Range Report: DPMS LRT-SASS 7.62 x 51 (new)

[Retro]

Picture of the groupings is posted here:

http://www.pbase.com/dsfsadfsadf/image/121345229

Range report:

Rifle: New DPMS LRT-SASS 7.62 x 51 upper, CMMG Lower, 1/10 twist, 18-inch bull fluted, stainless blackened factory barrel, Magpul precision stock.

Scope: Super-Sniper 15 x fixed power with La Rue SPR-19.3 scope mount

Trigger: 2.5 lb adjustable Geisselle trigger

Modification: Upper receiver is screwed in tightly with the lower receiver, no play at all.

Position: Front –Harris Pod (with La Rue bipod adaptor), Rear-sandbag, at bench

Interval: 2 minutes between each round with constant cheek weld, Magazine-fed

Range: 100 yards

Wind: 5 mph

Weather: misty and cloudy, 45 degrees

Ammo:
Center group: 5-rds, sighting in, Igman M118 surplus “match grade” 168 grain FMJ, 5 rds
R upper group: 5-rds, Igman FMJ, 1.1 MOA (4-rd cluster) with single 1.5 MOA flier (1st rd)
L upper group: 4-rds, American Eagle, 168 grain OTM, “For MIA use”, 1.1 MOA
L lower group: 5-rds, Igman FMJ, 1.0 MOA (4-rd cluster) with single 1.5 MOA flier (1st rd)
R lower group: 5-rds, Hornday 168 grain TAP BTHP, 0.8 MOA

Comments:

I could not explain the consistent 1st round flier with Igman M118 surplus match ammo. First round is fed by pressing the bolt release, and if it is the cause, then why didn’t it happen to Hornady and AE ammos? All groups are started with cold barrel at 1st shot.

Opinions regarding the flier problem will be appreciated.

 

[jpwilly]

Did you clean between 5 shot groups? Nice shooting by the way. The rifle, if it's new, is still not broke in yet. If your cleaning between groups expecially with certains solvants that can act like lubricant you could very well have 1st shot flyers.

 

[Retro]

jpwilly, thanks! I avoided cleaning the barrel at all for the 1st 40 rounds. I am with the Gale McMillan's school of thought. No no cleaning between groups. And order of the groups are listed from top to bottom with Hornady being the last group.

 

[jpwilly]

Okay, I can only say what you have probably already thought. Shoot a few more groups with the Igman and see if you get duplicate that same first round flyer or if you average 1 flyer per 5 shots taken etc. Could be that your rifle doesn't like something about the Igman ammo. There are so many variables that it's really hard to guess from where I'm sitting. Others will chime in and maybe have an answer for you.

 

[Retro]

Actually, I went back to all my groups with other rifles shooting Igman M118, there are consistent 1.5 - 2.0 MOA fliers, which I could not quite explain.. My own take is that by feeding with bolt release pressed, the 1st round may be bent a little bit during feeding, hence causing the flier. Then the question is why is 7.62 Igman prone to this and not the 308 commerical loads.

 

[Retro]

any other thoughts?

 

[Maverick223]

My best guess would be the standard "cold bore" phenomena (though this is typically a result of fouling, not temperature); but you may want to try inserting the first round by hand into the chamber (heck you may want to single feed all the shots for one group), also try burning the first shot then shooting a group. It appears to me that it is pulling one shot on all the groups (including the Hornady).

 

[Retro]

Yeah, I was gonna try that. Btw, that shot from the hornady group was the 5th shot, and it was because I was rushed because the range was about to go cold.

 

[Maverick223]

Btw, that shot from the hornady group was the 5th shot, and it was because I was rushed because the range was about to go cold.

Gotcha, in that case it looks like Hornady is the good stuff for you.