Extreme Cold Bore Shot Problem

[farmer7]

I've turned the nuts another 1/8th and closed them down and will retest today. I did try turning two flats but it took a huge amount of force to close the front one and then had huge difficulty getting it open with a small piece of bar levering it open, the rear one was impossible to close. When mounting I did always ensure to hold the mount forward as I tightened.

As for trying different mounts this was the only quality cantilever mount I could find, I dont know what they cost you guys over there but here it cost £185 ($305). The other brands you mention Redmanss I would probably have to import myself (if they're not ITAR regulated, which I suspect they will be. Mighty dangerous thing a scope mount! ) As for the QD function its of no use to me just all that was available!

Thanks again, I'll let you know how it goes.

 

[Redmanss]

God I hate ITAR sometimes...

 

[farmer7]

Pleased to say it appears to be thoroughly fixed!

I shot it this morning all 5 into .7" with no flier. All over an 1/8th of a turn of a nut! Obviously on the trip home each time previously something must have been moving slightly and the first shot was slamming it back up against the recoil lugs on the mount.

Just for reference if anyone in future finds this rather long thread about some stupid guy with a cold bore issue and is using an ADM mount, there appears to be a big difference in closing the levers tight and closing them tight using considerable force. There was no sign on the rifle rail or underneath the mount of any apparent abrasion from movement but there must have been some small amount of movement all the same. And to top it off it had returned to zero exactly on re-mounting, I thought the extra 1/8th turn may have increased tension and moved it slightly.

Thanks all who helped me out, its much appreciated. I'd buy you all a dram if I could! Thanks again.

 

[EddieP]

If you didn't live so far from Liverpool I'd take you up on that. Glad you fixed it, I can imagine how frustrating it must be.

Sent from my GT-I9100 using Tapatalk

 

[tickled pink]

I recently bought a new AR which suffers from extreme cold bore issues.

It groups pretty well averaging 0.7 MOA for 5 shots with some groups a lot better. But without fail the first shot of the day is hitting low by 3.5 inches at 100 yards with subsequent shots grouping together on zero. None of my other rifles suffer from cold bore problems or if they do its less than half an inch.

I have a ASE Utra CQBS supressor fitted, barrel is 18" semi-heavy 1 in 8". Fore end is a Samson Evo 12.37". Ammo is handloads using 73gr Berger LTB's.

Has anyone heard of such extreme shifts for cold bore? (Its cold bore, not a cold clean bore, I always fire a few foulers after cleaning).

Other than noting the impact of the first shot and correcting for it is there anything you can do to alleviate this in anyway? Is it likely to improve with a few more rounds through it?

I plan on using it for fox shooting and other long range varmints. Just cant quite believe it shifts so far for the first shot!

Any thoughts or opinions?

Thanks!

I do not know if anyone has told you about this.

OK first off you will need to change to using moly coated bullets or pre foul your barrel. When I was into High Power I found that most ARs would not shoot bug holes with a clean barrel. Most ARs needed about 8 to 11 fouling shots without moly coated bullets before they would shoot bug holes. With the moly coated bullets it would take my rifle 3 shots and then it would shoot bug holes. So what I would do after shooting my 80 plus shots in competition I would clean my Bushmaster DCM that would shoot 10 shot groups under 1/2" consistently at 100 yds. Then I would shoot 3 shots with moly coated bullets and then I was ready for competition right from the first shot the next time I competed. With a clean bore my rifle would shoot 3/4" group for the first group. If you guys don't believe me try it yourself. IT REALLY WORKS. This should eliminate your first bad group. So if you don't like to use moly just shoot about ten shots and don't clean your barrel for the next outing.

PS: Farmer7, Try my foul bore system and see if you can get your groups down under 1/2". I bet it will help.

 

[WaveNature]

Good to hear you got it worked out.

 

[0311 Hesco]

Yea, I am glad it worked for you too, man. I was def. wrong here; my bust!

 

[MoBoost]

I'm glad you got it sorted out. I was never a fan of cam-style scope mounts.
I use one of these when I shoot my AR if F-Class. It's simple and robust and lets me use any of my scopes with decent rings (and it's 20MOA).
Weaver AR Flat Top Riser Rail 20MOA FREE S&H 99675. Weaver AR15 Accessories.

 

[farmer7]

Thanks all, just to further confirm on further testing it is now perfect, no issues!

Good to hear you got it worked out.

You and several others were right on the money! It seems, on some rifles at least, the ADM mount benefits from being closed as tight as you possibly can. And as an extra bonus right on zero too! Thanks again.

 

[AZ2000]

Excellent, glad you got it solved and everything worked out for you.