Primers

richhodg66

Well-Known Member
OK, so messing around with low node cast bullet shooting. How much of a difference has anyone found between types or brands of primers in accuracy?

Also, and likely a conversation all its own, how much difference can enlarging flash holes in cases make with such loads? Seems I've read where some guys have seen significant improvements by doing this, but I've never tried it.

Thoughts? Discussion?
 

Jeff H

NW Ohio
I'm not a low-node guru, but it's still sort of the way I shoot the most, like 99%.

If you want to skip all the blather below, I'll say now that I've used a bunch of different primers in my own low-node shooting and cannot see them having any good or bad effect, regardless of which ones I use.

I produce limited data, in that I shoot the 357 Mag in revolver and carbine (mostly carbine/suppressed), the 30/30 at about 1200 fps and occasionally the 222 at 1800+, which I guess wouldn't count as "low-node."

Focusing on the 357, I've made it a point to ensure that any load I put together will be safe in both revolver and carbine and that the revolver will set off any primer I use, to include small rifle - even the sturdier Wolff "Magnum" SRPs, which aren't really magnums, but just have a thicker or heavier cup. I've been using S&B SPP,/SRP, CCI SPP, Wolff SRPM in a wide range of moderate loads, all of which are sub-sonic in a 3" revolver and MOST of which are sub-sonic in an 18" carbine. I've done this for much longer than I've owned the suppressor and this has been going on since 2008 or 2009.

Probably an important factor is that I use mostly Unique, some HP38/W231, but have also played a little with 2400, 300MP and IMR4227 in the few heavier loads I've messed with on this project, but have stuck with the same SPP/SRP qualifier. My loads must be able to use ANY primer I can get my hands on.

In the process of printing five shot groups at fifty yards with the various carbines at fifty yards, I've been able to shoot just over half-inch groups to just over one-inch groups regularly and reliably. I've shot from 125 grain LEE RFNs, LEEs TL 148 WC, various 158s, NOE 360180 WFN, 190 RDOs. Lube has mostly been 45-45-10 or BLL, a little PC, very little 50/50 Alox/Beeswax (traditional) and very few gas checks.

Maybe the 357 is just magic, or like cheating, but I'll be dipped if I could tell anyone that I could see any difference in what the primers are doing for me. In fact, I can't promise any of the above factors in any combination have had much of an effect at all, differentiating them from any other combination. This is in the carbine. The revolver has preferences, but they are related to it being a revolver. But then, the point of my experimentation has been to come up with loads which are safe and accurate (enough) using whatever I can get my hands on anyway.

The one thing that I can say distinguishes any above factor is that the 180 and 190 grain bullets tend to show a bit tighter grouping at fifty yards and POIs between ten yards and fifty yards are the same with these bullets. My barrel is an 18" MGM Contender Carbine barrel, full profile, 1:14" twist. The gun is not particularly well-suited to shooting teensy groups off the bench to begin with, being a break-open, short, light, etc. Likely, someone could hoot much better groups with stated loads than I can with this, but it's still no slouch.

EDIT: I"ve only found enlarging the flash-hole helpful with REALLY light charges of pistol powder in bottle-necked cases. This did elimate the problem of setting the shoulder back. The primers were backed out a wee bit before I started doing this, and stopped doing it once I enlarged the flash-holes. I won't get into the argument of how/why/what-if - I can only report what I just did - primers would be backed out without enlarging. Primers were flush after enlarging. At the risk of drawing criticism, censure, dire warnings, etc., I will share that the "really light loads" were as low as 1.2 grains of HP38/W231 in the 222 case with a 50 and 55 grain cast bullet. I've done the same with t he 357, but the rime negates the primer issue. These load cleared the (carbine) muzzle 100% of the time, were very accurate and very effective on varmints/vermin at close range (one to twenty yards).
 
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Mitty38

Well-Known Member
I like CCI, or Federal for low node. I have used only CCI or Federal for that. Why?
Because those are the two primers I happened to buy for low node first. In my limited experience I have noticed no difference in the two for low node. So that gives me another choice if one is out of stock. A direct replacement. I have never had to buy another brand for low node because one of those two has always been available to me.
 

Bret4207

At the casting bench in the sky. RIP Bret.
Enlarging flash holes was done for using primer powered plastic bullets, that I know. I also know that those cases were not recommended to be used with regular loads. UNIFORMING the flash holes has merit I think, but you have to remember that the flash hole isn't, say, a 1/4" in the first place. If bigger was better, they'd be that way already. I don't have the vocabulary to use the correct engineering terms, but in addition to allowing the primer flash to reach the power, the diameter of the hole also limits pressure going through the hole towards the primer. There is likely a point where flash hole diameter can contribute to pierced primers and gas leaks.

Just my 2 cents.
 

Jeff H

NW Ohio
My limited experience concurs with Larry Gibson's, but I was using a Mauser-type action (CZ 527) with the claw extractor and fixed ejector.

Since Larry was specific about a push-feed, I will note too that some will say that the claw extractor will eliminate headspace issues because the claw holds the base of the case against the bolt face. Well,.... NO! At least not necessarily. DO NOT count on that. The allowable clearances on an extractor are not the same as the tolerances on headspace. Yeah, maybe you'd get one tight extractor and it MIGHT mitigate (mask, actually) certain headspace problems, but it's really more likely to hide headspace problems - maybe,... on some guns.

If I were enlarging flash holes to prevent setting the shoulder back, I'd do it (DID it) even on a rifle with controlled-round-feed. Tossing out the idea that the extractor will hold the case against the bolt head is kinda clever and cute, but strictly hypothetical and specific to a given rifle. This idea is not going to hold water on every rifle. Sure, whoever may be touting the concept will be right about SOME rifles, SOME times, but do NOT accept it as a hard and fast rule. There are two trains of thought on that idea; those related by people who have seen and done, and those who reason that it must be so based on "pure thought." I can get pickup-truck loads of "pure thought" from any one of a number of my farmer neighbors for free, and they'll even load it for me.

I did NOT buy into the idea that the shoulders would be set back on bottleneck cases because of the firing pin driving the case forward or the primer pushing the case forward - either way. "BS," I said - as I know what force it takes using a press with a great mechanical advantage to do that very thing!

Well, maybe I was wrong. I found that enlarging the flash hole on bottle-neck cases, in which I was using VERY light loads, the shoulder did indeed get set back over the course of two to three firings. I enlarged the flash holes and it stopped. I should note that I was also using brass previously fire-formed in THAT chamber with a heavier load, because the "very light loads" I was using would not expand and seal up the chamber.

Using loads o the order of the minimum loads shown in the most recent Lyman CB manual, cases pretty much expand well enough. The "very light loads" I'm talking about are well below minimums seen in legitimate published data.
 

waco

Springfield, Oregon
For some of my rifles in "Low Node" Large pistol primers are more accurate That would be the .223 and 8mm.
Brand never matters but I Only use CCI or Winchester
Large pistol primers in .223?
What am I missing here?
 

Ian

Notorious member
To clarify a VERY misunderstood and often incorrectly repeated situation that causes shoulder setback from light loads: it is not the firing pin that pounds the case deeper into the chamber, it is the PRIMER EXPLOSION that does it as the primer tries to exit the pocket to the rear and simultaneously drive the case through the barrel.

Enlarging the flash hole reduces the pressure buildup in the primer pocket and thus the forward force acting on the case that sets the shoulder back.

Also it bears mentioning even though most if us know this well, the proud, spent primers common to light loads are due to insufficient pressure to make the brass stretch to the full confines of the chamber, so headspace remains even after firing and with rimless cartridges, tends to increase.

On to the topic, I often (but certainly not always) tend to get better accuracy with very "low-node" loads when I choose the mildest primer that will fit the pocket and function with the gun's firing pin. The larger the case internal volume the less it matters seems to be a trend. Also, the heavier the bullet (like stupid-heavy 230 or heavier .30s), the less a mild primer matters and many times a standard LR with higher brisance does even better. I never experimented with compounds/brands much but do like to use Winchester primers with Winchester powders as a general rule.
 

Jeff H

NW Ohio
.........

Enlarging the flash hole reduces the pressure buildup in the primer pocket and thus the forward force acting on the case that sets the shoulder back.

.........

My experience leans very heavily on THIS idea - well-stated by Ian. I've never been inside a primer pocket when the primer went off (or ever), but having paid close attention to what was going on outside, for several years, this plays out.

I'd read of experiments where someone had tested the hypothesis that the firing pin was setting the shoulder back, wherein it SEEMED that MAYBE this COULD be happening. That one never really settled with me and I couldn't quite accept it.

Having set a primer or two off in the shop, one gets the idea that there is significant force at play here. The problematic setback does not necessarily happen in one firing. Such loads often omit the case (body) sizing step, and after several loadings, it seems the effect accumulates - worsens.

The excessive headspace which develops may or may not be a case separation hazard, but inconsistent firing pin strikes (lighter and lighter - shallower and shallower) seem to lead to inconsistent ignition. Getting any kind of a low SD on really light pistol powder loads, like Unique can be a little bit of a challenge to begin with, and this does not help. This shows up past the 25 yard mark in vertical stringing. A faster powder would be the intelligent thing to do, but I'm set on finding the outer edges of what I can do (do well) with this powder. HP38/W231 are easier to "get there" in such light loads. Either way, inconsistencies at this load level seem to be exacerbated, especially once you move past the ten-yard mark.
 

popper

Well-Known Member
There are 2 projectiles in cases. The bullet and the primer. As velocity increases through a smaller hole and energy is the square of fps, primer can move. Larry was concerned more with proper powder ignition in light loads so decreasing restriction to primer 'flame' front solved the problem. I've never drilled one or even uniformed any. Most of my primers are CCI as that is what I could get. Haven't mesured SD for yrs. Been running some RD 30/30 loads, probably should.
 

KeithB

Resident Half Fast Machinist
There is enough energy in a primer to operate a self loading system based on primer setback. That system has been tried and there are several patents based on the principle.
 
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Petrol & Powder

Well-Known Member
Years ago I did some testing with standard pistol primers vs. magnum primers. With below max loads, I observed no significant difference in muzzle velocity between the two types but did see a reduced spread of velocity variations. Accuracy was not measurably different.

As for differences between brands, I agree with the findings of Jeff H, it's not significant enough to worry about and it may not even be measurable.
Accuracy is really consistency and there may be merit to always using the same type of primer in an established load, just to eliminate another possible variable.
 

Jeff H

NW Ohio
.........
Accuracy is really consistency and there may be merit to always using the same type of primer in an established load, just to eliminate another possible variable.

Even if it does no more than make me feel better about it.

My single most apparent inconsistency in shooting is ME. I just don't get to shoot as regularly as I used to. What I do shoot is pretty narrowly focused and for quite a while now, so my observations, though infrequent, have accumulated to a point that my confidence in my conclusions is pretty firm.

And, yeah, I do things I probably don't need to do to shoot at the level I shoot, but I do like to account for errant variables regardless. Makes me feel better about it.

DISCLAIMER: I tend to make things hard on myself by forcing the issue on simplifying and economizing. It's on purpose. My quest is to load ADEQUATELY accurate and effective ammo with as little as possible. I rationalize this endeavor's merit in noting that MY economy is a bit lagging and will be even more so when I retire, but honestly - it's just been a hell of a lot of fun to see how well I can get stuff to shoot with minimal expenditure of time and very limited other resources, such as space, material stuff in the way of the latest, neat do-dad for the loading/casting bench and, of course, cash. What I can share based on MY experiences may not exactly align with others' objectives, but maybe there's a tidbit or two which may be useful to someone, some time.

Frank Marsha had, and Ed Harris HAS a handle on this. I may be rehashing some of what they have established, but not because I don't believe them, rather that it's just a big pile of fun testing their hypotheses and theories. This really keeps the whole thing fun for me.
 

Petrol & Powder

Well-Known Member
I draw a distinction between handgun ammunition and rifle ammunition in terms of effort expended during reloading.

While improvements can certainly be made in the reloading of handgun cartridges and poor reloading practices will clearly harm accuracy, there’s a limit to what I’m willing to do. There are diminishing returns to all that work.

On occasions, I have gone to great lengths to produce VERY consistent handgun ammunition (sorting cases, trimming cases, hand weighing individual charges, culling bullets by weight, etc.). You can in fact improve the accuracy of handgun loads with very careful reloading practices, but those improvements are often very slight. Lots of extra effort in reloading handgun ammo is hardly worth the effort in the end. I have always felt that with handguns, trigger time is more important than glit edge accuracy of the loads. Having shot tens of thousands of rounds of both factory loaded ammunition and reloads, I hold firm in this belief. That is not to say that I just bang away as fast as possible. Nor does that mean that accuracy isn’t important. Practice must be deliberate to be useful and reinforcing bad habits does more harm than good. However, with handguns - trigger time still rules.

Rifle ammunition is another topic all together. In that arena I will spend the time and effort to make the very best ammunition possible. In the world of rifle ammunition, small inconsistencies will have large effects.

I rarely load more than 100 rifle cartridges in a session and 20-40 rounds per session is far more the norm. Handgun ammo is loaded by the hundreds.
 

Jeff H

NW Ohio
Separately, but maybe relative to @popper 's comment about CCI primers...

I have always been a CCI guy for primers, mostly for the sake of consistency in terms of my own peace of mind.

I'll spare you the long story and say that the previous two droughts made me stray from that brand-loyalty. I've used CCI SRP/SPP, S&B SRP/SPP, Wolff SRPM, Remington 6 1/2 SRP primers in revolver/carbine for the 357 MAG and strictly SRP in the 222 and 357 MAX, thanks to the previous two droughts.

One thing I can say with utter confidence is that I could not walk up to a target of mine and tell you that I used this primer or that primer based on what I was looking at.

Granted, I'm not a competitive target-shooter, but I'm a long, long way from the guy who gets his jollies just churning up the backstop ad making noise.
 

fiver

Well-Known Member
well... LOL
different primers react to different powders differently.

in many of the tested shot shell loads i've had done a primer can make over 1,000 PSI difference in a 10 or 11-K load.
that's 10%.
no difference, not gonna notice?
we surely don't have a 10% variance in our bullet weight and expect the same results do we?