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If, by "charge density" you mean that Unique takes up a whole lot of room for its weight, then no, neither powder you contemplate switching to will take up more room than Unique.

Unique is far bulkier than 231 or AA #7. They will fill less of the case with their respective maximum charges.

Unique is not responsible for jamming the gun. The "density" of Unique has nothing to do with your issues; it just simply fills more of the case. The powder charge suggested is reasonable and will not cause you problems.

What 45 ACP cases are you using that take small pistol primers? Are these these "cleanfire" type ammo that tends to small primer pockets? If so, these are an abomination to man. Mixing these up with large primer pocket cases is the bane of the progressive loader. I wish the manufacturers would knock it off and not complicate the loading procedure by switching primer sizes on us.

Rant over.

The "bur" is probably a wipe mark that shows the firing pin is protruding perhaps for too long. Have you changed your firing pin spring lately? Have you cleaned out the firing pin and its tunnel in the slide lately?

Loading a bit longer will lower pressures a bit, and it may help feeding to some degree. I'd try 1.220" to start and go from there if you wish.

A "jam" that locks back the slide sounds like you activated the slide stop. Could you be a bit more specific, including the exact position of the slide, whether the slide stop was activated, where the case was, and more details? It is common for people to say "it jammed" without being very specific and it makes the problem harder to diagnose.

You likely do not have "excessive pressure" issues. W231 is not a better choice than Unique when it comes to getting equivalent velocities at low pressures. "Charge density" is not your problem, either, as equivalent deep seating will cause issues with any powder, not just Unique.

Best to diagnose things besides the powder.
 

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Let's review how pressure works, and bleeds off, in the locked breech, Browning type system.

The barrel stays affixed to the slide, with lugs on the barrel bearing on the lugs in the slide. The barrel cannot and will not unlock until the bullet leaves the barrel and pressure drops off dramatically......the residual pressure is low to nonexistent when the barrel starts to drop away from the breechface.

Recoil spring strength doesn't affect it in any significant way...holding the breech closed, that is. Firing pin spring strength can and does cause problems with unusual marks on the primer, modified by inertia of moving and nonmoving parts. If the firing pin stays out while the barrel drops and unlocks, a small "wipe" mark that looks like a short comet tail is produced on the primer.

Changing primers may lessen the tendency, as well as shooting milder loads. And swapping out the firing pin spring. The pistol should not produce any wipe marks even with reasonably heavy loads.

Is this a true Series 70? That would make it a used pistol, and the amount of spring left in the firing pin spring might be questionable.

The misfeed sounds like either a bolt over base misfeed, symptomatic of weak magazine spring, or a three point jam.

What magazines are being used? If you're using extra capacity eight shot magazines that are flush fit, this tend to accentuate feeding problems. If JMB thought an eighth shot was a good idea he would have designed it with eight shot magazines and not seven shot. More powerful loads tend to bring any weaknesses of a pistol's operating system to the fore quickly. More powerful loads often jam the gun, due to weaknesses not found when lighter loads are shot.

Generally, the overall length recommended is intended to make the round as feed reliable as possible, but I note that truncated cones shapes come with recommendations of 1.200 to 1.230" depending upon who makes the bullet.

I'm presuming that's the shape you have. Ensure that chambering is still proper at the longer OAL if you seat it out. Check with the barrel out of the gun with a few loaded rounds to be sure.

As for the seating depth versus the room occupied by the powder, it's not seating depth versus powder fill that's important. It's seating depth versus the pressure of the load. All fast pistol powders are sensitive to deep seated bullets. Even those that leave more airspace in the case.

For example, using the powder fill raises pressure idea, Titegroup would have more latitude for a deep seated bullet without raising pressures through the roof than Unique, since Titegroup uses far smaller powder charges in a powder shape that takes up less room to begin with. That is, a fine ball powder rather than a flake powder. Except it does not work that way. Seating a bullet deeper raises pressure with Titegroup as well.

Seating a bullet deeper than recommended, or having it seat more deeply under the forces of feeding is the problem, and you're not doing that here.
 

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Yeah, mine do it too, depending upon how warm we're talking.

If the replacement firing pin spring doesn't lessen the tendency, you have to evaluate just how significant it is. It's probably not all that hard on the pin as most of it is probably withdrawn from the primer when the wipe is produced. But then I'll ask about that.

I suppose you could make a case for loads that don't do it at all as ideal, but see if you can address it with a fresh spring swap. It's worth a try.

Can you tell us the velocity of your loads, both wipe and non wipe and the bullet weights?

In two of my pistols, one a five inch Colt and the other a 4.2 inch Ruger P97 (very close to your Commander length barrel)
Ruger 7.9 Unique 185 Hornady XTP , mixed cases five shots averaged 1049 fps
Colt load as above 1131 fps

This load is at 1.220" OAL. If you peruse Alliant's data they allow 8.2 Unique with a 185 JHP but are a bit vague as to brand in their old data, but replicate this charge with the 185 Gold Dot in their new data at 1.200." Their overall length was 1.23" in their old data rather than my 1.220 so a bit of a difference there. Essentially if you follow their advice this is Plus P velocity but they mention it as a standard load. Power Pistol really doesn't outrun this powder in 185 grain weight even when PP is allowed Plus P, but does have a noticeable edge over standard pressure Unique in the 200 and 230 grain weights when Power Pistol is allowed Plus P

When 8.8 of Power Pistol is used in the dimensions above, and in the Ruger pistol with Winchester brass velocities are around 1015 fps. My "notes" section in my handloading book under the Ruger P97 has the comment, "Blast." Power Pistol is allowed 9.1 grains with the 185 JHP at 1.230" OAL. In Alliant's newest data shows 9.5 grains PP with the 185 Gold Dot loaded to 1.200."

So definitely not wimpy, for sure. 9.5 PP and a 185 Gold Dot in the Ruger P97 would probably give me a kind of extra blasty experience (8.8 was sure noticeable with the Hornadys), and probably also jam on the last shot on every magazine using the original 8 rounders with the Devel follower and weak springs. My P97 magazines have been converted to 7 shot with the anti tilt plastic followers and heavier springs. No more problems. But it will wipe with the heaviest loads.

If your gun's gonna wipe, these are the loads that will do it.

How deep's the wipe on your primers?
 
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