1st time reloading--Handbook vs Forums.

[Toddmcstiffens]

Hey folks,

I'm new to the Grendel and reloading. I just got my bench set up and was looking at the Speer manual that came with my kit. Thanks goodness I have a friend that has been reloading for many years who gave me 1/2 pound of AR-Comp and a few hundred primers(and lots of advise). The data in the Speer manual for a 120gr golddot has 22.7 min charge and 25.3 max charge. as I was researching on this forum and others I'm finding that 27-28gr for AR-Comp seems to be pretty common. I also noticed that for IMR8203xbr Nosler is calling for 25.0-27.0gr for a 123gr HPBT while Speer calling for 22.9-25.4gr of the same powder for their 120gr GD.

All of that being said... where is a good starting point for AR-Comp powder?

My rifle has a 18" Rainier Arms Match barrel 1:8 rifle length gas--(have about 150 rounds thru it able to get 5/8" groups with 123 black ELD-M red tip)

I have once fired (by my rifle) Hornady brass

I have 250 Nosler 123gr HPBT CC coming next week to load up.

Any info that would help me with a loading plan would be appreciated.

Thank you

[Klem]

Todd,

The reason there are different recommended min/max's is not simply down to bullet weight. You have two different shape and length bullets; one is a flat base and the other a boat tail. When you load them both to mag length in an AR (because of the mag length limit) they displace different volumes in the cases. This means different pressure characteristics. In this case it seems case volume is more influential than bullet weight where pressure is concerned. This is possible because they are almost the same weight. Also, they are two different manufacturers so they will have different measuring equipment and attitudes. One will be slightly more conservative than the other.

The difference between Forum and manufacturer advice is down to attitudes and responsibility toward safety. Testing equipment is also an issue. Manufacturers are likely to have all the expensive equipment to give more accurate data while Forum members look at their chronos, spent cases and broken bolts trying to read the tea leaves. Fear of litigation and reputational damage also encourages manufacturers to be conservative. Forum members are not held legally liable, plus I suspect some go quiet when their previously posted loads end up breaking a bolt. That said, long term Grendel shooters end up appreciating what is possible and what is not in the real world.

While manufacturers are known to exaggerate bullet BC's they are the opposite in load advice - conservative. The same with computer programs like Quickload with their compulsory "Be Careful!" and "We are not responsible" warnings.

For specific advice with those bullets, they are towards the heavy side for this calibre and from an 18" barrel AR Comp will not be the most efficient powder. Something slightly slower will. That said, you have it on hand, you want to use it and the difference between Comp and another suitable powder like H4896 will be only sllght; 30fps maybe. Comp will be fine.

I would use multiple sources of info and average them out. Then start 10% below the average max charge and work up in increments of 1% by weight. It needs to be at least 1% difference for you to see a difference on target. Your 10% low doesn't have to be many rounds, one or two to give you an idea it is safe, but when you get towards the top that's where you will eventually settle so shoot more rounds at those increments.

As far as pressure goes, velocity is a proxy for pressure. When close to the pressure limit 50fps represents an important difference in pressure but will not make much difference to the ballistic arc at 2,400fps, or when shooting animals (dead is dead). My point is, I recommend you don't push the velocity/pressure envelope with AR's as they are relatively fragile guns. Unless you are shooting at the longest range your barrel will permit I recommend being conservative, especially as you are new to reloading. Regardless, your gun, barrel and cases will last longer.

Do you have a chronograph?

[White Smoke]

Klem has some good advice. The easiest and simplest advice I can give you is to follow the recommendations of the manufacturer of the bullet you are loading. You will find different recipes for the same bullet from different sources. Just for example, if you are shooting a 55 grain Barnes MPG, use the data from the Barnes book. A Speer book might have the same bullet listed, but different recipes. Go with the book of the bullet you are shooting. If you go with someone's "special" recipe that shoots eyeballs out of prairie dogs at 500 yards, you could be in BIG trouble. HIS rifle is not YOUR rifle. Each rifle is an individual, and what shoots good in mine, may or may not shoot good in yours. Only use someone else's recipe if it falls within the specs in the book, the bullet manufacturers book, and then shoot it to see how it patterns in YOUR rifle.

[Toddmcstiffens]

Thank you for the great info Klem-- I do not have a Chrono yet--will have one by this spring. if I take 27gr AR-comp as low average of what I'm seeing on-line and reduce by 10% brings me tp 24.3gr which is about mid range charge in my Speer manual for a 120gr golddot. My gut is telling me that 24gr of AR-comp for a 123gr Nosler HPBT will be a good starting point. Does this sound plan reasonable?

[Toddmcstiffens]

thanks for the info White Smoke. Nosler Doesn't have load data for AR-comp for the 123gr HPBT. the powder was a precious gift from a friend and I only have 1/2lb. hard times to be getting back into this hobby. but the heart wants what the heart wants, and what the heart wants is hard to find and expensive...

[Klem]

Todd,

Yes, your starting loads are reasonable. One or two shots at 24gns will test the gun and your loads. Then a couple 1% higher for the next 4-5 increments. Then you can load more at each increment and look what is happening on the target. If you have a chrono you can plot the velocities on a graph and extrapolate what velocity will be at hotter loads. One thing to watch out for is when the load becomes compressed. Then the load/velocity curve changes and becomes steeper. Mildly compressed loads are fine as long as you know what is happening internally. Knowing what the velocity is at the muzzle gives us an idea of what the pressure is back at the breech.

By internal I mean 'internal ballistics'; what happens with pressure and velocity between when the bullet starts and when it exits the barrel. Then external ballistics takes over. 'External ballistics' is what happens to the bullet downrange. External is what every shooter wants to know but internal is what hand-loaders also want to know. To help us predict external ballistics we use ballistic calculators on our phones (e.g. Geoballistics or Applied Ballistics Mobile), online (e.g. JBM Ballistics.com), and weather meters (e.g. Kestrel). For internal we use muzzle velocity, what is happening to the case (e.g. flattening or cratering, or piercing of primers), recoil, where cases are being ejected, and broken parts like bolts. A few guys even source pressure sensing gear like strain guages, but this is rare and it costs money. With an AR it is almost impossible to get a good pressure trace reading without wrecking the integrity of the gun by machining access to the outside of the breech. Which is why a chronograph is such a valuable piece of equipment for both internal and external ballistics.

Working up a load without a chrono is like trying to get around when you are blind. You can do it but it's more dangerous and clumsy. Being able to 'see' what's happening with your bullets at the muzzle will give you confidence as you approach SAAMI limits. Perhaps your loading mate will get involved or lend you his.

1/2lb of powder will get you about 125 loads. 1lb = 7,000grains, divided by 28-grains per round.

[Toddmcstiffens]

Thanks Klem

I'm gonna get a chrono sooner rather than later.

[Dogue]

Great advice already given. I'll only add that loading for the Grendel is different from many other rifle loads, particularly .223/5.56. With .223 you'll often find max loads are very conservative because 5.56 runs at higher pressure, so you'll see people (and some charts) that give recipes that are well over the .223 max load. Velocity is king with this round as long as you're not sacrificing too much accuracy. But with the 6.5 Grendel you can break things like bolts (or worse) if you get over pressure. With my rifle I've run tests of several bullet/powder combos and it typically is more accurate a little under max loads, which is good because I don't like breaking stuff. Chasing that extra 50-100 fps isn't that important with the 6.5 IMO...accuracy and reliability are.

[LRRPF52]

[Toddmcstiffens]

thanks again guys. this is great info!

[LRRPF52]

Given the direction things are going, now is a good time to seriously think about owning physical copies of reloading handbooks vs relying on online sources.

Something to think about.

[Dogue]

Given the direction things are going, now is a good time to seriously think about owning physical copies of reloading handbooks vs relying on online sources.

Something to think about.

What? You think they'll censor the internet??? Oh wait.....

[peak98]

My set is ordered, thank you.
peak98

Given the direction things are going, now is a good time to seriously think about owning physical copies of reloading handbooks vs relying on online sources.

Something to think about.

[dammitman]

loaddata.com especially if you handload many different cartridges

[Klem]

Manufacturer tables and Quickload.