Wanted to post this here and get it out of the build forums. Will update as I hear back from MPA and BigHorn and try different things etc.. That way I can pass along what I learn to anyone else.
Just got my first build done with everything coming from Altus in Florida. Guts are the Bighorn TL3, AW cut action with proof stainless barrel resting in the MPA Comp chassis folder (new one without the castle mag cut). Barreled action is in the chassis torqued to 65in-lbs and the MPA lug lock is in and torqued to 30in-lbs. No mag no problems... action is smooth and slides easily in and out with no binding or catching.. Try to seat a magazine and problems start.
I got a box of ammo down the barrel and break in is done. Having mag problems though. Rifle came with a 5rd Accurate Metal mag and trying to get that mag to seat with rounds in it is difficult and to use that mag and have it feed feels like I'm trying to close an action full of sand and gravel and the brass has some nice scrapes from feeding out of that mag. Have to use a lot of force on the bolt knob/handle to get it to strip the round and chamber and it binds up and catches. If i press my thumb on the back of the bolt assembly where the firing pin cocked pin protrudes I can actually get the bolt to close easier without any binding.
Switched over to my magpul 10rd and 5rd AICS mags and those don't want to seat at all with any rounds loaded in them and when I could get em to lock in place the bolt feeds a couple of rounds fine but then I get the bolt riding over the top of the rounds and the mag follower is stuck and the rounds arent coming up high enough.
This is with a brand new magpul aics mag and ones that are older and work fine in my other rifles. The magpul 5rd mag seems to work better as far as feeding goes but still does not seat properly.
Got home and tried the magpul "fine tuning" like MPA has a video of with shaving a little material here and while now they lock into place fine, they still have same feeding / bolt over the rounds issue. So I think the TL3 with AW cut I got isn't going to run with the magpul mags... which sucks... cause they've worked in every other rifle/chassis I had... So that leads me to metal mags and trying to decide on which ones to try now.
Emailed MPA and BigHorn to ask what could be causing the issues and also what suggestions they had for me. Seems to me like the magwell in the chassis is too tight for the magpul mags causing them to bind and follower not work properly. But the accurate mag maybe rounds are too high up and thats why there’s so much binding and requiring so much force to chamber a round.
**UPDATE 1 - botched a magpul mag up with trying a little at a time sanding in order to get it to seat properly. Was able to get is to easily seat and lock into place but still was getting bolt over rounds and could not make it through a 10rd mag without having problems.
**UPDATE 2 - sanded and adjusted the feed lips on the accurate 5rd mag some and can get “easier” feeding but still binds up my action and bolt throw trying to cycle through the rounds quickly and brass is getting scratched up still. But still working on this mag to fine tune it and see if I can get it working smooth.
**UPDATE 3 - MPA wrote me back saying that the short 5rd accurate mag (which shipped with the rifle) is too short to lock up and seat properly and that could be causing my feeding issues. BigHorn wanted and got some pics sent their way. Altus said they would reach out to me and call. Member here is sending me an AICS mag to try and I'm going to try to borrow a 12rd MDT mag as well to try.
**UPDATE 4 - more polishing and tuning the feed lips on the 5rd mag (actually closed the gap some so rounds weren't up as high) and it is seating solidly and a LOT easier to feed and cycle ammo and brass isn't getting chewed up. Going to polish a little more and run the bolt tonight on and over the mag while I watch some TV and wear it in more. Gave up on the magpul mags after losing one to the modification bin... but have a bud that wanted / needed some so that works ok. Hoping the AICS and MDT mags work out the get go and then I can just pick some up of my own. Still disappointed that it required that much work and tweaking to get a 5rd accurate mag to work but with all the reading I've done it seems like that is the case with metal mags and a lot of rifles members on here have.
**UPDATE 5 - talked with Altus, BigHorn and MPA. All three suggested same things as members on here and that some ‘tuning’ for metal mags might be needed. Never realized that would be the case until this rifle build but with their suggestions and everyones help on here I’m getting it sorted out. What i’ve learned so far.... Magpul mags simply don’t fit in my chassis without too much modifying. Too tight in magwell causes follow to bind and the front of mag feed lips hit inside at front of action so those mags are gone. My only metal mag (5rd accurate - came with rifle) is super short in the magwell (MPA said it might not actually be able to seat and lock properly) is seating fine and mag lips were adjusted from 0.445-0.450 (maybe more) down to 0.410-0.420 and the bolt is not binding and dragging / chewing up the next round and it seems to be feeding a lot smoother and better now. Never had to tune a mag before but also never had metal mags and a custom action. All a learning curve for me but I think things are smoothing out and getting sorted. Huge kudos and thanks to the companies ( @BigHorn / ZAI Team @MPA @Altus ) who all emailed back and forth with me and offfered their tips and suggestions. Big thank you also to the members on here who calmly dealt with me and all my questions and concern with my new rifle build and (calmly) offered their help and wisdom with me and my not being able to understand the quirks that can come with doing a custom build ( @Sheldon N @reubenski @padom , and everyone else ). After I get the borrowed mag(s) in hand and try them out I’ll do another update to this and then hopefully be able to start a new thread about how amazing the rifle build is working out for me. Thanks and Cheers!!
** UPDATE 6 - Final thoughts and mag results testing for me is done and posted below.
Just got my first build done with everything coming from Altus in Florida. Guts are the Bighorn TL3, AW cut action with proof stainless barrel resting in the MPA Comp chassis folder (new one without the castle mag cut). Barreled action is in the chassis torqued to 65in-lbs and the MPA lug lock is in and torqued to 30in-lbs. No mag no problems... action is smooth and slides easily in and out with no binding or catching.. Try to seat a magazine and problems start.
I got a box of ammo down the barrel and break in is done. Having mag problems though. Rifle came with a 5rd Accurate Metal mag and trying to get that mag to seat with rounds in it is difficult and to use that mag and have it feed feels like I'm trying to close an action full of sand and gravel and the brass has some nice scrapes from feeding out of that mag. Have to use a lot of force on the bolt knob/handle to get it to strip the round and chamber and it binds up and catches. If i press my thumb on the back of the bolt assembly where the firing pin cocked pin protrudes I can actually get the bolt to close easier without any binding.
Switched over to my magpul 10rd and 5rd AICS mags and those don't want to seat at all with any rounds loaded in them and when I could get em to lock in place the bolt feeds a couple of rounds fine but then I get the bolt riding over the top of the rounds and the mag follower is stuck and the rounds arent coming up high enough.
This is with a brand new magpul aics mag and ones that are older and work fine in my other rifles. The magpul 5rd mag seems to work better as far as feeding goes but still does not seat properly.
Got home and tried the magpul "fine tuning" like MPA has a video of with shaving a little material here and while now they lock into place fine, they still have same feeding / bolt over the rounds issue. So I think the TL3 with AW cut I got isn't going to run with the magpul mags... which sucks... cause they've worked in every other rifle/chassis I had... So that leads me to metal mags and trying to decide on which ones to try now.
Emailed MPA and BigHorn to ask what could be causing the issues and also what suggestions they had for me. Seems to me like the magwell in the chassis is too tight for the magpul mags causing them to bind and follower not work properly. But the accurate mag maybe rounds are too high up and thats why there’s so much binding and requiring so much force to chamber a round.
**UPDATE 1 - botched a magpul mag up with trying a little at a time sanding in order to get it to seat properly. Was able to get is to easily seat and lock into place but still was getting bolt over rounds and could not make it through a 10rd mag without having problems.
**UPDATE 2 - sanded and adjusted the feed lips on the accurate 5rd mag some and can get “easier” feeding but still binds up my action and bolt throw trying to cycle through the rounds quickly and brass is getting scratched up still. But still working on this mag to fine tune it and see if I can get it working smooth.
**UPDATE 3 - MPA wrote me back saying that the short 5rd accurate mag (which shipped with the rifle) is too short to lock up and seat properly and that could be causing my feeding issues. BigHorn wanted and got some pics sent their way. Altus said they would reach out to me and call. Member here is sending me an AICS mag to try and I'm going to try to borrow a 12rd MDT mag as well to try.
**UPDATE 4 - more polishing and tuning the feed lips on the 5rd mag (actually closed the gap some so rounds weren't up as high) and it is seating solidly and a LOT easier to feed and cycle ammo and brass isn't getting chewed up. Going to polish a little more and run the bolt tonight on and over the mag while I watch some TV and wear it in more. Gave up on the magpul mags after losing one to the modification bin... but have a bud that wanted / needed some so that works ok. Hoping the AICS and MDT mags work out the get go and then I can just pick some up of my own. Still disappointed that it required that much work and tweaking to get a 5rd accurate mag to work but with all the reading I've done it seems like that is the case with metal mags and a lot of rifles members on here have.
**UPDATE 5 - talked with Altus, BigHorn and MPA. All three suggested same things as members on here and that some ‘tuning’ for metal mags might be needed. Never realized that would be the case until this rifle build but with their suggestions and everyones help on here I’m getting it sorted out. What i’ve learned so far.... Magpul mags simply don’t fit in my chassis without too much modifying. Too tight in magwell causes follow to bind and the front of mag feed lips hit inside at front of action so those mags are gone. My only metal mag (5rd accurate - came with rifle) is super short in the magwell (MPA said it might not actually be able to seat and lock properly) is seating fine and mag lips were adjusted from 0.445-0.450 (maybe more) down to 0.410-0.420 and the bolt is not binding and dragging / chewing up the next round and it seems to be feeding a lot smoother and better now. Never had to tune a mag before but also never had metal mags and a custom action. All a learning curve for me but I think things are smoothing out and getting sorted. Huge kudos and thanks to the companies ( @BigHorn / ZAI Team @MPA @Altus ) who all emailed back and forth with me and offfered their tips and suggestions. Big thank you also to the members on here who calmly dealt with me and all my questions and concern with my new rifle build and (calmly) offered their help and wisdom with me and my not being able to understand the quirks that can come with doing a custom build ( @Sheldon N @reubenski @padom , and everyone else ). After I get the borrowed mag(s) in hand and try them out I’ll do another update to this and then hopefully be able to start a new thread about how amazing the rifle build is working out for me. Thanks and Cheers!!
** UPDATE 6 - Final thoughts and mag results testing for me is done and posted below.
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