17HMR VMax vs. FMJ results

[JelloStorm]

Ok guys, finally got to take my 17HMR out and spend time at the range so here are my results.

The conundrum: I want to use 20gr FMJ for squirrel to damage less meat. Yet the VMAX shoot better.

Here is the results of today's shooting. Both groups are 5 shot groups @ 50 yards. Gun is a Savage FSS 17 HMR NON-heavy barrel. Shot off Harris bipod and rear bag.

Point of aim for both groups is the Acorn itself.

As you can see, the VMAX all grouped extremely well inside the Acorn, while the 20gr FMJ had a high and right diagonal string about 1.25" long by .5" in height (measured diagonally).

I'm pretty sure there's nothing I can do at this point, only try to take head-shots on Squirrels come small game season since the FMJ's wont perform at all out of my gun.

 

[BadBowtie03]

Re: 17HMR VMax vs. FMJ results

head shot those little nut grabbin bastards!

 

[wkrutledge]

Re: 17HMR VMax vs. FMJ results

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Badbowtie03</div><div class="ubbcode-body">head shot those little nut grabbin bastards!
</div></div>

X2

 

[JelloStorm]

Re: 17HMR VMax vs. FMJ results

Sounds easier said than done, especially here in Northeast PA which is heavily wooded. When you're in the woods you only have a second or two to take a shot before the little buggers are climbing up into trees and disappearing like little grey ninjas.

 

[JelloStorm]

Re: 17HMR VMax vs. FMJ results

Can anybody really elaborate on the science behind what makes a barrel prefer one load over another?

In my centerfires, the spread between 'like' and 'dislike' is far less pronounced than it is on the 17HMR.

But I can never find a solid answer as to the WHY.

 

[isaaccarlson]

Re: 17HMR VMax vs. FMJ results

harmonics, inside barrel finish, throat, etc....there is a lot to look at.

 

[TOP PREDATOR]

Re: 17HMR VMax vs. FMJ results

alot of folks that i've read here and elsewhere that tried the 20 fmj turned out with the same type of thing.

i was thinking of finally getting a .17 especially for fall turkey, but if the fmj's are flying around like that, i think i'll stay with the .22mag.

probably a barrel twist thing. i think since the inception of the .17, everything was based specifically around the 17 gr vmax and later when they came out with the 20 gr, they didn't fly as well.

now if they came out with a 17 gr fmj, perhaps they will fly better. obviously the 17 vmaxes are aces.

i know 3 gr isn't much difference, but the bigger / longer 20gr bullet that is quite small in size anyway and the FPS of the round itself can be causing a whole lot of difference.

 

[justin amateur]

Re: 17HMR VMax vs. FMJ results

Whether or not this will apply to your rifle can only be determined by testing.
My CZ 455 with the .17 hmr barrel would group the 17 gr rounds at moa.
but load with the 20 grain rounds and the spread was obvious.
Strays and flyers showed up, so I started hunting a solution.
Turns out that shimming the barrel at the fore end of the stock
cuts down on the flyers.

Here's the target from a bench testing session from bipod and rear bag.
Scope was zeroed for the free floated barrel before starting the session.
POA was the center of each bull, impact differences are caused by the shimming.

The shim material used is FelPro automotive gasket from the local parts store.
Oil, heat resistant and cuts easily with a knife or scissors.
Cut the size needed, stack for thickness and slip into the barrel channel.
The top left bullseye is with the shim placed just forward of the receiver.
Each succeeding bull the shims were moved further from the receiver towards the muzzle.
Each shim position produced a slightly different group.
The bottom right bull had the shim as shown in the first pic.
The shim is all the way forward at the fore end of the stock.
Wrapped under and around the barrel, preventing motion left-right and down.
That bottom right bull has 4 rounds in a single bug hole before my excitement
threw that flyer down and right. I don't think the problem is the ballistics,
but the additional flex taking place in the stock and barrel, at supersonic speeds.
3 grains is a 17% change in weight from the 17 to 20 grain round.
Makes a difference in the loads transmitted to the rifle.
Give shimming a try, made a big difference in my squirrel hunting.
Those ballistic tips are great for meat spray when varminting,
but the 20 grain fmj is a supersonic icepick out to 125 yards.

 

[RedGoat]

Re: 17HMR VMax vs. FMJ results

The FMJ isn't grouping as well as the Vmax, but it is still easily minute of squirrel @ 50yrds. If your main concern is damaged meat then load up the FMJs and aim center mass.

 

[JelloStorm]

Re: 17HMR VMax vs. FMJ results

Excellent theory jaia!

I just yesterday purchased a heavy barrel 93r17 that I'm going to install in a McMillan stock and have bedded. I'll have to save my targets for both ammo types for before McMillan stock is installed and after for a comparison.

 

[justin amateur]

Re: 17HMR VMax vs. FMJ results

Like most tips regarding accuracy, all you can do is try it
and determine if it works with your rifle. A free floated barrel
is supposed to produce the most repeatable results, but only
if the stock and receiver are solidly locked together. But looking
at the rail guns used in the unlimited class of the USBRA,
those barrels are locked down and the receiver is hanging off the breech.
The other problem is the type of barrel being used. A pencil barrel
will whip all over the place due to recoil. The only way to pull
accuracy from a skinny tapered piece of machined metal is to
lock it down in several places, all the way out to the muzzle.
I don't accept free floated as a rule, only another suggestion to be tried.
With my tapered barrels, shimming produces the greatest repeatable accuracy.

 

[JelloStorm]

Re: 17HMR VMax vs. FMJ results

I've been wondering if the pencil barrel on my FSS is what is causing the 20gr rounds to fly about. That's why I picked up a heavy barrel to piss with and see what I get before putting a good stock on and after.

 

[justin amateur]

Re: 17HMR VMax vs. FMJ results

I have a Savage 64 FSS, my all weather squirrel gun for thick brush.
Between the "tupperware" stock and pencil barrel, accuracy is horrible
at any distance beyond 75 feet. It's so bad, that in order to prove
it was the stock and barrel, I fabricated a test bed to play with.

Heavy Metal

 

[JelloStorm]

Re: 17HMR VMax vs. FMJ results

I noticed that on my new rifle, which is a 93E receiver and just ordered (took about a month to get in) the mag drops in and out of this thing much better than the FSS I've had for years.

Maybe Savage fixed the crappy mag releases finally.