Alpharms 15SA rail modification

supernova

supernova

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So last night I met Ravage at his place to check out his new Alpharms 15SA. Overall its a neat shotgun, almost a mix between a standard semiauto shotgun and an AR. The factory irons were just terrible and Ravage much preffered his Magpul backups. Just one problem. The rear fits tight but the front was nowhere near fitting. The rear rail isn't in spec either but the MBUS did slide on. The crossbolt was a tight fit. Upfront was a different story. The depth of the slots measured around .124" while the rear rail slots measured .120". Rear rail measured .834" wide while the front was wider it could be squeezed together to about the same. Ravage asked me if I'd take it home and make it work. I had to file the top and sides down quite a bit to get the MBUS front to slide on. The first pic shows the height difference after it was filed just enough to squeeze it on with some force.

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Here you can see the gross difference after removing enough material to get the front sight on.

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I had to move the front cross slot 3/32" further forward for the crossbolt in the MBUS to fit with the sight flush with the end of the rail. But it's on there and looks clean and proper. Some sanding with 80 through 1000 grit got rid of the file strokes and left the rail smooth and just the right size for a firm, snug fit with the MBUS.

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So be prepared to do a bunch of work to mount accessories on the plastic rails. Hopefully we can get out to the range to run some rounds through it and see if it functions properly. Not holding my breath.
 
I'm probably going to do the same thing, as I've got an MBUS front sight I want to mount on mine, as well. Want to try the gun out and make sure it works properly before I start messing with it, though!
 
Well the 15SA did good at the range today. Slapping the mags in seemed to cause feeding issues, gently locking them in made it run great. Ravage got it sighted in with score slugs then between the 15SA, my 870 and 100+ rounds we had an awesome time with clays and a gong. The 15SA cycles aggressively, spent hulls flew a good 10ft. So long as mags aren't slapped up into the magwell, it seems to run great.
 
Cool. That's reassuring. Trying mine tomorrow, so we shall see!


supernova said:
Well the 15SA did good at the range today. Slapping the mags in seemed to cause feeding issues, gently locking them in made it run great. Ravage got it sighted in with score slugs then between the 15SA, my 870 and 100+ rounds we had an awesome time with clays and a gong. The 15SA cycles aggressively, spent hulls flew a good 10ft. So long as mags aren't slapped up into the magwell, it seems to run great.
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It was a fun day shooting with Supernova I shot 2 boxes of score slugs and 2 boxes of 7-1/2 score target from my new 15SA and yes there were a few feed issues from the magazines but I think I narrowed it down to seating the magazines in too far because the last 6 magazines when pushed in on the open bolt till they just locked up those shot with no issues even with 2 magazines being mag dumped :)

The gun itself shot perfect no failure to fires or strike issues and it ejected every round fired and they flew pretty far like Supernova said, The only other issue I noticed was during the mag dumps when I was rocking out 5 rounds super fast the recoil got the gun jumping and I felt the folding stock wiggle like it wanted to fold up but this only occurred when dumping out 5 rounds as fast as I could pull the trigger under normal operation there was no movement with the hinge at all it stayed tightly locked down. The non stop recoil of 5 rounds being fired that fast and the gun moving while the buttstock was tight to my shoulder wanted to pop the latch up was what caused that little issue. Again not really an actual problem since there is no real reason to dump 5 rounds that fast besides for laughs.

I shot almost all the rounds using the flash hider choke I think its improved cylinder but not 100% sure as there is no markings on it I can see, The slugs grouped pretty nicely I would say consistently under 2" at close to 40 yards, I didn't really shoot for grouping tho this time out but I called it sighted in like shooting a rifle. The full choke using 7-1/2 at 15 yards would have vaporized a grouse lol. I still have more testing to do with chokes and spreads but thats the fun part hehe

Overall I really like the gun after shooting it, The initial out of the box impression with the handguard rail being out of spec disapointed me but thankfully Supernova stepped in and using his mad ninja skills got it resized to work. For only $500 its a good deal no question with the similar guns over $1000. I hope to get out again Sunday to shoot it a bit more.
 
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CobraGT said:
Had mine out yesterday - didn't feed reliably at all with Score slugs. Gonna have to try again with other ammo and see. Pretty disappointing so far...
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Seems everyone was knocking the mk1919 match due to the price. Should be interesting to see if it's more reliable than the alpharms
 
polskiogorki said:
Seems everyone was knocking the mk1919 match due to the price. Should be interesting to see if it's more reliable than the alpharms
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The 15SA shotgun itself is reliable I have not had a single issue with the gun itself and I am very happy with it, The fit and finish is not the best sure we all know that but those that are better are also 2 to 3 times more expensive. The problem has been with the magazines and looks like a lot of them were assembled wrong. I have done the modifications that Wolverine posted but have not shot them yet but i'm sure they will function better now.
 
Thanks for the info & pics , i'm trying to put magpul back up sights on mine as well. I guess i'll have to bust out the file and sandpaper.
 
Thanks for the info and pics I will do the same mod to mine .
The issue I believe is the mags as mentioned .
I had mine out again after cutting one coil of the mag springs and filing the sides of the follower down as the video showed.
there was a small ridge on the side of mine.
Big improvement on loading the mags .
It ran a lot better than previously with 2 FTF out 60 rounds . I did a mag dump 6-7 times and if ran smoothly.
Loading the first round from the mag using the bolt release jammed a couple times though .
I was using Remington 2 3/4 Target loads today. I have a lot of mags so I will keep track of which mag acts up.

Update ..Did the mod to my front rail for the MBUS , and installed the cocking handle cover I got from Bugout.
Found an old flashlight for the tacticool look ..lol
Thanks again guys !!

 
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