So I worked up a load for my 13” grendel with suppressor with varget and gold dots. I started at 25 grains going up .2 at a time until I got really good groups at 26.6-26.8. The problem is the 25 grains started at a 1926 avg and 26.8 are 1952 avg but my group steadily got a little higher the higher in grains I went up. So Im using a prochro and wondering if its just not reading right or if my velocity is just tapped out.

Ive had problems in the past with it not reading or just having a ridiculous number come out thinking about getting a new chrono…

Bullet weight?

You are at the plateu on speed. Adding more powder, not making more velocity. Go with 26.6 or 26.8 gr and call it good.

^This^
Step outside after dark and touch a round off out of that 13” barrel. Most advertised data for the grendel in my manuals is generated with a 24” barrel. That big ol’ fire ball of powder burning past the end of that little 13” barrel you will see is your velocity deficit.

And the way to get away from the blow torch, as well as pick up speed is to go to a faster burning powder. One could get themselves into a powder that is not listed as appropriate for 6.5 Grendel, but it works better due to the fast burn rate, for the short barrel. But you have to do some experimenting, you have to apply safety procedures, and you have to watch for signs that you need to stop adding powder.

As an example, I have a 7 1/2" AR pistol. And the load is a Hornady 68 gr BTHP. It makes speed out of such a short barrel, but the powder is not a listed .223/5.56mm powder.

H335, Benchmark and TAC are all listed powders for the Grendel and all have a faster burn rate.

TonyLama, my first thought was that Varget is too slow for that barrel length and I don't know a lot. I'd be looking for different powder, maybe IMR 8208 or even faster. Like JG said, he's running one that isn't even listed for the cartridge. That's a bit risky for me but if you know what you are doing...

I tried cfe 223 in it with hornady 129 interlocks since I have a ton of them and right when I found a good node I also had HUGE pressure spikes which made me forget that real quick even dropping it .2 grains it shot worse but no pressure signs. I have a 7 inch suppressor I run on it and was hoping it would get me to 2100 fps but how good it shoots might just try it for awhile till I find different powder. Ive just never had a load not move up much in fps with adding almost two grains of powder! On the plus side went by scheels this morning and they had small rifle primers so Im stocked for awhile kinda gave up on this load when I hit 200 primers left. Thanks guys I have about 1/2 pound of tac left and have had good luck with it so I will see if I can find some more I wish I could find 8208 but its like finding a unicorn in the wild right now.

I would drop down to 100 grain ballistic tips or partitions and pick up more speed. Either of those bullets would work well on medium game.

For a 13" AR barrel, you are running all slow burning powders for the 6.5 G and 120 grain bullet weights. I would drop down to a faster burning powder with the short barrel. The load will burn cleaner in an AR platform, achieve good velocity, and not be near as compressed of a charge. As you go up in powder charge, your velocity will go up and your group on where it prints on paper will go up. That's normal. With a slow burning powder, short 13" barrel, there will be more of diminishing returns the higher you go on the powder charge. Your 26.8 grains of Varget is not near max either, which explains the lower velocity. In many reloading data sources you don't see Varget listed, because it's almost too slow burning for the 6.5 G. With the right powder, I would expect 2100-2200 fps in a 13" barrel with a 120 grain bullet. But in my 6.5 G testing, the hot loads do not shoot as good as a load dialed down slightly.

Some guys that run 12.5 inch barrels say they still get more velocity from CFE and the 123gr bullets than 335 or 8208 but not by much 40fps or so. With the 120 to 123gr bullets you are mostlikely looking at around 2100 t0 2300 fps from the 12.5 inch barrels when running suppressed. Different barrels can make a difference some are faster than others.

Varget is not really the best powder for the Grendel, with max loads you are crunching powder as it is a little bulkier than some of the other powers in the same burn rate area. Or that is what people on the Grendel forum say about it that have tried.

Lots of information on this on the 65gendel forum. One of the preferred bullets for short barrels in the Grendel is the 129gr Nosler LRAB. High BC bullet that expands down to 1300fps

Well I have cfe laying around what grains would yall start at on trying the gold dots until I can find some 8208 or another bullet?

I would start it at 29.5 and work up but would expect good accuracy in the 30 to 30.6 gr range. That will still be below Max of I think around some bullets it maxes out between 31 and 32 gr though.

On a July day at 97 degrees I started seeing first pressure signs at 30.9 and just called that good. I would expect from what I have seen 30.6 to get you over 2200fps from the 13 inch barrel. Some barrels are faster than others though.