Observations from today's range day

[rdtompki]

My wife and I had steel challenge practice session today. We had settled on Bayou 147gr, 3.7gr WSF @ 1.15" as our standard load. I was shooting some left overs, primarily Bayou 124grTCG, 4.2gr WSF @ 1.11 (the TCG is .05" shorter than Bayou's LRN thus the short OAL).

Both loads are relatively soft, but what struck me after I ran through two mags of the 147 was the amount of smoke versus the 124gr load. The 3.7gr WSF behind the 147gr bullet is as low as will cycle our 9mm 1911s reliably, but I'm concluding that the pressures being developed are really too low to seal the chamber. I'm also seeing brass with smoke stains which seems to back up this conclusion. Does this make sense? I wasn't surprised that the 124gr was cleaner, but it was softer as well - seems contrary to the bigger bullet is softer mantra.

My wife and I are going through about 2500 rounds/month and I've got a two+ months' supply of the 147gr bullets so I'm inclined to up the load to 3.8gr in an attempt to clean things up, but I won't tell my wife who is very fond of the lowest possible recoil.

I'm also going to buy some more of the 124gr TCG and use those to make a final "selection" by which time I will also have a chronograph.

Any and all comments/responses appreciated and if you have WSF-specific experience more the better.

 

[parkowens]

Observations from today's range day.

rdtompki...I echo your comments on the smoke. I had a similar difficulty a week ago when I loaded my .45 ACP with 200 gr SWCs with 4 grains of H-38 and a 1.260" COL...I was going for a soft load and it was just not enough powder. In addition to the smoke and black marks on the gun and the brass, it was a terribly inaccurate load. The group was probably the size of a basketball at 15 yards. Today I went back to the range with a new load...5 grains of HP-38 under the 200 gr SWC with a 1.260" COL and it was like a miracle. No smoke, little or no black marks and the accuracy was amazing as can be seen in the attached photo of the target. I love working with recipes to get something that will work for me.

 

[dave333]

The heavy bullet low recoil theory works best with fast burning powders. I dont load WSF but I understand it to be a medium to slowish burner and powders in that range are most efficient at higher load ranges. Light charges with slower powder will get you exactly what you got, smoke and sooty cases, often times accuracy suffers too. If you want really soft recoiling loads try a faster burning powder like Titegroup, WST, Clays/Clay Dot, e3, or Accurate #2.

You may want to use a reduced power recoil spring so you can shoot even softer loads. I run a 14lb recoil spring in my XDM 5.25, stock is 18 lbs. My steel challenge load is 3.4gr Titegroup under a 100gr Ibejihead coated lead SWC, only makes about 109 PF, feels like shooting a .22. With a reduced recoil spring you also get the benefit of faster follow up shots as there is much less muzzle dip as the gun returns to battery.

 

[rsrocket1]

In the same gun, felt recoil is primarily dependent on momentum of the bullet exiting the barrel (its mass times velocity). If your steel challenge is not based on power factor, you want to shoot the softest recoiling load that will reliably cycle your gun and lock the slide back after the last shot. In practical terms, it doesn't matter if you are shooting a 120g bullet at 1100 fps or a 147g bullet at 900 fps they will feel the same in the same gun. I tried that with 120g 9mm loads and 180g 40 S&W in the same M&P gun while swapping barrels and you couldn't tell the difference.

As for clean vs. dirty burn, when loading to low velocities, you want a fast powder that builds up pressure without driving the bullet too fast. 9,000-10,000 psi is typically the minimum pressure needed for a clean burn. For 9mm, you want to use something like Red Dot, Clays, Titewad. Just remember not to try to push these powders too fast, you will run into pressure problems before you get to high speed bullets.

 

[rdtompki]

I'm running the stock 9lb recoil spring with a 17lb mainspring in our 9mm 1911s (I've removed the SA ILS). WSF is what I have on hand at least for the next several months so I'm trying to find the best combination of bullet weight and powder load. I'm going to be buying a chrono which should help. Whatever we decide we'll have to use up the 2+months of 147gr bullets we have on hand, more like 5 months since I'll be shooting that if my wife prefers the 124gr load.

 

[Jim Watson]

I haven't used WSF so I can't tell you what to do with it, just keep shooting and adjusting until you are happy.

I have noticed an interesting phenomenon.
I am normally in the slow and heavy school of low FELT recoil at a given power factor.
But I find that a 125 gr coated bullet is not discernibly different from a 147 gr plated.
Now a 125 gr plated bullet at the same velocity has more subjective recoil, almost as snappy as 115 gr econoball.
Strange but true... to me at least.

I have some 135 and 147 gr coated to compare as I use up the 125 coated and 147 plated.

 

[Toprudder]

In the same gun, felt recoil is primarily dependent on momentum of the bullet exiting the barrel (its mass times velocity).

Primarily, yes. I have to believe that some of the felt recoil is due to the pressure left in the barrel after the bullet leaves the barrel. If this is not the case, then the effects of a muzzle brake can't be explained, IMHO. It would be interesting to find a way to quantify this effect.

I believe this is one reason for the "fast powder, heavy bullet" observations.

 

[Jim Watson]

The mass of the powder has to be included in the "ejecta" for recoil computation.
It is usually assumed to jet past the bullet at a higher velocity, increasing its contribution to recoil. That is a large factor in a rifle where the powder weighs 1/3 to 1/2 as much as the bullet, and the racegunners want a high powder to lead ratio to drive their compensators.

You can calculate recoil on a momentum balance, powder mass included, but FELT recoil can still differ from the numbers. I speculate that acceleration and surge (rate of change in acceleration) may contribute to what you feel.

 

[Blue68f100]

WSF burns cleaner when at the upper end. I use it exclusively for my 9mm loads, Berrys 124gr. I shoot hotter load than you 4.9gr. This is with std springs in P229. Burns fairly clean there. For light loads you want to use a faster powder like BE or WST. WST is 10x cleaner than BE. Since it was designed for the low pressure shotgun shells it burns very clean. The negative is that there is little WST data for the 9mm. Older manuals had it but it's since has been dropped.