6.8 SPC Forums banner
1 - 8 of 8 Posts

·
Premium Member
Joined
·
10,810 Posts
-http://www.ar15techforums.com/BBS/showthread.php?t=89

New rifle setup- non match grade

A work in progress

I am not going to get into sights and triggers or any accessories, just basic setup.
First get the rifle ready to shoot, clean the barrel bore, Hoppes #9, Eliminator etc. no need for copper cleaner yet. After the bore has been cleaned run a alcohol patch down the bore
a few times to remove the solvent, then a patch with light oil, rem oil, wd40, etc then a dry patch to remove the excess oil. This just makes sure the barrel is clean with no grit in the bore to destroy it with the first shot.
While the carrier is out remove the bolt from the carrier and apply a little white grease or Tetra to the tail of the bolt behind the gas rings, it will clean up easier later. Coat the carrier rails with white grease, Tetra or Mobil 1 etc.

Hit the range and test fire the rifle for function, don't worry about accuracy or sighting in yet, if possible within rules at your range fire it pretty quick to test function at speed as most feed and fire fine when slow fired. If it eats everything you feed it fast then leave it as is, clean it well and start sighting it in, if not see below.

IMO everyone as soon as they buy or build a rifle or mags should load a few in the mag insert the mag in the lower and slowly let the carrier come forward pushing the cartridges out of the mag to see where the bullet tips hit, paying attention to the mag feed lip and carrier relationship. If there is a problem return the mags or tweek the front of the mag lips up CAUTION- bend a little at a time and check the feed, if they are bent too far it is very difficult to get them back down. Only bend about 1/32" at a time.without hitting the bottom of the carrier. The mag lips must be straight not wavy sloping up to the front so it is best to use pliers with wider jaws. If everyone did this we wouldn't have to worry about M4 ramps.
The tips of my bullets pass through the bolt lug notch at the top of the feed ramp, the tips never touch the feed ramps. With the 6.8 I use only PRI mags the older non waffle mags do not need to be tweeked to get to this point the new waffle mags need to be tweeked a little.
If the tips of my bullets hit the alum they are being damaged, I don't want damaged bullets so I tweek the mag lips to make the cartridges feed properly.
If the mag well is very large like POFs Gen IIs then if you pull back on the bottom of the mag like you see all the tacticool guys doing the mag pivots and points the feed lips down and the bullets hit low. There are many things that can make cartridges misfeed.
The upper receiver group has very little to do with feeding, the carrier and bolt can't move up and down or side ways, no adjustment there. The barrel is at a fixed height above the lower and inline with the bolt and carrier so there is no adjustment there. 99% is related to the mags or mag well including the mag catch button.
I want my mags to sit as high as possible in the lower, mag lips just barely touching the carrier bottom but they need to slope rear down /front up to aim the bullet as high as possible.
If the follower nose dives it couls also cause the bullet tip to hit low, anti tilt followers is the first step, the mag spring tweek below helps.

Typical mag and cartridge position I try to achieve, notice the tip of the bullet goes through the lug slot and does not hit the ramp.

Before spring tweak-

After spring tweak-


that is some of it.
 

·
Registered
Joined
·
793 Posts
Sticky! Sticky! Sticky!
 

·
Registered
Joined
·
147 Posts
-http://www.ar15techforums.com/BBS/showthread.php?t=89

New rifle setup- non match grade

A work in progress

I am not going to get into sights and triggers or any accessories, just basic setup.
First get the rifle ready to shoot, clean the barrel bore, Hoppes #9, Eliminator etc. no need for copper cleaner yet. After the bore has been cleaned run a alcohol patch down the bore
a few times to remove the solvent, then a patch with light oil, rem oil, wd40, etc then a dry patch to remove the excess oil. This just makes sure the barrel is clean with no grit in the bore to destroy it with the first shot.
While the carrier is out remove the bolt from the carrier and apply a little white grease or Tetra to the tail of the bolt behind the gas rings, it will clean up easier later. Coat the carrier rails with white grease, Tetra or Mobil 1 etc.

Hit the range and test fire the rifle for function, don't worry about accuracy or sighting in yet, if possible within rules at your range fire it pretty quick to test function at speed as most feed and fire fine when slow fired. If it eats everything you feed it fast then leave it as is, clean it well and start sighting it in, if not see below.

IMO everyone as soon as they buy or build a rifle or mags should load a few in the mag insert the mag in the lower and slowly let the carrier come forward pushing the cartridges out of the mag to see where the bullet tips hit, paying attention to the mag feed lip and carrier relationship. If there is a problem return the mags or tweek the front of the mag lips up CAUTION- bend a little at a time and check the feed, if they are bent too far it is very difficult to get them back down. Only bend about 1/32" at a time.without hitting the bottom of the carrier. The mag lips must be straight not wavy sloping up to the front so it is best to use pliers with wider jaws. If everyone did this we wouldn't have to worry about M4 ramps.
The tips of my bullets pass through the bolt lug notch at the top of the feed ramp, the tips never touch the feed ramps. With the 6.8 I use only PRI mags the older non waffle mags do not need to be tweeked to get to this point the new waffle mags need to be tweeked a little.
If the tips of my bullets hit the alum they are being damaged, I don't want damaged bullets so I tweek the mag lips to make the cartridges feed properly.
If the mag well is very large like POFs Gen IIs then if you pull back on the bottom of the mag like you see all the tacticool guys doing the mag pivots and points the feed lips down and the bullets hit low. There are many things that can make cartridges misfeed.
The upper receiver group has very little to do with feeding, the carrier and bolt can't move up and down or side ways, no adjustment there. The barrel is at a fixed height above the lower and inline with the bolt and carrier so there is no adjustment there. 99% is related to the mags or mag well including the mag catch button.
I want my mags to sit as high as possible in the lower, mag lips just barely touching the carrier bottom but they need to slope rear down /front up to aim the bullet as high as possible.
If the follower nose dives it couls also cause the bullet tip to hit low, anti tilt followers is the first step, the mag spring tweek below helps.

Typical mag and cartridge position I try to acheive, notice the tip of the bullet goes through the lug slot and does not hit the ramp.

Before spring tweak-

After spring tweak-


that is some of it.
H you are the man!!! thanks for the info and pics I believe this will fix my problem I'm experiencing with my mags...
 

·
Registered
Joined
·
151 Posts
Not to be the odd man out, but I'm not having any trouble with my 25-round PRI magazine. I'm using an RGUNS mil-spec lower and a Bison Armory 16" mid-length upper. Now, I admit I have only had the rifle together for 2 weeks, and this is the only PRI magazine I own...also, I have a grand total of maybe 50 rounds downrange, not including sight-in rounds for my AimPoint, but still. Mine has so far proven reliable. What kind of troubles are you guys experiencing, generally?
 

·
Premium Member
Joined
·
10,810 Posts
Not to be the odd man out, but I'm not having any trouble with my 25-round PRI magazine. I'm using an RGUNS mil-spec lower and a Bison Armory 16" mid-length upper. Now, I admit I have only had the rifle together for 2 weeks, and this is the only PRI magazine I own...also, I have a grand total of maybe 50 rounds downrange, not including sight-in rounds for my AimPoint, but still. Mine has so far proven reliable. What kind of troubles are you guys experiencing, generally?
Some of the mags are ok, I have 7 that were fine and 3 that had flat feed lips so I tweaked them up to 5/16" above the deck and now they run fine.
If they are flat the tips of the bullet will slam into the feed ramps low and either slow the bullet going into the chamber or just completely stop it.
 
1 - 8 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top