Questions on AR10T accuracy

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11 years 4 months ago #28841 by waynzwld
Replied by waynzwld on topic Questions on AR10T accuracy
I just now rechecked the distance from the ogive of the 168gr SMK touching the rifling to the bottom of the case.
Here are the results:

Hornady OAL tool = 2.310", zeroed with the jaws of the digital caliper bottomed out on the 30 cal adapter.

Standard OAL = 2.905" tip to case head from above measurement.

Max Length for magazine = 2.820".

Therefore 2.905 - 2.820 = 0.085" off lands.

Does anyone else have their measurements?

This is the worst group:

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11 years 4 months ago #28842 by OleCowboy
Replied by OleCowboy on topic Questions on AR10T accuracy
WOW, that is really random and not sure why, especially looking at your other grouping. Whenever that has happened to me I took a break, maybe get something to eat, clear my head and reset my rifle on the bench by removing everything off the table then setting it back up. For the kind of shot you say your are (and I believe you) that could come from a bunched up shirt behind the buttstock causing the shirt sleeve to be short and pull on your trigger finger and a whole host of other variables that are often unseen.

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11 years 4 months ago #28843 by waynzwld
Replied by waynzwld on topic Questions on AR10T accuracy
Don't know why it shot one that bad unless it hates Hornady 168gr HPBT match bullets.

The worst with Sierras:

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11 years 4 months ago #28844 by waynzwld
Replied by waynzwld on topic Questions on AR10T accuracy
First time out to test it, the scope went south on me. Sent it back to Pentax and they sent me a new one.

You don't want to see those targets :S

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11 years 4 months ago #28845 by OleCowboy
Replied by OleCowboy on topic Questions on AR10T accuracy
Yea, when you want to head into sub moa space then ALL the factors become important, you cannot overlook anything no matter how small. In addition the differences in 100% identical weapons start to become vast, especially in the bbl, no too are alike to begin with, but for 99.9% of the shooters will never know nor care. At my age I am just a 'pie plate' shooter...if I can hit a pie plate at 100 yds there is not animal or man on the face of this earth I cannot 1 shot 1 kill...

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11 years 4 months ago #28847 by waynzwld
Replied by waynzwld on topic Questions on AR10T accuracy
Here is a pic of my range (before I mowed it):

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11 years 4 months ago #28849 by 13fcolt
Replied by 13fcolt on topic Questions on AR10T accuracy
That is a very nice range you got there. Even has a grill so you can grab a burger and keep on shooting.

Anyway, .085 off the lands is still too much. Maybe I missed it before, but what is your barrel length? I just noticed your mv is in the high 2400 to mid 2500. That seems a little low to me considering factory 168 loads typically run low to mid 2600 out of my 20" barrel, 2700ish out a 24". If your are running a 16" then it's about right.

Sucks being uprooted right now with all my stuff packed up, I want to say your loads are right around 2 full grains less than the sweet spot for my rifle using RL15. As always be safe, work up slow, and watch pressure. I could be completely wrong.

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11 years 4 months ago #28853 by Siscowet
Replied by Siscowet on topic Questions on AR10T accuracy

waynzwld wrote: Here is a pic of my range (before I mowed it):

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Jealous! Nice setup. Sounds like Colt gave you some good feedback. Nothing really to add except keep us informed so we can learn as well.

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11 years 4 months ago #28856 by waynzwld
Replied by waynzwld on topic Questions on AR10T accuracy
After watching that crimping video, I think I will try a heavier crimp.
I have been using only a light crimp, didn't want to deform the bullets like in the video, but
I'll see if there is a difference with that heavy of a crimp.

Hopefully next weekend I will be able to test these loads.

I still would like to know what someone else who has an accurate AR10, how far off the lands their bullet is.

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11 years 4 months ago #28857 by bipe215
Replied by bipe215 on topic Questions on AR10T accuracy
Waynzwld,

I'm in the same boat. Bought a new 20" T and I'm around 2.90 to the lands with a 168gr SMK also. Haven't been able to break the one inch barrier. Keefer and I got our rifles at the same time, they are only a few serial numbers away from each other, and he has no trouble seating close to the lands. His gun out shoots mine also. I'm wanting to try a longer, heavier bullet with an ogive shaped closer to the tip ( if that exists).

Steve

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