Dot movement ?

[nexus]

Does the dot movement on your open blaster depends on your load data or on your compensator ? Sorry for my ignorant question ...

[Steve RA]

well, both - but recoil is the cause of dot movement.

[Wilfred]

What should be the normal movement? Up/down or sideways?

[Steve RA]

Up and down.

[OpenDot]

Up and down.

and returning to same position everytime as long as your grip doesn't suck

[eric nielsen]

You can see a lot of variation in dot movement with different loads. In general, more grains of slower powder give less muzzle rise, more slap in the hand, and more noise. If your movement is up/right instead of up & down, you can fix that with either modifications to your comp (slowly lower the walls on the right side of each up-port) or with your grip (cant gun slightly to the left to bring your elbows to the same level).

These days I use the elbows-almost-level canted gun in Open and Limited and Production. Not much, just a 3-4 degrees is all it takes. Helps call low/left trigger slaps since you know it wasn't the recoil pattern to blame.

For extra credit try this in Open, same powder/bullet: Load 4 rounds of nickel-brass ammo in mag. Load 4 rounds brass brass. 4 more rounds nickel brass. 4 more rounds of brass brass. Load gun and shoot 4-shot bursts at the berm or backstop. Watch dot.

[Jaxshooter]

Another thing that can change the movement of the dot are springs. You need to test your gun with different recoil springs to see what influence they have on dot movement. I have two open guns and I shoot the same load in both. One has a 9 lb variable recoil spring and the other has an 8 lb conventional spring inorder to get the dot movement the same in both guns.

[sandrooney]

I use the lightest spring that I can get the pistol to function with. 7# with a buff is what I have in it now.

8.3 VV 350 under a 124CMJ MGB Starline 38SC brass 1.250 OAL 176PF. I can't out shoot it.

[Flatland Shooter]

You can see a lot of variation in dot movement with different loads. In general, more grains of slower powder give less muzzle rise, more slap in the hand, and more noise. If your movement is up/right instead of up & down, you can fix that with either modifications to your comp (slowly lower the walls on the right side of each up-port) or with your grip (cant gun slightly to the left to bring your elbows to the same level).

These days I use the elbows-almost-level canted gun in Open and Limited and Production. Not much, just a 3-4 degrees is all it takes. Helps call low/left trigger slaps since you know it wasn't the recoil pattern to blame.

For extra credit try this in Open, same powder/bullet: Load 4 rounds of nickel-brass ammo in mag. Load 4 rounds brass brass. 4 more rounds nickel brass. 4 more rounds of brass brass. Load gun and shoot 4-shot bursts at the berm or backstop. Watch dot.

I find your suggestions very interesting. My open guns consistently rise up at around 10:30. I think I'll first try shooting with my gun slightly canted to the right.(I'm right handed so this may feel a bit awkward at first.)

I'd never thought about tuning the comp as you indicate, but I'll take some time this summer trying some new loads before I get that drastic.

The extra credit part is way over my head. Same powder and bullet but different brass will show me what?

Thanks.

Bill

[robot]

Dot movement doesn't matter, what matters is the dot comes back to the same spot as quickly as possible.

[Shadyscott999]

Dot movement doesn't matter, what matters is the dot comes back to the same spot as quickly as possible.

This ^^^^^

[rc51g]

i am new to open and i have been learning a lot on the forum. i have been working on dot movement for some time now experimenting with different loads, recoil springs, bullet weights. i have a matt mclearn 6 port comp and 3 holes in hybrid barrel. the gun is so flat that my problem was to get the dot to rise without the dip. it was very hard to be relaxed enough that the dot tracked up & down. after reading this and many other posts on the subject i read the part about the firing pin stop and main spring. so in goes a 19# main spring from a 17# and a 8# rs - bingo. dot tracks up a little then down to where it was, very predictable where i can time my next shot better. it rises about a foot at 25 yards. the main point to all of this is to always be willing to learn. let me know if i can help.

[wes777]

i have a third variable to add. Grip pressure. I say this because I have up and down movement, until I up the grip pressure. When I concentrate on my grip, the dot stays in the middle and "squiggles" for lack of a better word.