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  #31  
Old 10-06-2017, 03:19 AM
Ratbuster Ratbuster is offline
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Originally Posted by rick w. View Post
FWIW, PTG has always asked me on rimmed cases, if I wanted to headspace on the rim or the shoulder. I have always chosen the shoulder. My 17 Khornet with a GM mountain barrel shoots ok, and used the gages(shoulder) that PTG provided with the reamer.

One might peruse the crown with a q-tip, a real long shot as I have seen burrs on some crowns and the rifle was performing. A mystery to be sure.

Most barrel makers talk about removal of some length of the barrel fore/aft as their barrels were lapped.

0.050" seems like a lot of lead; just thought that was a bit odd for such a reamer.
I agree that lead surprised me too. It was jammed, just touching would a bit less. I will be trying different bullet seating depths for sure. If that solves the problem then I reseat all the ammo for my son in law because it will be quick to partially pull the bullets seat them to the best depth.

Thanks for the tip on evaluating the muzzle with a q tip. I did look at it with high magnification but visualizing is not necessarily going to tell the story. I wish my bore scope worked with 17 cal stuff.
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  #32  
Old 10-06-2017, 11:53 AM
Alan in GA Alan in GA is offline
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Default Barrel quality .....

I think your GM barrel is the reason. I've only purchased one GM barrel for a project experiment (45ACP bull barrel I fit to my Ruger 77). I knew I was buying a medium quality barrel from what I had read about them. In other words a barrel of average quality that would be a crap shoot as far as accuracy, but I would be doing the machine work myself.
I would never (?) buy a GM barrel for a rifle project involving expensive smith work and EXPECT match accuracy unless I wanted to GAMBLE for the results. I've always gone with $250 (bulk buy with gun builder friends) to $300+ blanks from PAC Nor (super match) and have never been disappointed with the results. I'd have to say you get what you pay for from my barrel buying experiences!
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  #33  
Old 10-06-2017, 03:18 PM
moorepower moorepower is offline
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Originally Posted by Ratbuster View Post
If you do a standard 17HH chambering to work with an action designed for the rimmed Hornet cartridge then indeed it will be headspaced off the rim. In my application using a Savage action headspacing off the rim is not an option. In my opinion it is better to HS off the shoulder anyway. In this case we have the HS correct. After firing the cases stretch .002 to .0025.

The 17HH SAAMI spec is woefully flawed. Take a look at the SAAMI chamber and case diagrams. SAAMI allows the recess in the breech to vary from .072 to .065 deep and a rim thickness from .055 to .065. So if you had a case with a thin rim that still met spec you could and up with a headspace of .017 and fall in line with the spec. That is not a misprint...17 THOUSANDTHS ... The Hornady cartridge rim is at or around .061 thick. If the recess in the breech is cut on the deeper side approaching that .072 allowable depth you end up with .011 headspace with Hornady ammunition, too much!

My smith requested 3 once fired cases in lieu of a GO/NO go gages as there are no gages for headspacing off the shoulder. I fired 3 rounds through a 17H 527 CZ Varmint model that shoots factory ammo nicely. After the first firing of each cartridge the shoulder advanced .011 for each one of them!
What I did was only run the reamer in far enough so that I have .063 cut for the rim. That way, I have 0-.002 headspace. I get you want to headspace off of the shoulder, but the loaded rounds are not uniform enough to do this. If I were to use the action you did I would make sure that the bolt head only had a cut the depth of .063. Once I fire a round in the Hornet, I do not touch the shoulder, and then you have a fire formed load. Its no different that blowing out a ai case or any other case. There are plenty of guys on this forum that are getting groups far less than 1" groups with the factory 20 grain Vmax ammo. I still think you probably got a bad barrel. That does not mean that a GM barrel is bad, in my mind YOUR GM barrel is bad. I would call GM and ask them if they could look at the barrel.
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  #34  
Old 10-07-2017, 03:35 AM
Ratbuster Ratbuster is offline
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Douglas,

I agree with you on the barrel. Luck of the draw. I know GM will send another one and ChuckShooter kindly volunteered to chamber the new barrel if Brandon chooses to go that way.

It's nice that you can chamber your own to control headspace. When you buy a factory Hornet you get what you get.

For a Savage model 12 action we could not headspace off the rim. Savage 12's are designed for rimless cases so when using it with a rimmed case like the Hornet rim has to stay outside the breech in order for the extractor to get over it.

BTW, I measured about 20 cases; base to shoulder datum were all very close with an extreme spread of 2 thousandths. Case stretching is minimal.

I ordered a bullet seater for the 17HH which arrives next week. It will be interesting to see how much accuracy improves by getting the bullet closer to the lands.
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  #35  
Old 10-07-2017, 01:26 PM
moorepower moorepower is offline
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Well that's a bummer, I did not think about the extractor on the 10-12-16 actions.
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  #36  
Old 10-08-2017, 03:52 PM
Ratbuster Ratbuster is offline
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Douglas,

At your leisure could you measure one of the rounds you shoot in your rifle chambered by the reamer you loaned me and tell me what the COAL and your jam or jump distance is? Also which bullet; I have both the 20 vmax and 25 HP.

I'm just curious to see how close our measurements compare since we used different headspacing methods

Thanks,

Phil
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  #37  
Old 10-09-2017, 06:06 AM
Double D Double D is offline
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Quote:
Originally Posted by Ratbuster View Post
Douglas,

At your leisure could you measure one of the rounds you shoot in your rifle chambered by the reamer you loaned me and tell me what the COAL and your jam or jump distance is? Also which bullet; I have both the 20 vmax and 25 HP.

I'm just curious to see how close our measurements compare since we used different headspacing methods

Thanks,

Phil
Phil,

If you are talking to me I can't help much. I am in Montana and the guns and ammo and notes are all in Oklahoma. So relying on memory and what my practice is for mass loading to fire form brass, my OAL should have been factory length.

Bullets were 20 gr. V-max. Groups were small, but didn't test for accuracy. I used 1680 powder. The groups had to be under 3/4 inch or i wouldn't have bothered with them.
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  #38  
Old 10-16-2017, 04:47 PM
Ratbuster Ratbuster is offline
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Default Much Better!

I partially pulled out and seated the bullets to get closer to the lands. Groups are now in the high 3's to low 4's. Not as good as guns i reload for but it is factory ammo and will be an effective squirrel puncher out to 250 yards.

I think this technique is a good option for non-reloaders who desire improved accuracy without having to spend a lot of time and money. A cheap press, bullet puller (I like Hornady Collet style) bullet seater and way to measure CBTO.
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  #39  
Old 10-16-2017, 10:44 PM
pwdrbrn pwdrbrn is offline
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ALRIGHT! !! Glad you found the solution, as easy as pie, just pull the bullets and reseat! Good grief, what a pain. At least it isn't a rebarrel job. Keep us posted on further details, Tom.
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  #40  
Old 10-18-2017, 04:44 PM
bburrell bburrell is offline
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"Groups in the high 3's and low 4's" Those are great groups. So many variables that it is difficult to consistently do better than that with any firearm let alone one built for sporting use using factory ammo (albeit reset bullets). Your SIL should be very very happy with the results. Wish all of my guns shot that well. Burt
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