Very odd experience with a Molot paradox choke

[jumbopanda 1]

My Vepr 12 has been pretty reliable overall, but during my last range trip I noticed a very odd issue with it. I was trying out my new paradox choke, shooting mostly handloaded Lyman 525gr slugs, and I had no cycling issues at all. However, I also wanted to find out how buckshot would pattern with the choke on, since the idea behind the Paradox Gun was that it would fire slugs accurately while still being able to pattern shot reasonably well. I fired two rounds of Estate 00 buckshot with the choke on, and both times the action did not cycle at all. Let me be clear, it didn't have a FTE...the bolt did not even unlock. I took the choke off and fired a few rounds of the same ammo, and it functioned just fine. I then put the choke back on and went back to shooting slugs, again with no issues. 

Oh, and the paradox choke throws shot everywhere, just like a fully rifled barrel would. It also made accuracy worse with the slugs I was using. 

Edited April 26, 2015 by jumbopanda

[JDeko 792]

can you post pics of what it looks like on your Vepr? I'm really curious about the aesthetics.

[jumbopanda 1]

Externally it is identical to any of the other factory chokes.

[JDeko 792]

Sorry, I was just curious as to how it looks on a Vepr or other AK-Style Shotgun [as opposed to the typical converted IZ-109 composed 73% of quadrails].

Edited April 26, 2015 by JDeko

[YOT 3,743]

Lesson learned?

 

Compatibility of shotguns and slugs can be a challenge. Try many different brands and weights of slugs. You will find one, or two, that your shotgun "likes". Stick with that. Basing your judgement of the choke off one brand of ammo is an incomplete assessment. 

 

I had a shotgun that would only group well with Federal 7/8 oz. foster type slugs, but is would put two in the same hole at 60 yards. ANY other slugs would group about 18" at the same distance. 

 

Keep experimenting before you make a judgement.

Edited April 26, 2015 by YOT

[jumbopanda 1]

I was a little more concerned/baffled by the bolt not even moving when firing buckshot with the rifled choke, but yes, point taken; shotgun slugs can be finicky.

Edited April 26, 2015 by jumbopanda

[RED333 1,025]

Are you sure the bolt did not move, or you did not see it move?

The bolt might have moved back a good bit, not enough to eject and then just pushed the fired shell back into battery.

I find it very strange that the bolt did not move. Was felt recoil any diff?

Edited April 27, 2015 by RED333

[jumbopanda 1]

Are you sure the bolt did not move, or you did not see it move?

The bolt might have moved back a good bit, not enough to eject and then just pushed the fired shell back into battery.

I find it very strange that the bolt did not move. Was felt recoil any diff?

 

I suppose it could have moved a little bit, but it must have been not enough to let the shell clear the chamber. The felt recoil was definitely different; it felt more like a push and less of a jolt. I wasn't really thinking about it at the time, but I seem to recall that when I pulled the charging handle back to clear the shell, I felt some resistance due to the hammer not being cocked.

[gunfun 3,931]

I would guess that your lyman slug load has a powder combination that is not burning well. What powder? How much?

 

Also, the wad and slug need to be a tight fit but still pass through the rifled portion intact. If they are too tight, you will get crap accuracy as the rifling will just mangle the wad off of the slug rather than grip them both and spin them.

[jumbopanda 1]

GunFun,

 

I've tried 20gr of Promo, 22.5gr of Green Dot, and 50gr of Blue Dot (this one rattles my skull). All produced poor accuracy and keyholing.

 

I've pushed my wads and slugs through the bore with a dowel, and the Federal 12S4 and Claybuster yellow wads are snug but not super hard to push through. They measure about 0.740" in diameter, whereas my bore is 0.732".

 

I've also tried Downrange yellow wads, but they are much thinner and only measure 0.720" with a slug inside. These slide down the bore freely.

 

I've found that recovered wads were torn up quite badly, so I decided to try something else in hopes of mitigating damage to the shot cups. I cut the shot cups off from the wads, then placed them on top of fiber wads and gas seals. The shot cups recovered from these loads actually looked pretty intact, but accuracy barely seemed to improve. Keyholing was still happening consistently.

 

 

I shot some more of the Estate buckshot through the gun without the rifled choke and it did the same thing as before, so I guess I can rule out the choke as the problem. Initially the gun ran fine with that ammo, but now the shells won't clear the chamber about 1/3 of the time. Maybe it's because the gun was dirty; I scraped some thick fouling out of the gas block after coming back from the range today. I'm still surprised though; is it normal for a Vepr 12 to become significantly less reliable after not being cleaned for ~450 rounds? That doesn't seem like a lot.

 

Another issue could be the fact that all of the malfunctions occurred with roll crimped shells. I just got a roll crimp tool, so I loaded up a bunch of roll crimped shells, in addition to the Estate factory loads which are also roll crimped. I know that roll crimped shells generally produce less pressure and velocity with a given powder charge compared to a fold crimped shell. Still, it seems weird that many of the shells wouldn't even make it out of the chamber.

Edited May 2, 2015 by jumbopanda

[gunfun 3,931]

Interesting. I'll have to re-read this later when my brain is clearer to think about it. A couple things I have found about the Dot powders. 1) they burn dirty and don't smell as nice as other powders. 2) green dot has a very narrow sweet spot for good performance. I have noticed that several loads toward the upper end of velocity for published green dot data burn inconsistently. Bad sour smelling smoke, noticeably inconsistent recoil & report, unburnt flakes of powder. (The bad smell is a flag to look for unburnt powder or erratic recoil.) Dial it back a couple grains and they run good. This was very pronounced in a .45 ACP recipe I worked up from scratch-ish. Even though I never got to a level where I was seeing pressure signs, I tore down the heavier charges for fear of squib loads. Medium power seemed to be pretty good performers though. Green Dot seems to have a very sharp bell curve of where it likes to work. I don't know if this applies to blue dot.

 

A couple green dot slug loads that should have been ~1300 FPS seemed weaker than than slightly lighter charges on the same recipe. I had a couple that just failed to burn properly and left a slug half way down the barrel. That's not a game I like to play.

 

I've been curious if magnum primers are really what green dot wants to work well. I know that federal primers are significantly hotter than other brands in the non-magnum, so I would probably be more inclined to use green dot data which asks for those.

 

Either way, I've decided to quit using it and just stick with better performing more useful WSF. I'll use up the rest of my stock on the basic trap load or the 45 ACP ball clone load I worked up. After that WSF is the way to go for me. It starts to work at slower loads up to significantly faster loads. All in all it is a good metering versatile powder. economical too.