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.243 t3

.243 t3

Well-Known Member
Question

Varmint barrel , what should the thread size be for it in 308 calibre?

Would the thread diameter make a difference to group sizes? As for some reason no matter what ammunition I put through the gun it seems to print two together then one about an inch or so away. I’ve checked everything on the gun. Nothing is loose. Barrel is free floating just really scratching my head!!

any idea ideas?
 
You should always go for the largest thread that the barrel will take, as long as it's common moderator thread. In some situations the thread will cause problems, and smaller thread will cause more problems. Some people never see a difference.

The advice used to be, for spigot threads you need 0.5mm shoulder (i.e. barrel has to be 1mm thicker than the spigot. And non-spigot thread, 1mm shoulder. At least 4.5y ago Ase Utra has gone for 0.75mm shoulder in both thread types.


As to the grouping, you cannot draw solid conclusions from 3rd groups. Also you need to know which shot is which. If you seriously want to find out what's going on, I suggest you make targets where you have different aiming point for each shot and mount them with level. Then follow a similar routine each time on range, including how the rifle is cleaned etc. and gather data over several sessions.

You can see if e.g. first shot is always away from the others. If you want groups, you can plot them on a piece of paper by measuring X and Y from aiming point for each shot. After you have data, you can start analyzing it or ask for help. And remember, you cannot eliminate any shot. If you pull a shot, make a note at shooting position which one it was and where you think you pulled it etc. You can add notes, but you cannot eliminate it. Many times pulled shots are nowhere near shooter thinks they went...
 
.243 t3 said:
Question

Varmint barrel , what should the thread size be for it in 308 calibre?

Would the thread diameter make a difference to group sizes? As for some reason no matter what ammunition I put through the gun it seems to print two together then one about an inch or so away. I’ve checked everything on the gun. Nothing is loose. Barrel is free floating just really scratching my head!!

any idea ideas?
Click to expand...
Had a Parker hale rifle that did exactly that never found out the reason tried everything I could think of just one of those things got rid of it in the end so frustrating drove me nuts.
 
There are 2 things to consider with thread size.....you generally want the widest practical thread but you have to balance this with having enough shoulder to back the suppressor onto, to keep it concentric to the bore....this is especially true of course with muzzle-forward suppressors.I think I threaded 4 rifles today it also depends on if the thread in the suppressor is stainless steel or allow the fine threads work better with stainless and the coarser ones with alloy.Caliber also comes into it quite often.I find I do an awful lot these days in the metric 14x1 thread.For a varmint weight barrel with a muzzle diameter of say 18-20 mm I would generally not go narrower than a 5/8 x 24 or if metric preferred 16x1.I also believe a longer thread is preferable about 16 mm in length I believe is better than some of the short12-14mm threads that are quite often found.
 
Forget all about thread size for now.

Is it always the same 1st, 2nd or 3rd shot that is the outlier? How many times have you tested it, is the ‘flier’ always landing in the same location in relation to the two ‘touching’ shots?

If it’s not always the same, you’re likely seeing the natural dispersion with the two closest being random luck, but the shooter will falsely ascertain he made two great shots, and the third was down to the equipment.

First one being off is more likely to represent cold bore shots, third round off’s more likely to represent t shooter error. Random off’s simply shows the natural group size or ammo inconsistencies
 
Having the suppressor fitted or otherwise, can make a significant difference to your groups.Sometimes improved, and sometimes diminished.Usually when we have a issue with a suppressor negatively effecting accuracy it can helped by either relieving clearance in the internal washers and front cap or alternatively checking and adjusting if necessary the fit of the rear Delrin bushing (most of ours are over-barrel suppressors) around the barrel.
 
triggertrix said:
Forget all about thread size for now.

Is it always the same 1st, 2nd or 3rd shot that is the outlier? How many times have you tested it, is the ‘flier’ always landing in the same location in relation to the two ‘touching’ shots?

If it’s not always the same, you’re likely seeing the natural dispersion with the two closest being random luck, but the shooter will falsely ascertain he made two great shots, and the third was down to the equipment.

First one being off is more likely to represent cold bore shots, third round off’s more likely to represent t shooter error. Random off’s simply shows the natural group size or ammo inconsistencies
Click to expand...
No it’s been tested with a few different makes , always the same 1st/2nd same place 3rd off to right of them , 4th goes to the right too and 5th if do a five shot group
 
Parallax set correctly?
How far in the scopes horizontal adjustment range are you? If at the ‘edge’ due to poor base to bore alignment, the springs will / can behave erratically and cause this exact issue.
Is the rifle properly floated as and bedded ?
 
Rifle not bedded and still in standard stock .

Normally shoot on 8-10 power .
Scopes a polar T96 4-16 x56 in tier 1 mounts all torqued up .
I will try a different mod on Monday and see if that makes a difference.
 
.243 t3 said:
Rifle not bedded and still in standard stock .

Normally shoot on 8-10 power .
Scopes a polar T96 4-16 x56 in tier 1 mounts all torqued up .
I will try a different mod on Monday and see if that makes a difference.
Click to expand...

Does it show how far you are in the adjustment range? Just because good mounts and rings and scope, doesn’t mean the holes in the receiver were drilled perfectly straight.

Shoot it without the mod and see what happens.

Standard plastic stock? What rifle? Could easily be there’s lateral toque in the receiver area, which can make this happen.
 
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