Author Topic: Testing for bullet Setback  (Read 1047 times)

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Offline newageroman

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Testing for bullet Setback
« on: August 07, 2021, 06:05:10 PM »
I just saw this test and have never done it but it makes sense. Thoughts?

He does a bullet setback test where you take the COAL before loaded and compare to COAL after loaded and see if there is any/excessive setback.
https://www.youtube.com/watch?v=2fiy1JRMA_c
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Offline newageroman

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Re: Testing for bullet Setback
« Reply #1 on: August 07, 2021, 06:44:20 PM »
1st bullet setback test is for 125RMR HPs in the SP-01 Race gun.
Will test 5 bullets. They will be loaded in a mag short-long coal
There will be endcap bullets of shock cases to prime/push rounds as he mentioned in the vid above ^^^ its really the 2nd bullet that we need to check.
1.0905
1.0915
1.0925
1.0950
1.0970
Ran then through the gun and had no bullet setback
I DID notice that the rounds did not feed well with the stock mags (no extensions) and the GripWell, so try with the standard LOKs back on or see where the catch up is. This was also a problem with the blue mag extensions but I think I had them sorted out for clearance.

Now to test the NAS BullShadow cases w 125 Berrys RN – minor rounds:
I just grabbed 5 rounds that were 1.149” and loaded them in a mag then hand cycled them.
Hand cycled them and only 1 round was 1.1485”, so that’s ½ thou on 1 out of 5 rounds. Don’t seem like an issue in my measured cases. What about you guys? I'm planning on using those shock cases hes talking about for 9maj.
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Offline Wobbly

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Re: Testing for bullet Setback
« Reply #2 on: August 08, 2021, 09:25:12 AM »
Most of what he says is helpful, but still rather basic. Some of the things said did raise an eyebrow. I don't know if this is a mistake due to scripting, or whether he really believes what he said...

0:35 We can use the case gauge to find high primers
Not clear how you find high primers exclusively with a case gauge. If you have a multi-throat case gauge like he did, then the fact that then the ammo is stood on its nose does the trick... but you could also stand the ammo on its nose in a plastic ammo box and do the same thing.

0:55 Oversize ammo spotted in the case gauge
One of the biggest issues I have with multi-throat case gauges is knowing that all 100 gauges are the exact same. He may know that about his gauge due to having used it for several years, but he didn't explain that it takes more than simply buying a big gauge to be sure. And when you consider that the entire point of gauging ammo is to remove all the variables, then you need your gauging method to be 100% sure.

1:30 Only checking the ammo that sticks in the gauge for high primers
High primers can happen in any round. Why only check the rounds that stuck in the gauge? That made no sense at all.

3:15 Checking with the barrel to compare the gauge
That part is 100% dead on. I fully agree, any "double check" is worthwhile.

3:38 "I'm not going to do this every time. I'm just trying to get a process."
What? A "process" is only a "process" when you do it every time. I may be misinterpreting what he misstated, but clearly a process is a process exactly because you do it EVERY time. The Tooth Fairy doesn't come along and magically fill in the gaps in your inspection just because you got tired or bored.

5:19 The soft hammer routine
I know that he's trying to mimic the effect of chambering and firing the gun on his ammo, which is a good thing. Don't get me wrong. But a strike with a hammer cannot be accurately quantified. So some fool watching this video is going to use a dead-blow hammer with more force, and all his rounds will telescope. So then he sets his taper crimp tighter, and the whole process goes downhill after that. I think you want to place a fixed amount of force on every round. Setting a scale in an arbor press is one way. I agree the hammer is "quick and dirty", but he simply didn't try to explain the force very well so that others could replicate it.... which was the whole idea of the video to begin with.


However, even with all my knit-picking, I think the main point he is making is that for competition, you need to spend a LOT more time with your ammo. That is absolutely true. There's simply too much variation in case wall thickness and case design (besides all the issues with steel cases and internal steps) to think that simply because your ammo emerged from a $100 set of dies in your $1500 press, that all the ammo is therefore perfect. Anyone versed in modern manufacturing and Continuous Improvement methodologies would laugh you right off the stage !

No, sir. Depending upon where you want to end up when the trophies are handed out, tells you what percentage of your ammo you want to test. The guys on the podium with the gold and silver medals are testing at 100%. That's simply the nature of any manufacturing.

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