155g Nosler custom Comps

[StoneTower]

I have about 4000 155g Nosler custom Comps that I am going to shoot in my Ar-10 upper (20" Eagle arms) on my Noveske lower. So far I have worked it up to about 2MOA and 100 yards with 44.6g of Varget and a Fed 210 primer (OAL 2.800). I started at 42g and it was shooting 2.5 - 3 MOA

I have "The complete Reloading Manual for the .308 Win" which is a collection of load data from different manufactures. The groups seem to be getting smaller as I work up in powder charge but I expected way better from that upper. The Nosler custom comp. is basically a copy of the Sierra BTHP and Nosler said to use Sierra's their data.

I see some load data that has the OAL at 2.775. Could this help me shrink my groups by seating deeper? I also see a max load in some of the load data of 47g of Varget. Should I go higher of the powder charge? I have yet to see any signs of pressure. I do have some blackened case necks which I believe could be a sign of low pressure and the case not expanding enough to seal the chamber before the bullet leaves the case.

What do you guys think?

Thanks,

David

[buffybuster]

Have you shot this upper with a known accuracy load (FGMM)? If so, what results did you get? Have you let someone else, that you know is a good shooter, also shoot this load?

Just trying to narrow down the variables. Chances are you're going to run out of magazine length before you run into the throat.

[Jicko]

Get some known good ammo and figure out how good your gun can do first... (or if there is any issue with your gun, for example, loose barrel nut etc..)

So, get a box FGMM 168SMK or FGMM2 175SMK, and shoot them thru your gun and see what group size you are getting first..... that will be the first start for your gun...

Get your reload to match that same performance and then work on getting them better.

NCC 155 is very similar if not identical to the OLD SMK 155 model #2155 (the new one model #2156 has a better BC).

Lastly, is your gun chambered in 762NATO or 308WIN? If you gun is chamber for 762, try not to use 308's max load... theoretically, that is NOT safe.

[JTROKS]

Nice Avatar dude. What is your barrel's barrel twist? It's been a while since I loaded up some 308 w/ Varget powder, is it almost full or way below the shoulder. Usually seating the bullets deeper to keep the podwer compressed helps with accuracy a bit, keeps a consistent position on the powder for a more uniform pressure shot after shot. When I load with Varget for my bolt Remmy PSS I seat long just enough for the rounds to function in the magazine.

[StoneTower]

Ok, I have yet to shoot any factory ammo in the gun. That may be the next step.

I believe that all ArmaLite/Eagle Arms AR-10 uppers are chambered for .308 so I should be ok there.

The barrel length is 20" and it has a 1 in 11.25 twist if I remember correctly.

I can do a lot a playing for the cost of a box of Federal FGMM. (Read FRUGAL)

I have heard that with some guns, Varget goes from not good to great in as little as 3/10 of a grain. I was also curious about seating depth as usually people want to get the bullet close to the lands, but as I understand it, you will run out of mag length with a factory Armalite upper before you even get close. To add to this a 155b bullet is shorter than the 168 and larger bullets whigh puts it even farther back. I know that a general rule is to seat at least the diameter of the caliber into the neck. I believe that 2.800 is not .308 into the neck. Could seating to 2.775 (.025 deeper help in any way and what will it do for the pressure).

One last thing...44.6g which is the most I have tried is below the neck. 45g is listed as compressed in some of the data I have. 47g is listed as max in the Hodgdon load data for a 155g bullet.

Thanks,

David

[Timberwolf]

There are way to many variables to your equation to give you a solid answer. You have an added caveat to the equation in that you're shooting a gas gun which in and of itself creates its own issues.

The bullet you are using was developed for Palma competition. Palma guys normally launch the 155 at around 2900 or more fps out of a 30" tube with a 1:13 twist. Rifles with a faster twist are a hit and miss. The key to accuracy though is to push them fast 2850 and above. As to how far the bullet likes to jump is a hit and miss from rifle to rifle. You will definately not be able to get it into the lands without exceeding mag length unless you have a tight match chamber which I doubt.

Take the advise of others and get a box or two of factory match ammo and see what level your rifle is at as far as accuracy. Then once your baseline is set you can start tinkering with your loads until you either achieve or exceed that baseline. Just remember no single factor in reloading makes an accurate round. Its a combination of many different factors that come together to make it and that means trial and error with your rifle, starting with known factors and working from there watching for various warning signs of pressure or other malfuntion.

[buffybuster]

There's nothing more to say until you shoot some FGMM through the rifle. Ideally, a couple of different shooters (of known ability) then average the results. That will give you reliable baseline on the accuracy of your weapon system (rifle, ammo, mounts, optic, bipod/rest, position, shooter, etc).

If you're getting >2moa groups with FGMM, then you might want to contact Armalite. If it shoots ~1moa, then the issue lies with the shooter or your load.

[30Cal]

IME, it has the same shape as the Sierra 155 (not the brand new one) and the 168. If you seat a 155 and a 168 to the same OAL, they'll be about the same distance off the lands. Neither one should be really all that sensitive to seating depth. 2.8" is probably going to work well enough in any rifle. Out of my Supermatch, it reliably shot about a minute and a half & better with irons from position, and I simply default to 0.020" off the lands for the 155/168's.

I can't comment on your charges; you didn't mention what sort of case you're using. Varget, IME, also seems to be more variable from one jug to the next. That said, 46-47grs in a commercial case, just off the top of my head, sounds about right.

[JTROKS]

When I'm using Varget I can go over the published data, but I seat my 168 SMKs deep enough so I don't have to single load. I've clocked 2750 with my Remmy PSS and it's one accurate load. Since you're loading for an auto loader you'll have to stick with data. A lot of your accuracy problem may be in your case preparation. When I did not know any better I expected range pick 223 brass of different headstamps to provide less than moa accuracy. Even once fired brass with same headstamp from surplus sold per 500/1K will not give you moa. Too many variations, you may get some of the same lot and here comes one from another and will give you a pressure spike causing your round to go higher or worst a blown casehead. Make sure all your brass you are working up a load for come from one lot. Full size, trim and if you want to go the distance anneal the cases. My R-25 grouped 2.5" with surplus 7.62 NATO ammo, with FGMM it will do moa until it needs cleaning. Now I want one with a longer tube.

[Jicko]

I can do a lot a playing for the cost of a box of Federal FGMM. (Read FRUGAL)

All the playing is kind "useless" since you DO NOT have a "control experiment". And you do waste a lot of money for your "playing".

Even if you get great results, you are just "lucky", and still you do not know if your load can do "better".

[westcoastr]

you might be surprised that a shorter OAL might shoot better, happened to me in my FAL. also repeating what timberwolf said, those palma's might not be the best for an AR-10. since you are cheap, try some hornady bulk 150 gr fmjbt, they are about 15 cents and are +/- 0.1 grains in weight! otherwise try a non-palma but match bullet.

also can try different powders.

also you never mentioned what brass you are using and the prep method.

[StoneTower]

you might be surprised that a shorter OAL might shoot better, happened to me in my FAL. also repeating what timberwolf said, those palma's might not be the best for an AR-10. since you are cheap, try some hornady bulk 150 gr fmjbt, they are about 15 cents and are +/- 0.1 grains in weight! otherwise try a non-palma but match bullet.

also can try different powders.

also you never mentioned what brass you are using and the prep method.

I am going to try several of the ideas that you guys posted. What makes the Nosler custom competition 155g a Palma bullet? What makes it any worse than any other 150g or 155g bullet? Nosler also makes them in a 168G custom competition (both are BTHP). I thought that for the Palma matches, they had to shoot a 155g bullet and it was the weight that made it ok to use in the match.

I am looking for ideas. What I will probably do next will be to bust out the some of the 2000 1964 LC match brass that I have and work up to 44.5g of Varget under a 168g Sierra BTHP and see how it does. Many guys who have Armalite AR10s have done well with that load. I am just having a hard time getting bullets in my area and I have close to 4000 of the Nosler 155g.

Just for the record, I have an Armalite 22-250 upper that I use on the same receiver and I can put 10 rounds in the size of a nickel with it. Unless the extra recoil of the .308 is causing me to flinch, I am probably not the random variable in the equasion.

[ar15barrels]

44.6gr of varget seems pretty mild.
I'm running 46.5gr under a 155 SMK in FC gold medal match brass.
I know that the Nosler and the SMK are not the same bullet because the nosler's BC is way lower.
The Nosler is probably shorter, allowing even heaftier powder charges.

[StoneTower]

44.6gr of varget seems pretty mild.
I'm running 46.5gr under a 155 SMK in FC gold medal match brass.
I know that the Nosler and the SMK are not the same bullet because the nosler's BC is way lower.
The Nosler is probably shorter, allowing even heaftier powder charges.

So Randall...do you think the Nosler 155g BTHP would work ok in a 11.25 twist 20" Armalite barrel or am I just barking up the wrong tree (with the wrong bullet)? I know that they are not the best, but I thought that I could get them to shoot at < 400 yards ok.

Have you ever seen where raising the charge just a few grains will tighten up the group say from 2.5MOA to < 1MOA?

With your experience and the fact that the Nolsler bullet may be shorter... is there anything to be gained by seating to 2.775 COAL rather than 2.800 COAL which I have been? If so, do I need to back off the powder as it may raise the pressure?

Thanks,

David

[30Cal]

http://www.sierrabullets.com/bullets/BallisticCoefficient-rifle.pdf

Sierra 155gr BC=0.450

http://www.nosler.com/index.php?p=11&b=5&s=4&t=30cal

Nosler 155gr BC=0.450

I've shot a couple hundred through my old 1:10" barrel and they did well. They also do well out of the 1:12" that I'm using now.