Underwood 220gr Hardcast (New Load)

[Intercooler]

Help me out here. With that RS setup do you have to pay $30 for each weight and $30 for a new setup when it has met its service life?

[4949shooter]

I could be wrong, but that looks like a captured guide rod and spring. If you want non-captured you would have to go with the Wolff rod and spring with adaptor.

[TheOtherMike]

TheOtherMike,


                      Did you view the video? What's your thoughts?

Yes, I just watched the video - thanks for bringing that to my attention. The data are interesting and I can see how they support the theories discussed in this thread. On the other hand, these are not controlled tests and the number of samples is rather low, yada yada yada. Here I go sounding like a jerk again, but I doubt the results are statistically significant and would hesitate to draw any conclusions.

For example, I can use the data to make a different argument. I'll refer to the 200gr UW trials. (Not trying to cherry pick. I didn't use the initial 155gr trials due to cold barrel and I didn't pay attention to the 40 or 357 data.)

Type	Weight	Average	Spread
Glock	17	1280	41
B.S.	22	1275	29
Tungsten	22	1277	36
Wolff	24	1292	17

I would expect a "loose" system (Glock RSA) to produce lower velocities. I expect a weaker spring that allows the slide to recoil too soon to produce a "mean shift" downward, meaning that the average velocity for such a system will be lower, due to a predicted drop in pressure before the projectile leaves the barrel.

Note that the Glock spring yielded the second highest average velocity, more than springs even 5 lbs heavier. The highest average velocity was realized with a spring only 2 lbs heavier than the spring yielding lowest average velocity.

Of all the unusual measurements of the springs made in the video (mass, rod diameter) the most significant factor (spring rate) wasn't addressed. How do we know what the actual spring rates are? What is the variability in a single manufacturer's products? I know some of you have made such measurements (Thanks!) and I have yet to look at your results.

The time between trials can be another factor as the barrel cools. Glock was always first, probably after a gear change. This may explain the higher spreads.

I could go on but I don't want to irritate anyone more than I probably already have. For me there still isn't sufficient information to support any conclusion, and I'm OK with that. I think a slow motion video of similar trials would be enlightening.

[Intercooler]

   Can you agree there is something there if the video and several ammo MFG's put it in writing? They are testing, testing and retesting with Chronographs and setups.

Another 10mm great was Mike Willard (SwampFox Ammo) who you might not know. He passed a couple years ago, but also wrote about it. I found his old video where he talks about this:

[TheOtherMike]

Not much to go on in the SwampFox video. Perhaps the biggest takeaway is that the equipment (chrono) is not as reliable or consistent as one may wish. I know nothing about chronos or their specifications. I also had no idea that they're affected by weather conditions. I've been considering getting a chrono someday.

I for one am learning with your help - thanks!

I am guessing that substantial efforts and premium equipment would be required to produce data identifying a strong correlation between RSA strength and projectile velocity. A large corporation like ATK or Olin/Winchester probably has the resources, but lacks the incentive. If such a company produced a report on this topic, I would review the data with high regard.

I am at the beginning of a journey of learning and will reach my conclusions carefully as knowledge is gained. I don't feel the need to settle on answers any time soon. I'll just sit back and study the data as it comes in.

[The_Shadow]

One thing I noticed was the chronograph was angled and if he was not shooting level to the screens that can affect the readings.  Also the light can enter the sensors at odd angles, these units see the bullet as a shadow to start and stop the timing circuits.  If shooting too close specks of powder can be blown forward and trip the timing circuits before the bullet gets there.

One thing I credit Mike Willard for, was he shared the load data and actually discussed things with the guys on GlockTalk.  he and I communicated on several occasions!

[4949shooter]

Mike Willard did tell us that the stock spring can cause the slide to open prematurely with the hot ammo. This is also what Tim Sundles from Buffalo Bore was getting at.

Both of these individuals are (and were) extremely knowledgeable. I would seriously take into consideration their input. Of course, Mike Willard is no longer with us.

[TheOtherMike]

I got some fresh UW 220gr HC and tried some at the range today. They're a bit smokey, but I was getting nice 2" groups of 5 at 10 yards. No popped primers, no smiles, had one FTF though (nose up & left). It was the 3rd round of 5 in the mag.

I just measured the cases I managed to recover.

  9 @ .431
  3 @ .430

Unfired diameter is just under .422 (call it .4215) and COAL is 1.252.

I was using a G20SF with a 6" KKM barrel and 20lb RSA.

Not sure what to make of the FTF. Maybe I limp wristed. Mags are new. I'll need to do more testing.

[Intercooler]

 Those brass measurements look good and about what I get. The dialed in load looks pretty good now!

[4949shooter]

Nice job!