Gunsmithing Wyatt's Extended Mag Box & Feeding Issues

[mdesign]

I have an extended mag box on a Stiller Predator SA and cannot make it feed well. Talked to a few of the folk involved and have tweaked the feed lips which helped some but we ain't there yet.

The problem is that the head of the case slips under the bolt and binds when the cartridge is half way out of the box and into the chamber. Does it the most on the 2nd cartridge to be fed out of a full mag of 4 rounds. The problem is always with the cartridge staggered to the side opposite of the rib on the follower.

I do not want to go to DBM as I will lose COAL which I need to use VLD style bullets. With the Wyatts, I can run a full 3" while the ACIS limits out about 2.870 if I understand correctly.

Anyone got any ideas or experience on what the solution might be?

 

[yote_slayer31]

Re: Wyatt's Extended Mag Box & Feeding Issues

Keep adjusting the feed lips. You might need to open the front of the feed lips so the case is turned loose sooner.

Other than that, do you have plenty of case head contacting the bolt nose?

 

[mdesign]

Re: Wyatt's Extended Mag Box & Feeding Issues

If I compare the amount of the case head that the bolt catches with a R700 SA that I have, I would say they are very much the same. It does seem to hang onto the case longer than my 700 SA.

I noticed that the lips of the factory 700 mag box are deeper, meaning they go further down the side of the mag box and are deeper in the front of the box than they are in the back portion of the box. The lips on the Wyatt are fairly shallow by comparison and equal from front to rear.

Actually, I have been toying with the idea of cutting the slot at the front of the feed lips a little deeper so that I could bend it to be more like the factory mag box. That is basically where the difference is between the two boxes.

 

[Aeon1]

Re: Wyatt's Extended Mag Box & Feeding Issues

I am guessing this is a short mag of some sort? How thick are the feed rails on the Stiller compared to the Remington you have? I have had a couple of custom actions where the feed rails were left a touch thicker than a factory action not allowing the larger diameter short mags to ride high enough to stay in contact with the bolt. As the nose of the bullet nears or touches the feed ramp the case sort of pivots on the thick feed rail causing the case head to drop away from the boltface. The trouble for me has almost always been the second cartridge down. I machined the rails on those actions down to factory thickness. If we had .750" diameter bolts this would be far less of an issue.

 

[mdesign]

Re: Wyatt's Extended Mag Box & Feeding Issues

My Stiller is a 7-08 and the R700 I'm comparing it to is a 243. The feed rails on the Stiller are .005-.010 narrower than the 700 and are thicker top to bottom.

I would not think that .005-.010 would make that much difference but the thickness does not appear to be helping.

 

[Aeon1]

Re: Wyatt's Extended Mag Box & Feeding Issues

I would compare the Stiller to the Rem as to how the cartridges sit when loaded. How does the bullet tip to feed ramp height compare between the two? I'll bet the bullet tip on the Stiller is noticeably lower. How do the cartridge horizontal angles compare between the two? Those things might help confirm if the thick feed rails are your culprit. Another thing, is the point where the feed rails open up in width the same distance away from the bolt on both actions? I have had some rails left longer that makes the cartridge pivot thing worse. It creates a larger cartridge angle when the bullet starts up the feed ramp forcing the case head down further than usual. With rails too thick and too long the problem is even worse.

 

[230grRN]

Re: Wyatt's Extended Mag Box & Feeding Issues

I have ran into this issue on extended mag box installs in the past.

The problem is in the mag box. As your feeding the round its causing the rear of the mag box to open, which in turn releases the upward pressure on the rear of the cartridges underneath the round being fed to be released, causing the bolt over base FTF.

This mostly happens with the 1st and 2nd rounds with the 3rd and 4th generally feeding but not usually all that smoothly.

My fix is to first figure out if the rear of the mag box needs to be closed up more than its factory width, then I silver solder the box together at the back to keep the box from opening during feeding. The front of the feedlips will need to be bent in to facilitate kicking the round out from under the feed rails in the reciever at the proper time as well.

If you want to PM me I'll walk you through it.

 

[mdesign]

Re: Wyatt's Extended Mag Box & Feeding Issues

230, sent you a PM...

A loaded round rides a little lower in the Stiller than the 700, not a lot but enough that the bullet contacts the feed ramp lower.

I got to believe Stiller knows their stuff so the trick is probably figuring out what to do with the mag box. Haven't heard of too many people having to modify their action to get traditional 308 class cartridges to feed.

 

[Hondo64d]

Re: Wyatt's Extended Mag Box & Feeding Issues

I had the same problem with the exact same combo you mentioned. Also had the same issue with the factory box, so I don't think the Wyatt box was the problem. I played with the box lips but it provided no improvement. After talking to Russ at Stiller, it turned out I was making the fix much more difficult than it really is.

1st, make sure your follower spring is not upside down. The long leaf goes under the follower.

2nd, take some needle nosed pliers and tweak the spring a little so that it raises the heal of the follower.

After I did these two things, it feeds as good as any short action 700 has ever fed for me.

John

 

[mdesign]

Re: Wyatt's Extended Mag Box & Feeding Issues

Thanks Hondo...sounds just like the conversation I had with Russ as well. I got the spring right (it was okay) but just curious, what follower did you have, was it the cast or stamped metal version?

 

[Hondo64d]

Re: Wyatt's Extended Mag Box & Feeding Issues

Cast.

John

 

[mdesign]

Re: Wyatt's Extended Mag Box & Feeding Issues

Just an update on this...Got it fixed up and it feeds very well. It had nothing to do with the action (I figured as much) and everything to do with the mag box. In the end, it was easy thanks to some very solid advice from those that have worked through this kind of thing.

Long story short, I got to studying the Wyatt version compared to the factory 700 ADL box (which fed great) and ended up making the feed lips on the Wyatt much more like the factory box. I had to modify things a little but nothing drastic. End of problem.

For all the guys that PM'd me and related all the issues they had experienced with Wyatts, kind of made me wonder why Wyatts does not make a basic modification to how this box is made. Very likely would solve some basic feeding issues. Oh well.

Thanks again for those offered insight.