Happy Sunday folks,

I just got back from the range testing my first handloads in 6.5 Creedmore  The rifle is a Remington 700 5R 1/8 twist ordered by a friend of mine. He is fighting Parkinsons diease and never got around to shooting it. The rifle had 18 shots through it with factory ammo before I ran 5 shots of my 120g Barnes with 43 grains of H4350.


After that 5 shot group I attached the magneto speed crony and groups went to hell. The top right target is 14 shots of the same load with crony attached. I am going to load up some more and try again with no crony.

The dots in the middle of the target were my aiming point for the next set of loads. These were shot using a Midway 107g bullet. The point of impact shifted 12" low!! Crazy. Groups were terrible with this bullet. My buddy who's rifle was zeroed using the same factory load I did had no point of impact change. He also has a Remington 700 only in a chassis. Any idea why POI changed so drastically with similar rifles?

Well a bayonet will change point of impact so I would think the crony mounted on the barrel would change things also.

That's excessive for a harmonic change, assuming this is 100yds. Looks more like the elevation screw slipped.

The rifles zero never changed. Last thing I did was run factory 147g through it and it was perfect. Very strange. And yes, this is at 100 yards.

Maybe you were using Creedmoor loads instead of Creedmore loads?

So, to be clear... when you got the nice 5 shot group you were running your handload 120 recipe, then when you put the MS bayonet on your group went to trash.

Did you take it off and re-run the test of the stuff you liked in that 120 grain 5 shot group and it went back to good again? Or... Did you run anything else just with and without the bayonet mount?

Sometimes just plain old cause and effect testing gives us our answer and sometimes it doesn't. But... if that group performance comes back without the bayonet, I would take it and run.

It seems severe but if it is repeatable then it doesn't matter what we "think". I would repeat the test and then check to make sure the stock is still clear and tight as well as the sights, then move along.

Yes the great 5 shot group and the crappy group next to it are the same ammo. I made another 20 to try next weekend.

Has anyone seen such drastic results using a magneto speed on the barrel? If it drastically reduced accuracy I can't see anyone using it do develop a load. Johnnys reloading on YouTube uses it all the time with awesome results.

Yup. Magnetospeed user here. I should've bought a labradar like you glorious bastards told me to the first time around.

Anyway, I use it with good effect. Generally it bumps 2moa up. Easy enough to account for. It does mess with group size a bit, but not terribly except on my paper-thin sporter. It has yet to make a bad load shoot good, but can make good loads shoot poorly. So just because it isn't the tightest, doesn't mean it's a bad load. After a while I can feel what the rifle will do and know how much error I can chalk up to the MS.

Also watch for it to slip off on your full-bore or featherweight guns. I have to move it every other shot on my LW 30-06. It stays put on my .223 axis, and on the other rifles that actually have recoil, they have brakes I can butt up against.

Usually I go .5gr on .223 and 1gr on .308 loads, so I would start 6.5CM testing with 1gr increments. Just to get a max charge and figure where you want the velocity to be. Then work smaller increments in your range. When you find that velocity node, take the chrono off and play with seating depth.

Generally, just accept that it will be a bit off.

Looking at the OP more, I want to be clear that the 12" low groups were with the MS on? Or was that simply change of ammo? You say "midway" bullet, which makes me think of the "seconds" they sell at a discount (which I have great luck with, for the price). Don't get your panties twisted if reject bullets don't make ¼" groups.

IME, regardless of ammo selection, I get the same POI shift from the MS. So my impacts will be 2moa high from the zero, but if I switch to ammo that is 3moa left (without), it will be 3moa left and 2moa high with the MS. If not perfectly clocked, it will rotate that shift opposite the bayonet, as you might imagine.

If those low groups are with the MS, then hopefully they'll tighten up considerably without it, accounting for that it did to the first load.

What does the MS do to the 147gr factory ammo you mentioned?

I wouldn't keep shooting 14rds into a single target like that. On a LW gun, it's opening up by the 3rd round, 5 on a normal, up to 10 on a heavy barrel. Assuming a spirited pace. If the first 5 didn't go so smooth, another 9 isn't going to be any better.

Magneto speed is ideally suited for grabbing a few velocities to average out to check your load.  After that its a gamble.  I have a CED chronograph.  It works pretty well but it is such a chore to set up I never use it at the club I am in now.  This time of year with pre deer season sight ins no way would I bother.


Lab radar if I had unlimited funds.

Well damn. Learn something new every day. My 147 grain factory groups were crap with the magneto speed attached too. I was starting to suspect the chrony but needed conformation.

This is the bullet I ran that gave me the low impacts. These came with the gun so I loaded them to help break in the barrel. I didnt expect one hole groups with them but didn't expect they would be shooting so much lower than a bullet with only 13 grains of weight difference.


The magneto speed also made the 147g loads group badly.

Lots to consider here. I don't normally shoot groups more than 10 shots. Was more focused on getting the barrel broken in at that point.

Seriously, thanks for taking the time to help.

Sam

Were the "midway" groups equally as poor with and without the MS? They still look plenty good for blasting ammo. You probably don't want blasting ammo with that rifle, but it is what is.

Odd they would print that low but still shoot a proper group (it may not be the best, but a consistent group it is).

Going off your bare muzzle vs MS, it didn't seem to shift the impact that much with the first ammo. Just blew up the groups... I'd expect similar deflection on subsequent groups and various ammo, but harmonics can be a cruel bitch.

I would do 3 shot groups for rough testing, but feel fine shooting 3 of them (9 shots with note taking, moving the bayonet back,, and reloading magazine inbetween). Then switch to 5 shots with a couple minute break between for more serious testing, and after the second string (10 shots) let it cool for around 5 minutes.

Load development is getting to be a job sometimes. Spending all day at the range for no real fun. If you have barrels of similar OD, it's easy enough to switch which gun has the chrono on it to make more efficient use of your time. Or do some plinking while barrels cool.

Now you know what to expect, so ideally when you take the MS off, the group should shrink. So just watch for ones that really open or close up. Sucks that you'll have to burn more ammo to verify it again after getting velocity numbers.

I always heard a fixed bayonet would change your zero.

I tried in once with my M1A

It did, and the muzzle blast off the flash suppressor put a sunrise pattern on the ring of the bayonet.

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