flattened primers

[ipsc1]

This past weekend I experienced severe primer flattening and some flowback. The load was 4.3 grains of Clays pushing a 180 gr MG at 945 fps, winchester primers. The gun was a new Edge.

My first thought was that it was the clays load, I had read all the warnings about pressure problems, perhaps the press had adjusted as I was reloading and my load became unsafe, so I switched to an old box of loads with 231 and finished the match.

Back home I went to the range with the chrony, and a para. The clays loads were still as tested (945 fps) and showed pressure signs in the STI but not in the para. Velocities in the para were about 10 fps slower. But then I found that the loads with 231 ( velocity 960) were also showing signs of flattening in the STI but not the para.

Are there other causes for primer flattening besides load pressures?

ipsc1

[Flexmoney]

Your bullets might be hitting the (different) ramp and could be geting pushed back into the case. Or..more likely...they are engaging the rifling. Meaning the chamber needs reamed (or your loads shortened).

Both clays and 231 are pretty fast powders for 40. Could be temperature sensative too.

[Ken Kwiat]

The reports of flattening aren't a huge concern but the flow doesn't sound good. Also, are you using Small Rifle or Small Pistol primers?

Per Flex's analysis, what's the OAL?

I shoot a comparably fast powder in my .40 loads (VV N310) and see some flattening as well (no flow). With the fully supported chamber it shouldn't be a problem. Also, I use very, very little crimp on my loads because of the higher pressures but, per Flex's comments, your chamber and how the load gets chambered is pretty important. I did have my chamber reamed some.

I know it's an obvious thing to say, but just be incredibly diligent of double charges when you're on the hairy edge of fast powders. I'm in the 3.x gr. range and there is all sorts of room in that case for 2x the load without visually noticing it. It happened to one of our shooters in CO last year and it did quite a number on his bull barrel and slide -- pretty scary.

For what it's worth, using the N310 under a 200 gr. or 180 gr. lead bullet makes for a very soft felt recoil load, IMHO.

Hope it helps.

Ken

[Jack Suber]

IPSC1,

Different barrels will cause different effects on loads. Your STI barrel is probably "looser" than your STI. If the STI is "tighter", then you will run higher pressures. I would think this is especially true with Clays. Back off on the load and work it up again for your STI. Also, check the OAL. If your STI chamber is throated long you might be having the bullets touching the rifling.

[Tri Burst]

I also use Clays, 4.4g with 180g MG at a OAL of 1.2 , and Win primers in my STI guns and have seen some flattening of the primers but not that much. I use to see some flow around the firing pin hole but fixed it by installing long firing pins in both guns and that has stopped the flow. First check to see if the rifling is reemed out to accommodate the long bullet length. Then check the length of the firing pin in each gun. If the one in the STI is shorter than the one in the para that could be the problem. In any event install a extra long firing pin in the STI. Don't know why the long firing pin stopped it but I would think it has some thing to do with the overall travel of the pin before it strikes the primer. The long pin doesn't have time to built up speed. Also I did notice some pierced primers with the short/standard pin but none with the long pin.

[Guest Larry Cazes]

Well, Clays with 180s in .40sw. There is probably good reason to assume that the flattening IS due to excessive pressure. Extremely fast powder......Relatively SMALL volume case. The result is a load that will be very pressure sensitive to small changes in a lot of different variables such as temp., OAL, setback, etc. Be very careful.

[eric nielsen]

The cause IS excessive pressure. Different symptoms in your different guns.

You could spend a lot of time and money to get all your 40cal guns to run okay with Clays and W231.

Or you could spend less time & less money and load either TiteGroup or N320.

PS - If you're shooting Clays & you're not worried about picking up other peoples brass, start worrying now.

[ipsc1]

Thanks for the replys. OAL ranged from 1.250 to 1.150, slightly less flattening on the longer OAL, but also slightly lower velocities and I assume pressures. Note: the OAL varied cause I loaded up different OAL's to test that variable, not because my reloading skills are that bad. Press was a 1050.

Winchester small pistol primers.

I've got some Titegroup coming to play with, been trying to get Vit powders since last winter but no one seems to be carrying any in Canada. At least not 310 or 320 or 330.

Post test inspection of the pistol revealed sort of a ledge on the breechface, I'm going to look at another edge this weekend and test fire some of my loads through it to see if it acts the same. If so I'll have to drop Clays as a major load for my 40 . If it is a pressure problem at 170 PF then I dare not load it up to something with a cushion between me and minor.

I had thought I'd be OK because I was under the max load and velocity listed in my Hogden manual, and the initial chrono test , as well as the second set, showed nice consistent velocities.

Is clays inverse temp sensitive? Cause I was indoors in a cool basement range when I experienced the flowback.

ipsc1

[Harmon]

i believe clays in a 40 is redlined(according to the books) at about 155 pf.

if i remember correctly,3.5 with a 180 is maximum load with clays, unless your using U clays. these are short loads btw.

i bet the sti gun has a tighter throat than the para, thus the same ammunition will create more pressure.

i suggest swith loads... while im not a fan of titegroup, many folks seem to do well with it.

[ipsc1]

Well my Hogden manual lists 4.4 grains at a velocity of 976 and a max OAL of 1.135.

I had less powder and slightly longer bullets. Anyway I tried some of my ammo through another new Edge and it looks fine afterwards, tried some of his ammo that hes been using this season, a titegroup load, and it shows signs of flattening in my pistol.

Showed the ledge on the breechface to my dealer and the gun is on its way back to STI to be examined. With less than 300 rounds through it I wasn't going to try and have it fixed locally.

I think that the problem may have been that that case head had a gap between it and the breech face because of the ledge, which was allowing the primer room to move backwards and slam against the breechface.

ipsc1

[Zak Smith]

FWIW, maybe 10% of my spent cases have primer shear at 5.1gr TG, 180gr MG, WSR, 1.230", from my SV. Stock firing pin.

-z