Double Grouping on Reloads?

Well, since my AR is set up for service rifle match shooting it has iron sights, I just automatically assume the same of others until told otherwise. Yes, the scope seems like the obvious suggestion, now that someone else thought of it. You've probably got something in the system (scope or base) that has two fairly stable positions that it tends toward. All the way left or all the way right. Recoil is apparently knocking it from one extreme to the other. The exact recoil profile for the powder and bullet used may tend to cause it more.

If you are at the range again with this load, after each shot, bang on the left side of the receiver with your palm, and push the scope and base left before each shot and see if the group doesn't tend to stay put. Then try it on the other side to see if it moves over.
 
I don't have anything in a 168gr bullet although I did just start a load development using the Hornady 168gr BTHP and IMR 4895 .

I don't use Varget and only use H335 for my AR . The powders most used for that rifle are IMR 4895 & 4064 . I've tried RL15 but not enough to have an opinion yet .

I almost exclusively use 175gr smk and 178gr A-max . Both the loads I use for those are on the light side because I found early on loads that shot well and never pushed to find something else at a higher charge .

175gr smk
40.7gr IMR 4895
Win LR primer
WCC-06 cases

178gr A-max
40.3gr IMR 4064
Win LR primers
Rem cases

If I were to go give my log book a good looking through . I'd find many other loads that work . I've used Power Pro 2000mr , N540 & 550 , 8208 xbr and RL-15 all with very good results .

N540 and the 190gr smk comes to mind as being a very good combo but I only had 2lbs of the powder . For the most part that's why I use 4895 & 4064 most . It's the powder that's most available to me .

Torque on the action screws is 35lbs on the front , 30lbs on the rear . 20lbs on the front and 15lbs on the rear worked maybe better but I felt that was to light for this type of bedding system . That's not a fact just a feeling . Savage calls for 40lbs on each if you like keeping thing by the book .
 
Last edited:
I vote scope problem--probably a minor variation inducing thing since for the most part it still gets you on target. I recently starting having problems with a couple of my scopes--both recent and fairly expensive purchases--and after finding the rings and mount were secure started looking at the scopes themselves and was surprised to find things like loose turrets--I'd check to make sure your adjustments are consistent with scope indicators. I've seen a dip in the quality of optics I've bought recently.
 
I have had the same issue with my Savage 12 F/TR in .223.

In my head- carbon, copper, powder (although I clean every 20 shots). I will check my action screws, mounts and rings tonight. If anything amiss, rifle goes to the range Saturday. If all ok, I will swap out scopes and give it a whirl on Saturday with a different scope.
 
Check your parallax....I've experienced this before and it if wasn't a scope, or base/ring issue it usually ended up being an operator error involving my parallax adjustments.
 
Demon :

Were you able to confirm your parallax caused you to have double groups ? It seems hard to believe that's even possible . I understand the concept but to be SO consistently inconsistent to shoot two different groups in the same string do to your cheek weld/hold seems not likely . I can see not having very tight groups because of parallax issues but to hold the rifle perfectly two different ways causing two separate groups in a string would be pretty impressive if it weren't such a bad thing . :D

That to me means you're on your way to being a world class shooter . Just a couple tweaks and you'll be setting records in no time .
 
It always has been bedding problems in my case. Something started touching something else when the gun became hot. Barrel, barrel channel, upper handguard are usual suspects.

-TL
 
It was easy to fix once I figured out the problem....My eyes aren't that great any more so when the target is in focus the parallax is out of whack...so if I'm not wearing glasses that help me focus, the target will almost always be out of focus when the parallax is adjusted properly.....it doesn't take much movement either direction to throw the crosshairs off due to parallax.....
 
Damon555 said:
It was easy to fix once I figured out the problem....My eyes aren't that great any more so when the target is in focus the parallax is out of whack...so if I'm not wearing glasses that help me focus, the target will almost always be out of focus when the parallax is adjusted properly.....it doesn't take much movement either direction to throw the crosshairs off due to parallax.....
Click to expand...
That shouldn't happen. There may be something wrong with how you adjust your scope.

You adjust the focus so that the crosshair is in focus. Then you adjust the parallax while focusing on the crosshair till the target image is the clearest, i.e. the image is right at the crosshair. Double check by moving your eye off the scope's axis, the crosshair should stay at the same spot on the target.

-TL
 
I had this issue with a marlin 25m .22 mag. 2 shots touching, next 2 touching 3/4" from the first 2. This rifle only has one action screw. So, added an action screw, pillar bedded the action, and lo and behold, 1/4" to 1/2" groups. Since that experience, I always check scope and mounts first, then look to the action. now, this was just a rimfire, but the principles are the same. On an AR, after the scope, I would look into the barrel nut, then wouldn't know where to look.
 
I've had double grouping problems on several AR's, each one ended up being a magazine feed lip or feed ramp issue.
An easy way to know is if the 1st-3rd-5th shot hit in one spot, and the 2nd and 4th shot hit in another. I start by sanding any sharp or rough edges off the feed ramps on the barrel extension, and if it continues, change the magazine or adjust the feed lips on them.
 
Txhillbilly : oh you have to elaborate on that . I''ve heard of mags in old M-14 having POI shift do to different mags . This has to do with how they fit and the real tight ones would cause the barrel harmonics to change compared to the real loose ones .

How would feed ramps effect any type of accuracy other then maybe gouging the jacket resulting in and inconsistent bullet ? Please be very detailed as to how this works :)

Thanks Metal
 
Last edited:
You must log in or register to reply here.
Back
Top