing the neck. This would create a "false" shoulder to hold the casing in place against the front of the chamber to avoid case separation.

 

[jockperkins]

Dave,

I may have made a typo -- it is a thousandth from the Carstensen die. The virgin brass is ten thousandths smaller than the chamber. When Virgin brass is fired it should have plenty of room for expansion and therefore, a lack of pressure. Hope this resolves the issue.