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Posted: 10/24/2010 7:11:03 PM EDT
I figured I ask here for some help and see what others are running in a similar set-up.

My rifle consist of an Armalite AR10 with a Noveske 21" barrel, free floated of course and topped off with a Leupold Mk4. The Noveske 21" barrel is 1:10 poly twist.

OK what I know works or did: The rifle seemed to like 168gr factory loads - Winchester balistic tips, Hornady and Blackhills w/ SMK. The Winchesters are expensive hunting ammo that I used right after I built the rifle b/c it was all I could find, but it was accurate, easily holding 1". Hornady isn't really available so I've only used it twice - regular 168gr did well, the moly didn't settle until the last 5 rounds of the box. The rifle LOVED Blackhills 168gr SMK easily holding under an inch with a best of .5" repeated several times. The problem was these loads seemed hot and I was having issues with popped primers. All test were 5 shots at 100 yards off a bench w/ bipod.

My problem: I want to have better reach* and for that I'm looking to go with 175gr SMK. I've bought some Remington match ammo with the same bullets as a base line. My components are Win, Blackhills and Remington brass, the 175gr SMK, Varget powder and Win and now CCI primers.

The Remington factory ammo is holding about a 1" 5 shot group at 100 yards and runs ~2640fps @ 15ft over the chrony. NO pressure signs. My latest load is 175 SMK over 43gr of Varget w/ win primer, it chrono'd ~2640fps @ 15ft (same day I chrono'd the Rem factory stuff) but will not hold less than 2" at 100 yards. POI is about an inch to inch and half under the Remington factory. So far the hotter the load the better the group while working up to 43gr but it's flatting the primers pretty good so I've stopped.

What I'm looking at doing is: 1) switch to CCI primers and rework the loads 2) go ahead and work it to 44gr of varget b/c while the primer is flat it's not popping out and the cases show no scretch marks 3) re-run my chrono test b/c I'm thinking something went wrong as the factory ammo's higher POI suggest a higher velocity 4) lastly relegate the varget to my hunting .30-06 loads and switch powders


Any insight, personal load data for a similar set-up, or suggestions are welcomed.

*- by reach I mean pass 600 yards, that's the furthest I've pushed the 168s and would like to go 800+.

Link Posted: 10/25/2010 6:43:40 AM EDT
[#1]
I run an 18" Noveske barrel on my AR10.

Your POI shift may not be due to velocity difference but due to the different pressure curve so your barrel is vibrating differently.

The bullet is probably leaving the barrel at a different point in time and the barrel is flexing differently as it exits the barrel.

Blown primers are bad but flattened primers in an AR10 are not always a sign of overpressure.

I can run 43 grains of Varget safely in LC brass with 175 SMKs but the brass can get beat up.

If I run 43 grain loads in Federal brass, I will find primers in my trigger assembly which is no good.

I also switched to a Slash extra heavy buffer and it helps with slowing down the extraction and stretching the brass before it contracts.

What do you mean by visible stretch marks on your brass?

You can only really tell incipient case head failure by using a paperclip.
Link Posted: 10/25/2010 12:34:57 PM EDT
[#2]
168's will shoot to 800 yards without problems. It's further than that when things get dicey.

Don't try to run the 175's as fast as the 168's. If you can get better groups at lower velocities don't worry about it. As long as you are 2550 fps +/- you'll be fine.

Try some other powders, namely;

IMR-4064
IMR-4895
RE-15
VihtaVuori N-140
VihtaVuori N-540
H-4895

Some rifles just prefer a different mix of components. I load 41.0 grains of IMR-4064 for 168's and 175's when using Lake City brass. You can go up a grain if you are using Winchester.

40.0 grains of H4895 and 40.5 grains of IMR-4895 will work with Lake City brass too. I use Winchester standard large rifle primers.

I can usually get good groups anywhere from 2500 fps to 2575 fps with any of these powders.
Link Posted: 10/25/2010 12:40:05 PM EDT
[#3]
BTW - 44.0 grains of Varget is a hot load in a bolt gun. Semi-autos cannot hold up to those kinds of pressures. The gas system will cycle too soon and too violently.

The other poster suggested Slash's buffers, and I do too, provided you have a collapseable stock. Otherwise run an AR10 rifle buffer. You can slow those down with Tubb's Carrier Weight System.
Link Posted: 10/25/2010 7:47:33 PM EDT
[#4]
Quoted:
I also switched to a Slash extra heavy buffer and it helps with slowing down the extraction and stretching the brass before it contracts.

What do you mean by visible stretch marks on your brass?

You can only really tell incipient case head failure by using a paperclip.

On stretch I meant extraction issues, like pulling the round out while there's still too much pressure. Damage case rims, etc.

I haven't really trusted only the paper clip method so I've pulled a few fired cases per headstamp and cut them in half and measured the web. Probably not necessary but I do that every go around.

Magpul PRS w/ rifle tube and buffer so no options from Slash but it's not like my rifle is beating brass or slinging them far away either. Nice little pile at 3-4 o'clock about 6ft away.

I think I'm going to restart from scratch.
Link Posted: 10/26/2010 3:58:31 AM EDT
[#5]
start at 39 g varget and work up in .5 g increments , mine likes 41.5 varget
Link Posted: 10/26/2010 5:42:26 AM EDT
[#6]
Quoted:
Quoted:
I also switched to a Slash extra heavy buffer and it helps with slowing down the extraction and stretching the brass before it contracts.

What do you mean by visible stretch marks on your brass?

You can only really tell incipient case head failure by using a paperclip.


I haven't really trusted only the paper clip method so I've pulled a few fired cases per headstamp and cut them in half and measured the web. Probably not necessary but I do that every go around.

Magpul PRS w/ rifle tube and buffer so no options from Slash but it's not like my rifle is beating brass or slinging them far away either. Nice little pile at 3-4 o'clock about 6ft away.


The case web does not have anything to do with incipient case head separaton as the crack will occur higher up on the case.

I am not sure why you guys think that Slash does not sell a heavy buffer for rifle tube AR10s.

I run the following Slash .308 Rifle Buffer with my PRS and rifle tube.

http://www.heavybuffers.com/ar10rifle.html
Link Posted: 10/26/2010 11:00:17 AM EDT
[#7]
Thanks for that link. I purchased his heavy AR10 carbine buffer and at that time he didn't show a rifle version. It wasn't that long ago either. It looks like his website has been changed too.
Link Posted: 10/26/2010 1:11:04 PM EDT
[#8]
Quoted:
Thanks for that link. I purchased his heavy AR10 carbine buffer and at that time he didn't show a rifle version. It wasn't that long ago either. It looks like his website has been changed too.


No worries

I think I have had mine in the rifle for a good 3 months or so and no issues.

I still haven't found an awesome load for the rifle but that is part of the fun.
Link Posted: 10/27/2010 7:03:53 PM EDT
[#9]
Thanks for the link for the buffer, I may give that a try just for the heck of it plus I'd like to surpress the AR10 down the road too.

Thanks for the suggestion, I'll start at 39gr again and rework the loads. If there's no love I'll go back to 168 SMK, maybe go 168 A-max.
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