Results 1 to 11 of 11

Thread: Excessive Pressure or Bad sizing?

  1. #1
    Member Valley Trash's Avatar
    Join Date
    Aug 2007
    Location
    Palmer
    Posts
    170

    Default Excessive Pressure or Bad sizing?

    The first attempt at shooting my handloads created some flattened primers. One rifle saw the flattened primers at one grain under max according to the most recent Nosler guide (none at lower charges). The other rifle had flattened and lightly cratered primers at max load according to the Speer Manual (none at lower charges).

    According to the Nosler Manual, flattened primers can be an indication that the resizing die was improperly adjusted and has changed the shoulder position of the case, causing excessive headspace and therefore causing case stretching, telescoping the primer and giving it a flattened surface.

    If that were the case, shouldn't the flattened primers have been seen after all charges?

    Both rifles are in very good condition, and therefore I didn't expect excessive pressure since I didn't exceed max loads. The cases were new, and I did "partial resizing" using the procedure in the Nosler Guide (left about 1/16-inch between the die and shellholder). Case mouths did not come from the factory very round.

    Velocities were lower than the guides (100 -200 fps) at all charges and were not consistent. Accuracy was not bad however. No signs of ejector marks and no problems opening actions after shooting.

    A poor pictures is attached....What would be your guess, excessive pressure or poor sizing?
    Attached Thumbnails Attached Thumbnails IMG_0090.jpg  

  2. #2
    Member
    Join Date
    Feb 2008
    Location
    Fairbanks
    Posts
    301

    Default

    Well I just started handloading so others may have better info but here goes.

    Flattened primers can be caused by soft primer, excessive head space or by high pressures. If the brass you where using was previously fired in that rifle and you have the shell holder 1/16" below the full length die then head space is defiantly not an issue. Full length dies are designed to return the brass to spec. if the shell holder is lightly forced against the die so being a 1/16" up you are not pushing the shoulder back at all.

    Many things effect pressure not just the amount of powder used. Seating depth, bullet to land distance, bullet type, and even different rifling in the barrel can have and effect. You could be seating the bullets deeper then the manual did, your bullets could be touching the lands or very close to them, you could be using a different design of bullet, and your barrel could be slightly tighter then the test barrel used, all of these would lead to more pressure.

    You may have found the max charge for your rifle. There is a reason that the manuals say to start at the starting load and work up. The max listed may be more then your rifles max. Different components including rifle lead to different results.

    For example using the speer manual and working up I got no pressure signs with 180gr Core lokts with 56 grains of IMR 4350 (listed max). Out of curiosity I loaded one round with 56.5gr and got a light shiny spot on the case head. Note that the speer manual does not list loads for the Core lokt bullets I used there regular loads.

    I then got some 180gr speer boat tails (which are in the manual), which I worked up using H4350. I got a small shiny spot on the case at 56grs max listed is 58gr. Perhaps my brass is softer then what they used, perhaps my rifle just does not like to push speer boat tails, perhaps my brass has less internal volume then the ones they used, who knows. Every combination is different and max is just that (recommended max) just because you do not reach it before pressure signs does not mean a thing.

  3. #3
    Member Valley Trash's Avatar
    Join Date
    Aug 2007
    Location
    Palmer
    Posts
    170

    Default

    I understand what causes pressure (the basics), this wouldn't even be an issue if I hadn't read that blurb in the nosler manual about "the resizing die being improperly adjusted". I would just assume over pressure...but reading that got me over thinking it I guess. Being that it happened in both rifles, I thought that, or other problems with my handloading procedure, may actually be the culprit for the flattened primers (rather than the powder charge). It would be nice to figure it out before I work up any more loads.

  4. #4
    Moderator
    Join Date
    Jan 2005
    Location
    Midwest
    Posts
    4,431

    Default

    Your die adjustment is fine. What Nosler is trying to say is valid but needs more explanation. If your loads chambered easily and the die wasn't touching the shell holder you're doing it right.

    Neither of your two primers are showing excess pressure. Both are moderate loads. I don't know what primers you are using there but it doesn't matter at this point. Just understand some primer cups are softer than other and flatten sooner. All primers will get flat on the bottom even with mild loads. It is when the primer starts to fill out the groove that we're nearing max. When you look at the primers there is still a groove between the primer and the case pocket as you look at the bottom. This is good. When you flatten them out from higher pressure that groove will fill with primer cup and when you push the primer out with the size/decap operation save the primer. It will have a hat brim at the bottom where it has expanded into that primer pocket groove. (This is the closed end of the cup) Your primers will not have that on these loads. When you see that hat brim effect, with CCI primer,s it is about 55,000 psi at the start that is about where you want to be, you could go above that a little and will need to experiment with it to learn to read primers. Of course these are just general rules and primer cups vary from maker to maker and from lot to lot so we must learn to read them. It is impossible to say that when a primer looks like this it is too much pressure.

    The headspace gap will allow the primer to push back out of the pocket then when the pressure builds the case will move back and smash the hat brim and it would appear larger than normal even with moderate loads. Your primers aren't there. I say if you're using modern rifles, proceed. Run it up you'll see the hat brim.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  5. #5
    Member Valley Trash's Avatar
    Join Date
    Aug 2007
    Location
    Palmer
    Posts
    170

    Default

    Thanks Murphy, that makes me feel better. I figured I may be a little over paranoid, which is par for me. All the primers that I thought looked flattened, were CCI. The one load I did (start load to max) using Remington primers did not look flattened, but my velocities were far less and even more variable than the same loads using CCIs (everything else the same).

  6. #6
    Member
    Join Date
    Apr 2006
    Location
    SwampView AK, Overlooking Mt. Mckinley and Points Beyond.
    Posts
    8,808

    Default Impressive

    It's better to be a little paranoid than too nonchalant.

    I just gotta say,,,, Murphy really knows how to explain things.

    "All primers will get flat on the bottom even with mild loads. It is when the primer starts to fill out the groove that we're nearing max."

    "When you flatten them out from higher pressure that groove will fill with primer cup and when you push the primer out with the size/decap operation save the primer. It will have a hat brim at the bottom where it has expanded into that primer pocket groove. (This is the closed end of the cup)"

    "Of course these are just general rules and primer cups vary from maker to maker and from lot to lot so we must learn to read them. It is impossible to say that when a primer looks like this it is too much pressure."

    I watch for ejector marks, on rifles that have the button type of ejector, and most of my few rifles do. Primers won't always tell you, when you have excessive pressure.

    That hat brim thing is something I've never read about in a reloading manual, but I've seen it, and I've done, just what Murphy says. Save the primer and examine it for the hat brim.

    He could be a reely mean guy, I dunno, but he's certainly, a real asset to this forum. Thanks Murphy.

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

  7. #7
    Member Valley Trash's Avatar
    Join Date
    Aug 2007
    Location
    Palmer
    Posts
    170

    Default

    I agree Smitty, I find myself taking notes whenever Murphy posts.

    Is it normal for primers to fall apart (inside part coming out of outer shell) when extracting primer from case? Most of the primers I pushed out of the fired brass did this. All were CCI.

  8. #8
    Moderator
    Join Date
    Jan 2005
    Location
    Midwest
    Posts
    4,431

    Default

    Quote Originally Posted by Valley Trash View Post
    I agree Smitty, I find myself taking notes whenever Murphy posts.

    Is it normal for primers to fall apart (inside part coming out of outer shell) when extracting primer from case? Most of the primers I pushed out of the fired brass did this. All were CCI.
    Thanks guys. And primers do normally come out in two pieces called the cup and anvil. I always look for that hat brim, I expect it to be there for any rifle caliber.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  9. #9
    Member
    Join Date
    Apr 2006
    Location
    SwampView AK, Overlooking Mt. Mckinley and Points Beyond.
    Posts
    8,808

    Default

    Quote Originally Posted by Murphy View Post
    Thanks guys. And primers do normally come out in two pieces called the cup and anvil. I always look for that hat brim, I expect it to be there for any rifle caliber.
    OHHHH,

    I thought that the hat brim was a sign of EXCESSIVE pressure, and have avoided it.

    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

  10. #10
    Moderator
    Join Date
    Jan 2005
    Location
    Midwest
    Posts
    4,431

    Default

    Quote Originally Posted by Smitty of the North View Post
    OHHHH,

    I thought that the hat brim was a sign of EXCESSIVE pressure, and have avoided it.

    Smitty of the North
    A broad brimmed hat, the kind they wear in Panama would be a sign. A good test is to fire factory brass in your gun, same brand as your brass, and if it does not make a hat brim then your handloads shouldn't either. It isn't a sure sign, as everything in this study of fired brass is just another indicator, but it is one of the things we watch. It is very common to have a hat brim on primers from normal pressure loads. When the primer flattens out and the hat brim isn't round but extrudes out to fill each area of the shallow groove around the primer pocket, that's a bad sign. When this happens you can see every machine mark from the bolt face on the pimer cup and about this time you will see burnished mark on the brass from the bolt face.

    Primer cups vary in hardness form brand to brand so we cannot say for sure at what pressure they will deform but after a while you'll get a feel for the way your primers are supposed to look if you stay with one brand for some time. Another thing to look for is the primer cup extruding into the firing pin hole in the bolt face. This will leave a little crater, a raised ridge around the pin strike on the primer. Some rifles will do this every time with normal loads but some only when the load is excessive. Some bolts have oversize holes for the firing pen and will likely leave a crater at the pin strike. We also get to know our rifle and what to expect in the spent brass. It just takes time and experience with a certain rifle and some comparison with factory loads.

    When you can read the headstamp backwards off the bolt face after firing, it is an excessive pressure load. This will mark the brass case head in some way also.
    Is there nothing so sacred on this earth that you aren't willing to kill or die for?



  11. #11
    Member
    Join Date
    Apr 2006
    Location
    SwampView AK, Overlooking Mt. Mckinley and Points Beyond.
    Posts
    8,808

    Default

    Murphy:
    OK, Thanks for clarifying that for me.
    Smitty of the North
    Walk Slow, and Drink a Lotta Water.
    Has it ever occurred to you, that Nothing ever occurs to God? Adrien Rodgers.
    You can't out-give God.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •