Feeding issues with new RRAR (AR mag)

Moderators: gds, bakerjw, renegade

Post Reply
Cajun Executioner
Silent Operator
Posts: 89
Joined: Mon May 21, 2012 2:08 pm

Feeding issues with new RRAR (AR mag)

Post by Cajun Executioner » Wed Mar 07, 2018 3:51 pm

I got a new RRAR that takes AR mags. It comes with a 10 round PMag. I won't be able to get out and shoot for about a week but this is my issue. I Put 10 rounds of my 208gr AMAX loads in the mag to see how they'd feed and the bolt is extremely tight when trying to close the bolt, to the point where I cannot close the bolt without forcing it closed. I then filled the mag with 10 rounds of my 110gr TacTx rounds and they chambered and ejected without issue. So then I measure the OAL of each round thinking that the AMAX may be longer but it's the opposite. The TacTx are seated to 2.233" and the 208's are seated to 2.21". I also checked both rounds with a comparator for the OAL from the ogive and the TacTx is .02 longer from ogive. I use the same brass for all of my loads and bump the shoulders back in one batch so the brass is all sized and trimmed the same.
The manual says the magazine well should be torqued 60-80 in-lbs and I torqued it to 60 lbs after I disassembled it. I even loosened it to 40 in/lbs to see if it helped but it didn't. I also tried using an older 10 round magazine that has plenty of wear. I keep getting the same results.
Any suggestions other than calling Ruger?
Last edited by Cajun Executioner on Wed Mar 07, 2018 5:34 pm, edited 1 time in total.

BulletFlight for Android
Cajun Executioner
Silent Operator
Posts: 89
Joined: Mon May 21, 2012 2:08 pm

Re: New RRAR with AR mag issues

Post by Cajun Executioner » Wed Mar 07, 2018 4:06 pm

Another thing I just noticed when looking at the feed ramps to see if they need polishing is I can see three threads from the receiver. It looks like the barrel can be screwed in another three threads into the receiver. I've been shooting 300BLK since they first came out but this is my first bolt action in BLK and it's my first RARR. Do you see the threads on the older RRAR's receivers?

User avatar
dellet
Silent But Deadly
Posts: 5969
Joined: Fri Nov 30, 2012 1:25 pm

Re: New RRAR with AR mag issues

Post by dellet » Wed Mar 07, 2018 5:02 pm

Sounds like the Amax loads are too long for the chamber. If your crimp is not too tight, you can measure a round before and after chambering to see if it got shorter. Check both the bullet length and also the base to datum line.

Take the bolt out, slide a round in and press it into the chamber with your finger, It should drop out by gravity. If not it is engaging the rifling. Make a dummy round or seat one of your existing rounds .005 shorter and check again

If it does drop out double check your base to datum length on rounds that failed and rounds that did not.

It would not hurt to double check neck diameter.
300 Blackout, not just for sub-sonics.

User avatar
dellet
Silent But Deadly
Posts: 5969
Joined: Fri Nov 30, 2012 1:25 pm

Re: New RRAR with AR mag issues

Post by dellet » Wed Mar 07, 2018 5:08 pm

Your thread title is calling this a mag issue, unless you can chamber a single round with out a problem with the mag removed, it's not a mag issue.
300 Blackout, not just for sub-sonics.

Cajun Executioner
Silent Operator
Posts: 89
Joined: Mon May 21, 2012 2:08 pm

Re: New RRAR with AR mag issues

Post by Cajun Executioner » Wed Mar 07, 2018 5:33 pm

dellet wrote:Your thread title is calling this a mag issue, unless you can chamber a single round with out a problem with the mag removed, it's not a mag issue.
I was pointing out that it's one with the new AR mags but I see how it can be taken wrong.

Cajun Executioner
Silent Operator
Posts: 89
Joined: Mon May 21, 2012 2:08 pm

Re: New RRAR with AR mag issues

Post by Cajun Executioner » Wed Mar 07, 2018 5:38 pm

dellet wrote:Sounds like the Amax loads are too long for the chamber. If your crimp is not too tight, you can measure a round before and after chambering to see if it got shorter. Check both the bullet length and also the base to datum line.

Take the bolt out, slide a round in and press it into the chamber with your finger, It should drop out by gravity. If not it is engaging the rifling. Make a dummy round or seat one of your existing rounds .005 shorter and check again

If it does drop out double check your base to datum length on rounds that failed and rounds that did not.

It would not hurt to double check neck diameter.
The AMAX are loaded shorter than the Barnes. They're also shorter from the ogive. And all the brass was sized, trimmed and prepped together. That's what has me confused. I'm going to load more at a shorter OAL when I have the chance so I can see if that helps. The only factory rounds I have are Barnes like the ones I loaded myself so that won't tell me anything.

User avatar
dellet
Silent But Deadly
Posts: 5969
Joined: Fri Nov 30, 2012 1:25 pm

Re: New RRAR with AR mag issues

Post by dellet » Wed Mar 07, 2018 5:55 pm

Cajun Executioner wrote:
dellet wrote:Sounds like the Amax loads are too long for the chamber. If your crimp is not too tight, you can measure a round before and after chambering to see if it got shorter. Check both the bullet length and also the base to datum line.

Take the bolt out, slide a round in and press it into the chamber with your finger, It should drop out by gravity. If not it is engaging the rifling. Make a dummy round or seat one of your existing rounds .005 shorter and check again

If it does drop out double check your base to datum length on rounds that failed and rounds that did not.

It would not hurt to double check neck diameter.
The AMAX are loaded shorter than the Barnes. They're also shorter from the ogive. And all the brass was sized, trimmed and prepped together. That's what has me confused. I'm going to load more at a shorter OAL when I have the chance so I can see if that helps. The only factory rounds I have are Barnes like the ones I loaded myself so that won't tell me anything.
Your max allowable base to ogive measurement will vary bullet to bullet. I t could be 1.655" on one and 1.750" for another.

Try it without the bolt and see if it hangs up. If you blacken the bullet with a sharpie you might see contact marks from the lands.
300 Blackout, not just for sub-sonics.

Mike7.62
Silent But Deadly
Posts: 171
Joined: Sun Feb 04, 2018 4:53 pm
Location: Mid TN

Re: Feeding issues with new RRAR (AR mag)

Post by Mike7.62 » Wed Mar 07, 2018 6:50 pm

I'd try a metal 20 round AR magazine from Okay, NHMTG, or another MilSpec manufacturer. I would also try a single load insert in one of these magazines and see how it works. Sinclair sells them for use in AR's and I use mine for 600 yard prone slowfire with 80 gr SMK's. It should allow you to lay a round on the magazine feed tray and load from there. They claim that this follower will work with the .450 BushMaster, so I don't see why it wouldn't with the 300 BLK.

https://www.sinclairintl.com/gun-parts- ... 34112.aspx

All that being said, if the mag works with the 110 gr Barnes, but not with the 208 Hornady, then I would suspect that the 208's are getting hung in the lands due to bullet design and placement of the ogive along the length of the bullet. IRC the 110 gr Barnes doesn't have a sharply radiused ogive, and the 208 ELD being a much longer bullet, has its ogive radius much further towards the point.

It would be good to know just how much leade that this chamber has, and where the different bullets contact the lands. Hornady makes a great gauge for this using a modified cartridge case. They bought out Stoney Point who originally made it, but it is the same thing. I use it to see just how far a bullet has to jump before contacting the lands, which allows me to seat the bullet farther out if possible, and subject to magazine restrictions unless I'm single loading.

Post Reply