Primer Effect - Small Pistol Divison.

[Jim Watson]

We see frequent angst over primer selection:
"The "recipe" calls for Acme primers but all I have is Brand X, what do I do?"
"I accidentally bought magnum primers instead of standard, what do I do?"

The usual response is:
"Reduce your load by 10% and "work up.""

So I thought I would check it out, as applies to bulk pistol ammo.
My current IDPA ESP 9mm load is a 135 gr BBI Hi-Tek coated RN and 3.8 gr HP38. For this test I sorted out all Winchester brass and weighed all powder.
Shot over a ProChrono Digital 12 ft away with a Springfield 1911A1 9mm, factory 5" barrel. Average of five rounds.

Winchester Small Pistol Standard - 1019 fps
CCI Small Pistol Standard ---------- 1020 fps
Federal Small Pistol Standard ------ 1021 fps
Remington Small Pistol Standard -- 1044 fps

CCI Small Pistol Magnum ----------- 1022 fps

Federal Small Rifle Standard ------- 1023 fps
Winchester Small Rifle Standard --- 1026 fps
CCI BR4 Small Rifle Match ---------- 1019 fps

Now isn't that interesting. Seven out of eight primers, rifle and magnum included, within 7 fps. And the oddball noticeably faster, is the plain Rem 1 1/2 small pistol standard, not one of the accepted "hotter" rifle or magnum. And then only by 23 fps from the average of the other 7; about 2%.

Of course you might get different results in different calibers or with different powders. But a large pistol magnum gave a whopping 11 fps gain over standard in .45 ACP loaded with Bullseye.

 

[nhyrum]

I've heard to reduce load by 3 percent when changing primers. Looks like this agrees with that

 

[Jim Watson]

Well, only when going to Remington in this case.

I also shot some with 3.6 gr powder and the magnum and rifle primers.
Velocity fell off by an average of 3% for a powder reduction of 5.5%

 

[jwrowland77]

Jim, I didn't realize you were on here as well as TRR. Lol.

Great work sir!


Sent from my iPhone using Tapatalk

 

[Unclenick]

I'm only seeing 2.4% velocity change, but yes, if the powder is running in a flatter part of its pressure vs. burn rate curve, you can have to change it by a bigger percent than the velocity change.

Rocky Raab had an old rule of thumb that if you change only one component (primer, case, powder lot number, bullet of same weight) in a load, 5% is the reduction to make. Today, if the bullet is the thing being changed, there are more variables, such as solids vs. jacketed vs. lead and long VLD vs. stubbier design and the like. But usually it works out for the bullet as well, if it is the same weight.

 

[nhyrum]

I'd also be interested in the standard deviation difference in the primers

 

[Reloadron]

I did a similar little science experiment this past summer but using .223 Remington from a bolt action rifle. I used only CCI brand primers of four types. The load data went as follows:
Cartridge: .223 Remington
Cases: LC 11 Brass
Powder: H 335
Charge Weight: 26.1 grains
Bullet: Sierra 53 grain HP Match
Note: All cases were trimmed to a uniform 1.750" and loaded to a C.O.A.L. of 2.250". All powder charges were weighed.

I fired 10 shot groups over the chronograph. The groups likely could have done much better but I was more focused on shooting accurately through my sky screens than focused on the targets 100 yards down range. The four primers I used were CCI 400 Small Rifle, CCI 450 Small Rifle Magnum, CCI BR-4 Small Rifle Bench Rest and CCI #41 for 5.56 ammunition. The CCI 450 and CCI #41 are both classified as a small rifle magnum type primer. So we have two magnum and two standard primers.

The boxes of my loaded ammunition:

The target labeled for each group of ammunition, these were ten shot groups at 100 yards:

The results in spread sheet form:

Draw your own conclusions but interesting in that the magnum primers did not always give the higher velocities for a given load. Next summer I would like to run a similar experement in .308 Winchester (7.62 x 51).



Ron

 

[Jim Watson]

I don't know how much SD tells you on five shot strings but...
In the base load of 3.8 gr HP38 WLP had the lowest SD 5, the "fast" Remingtons were the least consistent at SD 16. Others were all over the map in between.

The VERY lowest SD was with the 3.6 gr load, not in the table; FSR at SD 3.

A PhD who got interested in reloading analyzed a lot of .38 Special data, and concluded that a coefficient of variation, (SD as a percentage of the average) of 1% was "match grade" and up to 2% was not bad.
So SD 16 vs average 1044 is CV 1.5%, perfectly usable.

On the other hand, black powder when loaded right is very uniform. Velocity SD had better be in the single digits, CV well under 1%, and a good load will have EV in the single digits.

Reloadatron: I understand that CCI BR and #41 military primers are of "magnum force."

 

[tangolima]

My observation is that primers make more noticeable difference in lighter loads with slower powders. My own rule of thumb is 5% charge reduction or the minimum published load.

-TL

 

[Jim Watson]

I do not care to make up light loads with slow burning powder so that shift does not affect me.
I dropped HS6 because anything less than a top load was inconsistent and nasty. I don't have the "Clean Powder" hangup, but sub-maximum HS6 was the only powder that has ever coked up my 9mm to the point of malfunction in a single practice or match.

 

[tangolima]

Understood.

Your results are good. But it would be imprudent for a reader to conclude that primers have no effects on pressure and velocity. They do, depending on the circumstances, the effects may or may not be noticeable.

I like slower powders myself for different reasons. That's how I noticed the primers effects.

-TL

 

[Jim Watson]

To quote a usually reliable source (Me!) when we are considering what "applies to bulk pistol ammo" there are a lot of things that can be done that you would not do for maximum loads, hot rifle loads, or National Match pistol ammo.

 

[Unclenick]

Tangolima,

All else being equal (and realizing that it seldom is) slower powders, having heavier deterrent coatings, are harder to ignite than fast ones are. For that reason, you'll pick up on primer differences more readily with a slow powder than with a fast one.


Reloadron,

Jim is correct. You have 3 magnum primers and one standard one (the 400). Interestingly, your best group comes from the #41 military sensitivity spec primer, which is the hardest of the bunch to ignite.

You shouldn't get an average error if you let the spreadsheet do the figuring. Perhaps you did and it's a cut and paste error, but these functions are so commonly used by shooters that I'll put the Excel and Open Office formulas below for people new to it:

C12    =MAX(C2:C11)     Finds the maximum value for the range of values in C2 through C11
C13    =MIN(C2:C11)     Finds the minimum value for the range of values in C2 through C11
C14    =C12-C13         Finds the extreme spread based on the above two
       (Alternative C14 for when you don't figure min and max separately: =MAX(C2:C11)-MIN(C2:C11)
C15    =Average(C2:C11) Finds the average value for the range of values in C2 through C11
C16    =STDEV(C2:C11)   Finds the sample standard deviation for the range of values in C2 though C11

 

[Reloadron]

Unclenick, again don't overly look at the group sizes as I really was more focused on shooting through my skyscreens but yes, the best group was with the #41 primers.

Enter a question. The CCI 400 is a standard small rifle primer, The CCI 450 and CCI #41 are classified as Magnum small rifle. So if I have that correct then we are saying the CCI BR-4 (CCI Bench Rest 4) is classified as a Magnum prmer? My understanding is was a standard primer.

Thanks
Ron

 

[Jim Watson]

It's sure SHOOTING like a magnum primer... this time.

 

[Reloadron]

Jim,

Reloadatron: I understand that CCI BR and #41 military primers are of "magnum force."

Not sure on that Jim, I thought for the BR primers CCI suggested using standard primer load data. I know that the #41 primers are a magnum class primer but just not sure on the BR types. I'll shoot CCI an email as this has come up before and CCI generally takes a few work days but they do answer questions.

It's sure SHOOTING like a magnum primer... this time.

That's a fact!

Thanks for pointing that out.
Ron

 

[jag2]

Lots of good science here. Personally, I'm going to pray we never have another primer shortage so we can buy what ever primer we want. Same for powder.

 

[Jim Watson]

Yes, I hope the pipeline opens up and I get my Panic Backorder primers in.

 

[Reloadron]

Hopefully our supplies of primers and other reloading components will be secure and plentiful for at least the next 4 years. However, as past experiences have proved, it is indeed a fragile supply and it doesn't take much to disturb the supply. Fortunately primers and powder do have a long shelf life.

Ron

 

[g.willikers]

Thanks for the data.
During recent and not so recent component shortages, what ever primers could be found had to do, including using magnums instead of standard.
Beggars can't be choosers.
Judging from my own results, there wasn't enough difference to matter.
Powder drop variances were greater than what primers caused.
Glad to know it was really ok, and it would be safe to do should the shelves get empty again.
So, thanks.