17 Rem load inconsistency

[StevenCO]

Folks,

This is my first time dealing with the .17 Rem and I seem to have a problem getting loads to repeat from one bench session to the next. I don't mean by a little bit, but rather by an amount that is disconcerting. I weighed brass and then re-used the same brass after I had worked up loads. My extreme spread in 10 shots was 62 fps, but on the order of 80 fps slower than the velocities I obtained when working loads up a grain at a time. I went back to that same load again and got velocities slower yet. I've double checked about all I can in the way of scale calibration and so forth. The one variable that I cannot seem to account for is the neck tension. It seemed to me that the reloads are not as tight as before. The first load attempts was with new brass which, even after running through sizing dies, seemed tighter in the neck than my reloads.

Just how much can varying neck tension impact velocities?

For those interested in specifics:

Case Neck diameters:
Loaded round---------------0.193"
Neck after firing----------0.200"
Neck after re-sizing-------0.191"



Load workup:

20.5 gns 3329 fps
20.6 gns 3298 fps
20.7 gns 3384 fps
20.8 gns 3364 fps
20.9 gns 3479 fps
21.0 gns 3444 fps
21.1 gns 3440 fps Seemed consistent - Used in 10 shot string
21.1 gns 3456 fps
21.1 gns 3439 fps
21.2 gns 3488 fps
21.3 gns 3482 fps
21.4 gns 3476 fps


10 shot string:

21.1 gns 3362 fps
21.1 gns 3363 fps
21.1 gns 3411 fps
21.1 gns 3392 fps
21.1 gns 3407 fps
21.1 gns 3402 fps
21.1 gns 3424 fps
21.1 gns 3407 fps
21.1 gns 3415 fps
21.1 gns 3398 fps

Average 3398 fps
Standard Deviation---------21 fps
Extreme Spread-------------62 fps

5 shot group = 0.273"

Latest attempt

21.1 gns 3318 fps??? Only one shot fired.

Any thoughts?

Thanks

 

[StevenCO]

I have tried to answer and respond to comments below. Thanks.

What kind of dies? I have $200 Reddings and $25 Lee's and the Lee's win every time.

I am using Forester dies. I think the expander ball may be a little different than the Reddings. I will have to check on that.

What chronograph?

It's a Chrony F-1.

What kind'a brass? Probably Remington since that's about all you can usually find. That alone will cause some problems.

Yes Remington and it took a lot of sorting

Whose bullet, powder, primer? The 17 Remington can be kind'a fussy.

One's worst nightmare. I am using 37 gn VLD's in a tight twist,1:7) The powder is VVN540 and CCI450 primers. Fussy, seems to be an understatement.

How many rounds between cleaning? Frequently the grooves are only 0.0015" for the 17 Rem vs 0.003" or so for larger calibers. Therefore they need cleaned more often.

I have to clean it pretty much after about 15 rounds, or the bullets can go sideways....literally.

3318 for one shot. Clean, cold? Not cleaned - 2 shots, but it was cold Could have been a lot worse. Big difference between target shooting and live varmint shooting. If you'd like a real eye opener and can afford to go to the range frequently make about a dozen trips and shoot the first shot from a clean, cold barrel into the same target every time then the rest into another. There are some that will put them into the same spot but they're very rare.

I've thought about this. I guess I didnt' think about saving my target from previous trips to the range. I mostly like to hunt coyotes and the like, which is why I went this route. Generally, I guess the first shot is the one that counts....sometimes the next few. That's a good suggestion.

Five shots into 0.273"? I'd be pretty happy with that. I figure the 17 Remington is about a 300 yard rifle. Less than 0.3 MOA works fine at 300 yards..... I know, I've heard the story about the guy who shot a deer with a 17 Remington at 600 yards that dropped like a rock. Skull was like a bag of marbles..... whatever.

I am hoping to go out to close to 5 to 600 yds with this bullet. I can get 2 shots within about a 1 1/2 inches at 300 yds. The 3rd shot has been flying on me, which is why I am trying to dial the velocities down a little better. It shoots flatter than my 204 otherwise. If I can get it all squared up it should be pretty impressive... maybe a tall order.

 

[StevenCO]

Thanks for checking into that. I guess I still have some work to do. I'll try that.

Consistency or 100 fps??

I may take you up on those dies, but I need to do some work on the neck turning first. I thought I was rigged and ready for turning them, but then found that the shank on my 17 caliber pilot, that I special ordered a year ago, was smaller than all of the rest of the pilots with my neck turning rig. That's enough to drive one...well, anyway...

I will have to admit...moly coating scares me a little. But perhaps I need to look into it more,perhaps the subject of another thread if I can't find any threads already written).

Thanks again.

 

[StevenCO]

Quick update on this subject/load.

I turned the necks to cleanup about 50 to 75% of the neck and found, from what I can tell more consistent neck tension. I also kept with the sorted cases. What I found was that I was getting consistently lower velocities with a charge of 21.1 gns. So, I worked it up again and got the jump at 21.3 gns with the following variations....these were all shot on a cold barrel. For the last shot, the barrel may be fouling a little.

I'll have to try it again at the range.

VVN540 Muzzle
Load Test Charge Velocity
1 37 Grain 21.1 gns 3318 fps
2 37 Grain 21.1 gns 3314 fps
1 37 Grain 21.3 gns 3436 fps
2 37 Grain 21.3 gns 3436 fps
3 37 Grain 21.3 gns 3424 fps
4 37 Grain 21.3 gns 3404 fps


Anyway, for those interested, thought I would update.

 

[garyw]

STEVENCO.im in the same boat as you at the moment just working up loads for a rebareled tikka[lilja tube .197 nk ].found the magic load last week then worried about velocity/es/std deviation/and all the other sh*t that turns your brain to mush.then last weekend i was showing the rifle to the guy that got me started in small calibre rifles[hes a farmer]telling him about borrowing a chronograph for the loads iv worked up;any way he says, as we were watching some rabbits on one of his fields.shoot the rabbit nearest to you about 90 yds- 20 vmax whack!dead.now as thing settled shoot the one furthest away he says[ approx 170 yds]same result dead as a nail he then says right go ask both of them[rabbits]how fu****g fast them bullets were going!his point was rammed home.so dont worry about speed if everything goes where its meant to.
any ways good luck.
garyw

 

[StevenCO]

Dead is dead.

I'm sure I will come to that point yet. Still learnin' about this one though.