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

TheCZKid

Silver $$ Contributor
Well, I recently acquired a rifle, and am trying to get it to shoot as I expected it had the potential to, but no luck so far.

It's a 17 Mach IV or 4, depending on how you know it, basically a forerunner to the 17 Rem. Fireball. The rifle is built on a Remington XP-100 action (eXperimental Pistol), single feed. Has a 21" Lilja barrel, about 1:10.5 twist as well as I can tell. Built by a former member here. It's in a pillar bedded HS Precision stock, has the trigger reworked and breaks at 1 pound 6 ounces. The action was blueprinted.

Here it is with a Burris scope installed, with 1" Leupold rings. Out shooting a few days ago.

Shooting day July 25.jpg

I thought it might be the scope that was giving me the shotgun group patterns, so I changed out to my Leupold VX III 6.5-20x40mm with 30mm tube, and it was easier to see the targets, but no better luck in group sizes. I'm changing out the base and rings soon, to lower the scope, but that's not the issue, so the scope being so high is just temporary.

Shooting July 20 25.jpg


Here's the first sighter shots, and initial groups at 75 yards. These are all shot with newly formed, never shot brass, so that was a high consideration as to group sizes. This is an example of my newly formed 17 M4 brass on left, and once shot on the right.

0to1shot.jpg
Initial shots with 25 grain Vmax and 8208 powder, with Remington 7.5 primers, in Lake City formed brass. 18.6 grains showed the most promise. 8208 was Nosler's most accurate powder with 20 grain loads, so figured it wouldn't be terrible.

Targets17MIV 01.jpg


So, I loaded some more of the 18.6 grain loads of 8208, to fire-form more brass, and the groups were all over the place.

Targets17MIV 02.jpg

Decided to change to a different bullet, 20 Vmax, which shoots excellent in my 17 Hornet. And, tried Lyman's most accurate powder in 49th edition, H335. You can't tell, but the first shot on the first group just barely nicked the edge of the paper, top left, above the 17M4, this making first group 2.38". The rest you can see, and show some promise, but still erratic.
Targets17MIV 03.jpg
 
Check the front base to make sure it’s not too long.
Also check the front action screw, it only engages a thread or two.
Look at the scope base, the rear ring is lower than the front.
Hal
 
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.

Targets17MIV 04.jpg

So, I shot this powder / bullet combo again, and the groups were still not very good.
Targets17MIV 05.jpg

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.

Targets17MIV 06.jpg

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.

Targets17MIV 07.jpg

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.

Targets17MIV 08.jpg

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

17MIV Bedding.jpg
 
Check the front base to make sure it’s not too long.
Also check the front action screw, it only engages a thread or two.
Look at the scope base, the rear ring is lower than the front.
Hal
Pardon my ignorance, but what do you mean by front base?

I'll take the action out of the stock soon, see how high the front bottom action screw goes above bedded surface, good suggestion!
 
I think the rifle had under 400 rounds through it, but can't verify. I did a good cleaning, then shot, cleaned it better, and again last night. But haven't shot yet. I did check the crown with a magnifying glass, and it looks clean. It might just have a bad barrel, but it feels smooth when it's clean, very nice. But my borescope only goes to 20 caliber.
 
The 25 vmax looks unstable, which I would expect from a 10+ twist. The others look like a fouled or shot out barrel, have had both issues with 17 barrels. Front base screw into the barrel threads?( usually wouldn't cause the big poi changes you are having.)
 
The 25 vmax looks unstable, which I would expect from a 10+ twist. The others look like a fouled or shot out barrel, have had both issues with 17 barrels. Front base screw into the barrel threads?( usually wouldn't cause the big poi changes you are having.)
The fellow I got it from said he developed a load, then shot about 150 ground squirrels and a few crows. So, hopefully it's not shot out. But, it is possible. I cleaned it last night with Iosso and got it to feel really smooth from front to back. I might have to stick with 20 grain bullets, if the 10.x won't stabilize 25 grainers.
 
Unfortunately, I don't have any. I've got N120, RL7, CFE BLK, IMR 4198, IMR 8208, H335, TAC.

I'm off to the post office, work beckons!
That is a very nice rifle. I just dug out my wildcat cartridges book (compiled from handloader). The .17 Mach iv is listed and the author spoke highly of H322. N120 may be worth a try as it is between IMR 4198 and H322 before you run and buy some.
 
The 25 vm is too long for 10 twist. Will need short bullets, what velocity are you seeing ?
These are with 25 grain bullets.
Velocities vary with powders, but the 8208

SDFPS
8208 XBR17.051.13430
17.841.23606
18.262.23682
18.610.93846
19.429.73946

IMR 4198
15.021.63464
15.522.13574
16.025.33661
16.512.53778


With 20 Vmax
GrnSD FPS
H33518.0 3605
18.539.2 3826
18.7 3541
19.0*16.6 3826
19.527.4 3956
20.09.7 4065
20.6*14.7 4222
 
Last edited:
How much neck clearance do you have?

Is your front rail screw bottoming out on the tenon?

Carbon ring?
Initially, I had the brass necks too thick (about .0140), so I turned them thinner, now about .0125 to .0130 thickness, so about 4 to 5 thousands clearance.
No carbon ring I can see, but I can't see in the chamber with my borescope, as it's too big. I'll try to check that somehow...

The front rail screw should not be bottoming out, but good suggestion to verify! It shot bad with the original scope base, and now I have a different one.

17M4 3 action.jpg
 
Last edited:
I should have said the front screw on the base.
Sometimes the screw is too long and will hit the barrel before the base is tight.
Remove the rest of the screws first and wiggle the base to see if it’s tight.

Hal
 
Also, what about the firing pin and spring?
I was wondering about those, not sure how to diagnose if that's an issue. The primer strikes are not too deep, that I did notice, but they go bang. The rifle was built over 20 years ago, and sat in a gun safe for 20 years the owner said. The fellow had health issues, I found out, thus decided to sell his rifles.

How do I tell if there's an issue?
 
I should have said the front screw on the base.
Sometimes the screw is too long and will hit the barrel before the base is tight.
Remove the rest of the screws first and wiggle the base to see if it’s tight.

Hal
This action only has two screws, one on the bottom in the front, the other comes in from the top, under the bolt, and can't be tightened down too much, not sure of actual suggested torque, but bottom screw the gunsmith that built it told me 35 inch pounds on the bottom screw.

Action rear screw.jpg
 

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