I have a perplexing situation in that some 41 Magnum rounds I recently loaded seem to have excessively flattened primers, especially since they are minimum listed loads in two of the manuals I have, and below minimum for the powder manufactures (Hodgdon) data. I'll first list the basic conditions and data.

All rounds fired from a S&W 657 with 4" barrel
210 gr HDY XTP
19.5 gr H110 powder
1.580 OAL

Hodgdon minimum load 19.8 gr
Hornady minimum load 19.5 gr (bullet manufacturer)
Nosler minimum load 19.5 gr (with W296 - their accuracy load)

After noticing the flat primers which were with CCI 350 Magnum primers, I loaded a few rounds with both standard Federal 150 and also Federal 155 magnum primers to see if I got the same results. All charges were weighed with a Hornady Auto Charge and randomly checked with an RCBS 10/10 Scale. I also pulled the bullets from two of the original batch with the CCI 350 primers to check if I had messed up the charges, but found they were right on at 19.5 gr.

The attached images should show the results from left to right as follows, and the average muzzle velocity recorded with a LabRadar Chronograph.

First on the left, with Federal 150 primers - Average 1046 fps
Next with Federal 155 Primers - Average 1098 fps
Third row with CCI350 (flat) primers - 1213 fps ???
(Cratering doesn't seem evident even with the primers being so flat, also there was no problem ejecting the cases.)

The last and fourth row I show for reference, is a load using the same bullet and CCI300 primers and with 9.5 gr of CFE Pistol, which is listed as a medium load that should provide about 1300 fps with their testing.

So, anyone have any idea what is happening, and why the velocity is so different from the loads using the Federal primers?

I was always under the impression that magnum primers should be used with powders like H110, 2400, L'll Gun, etc.

Are the CCI primers really that hot to cause the increase in velocity and flatten them out? Maybe I have a bad batch with soft primer cups even though CCI are supposed to be about the hardest available?

Any input would be appreciated.

Thanks

Attached Images

	FP!.jpg (73.4 KB, 167 views)
	FP2.jpg (51.0 KB, 143 views)

The primers in the Picture except the 3rd row look normal to me. The 3rd row looks like warm Magnum primers. Have you checked your seating depth (Overall length) for the bullet in use? Sometimes a change of bullet, even in the same weight, can cause pressure spikes as the bullet shape may have changed a little longer resulting in deeper seating.

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H Richard
SWCA1967 SWHF244

I agree - only the third row look warm.

I agree with Richard. Only the 3rd row looks particularly flat to me.

Sorry if my post was not understandable or too detailed. I agree that the third row is the only primers that show a problem, the only difference as I tried to explain is that of the primers being different. Same bullet, same powder charge. same seating depth (OAL), same cases, i.e. Starline, all checked and double checked including as I stated pulling bullets and rechecking the powder charge in the questionable rounds. There is no difference between the first three rows except the primers. The only "flat" ones (third row) being CCI 350 Magnum primers. ???

"Flattened primers" are a poor indication of how high a load is. Real flattened primers, from excess pressure are flat, no radius on the primer edges, and no gap between the primer and case head. The gun has as much to do with primer appearance as chamber pressure.

I wouldn't mind seeing a sticky on "Flattened primers" as this is the 4,351st thread I've read about reading primers, and 90% of the answers/replies say, "primer appearance is a poor indication of pressure"...

Since you aren't having extraction problems I wouldn't worry about the looks of the CCI 350 primers. However, the look of those primers along with the increased velocity you see with using them tells me that the CCI 350 primers are igniting the H110 better and making it burn more completely and efficiently than either of the Federal primers. Evidently the CCI primers have a "hotter" load of priming material.

Third row definitely has a pressure problem as also shown by the velocity difference with others.My load in my .41 mag is hotter than yours(always with CCI Mag primers)but doesn't show anywhere near your 3rd row primers.
All I can say is that I once had a model 66 that had flattened primers and had sticky extraction where all my other .357 would have the brass fall out of the cylinder by their own weight.
Tight chambers?possible.I'd try the exact same load but with 210gr lead bullets to see if the result is any different and from there start investigating(lead being less sticky deforms more easily).

Load some sized empty cases and load all your cylinders.

Now using feeler gauges how much clearance do you have between the rear of the case and the frame.

If you have too much head clearance the primer can back out of the primer pocket and start to expand and mushroom. Meaning the primer will look really flatten and the magnum primer is driven more forcibly to the rear before the case is pushed back over the primer.

I have seen .223 cases that had been over reamed to remove a primer crimp and the fired cases look like they and larger rifle primers. When the primer is removed it looks like a mushroom or the head of a nail.



Below a animated image of a .303 British with excessive head clearance. Watch the primer back out of the primer pocket and then the case is pushed back against the bolt face. And the primer will flatten more with excessive head clearance.



Below the CCI 400 small rifle primer has the same cup thickness as their pistol primers. And at higher rifle pressures they will flatten more than the primers with a cup thickness of .025.

OK, I get all the info but if there was a head space problem why is there no noticeable "flattening", with primers (Federal) that are generally considered softer, especially when loaded with a minimum or less than minimum published load. What if I would go to a load in the middle of the published data or even the minimum listed Hodgdon data?? Maybe H110 is not a good powder for this situation or as I noted before has CCI had a problem with the Mangnum 350 primers??

In my 1982 Winchester reloading pamphlet it states with 296 powder a very heavy crimp is needed with this powder. And it states with the 41 magnum and 210 grain bullet to not to drop below 20.4 grains of 296 or dangerous pressures will result.

Many of the slowest burning Winchester ball powders had this warning. And my #10 Hornady manual it lists 19.5 grains of H110 as a start load with the 210 grain bullet with a standard Federal 150 primer.

I know my favorite powder in my .270 Win was Winchester 785 ball powder and it was discontinued due to detonation problems with light charges. If I remember correctly it had to due with the loading density and too much air space in the case. And this caused the burn rate to increase and high pressures and detonation.

I even had the same problem you are having with a 357 and Blue Dot powder and light 110 bullets.

Why don’t you give CCI-Speer a call and ask them? I’ve seen this discussed here before, and I’ve seen it myself in loading .32 Magnums, but I’ve never seen a convincing explanation. Incidentally, I always use Federal primers and the flattened .32s were primed with Federal 100s.

As to your .41 loads, did you notice a difference in standard deviation and extreme spread between the three primers, and what was it? I’m usually more interested in extreme spread than average velocity.

What about the H110 powder? Is this a new bottle that you haven't used with anything else?

The CCI350 are hotter & give higher pressure compared to regular primers but that third row looks pretty flat for what the load is. H110 needs magnum primers.

I've played with reduced H110 loads, in a difference cartridge, & you start getting large amounts of unburnt powder, then delayed ignition, then a squib if you keep loading down. I never saw high pressure signs with reduced H110 loads, just the opposite, and your's isn't really loaded down anyway.

And, you should not use magnum primers with 2400 powder loads. Speer/CCI/Alliant issued that notice many years ago.

One of my 41 Magnums give sticky extraction with moderately heavy loads, but extract fine in the other 41, because it's chamber's I.D.s have less taper & are virtually straight. The primers don't look any different though.

.

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Waiting for the break of day

Try making sure that all of your primers are fully seated with the face of
the primer slightly below the surface of the case head. I have experienced flat primers before with handloads with CCI primers that were not fully
seated because of the very tight fit in the primer pocket. I no longer buy
CCI primers because of the extra effort required to seat them. Some of
then were severely flattened even before being fired. Flattened primers
from excessive pressure do not occur at magnum handgun pressure
levels. Most loading manuals have good information on primers and
pressure signs in the information section preceding the load data.

200fps difference, impressive!!!

I'd up the powder to 20.5gr and then 21.0gr and re-test. More likely than you're on the edge of pre-detonation. If you up the powder and the velocity goes down with those cci primers, you'll have your answer.

FWIW:
My hornady 4th edition manual lists 1100fps out of a 6" bbl'd s&w model 57 for the same load (19.5gr of H110, fed 150 primer, 210gr xtp, rem cases)

The 1st sign of high pressure is not the flattened primer. It's the flow of the primer cup around the firing pin indent. You'll see that 1st/before you get cases sticking in the cylinders. It's extremely important with semi-auto's to check for flow around the fp hit on the primer faces.

I've used a lot of ww820 (pulldown powder with H110 burn rate), h110, ww296 in the past and still do to this day. I never use a minimum/starting load with any of those powders. I also found those powders do better with 6" bbl's or longer.

OK, first thanks for all the info and ideas. I checked the primers from the cases of the three bullets that I pulled and I'm confident that I am seating my primers properly. I also checked the chronograph results and found the last ten shot string of rounds loaded with the CCI 350 primers shows an extreme spread of only 47 and std. devotion of 14.8. I think this is well within what would be considered nominal results. In fact all the strings from all the rounds tested have a spread of less than 100 which from my past experience seems pretty good. The CCI 350 magnum primers have proved different/hotter than the federal and maybe other standard primers, which after checking, are what is recommended for these loads by all three loading data referenced. I think the best idea is to try increasing the load by a grain an see if it's the combination of magnum primer and low powder charge that is causing the issue. I will also try CCI 300 primers and maybe just use Federal primers (If I can find more of them) if I want to use this starting/lowest load listed.

Thanks for the info on the extreme spread. That, to me, would seem to indicate you are not getting wild pressure variations with the CCI-350s. 50 FPS ES is always my target for revolver loads (six rounds). Sometimes I get it, and sometimes not, but always - the closer, the better. I am another one who no longer buys CCI primers because of the difficulty I have doing a good job seating them.

H-110/W-296 is a slow burning spherical powder and in my experience, is best ignited with magnum pistol primers. I do think that the primers in the third row as pictured in the OP show signs of maximum pressure and that puzzles me as a variety of reloading manuals indicate around 19.5 gr of H-110/W-296 as the starting load. Sticky extraction and bulging case heads are a far better indication of excessive pressure and the velocities you recorded are what I would expect from the starting load. Soft primer cups? I guess it could happen, but CCI primers tend to be hard and to the point that they are harder to fully seat. I'm still wondering if it is a primer seating issue.

FWIW-I have a box of Blazer Brass .38 Spl. 125 gr bullet @ 865 f/s per the factory website. I've no idea what powder they're using and I haven't clocked them, but the primers are darn near as flat as yours with the CCI 350s.

Question: is your hammer spring at full factory tension? Part of the job of the hammer nose/firing pin is to support the primer cup that it touches. That also affects the rest of the primer. I had some strange looking primers in an M&P9 and they went back to normal with a change (overdue) of the striker assembly.

BTW, about that post on checking the clearance of the case head from the breech face/recoil shield. Meaningless. Check the distance between rear cylinder face and breech face/recoil shield. At the firing position the clearance should be 0.060-0.068 inches.

Handgun primer reading explained:

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Still Running Against the Wind

per post #11;
Minimum loads cane be dangerous too.............
mostly in rifle loads, no matter what primer, if the volume is around 50% or less.

The primer goes off and if the load is level, it will light off the total top part
of the powder in the case..........
instead of lighting the bottom of the powder and working forward.

The large surface area can cause a Detonation faster than normal and raise
pressures in rifles and pistol loads, enough, to damage a weapon.

One reason a minimum starting load is listed with all powders as well as maximum loads.

Below starting loads and compressed loads with Ball powders can lead to big problems.
Follow the data closely.

I gave up trying to read primers for over pressure, I get flat primers using minimum loads, so I don't even consider them anymore.

I don't know what people are using to seat their primers that say this but I use CCI exclusively & have loaded tens of thousands of them. I frequently load 200-300 rounds a week & have had no such trouble.

I give my primer pocket mouths a one-time quick chamfering & have always seated all my primers using the press mounted universal primer arm. They work without fault.

.

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Waiting for the break of day

Five out of Ten reloaders surveyed on the internet, prefer different primers than the other Five do.


Some primers are thicker. not harder(which may make them seem harder)



Ten out Ten, Flat Pistol Primer threads result in the same discussion/debate.

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Still Running Against the Wind