Primer Output pushes bullets into rifling.

[243winxb]

The firing of the primer moves the bullet into the rifling, before powder starts burning. The bullet pull is 35 lbs minimum, about .002" neck tension in 223.

https://apps.dtic.mil/dtic/tr/fulltext/u2/a622138.pdf

Should i worry about COL at all?

5. Conclusions- By employing short-barrel guns, high-speed imaging, and the ARL primer force breech, extensive evaluations have been made into the initial motion, velocity, and acceleration of small-caliber projectiles in both 5.56 and 7.62 mm. These studies have shown that the primer output alone can greatly influence the initial motion of a small-caliber projectile. The primer is capable of producing enough force to debullet the projectile and begin the engraving process prior to any significant propellant burning.

 

[Dusty Stevens]

Should i worry about COL at all?

If it didnt matter then seating depth changes wouldnt matter. That alone renders those conclusions invalid since i think we all know it does in fact matter

 

[BronzeArcher]

I've had a number of rifle misfires through the years where the primer detonated but the powder did not ignite. (This can be confirmed by disassembling the round afterwards. Evidence of a primer detonation is clumps of powder, ash in the primer pocket, and an obviously spent primer pushed out.) In no case was a bullet ever pushed into the rifling in these events. In contrast, I have seen the bullet pushed into the rifling by misfires in pistol cases when the primer detonates but the powder fails to ignite.

I'm not saying that the ARL study is wrong, but I am suggesting the results they see for a relatively hot primer in a small case with a light bullet may not translate to other primers in larger cases with heavier bullets.

One bit of conventional wisdom in high accuracy rifle reloading is to use the weakest primer that will reliably ignite the powder. Perhaps one aspect of this is to reduce or eliminate the motion of the bullet before the powder charge ignites. Could this be a contributing factor to lower velocity spreads and better long range accuracy from the Palma cases in .308 and other examples of mid-size cases finding better accuracy with small primers?

 

[243winxb]

I've had a number of rifle misfires through the years where the primer detonated but the powder did not ignite. (This can be confirmed by disassembling the round afterwards. Evidence of a primer detonation is clumps of powder, ash in the primer pocket, and an obviously spent primer pushed out.) In no case was a bullet ever pushed into the rifling in these events.

I have seen this in a 22-250 with CCI mag primer and H450 powder years ago.

There is another test comparing 100 pounds bullet pull to the 35 pound minimum bullet pull, in 3 different rifles. New, 10,000 fired and 30,000 rounds fired.
https://apps.dtic.mil/dtic/tr/fulltext/u2/862734.pdf

The 35 lb ones all went into the bore with 2 different primers.

c. Upon firing M193 cartridges without propellant, both types of* primers produced bullets in the bore, on all occasions of testing, when the bullet crimp ranged from "no crimp" (tampered cartridges) to 35-pound average bullet pull (minimum specification requirement). However, at a bullet pull of lOO-pound average, on all occasions of testing, the Number 41 type primer produced significantly more bullets lodged in the bore than did the Federal Number 195 primers.

 

[Uncle Ed]

Darn, now I have to do another Speer work up load test with bullet sealer, crimped bullets and CCI #41 magnum primers.

I wonder if Quickload will give me the start pressure for plastic bullets.

 

[nmkid]

I've had a number of rifle misfires through the years where the primer detonated but the powder did not ignite. (This can be confirmed by disassembling the round afterwards.

That happened to me this past summer but, hadn't posted because I thought I wouldn't be believed. Well, don't know if people would believe it now, but, it happened. Pulled the trigger, barely heard a soft pop and I just froze in my shooting position. Sat back, cycled the action and pulled the round out. First thing that went through my mind was that I had left the powder out. Nope, shook the round and it had powder in it.

 

[spencerhenry]

I have had a couple of rounds over the years with no powder in them, 45 acp cast bullets, 38 spl cast bullet with heavy crimp, never had a bullet move in the case. I had a 223 round with no crimp that had no powder, that bullet did not move in the case either.
On a case the size of a 308 or larger seems like it would take one hell of a primer, if a primer on a 38spl can't do it.

 

[AJC]

https://www.targetsportsusa.com/aguila-colibri-22-lr-ammo-20-gr-sp-p-2901.aspx
Every experience is unique to the factors that set the chain of events in motion. These little guys dont have any powder and shoot almost threw a 1/4 piece of plywood.

 

[alinwa]

Alla' that fancy taxpayer funded testing is well and good BUT..... In going back through my data books and memory banks I find perhaps 30 FTF events which include fired primers.

In my case the results vary from MOST extreme (and in this case dangerous)

----In the early 90's I was shooting a Sako A1 '6PPC USA' using home-ade necked down AK47 rounds (large primer) and actually had a 45gr NBT make it halfway down the barrel...... EMPTY case, large rifle primer. Firing again over this squib would have wrecked the gun.

To LEAST.... basically a non-event.

----I had one last week, 300WSM, no crimp, just over .001 nt, forgot the powder=nothing. I pulled and shot the bullet.

And it's NOT about the case volume, ie 'powder' or 'no powder'. I've had cases fail to fire where the powder comes out in goooey yellow clumps where the bullet didn't move.

I've only had 2 others move in non-PPC cases, one a 6BR and one a 6X47L where in both cases I was running less than .001 neck tension on turned .013 thick necks.

I remember a couple times in the 90's shooting neck-size only .262 6PPC forgetting the powder and having to tap the bullet back out of the leade with a cleaning rod. Always when running less than .001 nt. Many times though, when running a "more normal" neck tension setting, no bullet movement. That would have been Federal Small Rifle BR Gold Medal Match primers.

 

[joshb]

I’ll be the stubborn old mule that cries Bullcookies concerning the study. I’ve seen a bullet pushed out of a 308 case with .003 neck tension by a primer and no powder. I “loaded” it. I just can’t believe the bullet moves before powder ignition. Sorry. I’m in a foul mood.

Edited .03 to .003
I’m not all here. I just found out my dog has bone cancer.

 

[243winxb]

The first 2015 link/test is with powder. The bullets in 5.56 & 7.62 both make it to the rifling "prior to any significant propellant burning."

More so with the 5.56 and #41 primer with a case fill close to 100%
Ball powder may be harder to light and react slower to the primer firing??

The 55 fmjbt bullet has very little bearing surface, from my crude measurements. Less contact with the neck??

 

[rr2030]

Theoretically, any expanding gas inside the case would move the bullet, no ? Especially if the case is full or near full ?

 

[rammac]

I find this very interesting since quite often I have to adjust the data I use with QuickLoad to get a reliable match with the real world muzzle velocity data. The report mentions that the change in ullage will have to be accounted for when estimating internal ballistics data, I've found that adjusting the case volume in QuickLoad usually gets me to within a very reliable 30 FPS or so of the true muzzle velocity of a cartridge load.

 

[rammac]

Theoretically, any expanding gas inside the case would move the bullet, no ? Especially if the case is full or near full ?

I agree, there must be an equal and opposite force that pushes the bullet when the primer ignites.

 

[rr2030]

I have had a couple of rounds over the years with no powder in them, 45 acp cast bullets, 38 spl cast bullet with heavy crimp, never had a bullet move in the case.
.

Hmmm. Over the years I have had several .45 ACP and .38 special rounds with no powder. Light taper crimp on the .45's and light roll crimp on the .38's. In each instance I had the bullet move forward. With the .38's the bullet ended up between the cylinder and the forcing cone. All cast bullets. That has been MY experience. It is also the reason all my pistol boxes have wooden dowels the length of the barrel and caliber for any pistol I shoot. Almost 50 years of various pistol competitions have taught me that. Again, that has been My experience.

 

[chop house]

ullage

off point, but i am a dang near 70 yo crossword fan, and had to look this up. As my kids woud say.... 'good one'

 

[chop house]

Always when running less than .001 nt.

al, i think you just flipped on a light bulb in my brain. i hope it will turn out to be an 'aha!' moment.

over the years i have had cases that just wouldn't size consistently.... and i seat by feel, no force pack. I never got a handle on 'why' they shot so poorly and seating depth tests were inconclusive.

edit: also, i am 'prone' to trying to make short bullets shoot in long throated rifles which leaves vary little bullet in the neck. i have struggled with sooty necks and poor sealing. this kinda tells me i should try either a hard jam or a very much deeper seat

 

[msinc]

I have blown up two guns in my life...one of them twice. The first was a 700 in 223 with a very accurate Pac-Nor barrel. I managed to reload a block of cases in which one of them received no powder. I had ear muffs on when shooting and mistakenly thought I had a "short stroke" when the gun just went "click". I reloaded another round and promptly ruined that barrel. It bulged but didn't blow and I have the bulged section I saved {see above}. The "click" was in fact a case with no powder. The primer sent that bullet 3/4 of the way down the bore to stop some 18-20 inches from the breech.
The second was a Browning Hi-Power in which one round received no powder and the next received a "double" charge. First time I again had a bullet lodge halfway down the bore from the no powder round. Next round blew the barrel. I was lucky that time, the slide and barrel were ruined but I sustained no injury. Well, you can probably guess what happens next...I found and purchased a slide and barrel, go to the range and promptly blow the GD thing again with the double charge!!! This time not so lucky...I had half the brass case go thru my hand. I have to say that this is when I started doing a "visual" check on the powder charge in the case when reloading!!!
I think it is fair to say, for me at least, that a "primer only" case will move the bullet into the rifling. I have had this happen in revolvers too, and it always stopped in the forcing cone because the cylinder gap relived the pressure.

Edit: This has always been a good question...does the bullet start to move while under neck tension, or does the case immediately expand to "let the bullet go"??? Does neck tension, bullet seat depth, bullet to neck lube or lack of, bullet seated in carbon build up, bullet seated in bare brass/new brass really what makes the difference or is it that the barrel harmonics resulting from some of this make the difference??? Easy answer is always going to be "well it ALL affects things".......but easy doesn't always equal correct and what has the most affect on accuracy????

 

[JRS]

I would imagine the weight of the bullet also comes in to play. I can't see the ignition from a primer pushing a 400 grain bullet out of the case.

 

[hogpatrol]

Same goes for BPS muzzleloaders and why the use of standard shotgun primers isn't recommended. On ignition, they lift the pellets/sabot and bullets before the entire charge ignites.