Doing My Very First Reload w/ Sierra 125gr OTM-Advise Please

Moderators: gds, bakerjw, renegade, bamachem

Setxwarrior
Silent But Deadly
Posts: 176
Joined: Tue Jan 08, 2013 1:13 am

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by Setxwarrior » Wed May 08, 2013 8:23 pm

I'm getting similar results using 17.2gr of H110, 2.22OAL. I started at 17.8 and worked down by .2. @ 17.0 the groups started opening back up.
Image

BulletFlight for Android
User avatar
StorminNormin
Silent Operator
Posts: 78
Joined: Mon May 28, 2012 4:12 pm
Location: Austin, TX

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by StorminNormin » Wed May 08, 2013 10:09 pm

Setxwarrior wrote:I'm getting similar results using 17.2gr of H110, 2.22OAL. I started at 17.8 and worked down by .2. @ 17.0 the groups started opening back up.
Image
The highest load I have done is 17.2gr. I did not see any signs of pressure so I guess I could go higher to see what happens.

Two questions fo you:

1) Why would you start at 17.8 and work down? From what I have read, 17.2 is listed as the max load so I am wondering why your first load would be above the max load. From what I know, you are suppossed to start low and work your loads UP.

2) How was the accuracy above 17.2? Is 17.2 what you settled on?

Setxwarrior
Silent But Deadly
Posts: 176
Joined: Tue Jan 08, 2013 1:13 am

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by Setxwarrior » Thu May 09, 2013 11:58 pm

StorminNormin wrote:
Setxwarrior wrote:I'm getting similar results using 17.2gr of H110, 2.22OAL. I started at 17.8 and worked down by .2. @ 17.0 the groups started opening back up.


The highest load I have done is 17.2gr. I did not see any signs of pressure so I guess I could go higher to see what happens.

Two questions fo you:

1) Why would you start at 17.8 and work down? From what I have read, 17.2 is listed as the max load so I am wondering why your first load would be above the max load. From what I know, you are suppossed to start low and work your loads UP.

2) How was the accuracy above 17.2? Is 17.2 what you settled on?
What? You couldn't read my mind? Sorry, should have been much more clear.
1) I had already checked up from 17.0 to 17.8 in 0.2 increments, checking only for feed, function and pressure signs only.
2) Then while checking accuracy, it quickly became clear that as I moved down in charge the groups were improving. Here is 17.0 (yes, I settled on 17.2).
Image

Don't know why the pics are upside down. All groups are 6rds, using an AAC 16" upper and Nikon P300 optic.

nainkaigo
New Member
Posts: 5
Joined: Fri May 10, 2013 8:24 am

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by nainkaigo » Fri May 10, 2013 8:45 am

I am glad to see this thread! COAL for the 125gr OTM is something I have been struggling with. Last week I loaded up a number of rounds with a COAL of 2.21" like many others have. While the bullets shot well (I ran into ejecting issues, but I think I have an extractor problem as the bolt holds open on an empty mag), I found they did not stack well in a PMAG (Gen 2). The bullets were tipped in a fair amount. When putting one bullet on top of another I found the one below it tended to move freely forward and backward in the magazine. When I had 15 in the mag I could bang it and have rounds pop out.

Fast forward to yesterday and I received a Sheridan 300BLK gauge. When putting my bullets seated to 2.21 in the guage they did not pass. I realize it may be because at 2.21" the bullet is being pushed into the rifling. I kept pushing the bullet in until it would pass the guage. I found the COAL ended up being 2.16". I loaded up a handful like that to see how they would stack in a PMAG. They fit flawlessly. They stacked just like a normal .223 would. I measured the ogive of the bullet where it touch the rib in the PMAG and it was ~0.26" which is fairly close to the neck of a .223 case.

I have yet to shoot the bullets seated at 2.16". I was wondering if anyone else ran into a similar issue and if 2.16" is acceptable as it seems to offer the best feeding out of a PMAG?

User avatar
StorminNormin
Silent Operator
Posts: 78
Joined: Mon May 28, 2012 4:12 pm
Location: Austin, TX

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by StorminNormin » Fri May 10, 2013 11:08 am

nainkaigo wrote:I am glad to see this thread! COAL for the 125gr OTM is something I have been struggling with. Last week I loaded up a number of rounds with a COAL of 2.21" like many others have. While the bullets shot well (I ran into ejecting issues, but I think I have an extractor problem as the bolt holds open on an empty mag), I found they did not stack well in a PMAG (Gen 2). The bullets were tipped in a fair amount. When putting one bullet on top of another I found the one below it tended to move freely forward and backward in the magazine. When I had 15 in the mag I could bang it and have rounds pop out.

Fast forward to yesterday and I received a Sheridan 300BLK gauge. When putting my bullets seated to 2.21 in the guage they did not pass. I realize it may be because at 2.21" the bullet is being pushed into the rifling. I kept pushing the bullet in until it would pass the guage. I found the COAL ended up being 2.16". I loaded up a handful like that to see how they would stack in a PMAG. They fit flawlessly. They stacked just like a normal .223 would. I measured the ogive of the bullet where it touch the rib in the PMAG and it was ~0.26" which is fairly close to the neck of a .223 case.

I have yet to shoot the bullets seated at 2.16". I was wondering if anyone else ran into a similar issue and if 2.16" is acceptable as it seems to offer the best feeding out of a PMAG?
What type of firearm are you using? I am using a Noveske 10" 300 BLK and at 2.210" the rounds fit perfectly in the PMAG magazine and all feed and eject fine. At 2.210" the ogive of the bullet touching the rib is right at ~.25". In the end, whatever works for you is what you will want to use.

What type of ejection issues were you having?

nainkaigo
New Member
Posts: 5
Joined: Fri May 10, 2013 8:24 am

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by nainkaigo » Sat May 11, 2013 12:00 am

I am using a mix of parts. I am using a Spike's 10" Lothar Walther barrel. The ejection issues I have been having is that the bolt will lock back on an empty mag but will not eject the spent case. If I load more than one round in the mag it just crams the next round into the spent case. I haven't quite figured out the problem yet. I am going to try another BCG this weekend and see what happens.

If I manually operate the bolt it will eject just fine.

As for the seat depth, I measured the inside of my PMAG and the rib is about 1.575" from where the bullet sits to the rib. With COAL at 2.16" this puts it at the 0.26" diameter on the bullet. At 2.21" the diameter is 0.29"

Maybe it is something with the PMAGs I am using.

User avatar
StorminNormin
Silent Operator
Posts: 78
Joined: Mon May 28, 2012 4:12 pm
Location: Austin, TX

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by StorminNormin » Sat May 11, 2013 12:32 am

nainkaigo wrote:I am using a mix of parts. I am using a Spike's 10" Lothar Walther barrel. The ejection issues I have been having is that the bolt will lock back on an empty mag but will not eject the spent case. If I load more than one round in the mag it just crams the next round into the spent case. I haven't quite figured out the problem yet. I am going to try another BCG this weekend and see what happens.

If I manually operate the bolt it will eject just fine.

As for the seat depth, I measured the inside of my PMAG and the rib is about 1.575" from where the bullet sits to the rib. With COAL at 2.16" this puts it at the 0.26" diameter on the bullet. At 2.21" the diameter is 0.29"

Maybe it is something with the PMAGs I am using.
Are you using a H or H2 buffer?

nainkaigo
New Member
Posts: 5
Joined: Fri May 10, 2013 8:24 am

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by nainkaigo » Sat May 11, 2013 12:54 am

H2, my brother has an H I can try. I may give that a shot this weekend too.

This rifle assembly has been a nightmare. Between damaged parts, lost orders and parts availability, I am ready to be done with it! Just need to work out the last couple of kinks.

User avatar
StorminNormin
Silent Operator
Posts: 78
Joined: Mon May 28, 2012 4:12 pm
Location: Austin, TX

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by StorminNormin » Sat May 11, 2013 1:57 am

nainkaigo wrote:H2, my brother has an H I can try. I may give that a shot this weekend too.

This rifle assembly has been a nightmare. Between damaged parts, lost orders and parts availability, I am ready to be done with it! Just need to work out the last couple of kinks.
For a pistol legnth gas system, you want to run an H2 buffer in it and that is what I run in my 10" BLK.

I guess you will have to see what happens when you try the new BCG. If it works with the new GCG then it could be the extractor, or it could be the screws on the bolt carrier key were not staked properly and came loose. These are a few of the things I can think of with it ejecting just fine manually but not with a loaded mag.

nainkaigo
New Member
Posts: 5
Joined: Fri May 10, 2013 8:24 am

Re: Doing My Very First Reload w/ Sierra 125gr OTM-Advise Pl

Post by nainkaigo » Sun May 12, 2013 7:22 pm

I figured out the problem. I had to add an o-ring to the extractor and now it works perfectly. I tested the bullets seated to 2.16 and they seemed good. They did feed very well. I didn't have my chrony with me so I am not sure what the velocity was. They do stack better in a pmag. I will need to try standard USGI mags and see how they function in those.

Post Reply