Power Pistol in 40 S&W Compressed?

[sinbad339]

I just bought a px4 compact in 40s&w and plan to start loading for it. I have Power Pistol, and looking at my Lyamn's 49th for 155gr jacketed silvertip, 1.125" OAL says 7.0 starting and 7.8 max and no indication of a compressed load.

The Alliant site for a 155gr Gold Dot shows 9.0gr max, but no indication if it is compressed (not sure how they indicate it).

My Lee 2nd edition for 155gr XTP, 1.120" OAL says:
Power Pistol, 7.9c starting and , 9.0c max (the c indicates compressed). I realize these are different bullets and slightly different OAL, but the 7.0 starting surprises me that it would be compressed. I'm suspecting a typo in the Lee manual.

Any thoughts or insights would be appreciated.

 

[Wreck-n-Crew]

Lyman has it 7.0gr start and 7.8gr Max for a 155gr Jacketed Silvertip. Should be good to go within those starts and maxes.

As far asl Lee Publishing goes, if it is a Typo, they published the same data on the 40 cal die set. Start 7.9 and max 9.0.

If I recall correctly, Lee gets its data from other published sources and does no testing itself. Also if I remember correctly the XTP data comes from Hornady. If its in the Hornady Manual it should match Lee. One final if I recall Correctly, Hornady XTP load data is sometimes different than Similar weight HP's.

Guess I would be looking for someone with a Hornady manual to confirm.

 

[Airgead]

Hornady 9th Ed. doesn't list when a load might be compressed. I asked their support about that once and they omit that on purpose.

 

[CZ9shooter]

A few years back I helped a buddy work up a load with PowerPistol and Montana Gold 155 FMJs. I still have good notes though. 1.130 OAL. On our way to 9 grains we stopped at 8.6. Recoil and brass ejection was getting very "spirited" at that point. 1250 fps from an SR40.

Settled on 8.2gr for a good shooting load closer feeling to most factory ammo.

 

[LiveLife]

Are you using mixed range brass with unknown reload history and condition of brass?

When I note significant differences in published load data, I also check the groove diameter of test barrel used. Lyman #49 used .401" groove diameter test barrel instead of typical .400". So slug your barrel and if it is .401", go ahead and use Lyman #49 data. If it is .400", I would use more conservative powder manufacturers data.

Especially for 40S&W using mixed range brass with unknown reload history and condition of brass, if you are using near max/max load data, be sure to check the neck tension/bullet setback of your loads by feeding/chambering some sample dummy rounds from the magazine and releasing the slide without riding it for any measurable reduction in OAL as significant bullet setback will increase chamber pressure to over max.

For 40S&W, I prefer to use verified once-fired brass for max loads and mid-to-high range loads for mixed range brass.

We had too many "funny thing happened at the range" threads over the years.

Be safe.

 

[sinbad339]

I'm planning on loading mid-range loads, using range brass. I do look over cases pretty well after tumbling, and again after priming.

I'll settle on OAL by plunking the barrel (strange twist of words...), and expect to be slightly longer than what's in the manuals, but I don't know that yet. And, I plan on using Xtereme's heavy-plated bullets which are NOT the same as what's in the manuals.

My real concern here is the indication that 7.9g of PP may be compressed with a 155gr bullet. Maybe I'm too concerned about shooting a compressed load, but if I load some at 7.0, 7.2, 7.4, 7.6 gr, is there going to be a compressed load there, and will I get a big step change in pressure?

So, the possible outcomes seem to be...

No compressed loads for these charege weights, and no issues.
Compressed loads, but no "bad" outcome; just watch for pressure signs.
Big jump in pressure as the loads become compressed.​

 

[Sauer Grapes]

Good point bds. Anytime I am loading for SD or near max, I use 1 brand brass.

 

[Robert101]

Sinbad,
My Lee 2nd Edition does not list Power Pistol for the 155 XTP. You might want to review your data again.

 

[LiveLife]

I'll settle on OAL by plunking the barrel (strange twist of words...)

When we drop properly resized case or finished round in the barrel, it will make a "plonk" sound. Over the years, this test got referred to as "plunk test" and the term stuck.

Keep in mind that there's a difference between maximum OAL vs working OAL. The OAL that will allow the round to "plunk" and spin without hitting the rifling is your max OAL. But this length may not reliably feed/chamber from the magazine - http://www.thehighroad.org/showthread.php?t=506678

So you function check by feeding from the magazine and incrementally decreasing the OAL until the dummy round reliably feed/chamber and this is your working OAL.

My real concern here is the indication that 7.9g of PP may be compressed with a 155gr bullet. Maybe I'm too concerned about shooting a compressed load, but if I load some at 7.0, 7.2, 7.4, 7.6 gr, is there going to be a compressed load there, and will I get a big step change in pressure?

When I conduct load development with a new bullet/powder combination, I always determine working OAL and then max case fill so I know at what powder charge I will start compressing.

To determine max case fill:

1) Determine working OAL/COL

2) Measure several resized cases and bullets

3) OAL - Bullet length = Max case fill (to bottom of the bullet)

4) Then subtract max case fill from case length and measure this number down from case mouth (using the end of calipers) and mark inside the case

5) Fill powder to mark and weigh on scale. This is your max powder charge before you start compressing

OAL ... expect to be slightly longer than what's in the manuals, but I don't know that yet

Using published OAL may not ensure reliable feeding/chambering or produce optimal accuracy. Many factory barrels have longer leade/freebore that will allow more gas to leak before chamber pressures build. While many use published length average of 1.125" to SAAMI max of 1.135" for 40S&W TCFP/RNFP nose profiles bullets, if your barrel's leade is longer, you may need to load longer for more accurate loads.

With 165/180 gr TCFP bullets, I have used up to 1.143" OAL with greater accuracy - http://www.thehighroad.org/showthread.php?p=9362819#post9362819

With 180 gr RNFP bullets, up to 1.155" OAL for more accurate loads - http://www.thehighroad.org/showthread.php?p=9639622#post9639622

 

[LiveLife]

I plan on using Xtreme's heavy-plated bullets which are NOT the same as what's in the manuals.

While thick/heavy plated bullets are often rated to 1400-1500 fps, I still prefer to conduct my powder work up using plated or lead load data (if plated load data is not available) instead of using jacketed load data (as you can always go higher) and ESPECIALLY if you are using mixed range brass with unknown reload history and condition of brass.

2004 Alliant load data lists 155 gr lead bullet - http://www.thehighroad.org/attachment.php?attachmentid=182147&d=1364769070

155 gr Lead 1.125" OAL Max 7.0 gr (1,115 fps) 32,300 PSI

150 gr JHP 1.105" OAL Max 8.2 gr (1,215 fps) 33,000 PSI

So if your working OAL is longer than 1.125", I would comfortably use 155 gr lead load data for your plated bullet and use 10% reduction of max of 6.3 gr as my start charge.

And once you calculate the max case fill, you will know what powder charge will start to compress.

 

[sinbad339]

bds, thanks for the great suggestions; this has helped a LOT. I haven't checked the max case fill as you describe here, but will definitely do that for this load. That will relieve all my concerns about a compressed load.

As an aside, I don't post too often, but I learn something nearly every day that I read the forums here on THR. Thanks to everyone who responded. What a great community.

 

[rg1]

My results with Power Pistol and 155 Hornady XTP's using Win cases, CCI 500 primers, oal 1.125", in a G23 4.01" barrel.
8.0 grains Power Pistol----1143 fps
It's a good load and just me but I don't want to load higher. It's not a highly compressed load and nothing wrong with a mildly compressed load. In fact I prefer a powder that fills the case to the bullet base or slightly compressed. Seems to give me less velocity variations? I load 165 gr. jacketed flat point bullets up to 7.2 grains of PP for 1065 fps.