Magnetospeed and load development

[lennyo3034]

I'm doing load development for a 6mm Creedmoor. Currently using 110SMK Lapua brass and H4350.

41.0 shoots damn near .25 MOA and has an SD of 2 at 3035.

The issue comes when I take the magnetospeed off. Groups open up to 1+ MOA. As soon as I put it back on .25 again.

Any suggestions or should I just move on from this load?

 

[Bradu]

I'm curious to see the suggestions on this. What contour barrel are you running? I run m24 and mtu contours and have never had this happen to me so I didn't know if I was lucky or if you are running a lighter contour barrel and the harmonics are affected more. I bought an MK machine mount to try out for the next load development I do to see if it makes any difference.

 

[lennyo3034]

Marksman contour. Not what I would call light. Magnetospeed on right, not on left. 5 shots each.

 

[Toddmonty]

Run 41.5 and see if it’s tight on both targets, worked for me.

I ended up with a LabRadar, I really like it.

 

[Bradu]

No, I wouldn't call it light either. Now you have me wondering about my last load I worked up lol. I loaded 200 rounds after load development without checking it with the chronograph taken off. I've never noticed any kind of change before so I didn't bother testing another 25 like I normally do?‍ With my luck it will be the only time it changed.

 

[spife7980]

Do you plan on leaving attached the entire time? If not then you now see why just going off a chrono test is fools gold.

 

[bfglowkey]

Ya, I lean towards OCW development and don't put Chrono on until I have settled on my node. Usually have 2 nodes and get data on both. Working for me so far and helps keep me from velocity chasing.

 

[BCX]

Someone on Facebook had a similar problem w a lighter contour. I believe he played w the seating depth and was back to .25 moa groups. I also run a Marksman contour w a Magnetospeed but haven’t had any issues w group sizes changing.

 

[Milo 2.5]

Marksman contour. Not what I would call light. Magnetospeed on right, not on left. 5 shots each.

I'd say you'll have to tweak the load in some fashion, your magneto is acting as a tuner. I had the same, marksman contour, 6 creed, 110's, but RL16 powder, groups at distance were amazing with magneto on. I went so far as to pull the suppressor, and put a brake on which did the trick, not where I wanted to be though. Not sure just what you could do here, mess with neck tension?
EDIT: That was the only marksman contour barrel that I've had it happen, and I've shot out quite a few.

 

[lennyo3034]

I will try shooting with suppressor next. The above groups are unsuppressed.

If that doesn't do it, any recommendations on what to try first? Powder charge vs seating depth? All my shooting was at .010 jump with the 110 SMK.

 

[Milo 2.5]

I will try shooting with suppressor next. The above groups are unsuppressed.

If that doesn't do it, any recommendations on what to try first? Powder charge vs seating depth? All my shooting was at .010 jump with the 110 SMK.

I do not, like mentioned, develop w/o it on. Try the can first, may just work. Here, in a lot of guns, many diff cases of 6mm, 8 thou off has been gold with the 110, many diff lot #'s of them.
Shooting the 110 myself, I find myself doing a lot of partial neck sizing after setting tension to bring loads in, more tension. Right now on my dasher, I'm doing a .265" 5/8" of the way down the neck, definitely pushing the pressure ring of the bullet past the line too, most say this is a big no no, but it is working so far.

 

[BLKWLFK9]

i have a marksman contour as well and i run my magneto on my suppressor and i barely even have a shift in impact from the can on to off, if any at all.. Try running it on the can.

 

[Sheldon N]

The issue comes when I take the magnetospeed off. Groups open up to 1+ MOA. As soon as I put it back on .25 again.

I have seen the magnetospeed improve groups and I have seen it make groups worse, depending on the barrel. You can't trust the results you get on paper with it attached. I'd suggest either finding a way to free float it off the barrel, or do your velocity gathering separately from the group testing/OCW on paper.

 

[lennyo3034]

So back to the range, same load as yesterday.

Unsuppressed shot much better, in line with what I was expecting. It's possible the wind was blowing my target around yesterday, but it wasn't that windy.

TBAC group was also pretty good. POI shift was more than expected.

 

[Rick7353]

I'd say you'll have to tweak the load in some fashion, your magneto is acting as a tuner. I had the same, marksman contour, 6 creed, 110's, but RL16 powder, groups at distance were amazing with magneto on. I went so far as to pull the suppressor, and put a brake on which did the trick, not where I wanted to be though. Not sure just what you could do here, mess with neck tension?
EDIT: That was the only marksman contour barrel that I've had it happen, and I've shot out quite a few.

You could play with seating depth. I know that limbsaver has a push on for the bbl. My son uses one and likes it.

 

[Diver160651]

I had a similar issue.. but the gun never shot well as well as yours and never at all ok with out it LOL..

Changed the barrel and presto - happy again

 

[Deleted member 10043]

Limitation of a chronograph attached to the barrel. It's accurate but the glamour wears off quick.

 

[Olen_4504]

buy the mount that attaches to picatinny or arca and keeps the chrono off the barrel.

 

[lennyo3034]

Update: I was able to get it shooting well with a minor change in seating depth. However these 110 SMKs were purchased mid 2017 and shot very well. Once I ran out, I bought more from a newer lot and accuracy went to shit. 1.5 MOA with the same load that was almost .25 MOA. Length to ogive changed by almost .020”. I played with seating depth but still couldn’t get them to shoot. I’ve switched to 105 hybrids now.