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Old 11-08-2010, 05:46 PM
17tbs 17tbs is offline
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Question 17 mach 4 orfireball velocity questions fast can I make a 17 grain or a 19 grain copper bullet go out of a 21" barreled 17 fireball/Mach IV? Help I just want some experienced advice for what I could expect.

Last edited by 17tbs; 02-19-2016 at 07:27 PM.
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Old 11-13-2010, 06:44 PM
malahini40 malahini40 is offline
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Default 17 Mach 4

A few years back I built a 17 Mach4 for a customer and he chronoed some loads with the [then new] Hornady 20 gr pills. He is getting a bit over 4000 fps and VERY sub MOA! I would expect about the same for the 17 gr and a bit faster. BTW it is a Shilen barrel ---1-10 twist and 22" long.
Aloha, Mark
When the fear of death is no longer a major concern?---The rules of war change completely!
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Old 02-18-2016, 08:52 PM
17tbs 17tbs is offline
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Default Update

4764fps 17gr gsc sp solid nearly full to the base of the neck with xx.xgr h4198, cci br400, remington 17 fireball brass, remington svs 26 inch 1 in 9 twist.
That is a case nearly full of h4198 up to the bottom of the neck. Don't use a 20gr std bullet to use with the same powder load, it is unsafe with any other bullet. The gsc 17gr sp solids are drive band bullets allowing about 0.5 gr more powder in the 17 REMINGTON FIREBALL.

Read what Kenny wrote below first, then consider the safety margins you SHOULD follow for safe practices and loads.

Don't use the above load if you dont have a 17gr GSC drive band bullet.


" GS Custom HV, FN and SP bullets are manufactured so that the shaft fits the bore diameter of the barrel (A). A series of driving bands are machined to fit the groove diameter (B) of the barrel. The bullet shaft rides on the lands of the rifling (green sections) and the ogive and boattail are not engraved. Although the shaft touches the barrel, material is not displaced from the shaft of the bullet. The thin drive bands on the shaft simply deform (red sections) into the spaces behind them and the resistance to engraving is the lightest of all bullet designs. "

Last edited by 17tbs; 02-19-2016 at 06:51 PM. Reason: Safety note
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Old 02-19-2016, 03:30 PM
sicero sicero is offline
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My experience advise.

Use only published loads with pressure testing information.

You'r welcome. Kenny

I pride myself in being able to make decisions with little information.
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Old 02-19-2016, 07:01 PM
17tbs 17tbs is offline
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Thumbs up Safety first

It goes without saying, but I'll say it anyhow, SAFETY FIRST,

Following what you said Kenny will keep all our parts attached and shootong safely for years.

This following is a WARNING pulled directly from the GSC website, follow it to the letter. Warning!!Warning!!


Do not use HV, FN and SP bullets load data for any other type of bullet, our HP range included. Dangerous pressures may be generated, leading to damage to the firearm and injury. See the HP Load Data for HP loads and consult the load guides of other manufacturers for data concerning their products.

That being said, there are NO PUBLISHED LOADS FOR THE GSC .172 CALIBER BULLETS. All of the loads I have carefully worked up to in one tenth grain increments.

Thanks Kenny for reminding me to post this.

Don't go attempting to duplicate my high velocity with any other bullets, it is not safe. For instance a 17grain vmax .172 Hornaday is at max pressure at about 1/2 a grain LESS than with the GSC bullet of 17grain. The GSC bullets were also moly coated. You can order them either way from GSC.

Taking that all into consideration the 17gr GSC SP .172bullet is easily capable of going a lot faster than you can push it in a rifle, so don't worry about it not getting to the target, it was designed for extremely high velocities from the outset, and it gave me considerable room for adding powder in tenth grain increments until the chronograph reading indicated it was going several hundred feet per second faster than the .172" 17gr vmax from Hornaday.

I pride myself in making informed decisions with required information, no guesswork keeps me safe.

Last edited by 17tbs; 11-21-2019 at 04:11 AM.
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.172 copper solids, 17 fireball, 17 mach iv

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