Load Resistance Discrepancy

[ET]

I know I haven’t produced anything with PT unit just yet but decided I should review what I plan to test. Basically, I’m working in .503” to .506” outer diameter measurement in different stages with bullet sabot combination. So, decided to do measurements on what I will be using and got a real surprise. Out of 20-250gr bullet sabot combinations, 14-.505”, 4-.504” and 2-.503”. So, I increased the bullet diameter for that particular sabot usage and now have all read .505” For what I plan to test I need consistent parameters. This also makes me wonder how this would affect group sizes or where the odd flyer might come from?
Now with black-powder or substitutes this may not be such a determining factor but we are using smokeless powders and that’s a new ball game. There are other tests I plan to do as well as trying a few different load resistance tests. Guys I’m just as anxious as you are to get something started.

Ed

[encore50a]

When you test force, be sure not to accelerate any faster, or decelerate any slower between objects.  One smooth movement...….

[ET]

Sept 2, 2019 14:30:41 GMT -5 encore50a said:

When you test force, be sure not to accelerate any faster, or decelerate any slower between objects.  One smooth movement...….

Agreed. That is what I have been trying to do utilizing just enough force on the ramrod to keep bullet/sabot moving and monitoring spring gauge response. For now will be doing 3-shot groups with dry patching between shots. Next time no patching between shots, after that observe wait time between shots. One parameter change at a time.

Ed

[encore50a]

Great that you're aware of acceleration.  Many may not pay attention to that critical factor.
I'm a retired industrial ergonomist, so I use one of the tools left over from my job.  Ramrod screws right to it.

[ET]

That is a handy and more accurate tool than I have but the tooling I have is sufficient to serve my purpose.
So many have labeled the 50 with sabots inaccurate. At this point I wouldn't argue that opinion. There were outings I would get great groups, then every so often a flyer or groups would open slightly next outing. Okay there has to be a reason for this inconsistency at times. Now we assume our components are precise but that's not what I've discovered with sabots. My bullets are knurled and then mic'd to within .0005" so when I saw the difference in overall diameter with these bullets and sabots that doesn't seem to be the case. By closer study of PT's generated I hope to find some good information of different powder burn starts, burnout and remaining bore pressure after the burn is completed. This will be a long term study with one variable change with each group of testing.

Ed

[ET]

Food for thought about load resistance.
The 45 has become popular because of its accuracy and simplicity in the field. Okay but the bullet needs to be prepped with possible knurling, sizing die and for some a full form die. This, results in a load specific consistent fit.
The 50 with sabot is often thought of as put bullet in sabot and shove it onto the powder. Here there is no thought given to load specific consistent fit other than some load resistance for fit.
Now what would happen if we applied the principal of load specific consistent fit to a bullet/sabot?
What benefits could be gained?
These are 2-questions I want to answer from future results acquired.

Ed

[encore50a]

Sept 3, 2019 7:02:24 GMT -5 ET said:

Food for thought about load resistance.
The 45 has become popular because of its accuracy and simplicity in the field. Okay but the bullet needs to be prepped with possible knurling, sizing die and for some a full form die. This, results in a load specific consistent fit.
The 50 with sabot is often thought of as put bullet in sabot and shove it onto the powder. Here there is no thought given to load specific consistent fit other than some load resistance for fit.
Now what would happen if we applied the principal of load specific consistent fit to a bullet/sabot?
What benefits could be gained?
These are 2-questions I want to answer from future results acquired.

Ed

Interesting...……

Before I stepped it up to a UML, and now smokeless, I had an Encore Pro Hunter that I did considerable load testing with.  Now many liked easier loading sabot/bullet combinations, yet I preferred the combination to be tighter.  I was sending the Barnes 250gr TMZ and included sabot using 75grsW BH209, which the loading force in that particular barrel was a constant 34 to 38#.  Some stated bullet seating force made no significant difference, while my experience was different.  I seated the bullets with a HARD THUMP, which when measured averaged 106# force.
That rifle was extremely accurate and once the barrel was fouled, it never gave me a flier.  However, what would cause groups to open was an eroded flash hole.  Every time the groups started opening, replacing the breech plug solved the issue.
Shooting my new .45cal rifle with smooth sized Fury bullets,  the force to load w/o sabots is a VERY consistent 19#.

[ET]

Encore50a

Thanks for that useful info and pointing out flash hole wear as a factor to consider, that in my case is the Vent.

Ed

[jims]

Now I got less fliers with the Harvester sabots than MMP in my .50s but others results may vary.

[ET]

Sept 3, 2019 19:14:29 GMT -5 jims said:

Now I got less fliers with the Harvester sabots than MMP in my .50s but others results may vary.

Pretty much my story too with sabots.
If others want to do their own simple experiment just slow your bullet/sabot down the bore and watch for different resistance. When a noticeable resistance change is felt, observe where that bullet hits the target in relation to your group. You still have to be mindful of bore heat so that a second variable doesn't come into play.
If your content and happy with what you got with sabot loads then ignore my posts on the subject. Not trying to take anyone out of their comfort zone. For me I'm just trying to seek some answers for the why's with sabot loads.

Ed