This Rifle won't Shoot! Diagnosing the issue(s).

[TheCZKid]

The body and the sizing die marks look different ?

Here's two more cases.
Left one is my current final version of an un-fired, or 0 x shot case.
Right case has been shot twice, or 2 x fired, and is not resized.

I just was noting the differences in them. The un-fired would have slightly less internal capacity, and won't shoot as accurate as well. The fireformed case should be more accurate, have slightly more case capacity, and the shoulder and neck corners and nicely defined!

 

[TheCZKid]

I shoot a lot of xp-100s in their original pistol configuration. Torque the front action screw as normal. The rear screw being an 8-32 you just make snug. It doesnt need torqued to 1/4-28 specs! The mark on the right side kinda looks like it corresponds to where the trigger pin is, is there any depth like it was relieved with a mill?

I bet the 10.5 twist is gonna hold you back from any of the plastic tipped bullets. I agree with an earlier poster that said get some 20gr noslers without the plastic tips. the 15.5gr ntx is lighter because of being lead free but it isn't shorter than the 20vmax.

That spot looks like the gunsmith just removed the bedding down to the aluminum, and it is in the spot where the trigger pin is located. I think there was a slight flare on the metal on the action, from putting the pin in, so he just removed the epoxy so there would be no contact with that slight burr.

As for as determining which bullet to use correlating to a specific twist rate, what is the criteria? I thought it was weight, but many here indicate it's the length of the bullet, and then flat base vs boat-tail, and plastic tip or not.

I'm not familiar with what is supposed to be important regarding choosing other than weight, if someone can help explain that, much thanks.

 

[jelenko]

From Wikipedia for Miller's stability factor:

m is the mass of bullet, t is the rifling twist, d is the bullet diameter, l is the length of the bullet.

My note: The stability factor goes down by the cube of the length of the bullet.

 

[Coyotefurharvester]

So no chamfering the case mouth. Just deburring after trimming 223/556 brass?

 

[TheCZKid]

So no chamfering the case mouth. Just deburring after trimming 223/556 brass?

Yes, I chamfer and deburr the necks more than once in the progression of forming and neck turning the brass, from 223 to 17M4.

 

[rickiesrevenge]

You can look up a stability calculator like the berger one. Bullet weight, twist, diameter, speed and length. Plastic tips and boat tails add length. 17 cal vmax are flat base with the exception of the 17gr. Berger used to make 15gr, 18gr, couple different 20gr, 22gr, couple 25gr, couple 30gr and a 37gr.

Im pretty sure I have some nosler 20gr hp bullets. If you want them send me a PM and I'll look.

Aaron

 

[BoydAllen]

Decided to try a faster powder, one my 20 Vartarg likes, and suggested by my buddy Rick in Oregon. The first group shows promise, and yet, there's a lot of large unexpected flyers. The SD's were a lot better with this powder.

View attachment 1679426

So, I shot this powder / bullet combo again, and the groups were still not very good.
View attachment 1679427

Decided to try a yet faster powder, CFE BLK, and the first shot hit the bottom bull, and as you can see, first two groups followed same LOW - HIGH - MIDDLE pattern, abandoned the remainder of the string.

View attachment 1679428

Then tried a stick powder, IMR 4198, grains as big as lodgepole pines! But it did okay, still nothing much below an inch. These were mostly shot in once fired brass, for better results, and now that I had some. Note the first bull was shot with un-shot brass, second bull is same load with once shot brass, and the group is noticeably smaller. These I decided to try another bullet, Hornady 25 grain hollow point, hoping this would be a game-changer.

View attachment 1679430

Last target, shot with mostly once shot brass, and Hornady 25 HP bullets, 8208 powder, redid the best part of the ladder from earlier. Only one group under an inch.

View attachment 1679431

I checked the bedding on the rifle, and it looks good

View attachment 1679432

I believe that your rifle will require quite a bit of modification to the bedding and a little bit to the action to work properly. Here is an article that shows the action screw layout of an original XP 100. If you are going to stick with the existing rear screw location I believe that it needs to be increased to the same diameter as the front one, and you should have pillars at both locations. The original layout shows the use of a tang screw, and your picture does not show any provision for that. To restore that, you will need to install a pillar and do the bedding. Added a bit later" Reexamining your bedding picture, the only place a screw should touch is at its head and the action. If it touches the stock anywhere else that will cause accuracy problems. Looking at the picture I do not see any clearance. Big mistake.

https://www.bergerbullets.com/articles/norman-johnson-remington-xp.pdf

 

[TheCZKid]

Since yesterday, I cleaned the barrel until I think it's finally down to the metal again. I should not have assumed I got it clean the when I first got the rifle. The likelihood is the barrel was quite fowled. I also worked hard to make sure there was not carbon ring at the front of the chamber any longer.

Made a few more changes, first went to a scope I had confidence in, and last night went back to the Redfield single piece base, and installed new Burris Signature rings, got it all leveled and torqued down, laser bore sighted.

Also, I was able to make some space between the bolt handle, which was touching the stock, thank you guys for all the suggestions on what to look at and do.

So, I had some tests loaded before I started this post, and today went out and shot those, Plus, I shot 3 rounds of Remington factory ammo, 17 Fireball Premier AccuTip-V 20 grain tipped flat base. At least, that sidesteps the variables of my own reloading, and my brass.

The first target has first bull with some unfired brass, H335 19.0 grains, 20 Vmax Rem 7.5 primers. The rest are once fired brass, ladder of H335 in 19.0, 19.3, 19.6 and 20.0. Slight breeze 0-5 mph, 78 degrees.

All of the groups on average are better, the 19.3 has very high SD of 40.1, and 19.6 was worse, at 50.3. Last group shows promise at 20 grains and SD of 10.3. I wonder what a different bullet might do?



This second target has first bull with factory Remington ammo, not a great group, SD of 28.8. The other three groups are all with unfired brass, and 19.0 grains of H335, with 20 grain Vmax, I wanted to fireform more brass.



These fireforming groups aren't terrible, with the unfired brass, so overall, I'm very happy with knowing the barrel is likely NOT shot out, probably just fouled from a few hundred rounds from the last owner.

I'll be working on the other issues, as I continue to look over this suggestions on this post, and want to thank you all for sending helpful comments.

 

[jelenko]

To me, those groups are terrible.
I'm thinking you've got an action that is supposed to be well bedded => I would think 3/4" - maybe 1/2" - groups are 'not terrible'.

Just from his past posts, I'd be concerned about BoydAllen's comments. If I've got it right, you've got a project frankenrifle.

 

[TheCZKid]

To me, those groups are terrible.
I'm thinking you've got an action that is supposed to be well bedded => I would think 3/4" - maybe 1/2" - groups are 'not terrible'.

Just from his past posts, I'd be concerned about BoydAllen's comments. If I've got it right, you've got a project frankenrifle.

Those groups are, for the most part, terrible, but not as terrible as the earlier ones. It's progress, not perfection at this point.

I'm working with some newly formed brass, and a rifle I'm trying to evaluate what's making it not shoot well. So yeah, I guess from your perspective, it's a frankenrifle. People making a rifle from the XP-100 action is nothing new, so I'll get more input from those who have experience with this layout. Probably including my gunsmith. If I had $3000 to have a custom rifle made for me by a reputable gunsmith, I'd have gone that way. I'm on a budget, and this rifle came available, and I purchased it.

The XP-100 is a good action for small varmint calibers, and the stock is in nice shape, the barrel doesn't appear to be shot out, those are the basic building blocks I'm working with. The rear screw on this action comes in from the top, and that's how these tend to work, in a rifle format, and I don't think that's supposed to be any major concern. YMMV

 

[dfrosch]

Did you get any indication of a round count on the barrel? Was it someone's prairie dog rifle for 20 years?

 

[TheCZKid]

Did you get any indication of a round count on the barrel? Was it someone's prairie dog rifle for 20 years?

I was told by the owner, he did load development, then shot about 150 ground squirrels, and a few crows, and then it was in the safe for 20 years. I don't have a borescope that goes down to 17 caliber with a 90 degree mirror, so actual condition of the bore and throat is impossible to say right now. Worst case scenario, I'll turn this over to my gunsmith and have him change it over to a 20 Vartarg, and have him solve any issues need solving. But for now, I'm determined to see if I can get it to shoot consistent half inch groups, that's the goal.

 

[timeout]

I thought for sure that the lighter and shorter bullets would have tightened those groups. I must compliment you on your patience. By now I would have laid that rifle behind my F150 and backed out of the garage.

 

[Goatsnguns]

I just wonder how many misses the original owner had between squirrels?????

 

[450BM]

My 17 Fireball shoots well 1/2” ish with 18.2 gr of 8208 and 20gr Vmax’s or 20gr Dogtown (which I think are Nosler). Avg fps was 3650 (I chronographed them but don’t have the data in front of me). Faster than that and the groups were opening up. Rem 700

 

[TheCZKid]

I just wonder how many misses the original owner had between squirrels?????

I wondered that myself! He might have shot 500 rounds to get those 150 squirrels.

 

[TheCZKid]

My 17 Fireball shoots well 1/2” ish with 18.2 gr of 8208 and 20gr Vmax’s or 20gr Dogtown (which I think are Nosler). Avg fps was 3650 (I chronographed them but don’t have the data in front of me). Faster than that and the groups were opening up. Rem 700

8208 was the first powder I tried, as Nosler had it as their best accuracy load. I did my tests with 25 grain Vmax, I might have to try it again, with 20 Vmax. I'm pretty sure my earliest groups sucked because of three contributing factors, (1) The necks on the brass was too thick, causing the brass so not have enough room to release the bullet, plus it was unfired brass (2) the barrel was completely fouled, and needed to be cleaned completely, and (3) my twist rate is too slow for 25 grain bullets, which was what I first tested.

So, now with a clean barrel, thinner necks and fired brass, I think I'll start over with 20 grain bullets, like Nosler Varmageddon FBHP, and see if I can do some ladder tests. Need to figure out how much freebore this barrel has, as I have no reference point for seating depth, except factory bullet COAL listings.

 

[ELR LVR]

The only thing that will cause a nice rifle to shoot patterns like that is the bullet is unstable.

I wouldn't do a thing until you shot some lighter bullets.

Bingo!
Slower than 10 twist was the red flag in my opinion too
(But all the other things should still be addressed)
-----------------------------------------------------------------
I can shoot groups like shotgun pattern if a sling Sierra 69 TMK's through my 14 twist 22 BR
But if I put 52 Bergers in there, it's one ragged hole

 

[ELR LVR]

Black patches on squeaky clean barrel...This can be confirmed by rubbing a patch with Iosso on the outside of the barrel or just on a piece of steel.

This is why I stopped using Iosso
Black on squeaky clean means it is polishing further
A highly polished barrel is NOT what we long for - Promotes coppering up
It's a catch 22, you're getting the barrel clean, but hurting it more by polishing further to get it clean
------------------------------------------------------------
There are other methods than using Iosso or Flitz
Flitz will give the same result

 

[TheCZKid]

This is why I stopped using Iosso
Black on squeaky clean means it is polishing further
A highly polished barrel is NOT what we long for - Promotes coppering up
It's a catch 22, you're getting the barrel clean, but hurting it more by polishing further to get it clean
------------------------------------------------------------
There are other methods than using Iosso or Flitz
Flitz will give the same result

I tend to agree, but my first concern with this barrel, now, is to actually get it fully clean. Then I will have a baseline, for knowing that the fouling is not the main source of the erratic shooting patterns.

I'm in Bend, OR and plan to pick up some Nosler 20 grain Varmageddon FBHP bullets tomorrow. I'll give those a try. I'm hoping the short lighter bullets will make an improvement over the 20 Vmax, and other 25 grain bullets I've tested. Hopefully, those will be a good fit for the slow twist rate.

BTW, what are your "other methods" you might recommend for a cleaning regimen? I've got some I use, but want to hear yours.