Small Pistol in place of Small Rifle primers in an AR15

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totaldla

New member
So please don't beat me up too bad as I'm just trying to understand. I've plenty of Small Pistol but no small rifle primers.

I took some 5.56 cases (new Starline and once-fired Lake City)and seated small Pistol primers in them (CCI500 & WSP). I then dropped each case into the chamber of my Ruger AR556 and slammed the bolt (from bolt release) on each a couple times.

IMG_20201112_121502497_HDR~2.jpg

Left to right above: New Starline 5.56 brass with CCI500, once-fired Lake City with CCI500, New Starline with Winchester Small Pistol. All of of them dropped into chamber and then bolt dropped from bolt release 3 times. Appears that Winchester Small Pistol is softer than CCI500.

So I know that an AR15 really can't fire out of battery. But I'm wondering what the big deal is if it slam fires.

Please be gentle....
 
Q

QBall45

New member
The truth is the AR15 can and has slam fired. This is a known fact with all floating firing pin firearms. Because of this, the industry has given us harder primers such as the CCI 41 primer which is specifically designed for floating firing pin guns. At no time is it acceptable to substitute pistol primers for rifle primers. I will suggest that you immediately cease and desist. Stop using pistol primers for rifle primers as this is an unsafe practice.

There is no need for gentleness where personal safety is concerned.

Sent from my SM-N975U using Tapatalk
 
Z

zxcvbob

New member
Can you find somebody to trade with? For example, I have 10's of thousands of small rifle primers (Wolf. I got a good deal on them) and no idea how many pistol primer but not nearly as many even tho' I use them more.

No, I'm not looking to make a deal, just saying look for someone in the same boat as you but on the other side.

SP primers might not be able to handle the chamber pressure in a rifle. They also might not be juicy enough (that's a technical term) to reliably ignite rifle powders. It's not all about slam-fires.

I have used SR primers in pistol rounds without any problems. (I've not tried the Wolfs, I used Federals for that) The potential problem there failure to fire due to light-strikes. This can especially be a problem with double-action revolvers.
 
T

totaldla

New member
zxcvbob said:
Can you find somebody to trade with? For example, I have 10's of thousands of small rifle primers (Wolf. I got a good deal on them) and no idea how many pistol primer but not nearly as many even tho' I use them more.

No, I'm not looking to make a deal, just saying look for someone in the same boat as you but on the other side.

SP primers might not be able to handle the chamber pressure in a rifle. They also might not be juicy enough (that's a technical term) to reliably ignite rifle powders. It's not all about slam-fires.

I have used SR primers in pistol rounds without any problems. (I've not tried the Wolfs, I used Federals for that) The potential problem there failure to fire due to light-strikes. This can especially be a problem with double-action revolvers.
Click to expand...
Good point about trading and I understand the point about pierced primers as I don't want my bolt chewed up.
 
H

higgite

New member
But I'm wondering what the big deal is if it slam fires.
Click to expand...
Think about it. If a slam fire due to a soft primer is followed by another and another and so on..... you no longer have a semi-auto rifle. You have a full auto rifle with no trigger control. That's not a surprise that you want nor are you likely to be prepared for when you close the bolt on a fresh magazine.
 
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hounddawg

New member
Ask around and I bet you will find someone willing to trade pistol primer for rifle primers. I did that a couple of weeks ago when one of the local IDPA shooters approached me at the range wanting to know if I would sell him some pistol primers. I told him I would not sell at any price but I was willing to trade a couple of thousand one for one. We were both smiling when he left my house

If there are pistol competitions near where you live that would be a good place to start asking around

Oh and like everyone else I would not recommend you not do the pistol primers in a rifle unless it is a pistol caliber rifle like a .357 or 9mm
 
T

totaldla

New member
higgite said:
Think about it. If a slam fire due to a soft primer is followed by another and another and so on..... you no longer have a semi-auto rifle. You have a full auto rifle with no trigger control. That's not a surprise that you want nor are you likely to be prepared for when you close the bolt on a fresh magazine.
Click to expand...
That has never, ever happened.
 
Z

zxcvbob

New member
603Country said:
Going on memory, I do believe that unclenick recently said that CCI SP Magnum were the same as SR primers.
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Yes, but the crucial word there is "were". I think CCI claims now that they are different. (probably not much different, tho') But are the 500's the magnum primers? I think those are the standards.
 
T

totaldla

New member
The 550 is the small Pistol magnum.

Btw, I took your advice and traded for some cci450. I had lots of offers in a very short time - folks were really hungry for small Pistol primers.
 
T

T. O'Heir

New member
"...can't fire out of battery..." That not the rifle. Slamfires are usually caused by improperly seated primers.
The issue with SMR vs SMP primers is the priming compound isn't the same. I'd be guessing that given the current Covid Panic shortages of everything, you could probably name your price for small pistol primers.
"...the CCI 41 primer..." Cups are the same as any other primer. CCI #41 primers are nothing more than small rifle magnum primers. CCI "Military" primers is a brilliant marketing scheme.
 
H

HiBC

New member
A person I shoot with has a very nice loading bench setup.There is a drawer/bin for 100 ct pkgs of primers,each labeled.
Somehow (darn Humans!) a pkg of LG pistol primers ended up in the LG rifle drawer.
Those got loaded into 308 rounds.

I was shooting some of them in my DPMS LR-308 (AR-10 style)

Old habit,as I picked up the brass from the first mag,I noticed the primers.

All had a hole through them. The thinner cups sheared neat little discs through the firing pin hole.
I didn't know what was going on at that point. I cased the rifle and was done shooting it for the day.

Bolt disassembly showed some of the discs inside the bolt body with the firing pin.

I speculate that continued firing may have bound the firing pin into a fixed firing pin,which would have resulted in ignition without the locking lugs engaged.

There was light gas cutting of the firing pin tip. No doubt I could have polished it out,but a DPMS replacement was cheap and available.

Ejector plunger...I don't recall...it may have required cleaning.

Hopefully,this gives you enough info to make your decision.

In times of component shortages,the last thing you want to do is pull bullets to salvage components..

On inertial slam fires,yes,they can happen. Note only the Armalite AR-10 has a firing pin return spring.

I'm not sure how the millisecond timing of all this works out,but the firing pin is still traveling forward as the bolt body comes to a hard stop,but note the bolt carrier has not yet moved forward,camming the locking lugs into place.

The firing pin to primer strike occurs while the bolt is unlocked. Is there enough ignition delay for the bolt to go to full lockup before chamber pressure? I don't know.Maybe.
 
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T

totaldla

New member
HiBC said:
A person I shoot with has a very nice loading bench setup.There is a drawer/bin for 100 ct pkgs of primers,each labeled.
Somehow (darn Humans!) a pkg of LG pistol primers ended up in the LG rifle drawer.
Those got loaded into 308 rounds.

I was shooting some of them in my DPMS LR-308 (AR-10 style)

Old habit,as I picked up the brass from the first mag,I noticed the primers.

All had a hole through them. The thinner cups sheared neat little discs through the firing pin hole.
I didn't know what was going on at that point. I cased the rifle and was done shooting it for the day.

Bolt disassembly showed some of the discs inside the bolt body with the firing pin.

I speculate that continued firing may have bound the firing pin into a fixed firing pin,which would have resulted in ignition without the locking lugs engaged.

There was light gas cutting of the firing pin tip. No doubt I could have polished it out,but a DPMS replacement was cheap and available.

Ejector plunger...I don't recall...it may have required cleaning.

Hopefully,this gives you enough info to make your decision.

In times of component shortages,the last thing you want to do is pull bullets to salvage components..

On inertial slam fires,yes,they can happen. Note only the Armalite AR-10 has a firing pin return spring.

I'm not sure how the millisecond timing of all this works out,but the firing pin is still traveling forward as the bolt body comes to a hard stop,but note the bolt carrier has not yet moved forward,camming the locking lugs into place.

The firing pin to primer strike occurs while the bolt is unlocked. Is there enough ignition delay for the bolt to go to full lockup before chamber pressure? I don't know.Maybe.
Click to expand...
On a typical AR15, If the bolt hasn't turned in, the firing pin can't hit anything. Or at least that is my understanding of how it should work.
It is true if you reset the trigger fast enough you could have the hammer hitting the firing pin before the bolt lugs engage.
Fun thought experiment :)
 
H

HiBC

New member
On a typical AR15, If the bolt hasn't turned in, the firing pin can't hit anything. Or at least that is my understanding of how it should work.
It is true if you reset the trigger fast enough you could have the hammer hitting the firing pin before the bolt lugs engage.
Fun thought experiment
Click to expand...

OK. Ill bite. With the bolt extended, the BCG assembly strips a cartridge,the cartridge enters the chamber The cartridge shoulder meets the chamber shoulder. The bolt head fully enters through the barrel extension with the locking lugs still aligned with the recesses in the barrel extension. No bolt rotation has taken place. The forward motion of the bolt and cartridge are at full stop...however! The floating inertial firing pin,I would agree,is prevented from falling out the rear of the bolt by the firing pin retainer pin which travels with the bolt carrier. But what stops the firing pin forward travel? The flange on the firing pin hits the tail of the bolt body,or maybe the step on the small end of the firing pin hits a shoulder within the bolt body,but Nothing else inhibits the firing pin forward travel. Bolt forward travel is full stop. Bolt carrier is still traveling. Hammer is at full cock,on safe even. Hammer plays no part.You did not drop the hammer on your dinked rounds.

So,now please tell me how you got those dinks in your primers from the remaining operational sequences.
The only motion left for the bolt is rotation into lockup .The bolt has no linear motion. The last time we checked,the firing pin was traveling forward with the bolt,free to float within the bolt.
Then what happens?
 
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T

totaldla

New member
HiBC said:
OK. Ill bite. With the bolt extended, the BCG assembly strips a cartridge,the cartridge enters the chamber The cartridge shoulder meets the chamber shoulder. The bolt head fully enters through the barrel extension with the locking lugs still aligned with the recesses in the barrel extension. No bolt rotation has taken place. The forward motion of the bolt and cartridge are at full stop...however! The floating inertial firing pin,I would agree,is prevented from falling out the rear of the bolt by the firing pin retainer pin which travels with the bolt carrier. But what stops the firing pin forward travel? The flange on the firing pin hits the tail of the bolt body,or maybe the step on the small end of the firing pin hits a shoulder within the bolt body,but Nothing else inhibits the firing pin forward travel. Bolt forward travel is full stop. Bolt carrier is still traveling. Hammer is at full cock,on safe even. Hammer plays no part.You did not drop the hammer on your dinked rounds.

So,now please tell me how you got those dinks in your primers from the remaining operational sequences.
The only motion left for the bolt is rotation into lockup .The bolt has no linear motion. The last time we checked,the firing pin was traveling forward with the bolt,free to float within the bolt.
Then what happens?
Click to expand...
I wish I had a video showing this...

The firing pin cannot protrude from the bolt face until the bolt is 90+% rotated into the locking lugs (WAG from watching the bolt on my AR late at night). The dimple happens because the bolt slams home and rotates fast enough that the firing pin can make a mark. If the primer exploded, the locking lugs are mostly engaged, and all is well. To further reduce the chance of slam fire, some manufactures reduce the weight of the firing pin.
 
H

higgite

New member
HiBC said:
The only motion left for the bolt is rotation into lockup .The bolt has no linear motion. The last time we checked,the firing pin was traveling forward with the bolt,free to float within the bolt.
Then what happens?
Click to expand...

The firing pin travels with the carrier, not the bolt. When the bolt hits the breech and stops traveling forward, the carrier and FP are still moving forward. A shoulder on the FP and a restriction inside the carrier keep the FP from moving forward far enough to protrude through the bolt face until the bolt has receded into the carrier far enough that the lugs are almost totally locked, as totaldla said. He is right about that.
 
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