Primer piercing but weird

[BallisticsGuy]

I've never seen this problem before and I think it might be to do with my firing pin and not my load. I just switched to small primer 6XC brass so I could positively identify any of my old brass that had gotten damaged and which was large primer and keep it out of my match ammo.

I can take the same powder charge and put it in a LRP case and there are no pressure signs at all. Do the same thing on SRP brass and 3 out of 5 end up with a perforated primer. ***? Do I need to change out my striker or what? The primer strikes do look really deep so I guess it could just be striker protrusion is too much. Does anyone know what kind of protrusion difference there should be (assuming there is a difference) between SRP and LRP?

I have something like the same thing going on on a different match rifle where some of my loads are on SRP brass and some are on LRP brass and I shoot them out of the same gun with no issues at all so I'm a bit at a loss.

 

[cohunt]

what primers? small primers have a thinner cup thickness

 

[JKB57]

try using the CCI AR primers for this they are a little thicker and designed for this problem

 

[BallisticsGuy]

Right now I've got CCI 400's being ventilated. I've got some 450's and some #41's and some BR4's on hand. I actually run BR4's in the other rifle that uses both LRP and SRP brass. I wonder if that's why I've never encountered the issue before.

 

[bigedp51]

Below CCI 400 fired in a AR15 rifle, Look at the chart above posted by cohunt in post #2.

You need primers with a cup thickness of .025 to prevent the pierced primers.

NOTE, pistol primers have a cup thickness of .017 to .020 and the CCI 400 primers have a .020 cup and are for lower pressure cartridges. (see below)

CHOOSING THE RIGHT PRIMER - A PRIMER ON PRIMERS
http://www.sksboards.com/smf/index.php?topic=56422.0

CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page.

NOTE 1: According to Speer/CCI Technical Services - Both the CCI 550 Small Pistol Magnum and CCI 400 Small Rifle primers are identical in size. Both primers use the same cup metal and share the same cup thickness. Both primers use the same primer compound formula and same amount of primer compound. They can be used interchangeably.

 

[bigngreen]

Many times you can solve this issue by getting your bolt bushed and pin turned down, with the little softer cups a sloppy pin just don't cut it, on thicker primers you just get muffin top.

 

[25WSM]

The way I'm reading this is you have an established powder charge you use. And this charge works in your lrp brass. Then when you put that same charge in your srp brass it pierced the primers. If this is what you are trying to say then it's probably that the srp brass has less volume and therefore creating over pressure. You just can't take a load that works in one brass and put it in another and expect it to work. You need to work up the load for your new srp brass. You just can't mix and match any components up and expect it to work. Always drop back down on charge weight and work back up to a safe load. Pierced primers are almost always caused by too much pressure. A loose firing pin fit can do it if you run too much pressure. A firing pin protrusion of 50 to 65 thousands. Different guns will have different specs on this.
Try backing down the charge weight and working back up to max.
Shep

 

[bigedp51]

In the OPs old cases, he used large rifle primers that have a cup thickness of .027

The CCI 400 small rifle primers in his new cases have a cup thickness of .020 and are the same thickness as pistol primers.

Switch to small rifle primers with a cup thickness of .025, they are only .002 thinner than large rifle primers.

CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page.

NOTE 1: According to Speer/CCI Technical Services - Both the CCI 550 Small Pistol Magnum and CCI 400 Small Rifle primers are identical in size. Both primers use the same cup metal and share the same cup thickness. Both primers use the same primer compound formula and same amount of primer compound. They can be used interchangeably.

 

[Frog4aday]

The way I'm reading this is you have an established powder charge you use. And this charge works in your LRP brass. Then when you put that same charge in your SRP brass it pierced the primers. If this is what you are trying to say then it's probably that the SRP brass has less volume and therefore creating over pressure. <SNIPPED STUFF> Try backing down the charge weight and working back up to max. Shep

THIS^^^^

 

[tdot]

In the OPs old cases, he used large rifle primers that have a cup thickness of .027

The CCI 400 small rifle primers in his new cases have a cup thickness of .020 and are the same thickness as pistol primers.

Switch to small rifle primers with a cup thickness of .025, they are only .002 thinner than large rifle primers.

CCI 400 -thin .020" cup, not recommended for AR15 use by CCI/Speer. Good for .22 Hornet, .30 Carbine. See Note 1 at the bottom of the page.

NOTE 1: According to Speer/CCI Technical Services - Both the CCI 550 Small Pistol Magnum and CCI 400 Small Rifle primers are identical in size. Both primers use the same cup metal and share the same cup thickness. Both primers use the same primer compound formula and same amount of primer compound. They can be used interchangeably.

Do you know of a SRP with a thicker cup? I briefly looked into switching my 308 to smaller primer but didnt want hassle of the thin cup.
Thanks

 

[bigedp51]

Do you know of a SRP with a thicker cup? I briefly looked into switching my 308 to smaller primer but didnt want hassle of the thin cup.
Thanks

Look at post #2 by cohunt, it has a chart with the cup thickness of the various primers.

This makes me wonder how many of you are readings all the postings.

NOTE, Remington ran Lake City Army Ammunition Plant from 1941 until 1982 and used the Remington 7 1/2 primer with a .025 cup thickness in all the 5.56 ammunition.

 

[tdot]

Look at post #2 by cohunt, it has a chart with the cup thickness of the various primers.

This makes me wonder how many of you are readings all the postings.

NOTE, Remington ran Lake City Army Ammunition Plant from 1941 until 1982 and used the Remington 7 1/2 primer with a .025 cup thickness in all the 5.56 ammunition.

Ah yes, there it is. Thanks for that. Funny that you just called me out on one of my biggest pet peeves. I hate when people dont actually read. In my defense, the chart didnt show up on my phone, which is what I was reading it on earlier, but I see it here on my computer.

 

[25WSM]

I think it's crazy guys are looking for thicker cups. The primers are already more than strong enough. A cci 450 or a rem 71/2 or fef 205m has enough strength to wreck a brass in one firing. They seldom fail if the pressure is within spec. Afterall primers is one tool we have to observe pressure in our loads. And a blanked or pierced primer is one of those signs that says you just stepped on the pedal way too hard. Sometimes by accident but alot of times on porpose.
Basically if you can't make reloads the fall within the safe pressure max that are set by the manufacturers then you should stop reloading. It's not safe for you or those around you. You know who I'm talking about. Goes like this. ( My 7-08 imp shoots 3400 fps with a 168 vld.)
There special little case somehow beats down magnums with twice the powder capacity. There is one variable we have to all adhere to when reloading, pressure. You go over the max and things fail.
Shep

 

[TRG65]

I shoot a lot of small primer brass in cartridges that can use both, 308 Lapua Palma, 6.5x47(SRP only), and 6.5 Creedmoor Lapua SRP. All of my rem 700 or 700 clone actions have had to get the bolts bushed. I've sent them all to Gre-Tan. My RPR and Sako TRG didn't need bushed, but my 700 actions did. All I use are the CCI mil spec srp's. With very reasonable loads, a 700 action even shooting the CCI 556 primers, can pierce. I recommend doing both (having the bolt bushed and run mil-spec primers) if your loads are edging to the warm side.