Conflicting info, now I'm not so sure. (Primers)

[LenH]

I was out and about Sunday afternoon and stopped in a a place looking for small pistol primers, all this place had was Winchester small pistol mag. primers. The
sticker on the shelf showed $2.29 per 100. I thought this was a mistake but grabbed the last box of 1000 they had. I noticed that the bar code on the box
had been marked out with a black marker but headed to the check out any way. I had another item or 2 and the young woman opened the box of primers and scanned
one pack of the primers and totaled up the items and I asked her if she was sure about that and there was an OOPS and she had left off the other 900 primers.
My conscience made me inquire but I almost got that thousand primers for $2.29.

I have always got regular primers but the shelves had been picked over and that was all they had left. I have been searching for the difference between regular and mag. primers.
There is a bit of conflicting info on this site. Some say reduce the load by 10% and work it back up, others say there is really no difference and say load and shoot.
Now I'm not so sure. I load .38 special using 148 to 155 grain bullets lubed with Tac-1 and 3.1 grains of Bullseye. That is a very mild load and it don't rattle my wrist
at all and can go through a hundred rounds easily. If it ain't broke, there is no need to tinker with it unless the primers can make a difference.

[tazman]

The only time changing to a magnum primer becomes a safety issue is when you are running max pressure in your load. It may have an effect on the accuracy due to changing the dynamics of the load.
In most cases, particularly with handgun loads, you won't notice much difference.
I had one load for a 9mm that, when switched to magnum primers, improved the groups significantly. This is the only handgun load I noticed a difference.
Rifle usage is a whole different ballgame. Switching to magnum primers can make a huge difference.

[USSR]

LenH,

Don't sweat using those Mag primers with your light .38 Special load. It will work fine.

Don

[Froogal]

I always load a little on the light side anyway because I do NOT like recoil. I use the Winchester small pistol standard primers, but have used the small pistol magnum primers, and absolutely cannot tell any difference.

[sutherpride59]

I won’t pretend to be an expert but I have used both mag rifle and pistol primers Because of a local reloading store closing out. Some companies the mag primers are a thicker metal as a load that would give you a slightly flattened primer will result in a more rounded primer. They have more flash due to a (here is where I am regurgitating what I heard and could be wrong) Hotter burning primer compound with a longer burn time. It will for sure add more pressure to an established load but no more than a small powder charge increase. That being said if you are working well below max load it won’t be a problem but it might be a good idea to load down and work your way back up for accuracy sake if you have a pet load and just denote in your load data to replicate the load with mag primers use X grains of powder.

[Patrick L]

I am ashamed to confess, as a much younger man I did NOT point out the OOPS. I got about 3 or 4 thousand 209 shot shell primers for about $1.99, instead of $19.99, since the teenaged girl cashier didn't realize the sleeve price was just for 100.

We've all done things we're not proud of.

As for the substitution, once I accidentally bought magnum small rifle primers. I typically load mild practice loads, well below published maximums, so it created no issue. I just shot them up. I wouldn't just substitute them in anything anywhere near the max though.

[reddog81]

Was that at a Sportsmans Warehouse? I was out the weekend before last and stopped in the local store and all the primers were similarly priced and very picked over, but still able to get 1,000 SP, SR, LP of various brands. I grabbed the primers 3,000 and headed up to the register only to notice they had a sign on the register limiting purchases of primers to 1,000 (no sign in the gun area or reloading area, only at the register). The cashier scanned everything and didn't say a word. I figured 3,000 primers for under $70 was a great deal.

I understand the concept of limiting purchases when people are panic buying, but it makes no sense to drop the prices from $33 to $23 and then limit the quantity people can purchase...

[dragon813gt]

Anytime a component is changed the load should be worked back up. I realize most people don’t follow this procedure.

[LenH]

Reddog81 - that it was and I found the only box of SP primers they had. I probably should get some Large rifle at that price.

[reddog81]

At that price I figured I'd stock up even though I had a couple year supply at home and wasn't looking for primers.

[mdi]

When folks reply "just shoot 'em" it is usually when a low or mid-range load is mentioned. If you say you are using 2.9 gr of Bullseye and want to know if a Magnum primer will work, some will tell you yes it'll work and that's an OK answer but if you are using 3.8/4.0 gr. of Bullseye there could be a problem with "hotter" primers raising pressure. Just figger a Magnum primer raises the chamber pressure and if your charge can handle it, well fine. But, common safe reloading practice is to reduce the powder charge anytime you change a component.

I don't have the figures handy but there are charts on line on how much a Magnum primer raises chamber pressure over that of a Standard primer...

[gwpercle]

There is a little difference but not much ...low and mid range loads might not show but a few fps gain . Maximum loads you have worked up in your gun with regular primers ...then drop 2.0 grains and check the velocity...just to be on the safe side .
Buy primers when you can ... the only primers I wont buy are Berdan Primers .
Gary

[Mal Paso]

I've heard from a couple sources that the difference between Federal standard and magnum primers was the cup thickness not the charge. It's all Mystery Meat when none of the primer manufacturers will say anything about their products other than "They are the best".

[megasupermagnum]

I've heard from a couple sources that the difference between Federal standard and magnum primers was the cup thickness not the charge. It's all Mystery Meat when none of the primer manufacturers will say anything about their products other than "They are the best".

I always wanted there to be more information about primers. Something as simple as a chart would help tremendously. As we all know, a powder burn chart is not a locked in guarantee, but it does show with relative accuracy how a powder will perform. I don't understand why something similar could not be made for primers.

[Rich/WIS]

The old NRA loading manual had an article about this and testing showed that the Mag primer did indeed increase pressure in the rifle loads they tested. IIRC it was about 5K PSI difference, but these were full power rifle loads. I have used Mag primers but in loads with ball powders that are harder to light off. At the low end of the load spectrum probably not enough difference to worry about.

[Hick]

I had a shortage of small pistol magnum primers for my 357 Magnum revolver and 357 Magnum rifle, so I tested all my revolver loads to see what would happen if I went down to standard primers-- saving the magnums for the rifle. The results were very consistent-- for all my different loads velocity with the magnum primers was right about 100 fps higher than with the standard primers (all winchester primers). So, this tells me pressure will definitely be higher with magnum primers. But-- as others have said, not a problem unless you are approaching max loads.

[fredj338]

Anytime a component is changed the load should be worked back up. I realize most people don’t follow this procedure.

You guys are missing something. It all depends on the load & powder used. If you are running light target loads with faster powders, there is no pressure issues swapping primers. When at the top end with any powder, everything matters. So you cant really say drop 2gr or 10%, it just depends.
I have found mag primers offer diff results with diff powders. Fast powders don't seem to change much when swapping std top mag primer. Medium burners show more vel gain, thus more pressure. Slower powders show the most vel gain. This is just based on testing a couple powders in each category but the chrono tells me not to worry with light loads.

[dragon813gt]

You guys are missing something.

I’m not missing anything. All load manuals will tell you that if you change any component you’re to drop down and work back up. I realize that very few people do this. But that’s there prerogative.

[jsizemore]

I started loading for 9mm in a Sig P226 pistol built in 2014. It has a stainless slide ( they're all stainless, some don't get coated). The barrels have roto forged rifling and the stock barrel didn't shoot cast worth a darn. Lots of leading. Got a different chrome lined barrel and after lapping it did fine. I decided I wanted to find a west germany P226 with a button rifled barrel. I hoped it was more cast friendly. I made a trade with a friend who had a backup spare that decided to go Glock for competition. The load I'd worked up used a published load a couple tenths below max and shot fine in the stainless pistol. I had used up a couple thousand Winchester standard SP primers from the same lot and ran out. I had a different lot on standby and tested 10 in the stainless pistol. All good so I loaded the remainder and discovered they were Winchester SP MAGNUM primers. I didn't worry since they worked in the stainless gun.

After 10 rounds in the cast iron west germany gun I had gas cutting in the breech block face corresponding to the primer/primer cup interface on it's first trial. The blueing on the frame and slide was still intact the gun was so unused. Of course, I'm sick. Checked lockup and both guns did the same. Same for plunk test, headspace and fired cases fit the same in both guns. Breech blocks for the cast iron Sig are no longer available.

Interweb search turns up that SP magnum gas cutting was real common with SP non magnum loads back in 2008 when there was a components scare. Brian Eno's site turned up an outfit that did micro tig welding and I contacted them. The Covid thing had started so they weren't doing gunsmithing work at the time. I got up with an outfit in Pa. called Lewis-Bawol that does micro tig welding. They got my priority mail package, welded it and had it shipped out the same day. They charged me $25 +shipping. I had a friend do the grinding and I did the final lap. His grinder at work goes to 10 thousandths. Dykem on the original surface was just kissed.

So far I have 3000 rounds through the cast iron P226. The weld is still a mirror finish. I ran out of the N320 I was using and started on Clean Shot. I put the Magnum primers in a different storage container from standard.

Folks said they had gas cutting from standard primers with target loads especially in revolvers. The thought was/is that target loads don't develop enough pressure to seal the primer cup to the brass. Cup material is too thick in magnum and most standard primers. For target loads Federal standard SP primers are the one to use.

[dale2242]

I did a test with 45ACP using Magnum primers with my standard load.
I tested them in 2 different 45s.
The load was midrange load of 700X and a 452460 bullet.
Magnum primers showed an average increase of 20 FPS in velocity.
There was no change in accuracy in either gun.
I saw no difference in pressure by looking at the primer.
I know looking at primers is not a sure sign of increased pressure but I have no other way of telling.