how changing components affects MV and PSI

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hawglips
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how changing components affects MV and PSI

Post by hawglips » July 22nd, 2014, 10:55 am

With the scarcity of Federal 12 ga hulls lately, I sent a few existing Fed hull loads to the lab using different hulls to give some more readily available options. The results came back today, and were mixed.

So, I was thinking let's have a little fun with it. It's the off-season - might as well get a discussion going about how different components affect velocity and pressures, and how this stuff does or does not work out the way you hope.

It would be fun to see everybody's predictions on the change in MV and PSI. Don't be shy - I missed one by several miles myself. I'll be surprised if anyone accurately predicts them all. This could be fun. :D

Just give your expectation/guess on the change (upward or downward) in average MV and chamber PSI:

1) Federal 3" Lil Gun 2 oz load -- changed to Cheddite 3" Lil Gun load (changed new hull/primer, and from fold crimp to roll crimp)
2) Federal 3" Lil Gun 2 oz load -- changed to Fiocchi 3" Lil Gun load (changed new hull/primer and wad from TPS with cork and felt to CSD 100)
3) Federal clear 2-3/4" Lil Gun 2 oz load -- changed to Cheddite 2-3/4" Lil Gun load (changed new hull/primer only)
4) Federal clear 2-3/4" Lil Gun 2 oz load -- changed to Fiocchi 2-3/4" Lil Gun load (changed new hull/primer only)
Last edited by hawglips on July 24th, 2014, 4:25 am, edited 2 times in total.

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Re: how changing components affects MV and PSI

Post by Johndoe » July 22nd, 2014, 1:09 pm

Internals and the CSD kill any guesses for me. I have not used the CSD. Not sure if the wad or the felts and cork provide more cushion.
My thoughts are less primer would lower most. But smaller inside volume would increase pressure but maybe not velocity.
Look forward to the results.

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Re: how changing components affects MV and PSI

Post by Grunt-N-Gobble » July 22nd, 2014, 10:56 pm

I can't bring anything to the table for guesses either. Never used the CSD wads

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Re: how changing components affects MV and PSI

Post by N2deer » July 22nd, 2014, 11:18 pm

Im not smart nor experienced enough to guess. But it sure does interest me.

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Re: how changing components affects MV and PSI

Post by Southern Sportsman » July 23rd, 2014, 2:00 am

N2deer wrote:Im not smart nor experienced enough to guess. But it sure does interest me.
Same here
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Re: how changing components affects MV and PSI

Post by pedro » July 23rd, 2014, 5:34 am

My guess, and only a guess,
1 &2 lower p2 and velocity.
3 higher p2
4 lower p2

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Re: how changing components affects MV and PSI

Post by Spuriosity » July 23rd, 2014, 6:46 am

1) No significant change (Different hull lowers vel and press, but CSD increases them due to less cushion effect).
2) "
3) Pressure decreased by 1,000 psi and vel by 100 fps
4) Pressure decreased by 500 psi and vel by 50 fps

This should be a hoot. (I really have no idea)
Last edited by Spuriosity on July 23rd, 2014, 11:43 am, edited 1 time in total.

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Re: how changing components affects MV and PSI

Post by hawglips » July 23rd, 2014, 7:31 am

Here's what I expected would happen:

1) slightly lower MV and PSI
2) slightly lower MV and PSI, but maybe somewhere between the Fed and Ched
3) lower MV but similar PSI
4) lower MV but similar PSI

The CSD100 is a cushioned wad and based on some of my existing data, I suspected that the isolated effect of switching from TPS (with cork and felt) to CSD would yield a higher PSI and MV. Then I figured that switching hulls from Fed to Ched and Fio (both of which have cooler primers but less room) the isolated effect of switching hulls would be lower PSI and MV.

I'll let a few more chime in before giving the actual lab results.

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Re: how changing components affects MV and PSI

Post by toasty » July 23rd, 2014, 9:58 am

hawglips wrote: 1) Federal 3" Lil Gun 2 oz load -- changed to Cheddite 3" Lil Gun load (changed new hull/primer and wad from TPS with cork and felt to CSD 100)
2) Federal 3" Lil Gun 2 oz load -- changed to Fiocchi 3" Lil Gun load (changed new hull/primer and wad from TPS with cork and felt to CSD 100)
3) Federal clear 2-3/4" Lil Gun 2 oz load -- changed to Cheddite 2-3/4" Lil Gun load (changed new hull/primer only)
4) Federal clear 2-3/4" Lil Gun 2 oz load -- changed to Fiocchi 2-3/4" Lil Gun load (changed new hull/primer only)

1) CSD gives me higher pressures and a little less mv than TPS, but the cheddite hull will give a little less pressure and a little more MV, but the CSD will. Higher Pressure (I think it will be over 12000psi), Same MV
2) I get comparable velocity with Fiocchi and Fed hulls, New fiocchi hulls use 617 primers, which is comparable to fed 209a. Higher Pressure (Highest Pressure of all your loads), Same MV
3) I love 2 3/4" cheddite hulls. Higher MV, Lower Pressure
4) Same MV, same Pressure

Great post, can't wait to see results.

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Re: how changing components affects MV and PSI

Post by blunderbuss » July 23rd, 2014, 11:13 am

pedro wrote:My guess, and only a guess,
1 &2 lower p2 and velocity.
3 higher p2
4 lower p2
I agree, the csd should raise pressure. Cheddite and Fio lower. 8-)

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Re: how changing components affects MV and PSI

Post by Shooter » July 23rd, 2014, 12:23 pm

Rifle cartridges are fairly predictable, but shotshells are, well,.... like a box of chocolates. You never know what you're gonna get.
Even with all the combinations of hulls and powders over all the years of experience with me, I still get shells that are off the charts high and low.
Every once in a blue moon, I hit something that is just awesome, but usually I'm not even close, even when referencing a published load.
There are just too many variables. Hulls, wads, powders, primers, fillers. Everything makes a difference!

In theory, you would think that there would not be much change at all with the hulls and wads, but I know better,...lol.
It would not surprise me if you got just the opposite as expected! :mrgreen:

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Re: how changing components affects MV and PSI

Post by hawglips » July 23rd, 2014, 1:16 pm

1) Federal 3" Lil Gun 2 oz load -- changed to Cheddite 3" Lil Gun load (changed new hull/primer and fold crimp to roll crimp)
I expected: slightly lower MV and PSI
Actual Result: MV down 52 fps, PSI down 1202 (1179 fps, 10130 psi)

2) Federal 3" Lil Gun 2 oz load -- changed to Fiocchi 3" Lil Gun load (changed new hull/primer and wad from TPS with cork and felt to CSD 100)
I expected: slightly lower MV and PSI, but maybe somewhere between the Fed and Ched
Actual Result: MV down 13 fps, PSI down 1604 (1218 fps, 9729 psi)

So, my expectation on the MV and PSI compared to the Fed load was correct on both, but I was surprised to see the Ched with higher PSI than the Fio load.

3) Federal clear 2-3/4" Lil Gun 2 oz load -- changed to Cheddite 2-3/4" Lil Gun load (changed new hull/primer only)
I expected: lower MV but similar PSI
Actual Result: MV up 35 fps, and PSI up 2488 (!!!) (1227 fps, 12875 psi)

4) Federal clear 2-3/4" Lil Gun 2 oz load -- changed to Fiocchi 2-3/4" Lil Gun load (changed new hull/primer only)
I expected:lower MV but similar PSI
Actual Result: MV down 34 fps and PSI down 642 (1158 fps, 9696 psi)

I was totally surprised by the results I got with the Cheddite load. I'd have never figured that going from a Fed to a Ched hull would do that. And this is why one shouldn't assume very much.

(Note that I copied and pasted wrong on the Ched 3" load - it was hull change only.)
Last edited by hawglips on July 24th, 2014, 4:25 am, edited 3 times in total.

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Re: how changing components affects MV and PSI

Post by N2deer » July 23rd, 2014, 1:38 pm

Thats interesting and goes to show why testing should be important.

I like that number 2

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Re: how changing components affects MV and PSI

Post by bigdoc » July 23rd, 2014, 3:31 pm

Very cool .Good job. That #2 load sounds great.

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Re: how changing components affects MV and PSI

Post by Grunt-N-Gobble » July 23rd, 2014, 5:17 pm

Well, I for one am happy to hear about the Fio hull, since that is what I've been using. Good to know.

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Re: how changing components affects MV and PSI

Post by pedro » July 23rd, 2014, 5:28 pm

Interesting and fun.

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Re: how changing components affects MV and PSI

Post by toasty » July 23rd, 2014, 10:12 pm

Well, that is surprising. Jump in MV and pressure with the 2 3/4" cheddite, but lower with the 3" cheddite. Didn't see that coming. I though the CSD wads gave quite a bit higher pressures. I was wrong which is great because I love the CSD wads, no spacers makes them fast to reload. Great post, that was fun to learn I don't know near as much as I thought I did.

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how changing components affects MV and PSI

Post by Reloader » July 23rd, 2014, 10:19 pm

The only one that surprised me was the 2-3/4" Ched as well. The good thing is that all were relatively low pressure.

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how changing components affects MV and PSI

Post by Reloader » July 23rd, 2014, 10:20 pm

The cushion stem CSD/B&P wads are fantastic wads for lead and Hevi as well.

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Re: how changing components affects MV and PSI

Post by T-town » July 23rd, 2014, 10:39 pm

What level pressure is the benchmark as far as safety is concerned in modern shotguns? That 2 3/4 cheddite load is what my gun liked last year.

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Re: how changing components affects MV and PSI

Post by hawglips » July 24th, 2014, 3:57 am

toasty wrote:Well, that is surprising. Jump in MV and pressure with the 2 3/4" cheddite, but lower with the 3" cheddite. Didn't see that coming.
I'm scratching my head over that. However, I neglected to specify that the Cheddite 3" was roll crimped while the 2-3/4" was fold crimped. My bad. Even so, I didn't expect that much of a difference. (I'll go put that in the OP for reference....)
Last edited by hawglips on July 24th, 2014, 4:24 am, edited 1 time in total.

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Re: how changing components affects MV and PSI

Post by hawglips » July 24th, 2014, 4:18 am

T-town wrote:What level pressure is the benchmark as far as safety is concerned in modern shotguns? That 2 3/4 cheddite load is what my gun liked last year.
At 1227 fps you have way plenty speed - so backing off a grain or two is going to still leave you in real good shape on MV - maybe 1125 - 1175 or so. At 12875 psi you're not going to blow a modern gun up. If you are roll crimping, you're probably getting lower PSI than these fold crimped shells anyway. The highest reading of the string was 13600 which is still below SAAMI MAP for a 3.5" shell. I don't worry about a shell very much if it's under 14000 psi on average in a modern gun. So if the shells were for me to shoot, and I already had some of those loaded up, and they patterned to suit me, I wouldn't worry about them. But I'd back off a grain and a half probably if I was going to load some up with that hull - figuring on about 35-40 fps per grain. But then that brings us back to the point that - you never know....

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Re: how changing components affects MV and PSI

Post by Spuriosity » July 24th, 2014, 8:02 am

Great stuff Hal. Thanks for sharing. I was pretty close on #4 - predicted 50 fps and 500 psi loss / actual being -34 fps and -642 ,psi. I missed the others pretty badly. Just goes to show, there is no substitute for testing - educated guesses aren't worth much.

I used to read everything the late Don Zutz wrote concerning shotgun ballistics and reloading theory vs experience. The way he explained the apparent paradox that vel. and pressure can actually go down when substituting a primer with greater brisance, was that the stronger primer actually moves the payload forward a touch before the charge fully ignites. Doing so, enlarges the combustion chamber available when the powder ignites, which will tend to lower vel and pressure. Although counter intuitive, I suppose the explanation makes some sense. Perhaps, Toasty will weigh in. Being an engineer by training, he knows a lot more about it than most. The problem, as you demonstrated, is that you just can't predict with any degree of accuracy.

Anyway, thanks. That was fun and very informative.

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Re: how changing components affects MV and PSI

Post by hawglips » July 24th, 2014, 9:13 am

Spuriosity wrote:I used to read everything the late Don Zutz wrote concerning shotgun ballistics and reloading theory vs experience. The way he explained the apparent paradox that vel. and pressure can actually go down when substituting a primer with greater brisance, was that the stronger primer actually moves the payload forward a touch before the charge fully ignites. Doing so, enlarges the combustion chamber available when the powder ignites, which will tend to lower vel and pressure. Although counter intuitive, I suppose the explanation makes some sense.
That is very interesting.

I wonder whether and/or how much such an enlarged combustion chamber (particularly with these slow burning powders) might also come into play when discussing everything from the role of crimps and shell length to the use of filler and the volume of the payload...

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Re: how changing components affects MV and PSI

Post by Johndoe » July 24th, 2014, 3:36 pm

What about the CLBC. I know Ronny and Barry like the LBCs. I just have not gotten the patterns I want with Hevi. I also didn't want to buy an Indian Creek choke and Ronny says the LBCs and ICs work well together. JellyHeads and the LBCs didn't go together for me.
From what I gather these wads keep pressures lower. Anyone use them.
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