The Learning Continues

[ET]

Well the other day with starting testing again was an educational one. Let’s start with temp affect on load resistance. What measured as 20lbs load resistance before now changed to 40lbs in colder temps. It threw my intended testing in disarray. Okay with successive firing I got the bore temp high enough to regain my 20lbs load resistance range and produce a couple of decent traces. The Rise Time was 70.



So now I need to adjust my bullet diameter for different temp range to maintain my desired load resistance. I’ve decided to stay with one load resistance, 20lbs. Basically, control load resistance variable.

I have enough info with the 3/8” recessed plug and my next test run will be with the Standard Savage BP.
My computer doesn’t like the cold weather as the PT screen blacked out and reset itself periodically.
The Chronograph is still a work in project but making some progress.
This project has really become a challenge but the knowledge I hope to gain will optimize SML experience, chuckle.

Ed

[jims]

I hope warmer temps arrive for your testing soon.

[ET]

Mar 13, 2020 11:55:04 GMT -5 jims said:

I hope warmer temps arrive for your testing soon.

So do I.
This testing was done at ambient temp of 47F. I'm going to wait until ambient temp is at least 55F.
I've already produced bullets with a smaller diameter knurl, .453 diameter. Now I also am going to monitor temp affect on load resistance.
I will also add that the traces I produced with the 3/8" diameter recessed BP suggest to me it will make a good load for 250FTX bullets.

Ed

[ET]

After carefully reviewing my approach to testing from my latest results I now feel I have to alter some testing parameters.
First off, I really have less control on say a specific load resistance because temp will automatically change that. But what I can do is try to keep the load resistance in a designated range and monitor the ambient temp response. Example is by knurling my specific bullet say to .454 for temp range of 60-70Fto keep a load resistance around 20lbs-25lbs. Now when the temp goes higher, I will knurl a bullet to .455 to compensate for loss of load resistance when it drops below 20lbs. Hope you get the drift of what I trying to convey.

Below is the trace info for the trace above with reformatted additional info.



Ed

[encore50a]

Just wondering, how are you accurately measuring your loading forces?

[ET]

Mar 14, 2020 19:22:13 GMT -5 encore50a said:

Just wondering, how are you accurately measuring your loading forces?

With the use of a handmade tool. It is not dead accurate but close enough to give a good indication.



The long left mark is 40lbs, small right is 35, next long is 30 and so on.

[encore50a]

Mar 14, 2020 21:31:35 GMT -5 ET said:

Mar 14, 2020 19:22:13 GMT -5 encore50a said:

Just wondering, how are you accurately measuring your loading forces?

With the use of a handmade tool. It is not dead accurate but close enough to give a good indication.



The long left mark is 40lbs, small right is 35, next long is 30 and so on.

Thanks for the reply and photo.  Great to see the innovation.

[jims]

It keeps it more constant in pressure or at least reduces the variables. Keep up the good work and testing.

[ET]

Thanks for those encouraging words.
For years I depended on others shared experiences and in a small way still do because I don’t have all the answers. Now it’s time for me to forge ahead on my own to gain more knowledge of my SML that I will gladly share. My testing is done outdoors in real time conditions to know what to expect when conditions change. Eventually I should be able to simply decide what bullet dia. I need for a given ambient temp range to reproduce the load resistance range I want. This will take a while but I have no immediate plans to leave town, chuckle.

Here’s a thought to ponder. With my 3/8” recessed plug, 4227 and 250 bullet producing around 35k and Rise time of 70 what do you think would happen if I could duplicate that peak pressure with a 225 bullet using 4227?

Ed