Accuracy Issues

[THE300BLK]

I’ve got a 20” Grendel Hunter 6.5 Grendel upper and finally got ahold of all the necessary reloading components and I am trying to develop a load and it’s off to a HORRIBLE start. I’m shooting nearly 3”-4” groups at 100 yards! I’m definitely capable of shooting tight groups and have shot cloverleaf groups out of this gun with Federal Fusion 120 gr SP, but my current quest to find a tight shooting load is rendering more than disappointing results. Due to lack of availability of reloading components, I’m limited to Ramshot TAC and 123 gr Hornady FMJs and SSTs. So far, I have loaded everything from min to max load according to Sierra load data and my tightest group is still over 2.5”. I’m using brand new Starline brass and CCI small rifle primers. I can’t believe that ALL of the loads in the Sierra manual for TAC would be that inaccurate. I thought TAC was supposed to be a very accurate powder for the Grendel. Am I missing something???

[tdbru]

Have you tried changing the seating depth +/- 0.010" and re-trying. of course in the AR you are limited to magazine length if you want to run the reloads out of a magazine. I am not sure how well the Hornady FMJs group, but SSTs usually group respectively. do a seating depth ladder and see if you can find the node.
regards,
tdbru

[THE300BLK]

Thanks for the reply tdbru, I have not yet tried adjusting seating depth, I just shot for middle of the cannelure

[grayfox]

You have a couple things working against you in this.
Grendel hunter is what is called a "rack grade" barrel, so it can be luck of the draw as to getting an accurate load. That, plus the SST is a fairly "finicky" bullet that can be tough to find accurate loads for (some folks have found such, others can't make it shoot worth a darn). I had a GH bbl once and could get it to shoot the sst but only with one load of AR comp powder...
It's pretty hard to work up accurate loads without a chrono, do you have one and have you shot any ladders to see what the powder/MV performance for your barrel, powder and load combo is?
My last suggestion is what is the round count for this rig, you might need 50-100 shots before the barrel starts to settle itself in.
PS, Hornady has load data for their 123-class bullets, have you looked at that data?

[THE300BLK]

Thanks grayfox, sounds like I might be chasing my tail. I only have 105 rounds through this barrel. I do have access to a chronograph but only used it for one load that yielded just under 2400 fps, but the groups were crap so I went back to the drawing board. I do have a picture of the 123 gr Grendel page from the latest Hornady manual, but that’s it as far as Hornady reloading data. The other element is the weather. Obviously winter isn’t the best time to be trying to develop a load, but I wouldn’t have expected groups this bad!

[jasper2408]

My take on this is you can't force a rifle to like a certain powder/bullet combination. Might need to change one or the other to get something that groups decent.

[grayfox]

TAC is not the speediest powder, but should be doable. Also note that for the Hornady data, it is from an 18" barrel, so there should be some extra MV possible for your 22...
CFE and Lever are the ones giving the highest MV for this class as I recall, with AR comp another although not listed in Hornady...
8208 xbr is a contender but need to watch for over pressures when close to 28.+ grains in the 123 class, its limit for a given barrel comes up quickly.
'Course the first 2 mentioned, they do have some temp variability...
That chrony would help you a lot, knowing MV's is really necessary IMO.
If memory serves me the SST lots of times gets best groupings at around 2.245, for bolt action you have more OAL room to play with, but in an AR there is a limit.

[TedBrewer5]

Are those hornady 123 the bulk bullets from mid south? I have been having a problem getting them to group in my 20” psa upper. So far I have tried 8208,ARcomp and H4895. Best I can get is 2”. Frustrated because 3 of 5 group and then two have a mind of their own. Sierra 120 pro hunters with 28 gr 8208 go .75” so I know the gun can shoot

[THE300BLK]

Yes, they are the bulk 500 count bags from Midsouth. Interesting that you are having problems with them as well????

[mdram]

i would shelve the fmj for now and concentrate on a better bullet, the bulk hpbt do ok for me and are not much more than the fmj

[TedBrewer5]

I would be happy with the FMJ if they would go 1.5 in a loose group.
Been working on 120 Speer gold dots and just got some nosler 129 gr ABLR to try

[3404speed]

Did you ever get it to shoot tighter groups?

[Zeneffect]