loads effect on windage

[mdevlin53]

I was shooting some 32-20 yesterday and it leads me to a question. I am shooting a M25 Husqvarna bolt action single shot rifle with a 25 in barrel. half of my rounds were loaded with 3.5 grns of tightgroup and the other half were 10 grains of 2400. The shots for the 2400 were high and to the right and about a 6 in group. The tightgroup were high and to the left and about a 2.5 in group. So can someone tell me why there would be a difference in the POI in the left right direction. I think i could understand an elevation change dut the windage has me scratching my head.
Michael

[williamwaco]

Assuming all else is equal, it is caused by barrel vibrations due to the different pressure curve of the two powder charges.

[popper]

Recoil? Trigger pull? Flinch(those light loads surprise you after heavy loads)? At what range? Quite a bit of diff in burn rate.
barrel vibrations You can check this and hot bbl by alternating loads. I noticed a diff between unique and 2400 but it's me. 2400 gave larger groups.

[mdevlin53]

There was a differnce in felt recoil as smal as it was, I had seen this years ago with different makers of 22 magnum cartridges and had not given it much thought. I dont seem to see this as much in my larger cases. Aside from the 45LC i shoot in a lever action the 32-20 is the only small cartridge i load.

[mdevlin53]

I was shooting at 25yards. Its a light round for this rifle so there was no flinch. the trigger pull was the same for each. I shot ten with the first load and put up a new targer and shot ten with the second. barrel never got hot. when i went back to the first load they went right again. bretty consistant. I may just stay with the tightgroup as it was a much better group. I may try a few with unique or perhaps 4227.
This round in this gun is going to cost me because i could shoot it all day and not get tired of it. Had to throw another 200 boolits this morning so i can fill them back up.

[Mk42gunner]

Do you have a factory extractor in your rifle? If so could you post a picture?

The reason I ask is that I have a #26 in .25-20, and am using a homemade extractor. I used a piece of bandsaw steel with a piece of steel soldered to it for a lug. It works, but leaves a lot to be desired.

Now to find where the kid hid the three boxes of .25-20 cartridges........

Robert

[mdevlin53]

Mk42gunner hold on pictures comming tomorrow, I will take it out and send some pictures with a few dimentions as well. I am not sure if it is an original but it works well sometimes it even ejects the case out of the reciever.
Michael

[Mk42gunner]

Thanks,

I appreciate it. From what I could find on the internet when I bought mine; most of these little rifles were imported without the extractors. I found a picture somewhere that a guy had heavily modified a Marlin 336 extractor, but I figured why buy something just to cut it up?

Mine pulls the case out, but I still have to flick them off the bolt.

Robert

[runfiverun]

so a load somewhere in the middle would be about right then.
or bump the tightgroup load a titch.

[mdevlin53]

Mk42gunner here are some extractor pictures hope they help:
http://castboolits.gunloads.com/imagehosting/thum_237435083f1085cd32.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7107)
http://castboolits.gunloads.com/imagehosting/thum_237435083f118c934b.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7108)
http://castboolits.gunloads.com/imagehosting/thum_237435083f127344a3.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7109)http://castboolits.gunloads.com/imagehosting/thum_237435083f1338b804.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7110)
http://castboolits.gunloads.com/imagehosting/thum_237435083f143c26ae.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7111)
http://castboolits.gunloads.com/imagehosting/thum_237435083f16b0d9bd.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7112)
http://castboolits.gunloads.com/imagehosting/thum_237435083f17ae4edc.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7113)

[mdevlin53]

Runfiverun according to the Lyman manual 3.6grn is the max load and i am at 3.5grn. Now this is a rifle and not a pistol, how much could one exceed the max load. the rifle is 1920s vintage but a fairly strong design is this just a matter of going up a tenth of a grain at a time and looking for pressure signs.
I was thinking that i might drop back to 3 grains and then make up 10 each of tenth grain increments from 3-.3.6 and see if there is a sweet spot.

[44man]

Barrel vibrations and velocity to twist match. You do the same with a fixed sight revolver, working loads to hit to the sights.
Wind has no affect at 25 yards.

[Larry Gibson]

Recoil difference between the two loads is most probable cause of POI change. One load is considerably milder than the other. Barrel harmonics affects the accuracy (group size).

Larry Gibson

[runfiverun]

i wouldn't push the pressure envelope.
especially with titegroup.
if one powder that's fast hit's left and one thats slower hits right i'd split the speed something like unique,green-dot.
it would up the velocity without upping the pressure.

[mdevlin53]

I have some unique so i will probably try it in the next run, I'll take a look at the charts and see if i can match the fps for each powder and see where the POI is. once i figure out which load gives the best group size i can alway drift the sights to move it to center.
It still amazes me that it would move the POI left and right while keeping the elevation pretty consistant. I guess this is what we try to do understand each load and how it works in each rifle and find the best match.

[mdevlin53]

One final question. How can the Lyman manual and IRM data be so differnt. Lyman has 3.0- 3.6 grns of titegroup and IMR has 2.7-3.0 this is for the. 314/117grn boolit. It seems like a big difference.

[popper]

mdevlin53 - I mentioned flinch because I have it. Found out when I had a FTF, bbl took a nose dive. Same thing happens on light loads. Know what you mean, you can put a lot of lead downrange with plinker loads.

[Mk42gunner]

Mk42gunner here are some extractor pictures hope they help:
http://castboolits.gunloads.com/imagehosting/thum_237435083f1085cd32.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7107)
http://castboolits.gunloads.com/imagehosting/thum_237435083f118c934b.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7108)
http://castboolits.gunloads.com/imagehosting/thum_237435083f127344a3.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7109)http://castboolits.gunloads.com/imagehosting/thum_237435083f1338b804.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7110)
http://castboolits.gunloads.com/imagehosting/thum_237435083f143c26ae.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7111)
http://castboolits.gunloads.com/imagehosting/thum_237435083f16b0d9bd.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7112)
http://castboolits.gunloads.com/imagehosting/thum_237435083f17ae4edc.jpg (http://castboolits.gunloads.com/vbimghost.php?do=displayimg&imgid=7113)

Thanks for taking and posting the pictures. I think I am going to try to make another one, mine doesn't have nearly as much angle forward of the bolt. Other than that, the two look remarkably similar.

Robert

[runfiverun]

that is a huge difference about 20%.
they will [should] have different pressures asociated with thier top loads.

[fcvan]

While working up some 30-06 loads with Unique I could watch the groups shift with each increase in powder. Picture a clockwise spiral where the groups tightened up while moving up, around, and toward the point of aim. I'm still working on the load for the Springfield 03-A3 using a Lee 309-150 RF. I'm going to shot the next batch as cast with Liquid Alox and repeat the previous charge weights and see how the groups respond. Frank

[mdevlin53]

fcvan
I think i see now. I thought that changes in powder loads would effect elevation in a prettymuch linear way. more powder would go up less would go down and left to right would be a matter of adjusting the sights. what i saw was one spot in the spiral. now i think i get it. the next shooting session should be interesting.

Runfiverun i went back and double checked the charges and there is a difference between what is listed on the IMR website and the Lyman book. seems like a lot but in this particular rifle the higher load was handled well it all goes to show you that loads should be checked against multiple sources and started below the max.

[mdevlin53]

Just an update. I loaded up several different loads with unique and titegroups. Tenth grain increments between min and max. I found a couple that gave me some pretty good groups but on a whim i also loaded up 10 with 4.5 grns of trailboss. It was the most accurate by far and also closest to point of aim. Got to tell you i was surprised. I went home and loaded up some more so i can see if i can repeat the accuracy.:

[fourarmed]

If a bullet is precessing due to understabilization, a bad crown, or whatever, it will follow a spiral path around its base trajectory. I doubt that this would produce such large differences at 25 yards, however. If you get windage shifts at different ranges with the same load, this is always something to check.

[geargnasher]

While working up some 30-06 loads with Unique I could watch the groups shift with each increase in powder. Picture a clockwise spiral where the groups tightened up while moving up, around, and toward the point of aim. I'm still working on the load for the Springfield 03-A3 using a Lee 309-150 RF. I'm going to shot the next batch as cast with Liquid Alox and repeat the previous charge weights and see how the groups respond. Frank

A bolt-action .30-'06 and Unique is probably the most vivid way to discover the effect of barrel harmonics. Change the load .2 grain and watch the group change shape and size as well as POI.

The OP is experiencing some pronounced harmonic effects. Probably tweaking the loads in tiny increments with the same powder will likely show almost as dramatic a difference in horizontal POI as different powders will when speaking of fast, pistol/shotgun powders.

All spin-balanced projectiles yaw and do a loopty-loop spiral coming out of the muzzle, but usually settle down in around 5,000 caliber lengths, which equates to a few yards, but can be as much as 20 or more before they settle down and snug up the groups with larger calibers. 50 yards is a much better judge of load potential than 25. 100 is even better.

Gear