"And the problem is..." ???

[NoZombies]

Okay, so I've acquired a new project rifle from a guy here on the board, he abandoned the project due to poor accuracy.

Upon collecting the project from my FFL yesterday, I promptly fixed the headspace, fixed the sticky firing pin, and messed a little bit with the bolt etc. Now the gun functions fine. I've got lots more work to "finish" the gun, but for now, I wanted to see where I was starting from.

When I took the gun to the range today, I set up a target and started the process of trying to see what the problem was. I tried several loads, ranging from light to heavy (relatively speaking) and couldn't get anything to group worth beans.

As I was shooting through all my test loads, I noticed a pattern to the targets.

The first shot would hit high and to the right, the second would hit low and left, third would hit low center, fourth would be back high and almost as far right, fifth was low and slightly less left, sixth back to being low center and so on. Sometimes the pattern would skip one of the locations, but every target looked similar.

The photo is the worst one (overall spread) but the best example of the "patterning" that occurred.

I'm trying to figure out what might be causing this. Any suggestions would be helpful. The target was shot at 25 yards, and yes, that's a 7" group! :holysheep

The previous owner mentioned instability, but I didn't notice any problems with that, heck you can kinda see the shape of the lands that engraved on the boolits.

http://nozombies.com/cast/581-3.jpg

[Bret4207]

First off, did you de-copper/jacket foul the bore? If it's an older rifle with some rounds through it that's the first thing I'd do. Check the crown too.

Repeatable grouping that moves around usually means a bedding issue or loose sighting system.

[old turtle]

Check for any pressure on the barrel. Bret is right. All else fails crown may be it.

[oneokie]

Horizontal stringing is usually caused by bedding. Telling us what rifle it is will help in determining the cause of the stringing.

[bigdog454]

Check first to see if the barrel is free floating, if it is then use the match book trick and place a pice of match book (ie paper spacer) under the fore end. if the barrel is not free floating, place the match book near the receiver between the barrel and the stock. after testing these tricks if the results are the same then check the crown of the barrel. also glass bedding the action may help, but it sound to me as if there is some force between the barrel and the stock that is changing as the barrel warms.
BD

[steg]

You didn't mention if you were using a scope or not. if it's scoped maby the scope has given up the ghost. It happened to me once and it took forever for me to figgure it out, the scope was brand new out of the box, changing the scope changed everything in my case...........steg

[Bret4207]

Steg, had that once too, only it was an oil pressure gauge. Nothing worse than an oil pressure gauge that isn't showing oil pressure cuz it's broke....except one that isn't showing oil pressure cuz you gots no oil pressure!

[Larry Gibson]

A 7" group at 25 yards is a little more indicative of something more seriously wrong than the usual bedding, slight crown damage or even loose scope mounts. I've seen a lot of scopes go bad over the years but a 7" group at 100 yards is more likely, unless the reticle just falls out of place and that is very noticeable.

What rifle?
What sights?
What cartridge?
What are the specifics of the load used?

Larry Gibson

[NoZombies]

Hey guys,

The rifle is a Remington 581 converted to .32 S&W long, using a NOS Mauser barrel. I checked the bore, and cleaned it good when I got it, there was no copper fouling present. I was using a cheap 6X40 scope, that was working fine 2 days beforehand on another rifle.

The loads I was using where ladders using tight-group and Hornady 90 gr swaged SWC's (cause I haven't been able to cast in a while :( ) I worked from 1.5 grains to 2 grains in .1 increments, and saw no major improvement, the best group was about 6" at 25 yards. All the loads did the same thing with running around the target, with the heaviest load shooting more on the horizontal center line, but still stringing badly.

I'll change the scope and rings (it's a grooved receiver, and will likely remain such) before I shoot it again, but I suspect it's the bedding, which I suspected would be a problem when I got the gun. (I'll post photos of the bedding it has now, later) I'm gonna start by free floating the barrel and bedding the action. Sadly with only one action screw, bedding the action will be less solid than I'd like, but I think any change will be an improvement.

The crown looks okay, it was cut by a gunsmith, and is recessed, with no obvious flaws.

I probably need to open up the chamber a bit as well, or at least add a throat to it, as it was chambered for flush seated WC's. It works fine with SWC's having their shoulder flush with the case-mouth, but I'd prefer to have a little bit of a throat. It's not like I'd be able to shoot the thing out with this cartridge anyways. :) Currently the chamber diameter is .332, which is a little tight for a .32 S&W long. My revolver's in the same caliber run .339-341. I do have a .339 chucking reamer, so I might just run that in there to see if it makes feeding the cases into the chamber a bit easier, then figure out the throat later.

I also need to fit an ejector, pulling the cases off of the bolt face is annoying at best. especially from the tiny ejection port with a scope mounted.

http://nozombies.com/cast/581-1.jpg

http://nozombies.com/cast/581-2.jpg

[runfiverun]

i'd bed the entire action into the stock.
especially check the bottom of the action and the rear of the action to the wood you have movement in the stock somewheres.
bed the whole thing in. but mark the metal to wood fit and remove any touching spots first.
i'd bed the bbl in too [the whole thing]
and the magazine too, it could be rubbing in spots.
check the length of any spacers or action screws they can allow movement or be too long.
i have had to fill in screw through ways and make new ones or use a straw [like the big sized ones from mc donalds to keep a path opened] or a piece of hollow brass or tin metal.

[onondaga]

Vertical dispersion usually indicates bullet fit and bore finish disparity when heat is not a factor. Hone the bore with polishing compound till slick and then slug the bore to select bullet diameter .001 to .002 overbore diameter for cast bullets. Have fun, looks like a great project!

[oneokie]

Sadly with only one action screw,

There is your problem. See RFR's post for a fix.

[NoZombies]

After taking another look, I think I need to remove the barrel and bed the action to the stock, and then free float the barrel in the forend to see if that helps. If a free floating barrel helps, then I'll probably bed the barrel and see if that makes it better or worse from there.

[azcruiser]

I look at that as instead of a 7 in group but 2 groups one 3in and a 1in group . At 25 yd's would
think even with know sight it should group better.Since it's A grooved receiver next trip to the range try a 5 shot group at 25 yd's no sights just looking down the barrel.My guess is something with the mount maybe threads on the clamps or rings or even the screws somethings moving that shouldn't be or its moving in the receiver groove. Had a scope once that I thought was broken turned out the screw on one side of the scope ring felt tight but was a bit to long and in fact the ring was loss. MY 2 Cents

[Larry Gibson]

After taking another look, I think I need to remove the barrel and bed the action to the stock, and then free float the barrel in the forend to see if that helps. If a free floating barrel helps, then I'll probably bed the barrel and see if that makes it better or worse from there.

I agree with you on bedding the action first. I don't recal if the 581 has a stud the bedding screw goes in or if it goes into the receiver. If there is a stud then bed that to. Not much if any recoil there so that sould do. Assuming the barrel is off a Argentine 7.65? I shoot lots of those bullets out of my .30s and .31s including the 7.65 Argentine and they shoot into 1" or so at 50 yards if the velocity is not over 800 - 900 fps.

Suffice to say I suggest you load up 5 shot strings of 5 shots each using Bullseye from 1.5 to 2.1 gr in .2 gr increments or perhaps up to 2.4 gr. Do you have any idea of the velocity?

Larry Gibson

[Dark Helmet]

I beleive your .339 chucking reamer will be too large, measure a sized case and then one with the desired diameter boolit seated.

[The Double D]

You fixed head space? How did you do that?

Is the barrel threaded or slip fit?

NOS Mauser barrel. New old stock? What caliber? 8mm? What twist? 8 mm Mauser is for 180 grain bullets some where around 1 in 9.5 twist. 90 grains bullets are going to need a slower twist.

Single screw guns can be bedded and made to shoot. They need bedded in front and behind the screw so the action and barrel don't move. Better to have two screws.

Slip fit barrel, shooting 90 grain WC through a fast twist barrel, unbedded with one screw. Sounds like a basket of problems to me.

[Mk42gunner]

At least the boolits appear to be stable.

How is the barrel retained? Is the barrel tight in the receiver?

This is a single shot conversion, right? I just took my 581 out of the stock to look at it. If you bed the action and allow a build up of bedding material in what was formerly the magazine opening; it would act as a recoil lug and also stabilize the action from side to side mmovement.

That's my best guess, without actually seeing the rifle.

Robert

[NoZombies]

I've made some headway with the project, and discovered what might have been "the" problem, but won't know until I make some adjustments.

I'll update the thread when I know something more for sure, and answer more questions then.

Now... where are those tubes of JB weld?....

[nicholst55]

Is your scope staying in the same position, or is the entire scope moving each time the rifle is fired? I had an air rifle that drove me nuts until I figured out that I needed a recoil (scope) stop for the scope mount!

Beeman Scope Stop (http://www.airgundepot.com/beeman-scope-stop.html)

[BOOM BOOM]

HI,
I can not believe it a forum on practical zombie survival ! What next!:lol:

[NoZombies]

Next they'll make a TV show about Zombies or something.

[NoZombies]

Well, I haven't shot it yet to test my theory, but I suspect I will see improved accuracy on my next outing.

When I removed the barrel (which, at the moment, is held in place with a series of set-screws BTW *yikes*) and screwed the action down in the stock, I was amazed to find that the barrel wouldn't come within 1/8" of lining up with the action. There was a huge amount of pressure on the connection point.

So, I cut out most of the bedding in the barrel channel, and built up the bedding for the action. Now, after several hours of work, the barrel floats freely and the action is solid in the stock. I suspect I will at least see improved accuracy. Hopefully I'll get to go shooting and test my theory later in the week or over the weekend.

Thanks for the input guys! I'll report back when I get to shoot the gun again.

[NoZombies]

Thanks for the advice guys! Finally went shooting again after doing the bedding work.

Two best groups today measured .417" CTC with .32 long ammo and .167" CTC with .32 ACP ammo.

More details here:

http://castboolits.gunloads.com/showthread.php?p=1081285#post1081285