Dirty_J

Just file down the edges. You can get it narrow enough for the MPX.

Also noticed an exceptionally sharp transition from the ramp to the chamber on mine. Also softened and polished it. Between that and swapping to all new stainless mags, mine seems to be sorted out.

I also grabbed a couple of the stainless mags. Ran like a top in mine, so I grabbed 4 more snd ditched the blued mags the gun was giving me trouble with (through after tuning they were running ok)

Found another site showing how to tune the feedlips for case rim height and angle. Taking the calipers to 3 brands of ammo I have on hand shows 0.006" variance from smallest to largest. Hitting the top of the chamber can be due to the bolt skimming across the rim and grabbing the cartridge after the rim. https://www.wirthweinguns.com/Ruger-MK-Mags.php

Will give it a go. Thanks. Mod the same for MKIII and MKIV? Think the tubes are the same right? Just different base pad?

Had my first outing with a "new to me" 22/45 MKIV today and had some less than stellar results. 1) With a full 10rd mag, it would occasionally send the first round to the top of the chamber and wedge in place. Is there normally a small ledge between the feedramp and the chamber? Looks problematic to me, but thought I'd ask before messing with it. Tried to sling shot. Tried to use the bolt catch. Problem occured both ways. 2) This same malfunction would sometimes occur a few rounds into the magazine Tried a variety of ammo. Blazer. Aguila. CCI Standard velocity, Federal and minimags. Copper jacket and lead. Round nose and FMJ. Some were worse than others, but none perfect. I could not attribute it to one ammo type or magazine (had 4 to use) Is it normal that the top bullet can wiggle up and down in the magazine? I know with center-fire cartridges this can absolutely cause such feed issues. Not sure if rimfire is different. 3) The gun would also only occasionally lock back when empty. Even with the high velocity stuff. Is the bolt catch finicky or do you think I'm getting a short stoke? It's doing this even with the 1200+ fps stuff, so if short stroke, there's got to be something going on with the action.

I agree. None of the serious JP shooters around here left them stock. Trigger. Handgaurd. Buttstock. All replaced. Furthermore... Two of them dropped the JP's for Mpx's this year!

I've shot a crap ton of Blazer brass through my MBX extension. Mini specifically. No feed issues to speak of. But it's HOT ammo in a full length PCC

I HATE Sig products... But recently started shooting an mpx. It's phenomenal. No dot movement. None. Has some reliability quirks. Needs to be cleaned more regularly that a straight blowback... But it's a great performer.

Blazer 124 will damn near make major out of a rifle. If you're staying with factory ammo, id go 115 for sure. Better recoil impulse typically.

Ewww. Ya. I shower immediately upon getting home. Cool water too... to keep the pores tight and limit potential absorbing.

Looks like it's 5 now. https://www.cdc.gov/niosh/topics/ables/ReferenceBloodLevelsforAdults.html

No need to switch from 115's. I actually prefer them in my Mpx!

Safariland