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<  16ga. Ammunition & Reloading  ~  Stacked fiber wad load pressure
16'er
PostPosted: Fri Feb 22, 2019 6:19 am  Reply with quote
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Joined: 08 Oct 2006
Posts: 1393
Location: Tappahannock, Virginia

From various posts here on The Society I had gathered the impression that all things being equal, switching from a plastic gas seal wad to a stacked fiber card load the pressure would be lower for the stacked load. (Same hull, powder, primer, and drops). Reasoning was the plastic wad and gas seal were so much more efficient at capturing the burning powder and pressure, where as fiber wads allowed some of the pressure to blow-by as the charge was ignited.

This seemed to make sense to me, and I felt pretty comfortable with what I had come to believe. I was poking around the collective reloading data outside our fine brotherhood and came across this thread when searching for some insight on bismuth loads:

https://www.duckhuntingchat.com/forum/viewtopic.php?f=14&t=852841&sid=2b850f2bc2f238a6984b171bc2a53966

One of the thread authors claims higher pressure with stacked loads, due to very little to no give in crush for fiber vs plastic wads.

The load data I use for my stacked loads is 18grs unique in a federal hull with a win 209 primer, 7/8oz shot. There’s one nitro card and two fiber wads, I use an overshot card if roll crimped. I have no reason to believe this load has any pressure issues, and I’ve used it only in nitro proofed fine condition doubles. When looking at the spreadsheets it seems like a reasonable load. It drops pen quail and chukar just fine. It does leave the bore quite dirty, a product of unique and the leading of the barrel by the uncontained shot no doubt.

I’ve not pressure tested this load, and the member who shared it with me did not provide a tested pressure. I’m comfortable with the specific load, but moving forward with future loads some of my assumptions may need to be revisited?

What do other members think of these two seemingly contradictory theories of fiber wads and effects on chamber pressure?

Thanks,

Dean
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16gaDavis
PostPosted: Fri Feb 22, 2019 10:55 am  Reply with quote



Joined: 24 Jun 2013
Posts: 2062
Location: canandaigua - western n.y. (formerly deerhunter)

when plastic wads 1st came out ,the recommendation was to drop the charge 10% when going plastic . I would say at best your Unique load is quite on the mild side . We usually use 19/20grns with the plastic wad loads with your components - no worries .

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duckdup
PostPosted: Fri Feb 22, 2019 7:05 pm  Reply with quote



Joined: 12 Feb 2018
Posts: 258
Location: West-central Missouri

If you look at the old Hercules load manuals, they do mention the 10% reduction for plastic over-powder. I'm using 1/2 grain more Unique than you with hotter primer and 30grams of magnum or nickel-plated lead shot. This is from a Hercules manual from 1983 with a few less pellets than the 1&1/8 oz shot in the manual. Nitro card & two 1/2 inch fiber wads; the Manual calls for 50# wad pressure. Usual soot from the Unique powder but no lead issues.

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AKDan
PostPosted: Tue Feb 26, 2019 7:45 pm  Reply with quote



Joined: 18 Apr 2018
Posts: 28
Location: Alaska

I got out the manuals from the fiber wad/plastic wad transition period. On loads that were exactly the same except fiber vs plastic wads, the fiber wads usually, but not always, had lower pressures. Apply prudence.
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MSM2019
PostPosted: Tue Mar 05, 2019 4:16 am  Reply with quote



Joined: 04 Mar 2019
Posts: 1819
Location: Central ND

16’er

I would imagine that there are loads out there using card and fiber wads that produce more pressure than similar loads using plastic wads.

As another poster stated your 7/8 oz. load using Unique is pretty mild, regardless of which wad you are using.

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WyoChukar
PostPosted: Tue Mar 05, 2019 9:46 am  Reply with quote



Joined: 16 Jul 2015
Posts: 2124
Location: Hudson,Wy

That's a good point. Also note that some of the 2 7/8 10ga. data I have been studying lately calls for a plastic gas seal topped by fiber wads. I do recall long ago that Tom Roster wrote that when developing his long range lead shot hunting loads that the densest patterns came from the combo of plastic gas seal+fiber filler wads+plastic shot wrapper instead of one piece plastic wads.

I am wondering these days, because of available data, what the pressure difference is between a 6 pt. fold crimp and a roll crimp. I read a statement here that fold crimps give slightly higher pressure but then noticed an example in my 10ga. data where two identical loads were listed, one fold crimp and one rolled. Velocities were about the same and the roll crimp listed higher pressure. Hmmm. There were no other identical loads to compare.

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MSM2019
PostPosted: Tue Mar 05, 2019 9:59 am  Reply with quote



Joined: 04 Mar 2019
Posts: 1819
Location: Central ND

There is a rule of thumb that says fold crimps usually create 500 PSI more pressure than a roll crimp. Way back when I tried that test with a few light hunting loads that seemed to be about right. I also found that the velocity stayed the same regardless of which crimp was applied to the shell.

Honestly though, 500 PSI in shotshell ballistics is basically a nothing. and I would never change a load to accommodate for a crimp type.

The one rule of thumb that does always come true is the one that says there are no absolutes with internal shotshell ballistics.


Wyochukar with that data did they specify the crimp depths for both crimps? That would definitely be a variable.

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WyoChukar
PostPosted: Tue Mar 05, 2019 10:27 am  Reply with quote



Joined: 16 Jul 2015
Posts: 2124
Location: Hudson,Wy

I thought about that and the information I have does not list crimp depth. I did just find a second pair of loads in there, bismuth section, that showed a drop of 600 psi for the roll crimp. It makes me wonder if the other set is a misprint since it shows a 600 psi increase. The data in the sheets was tested by Tom Armbrust.

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