Welcome, Guest. Please login or register.
December 06, 2019, 03:51:15 AM
Home Home Help Calendar Login Register
News:

Please support BullpupForum.com sponsors!!
. . . Midwest Industries . . . BullpupArmory.com . . . Shooting Sight . . . BullpupUnlimited.com . . . Homeland Guns . . . . . . . . . . . . Desert Tech . . . GallowayPrecision.com . . . K & M Arms . . . . . . Geissele Automatics
+  BULLPUP FORUM
|-+  Bullpup Rifles (Auto & Semi-Auto Centerfire)
| |-+  IWI TAVOR
| | |-+  IWI Tavor SAR & X-95
| | | |-+  Tavor Accuracy
Pages: 1 2 [3] 4 5 Print
Author Topic: Tavor Accuracy  (Read 55715 times)
RoniRider
Member
**
Offline Offline

Posts: 15


« Reply #40 on: March 02, 2014, 03:57:37 PM »

UPDATE***
OK, so I have shot two different days to give you an update on my POI shift.  In hindsight, I wish I would have shot again before installing a new muzzle brake, I think the results will still give us some insight to the heat/accuracy issue I am experiencing.  Day I, my impacts we high due to a new muzzle brake installed ( adjusted zeroed for the next day).  The Cold bore shots are circled.  After 3 (30rd) mags, you can see the spread still goes high and right (the uncircled holes).  Perhaps not so much, due to the harmonics of the barrel being altered by the heavy muzzle brake. 

The second target is the next day of shooting with a cold dirty bore.  since I adjusted the zero the first day with the barrel a little warm, I guess the zero came back down and left more when cold. 

The last target is the Tavor w/Mepro21 VS. M4 iron sights at 50yds. Cool barrel. 

ALL THESE SHOTS WERE FROM THE SITTING POSITION. (WISH MY RANGE HAD BENCHES).


* Day 1 M Brake.JPG (88.85 KB, 640x478 - viewed 586 times.)

* Day 2 Cold Dirty.JPG (90.45 KB, 640x478 - viewed 1026 times.)

* photo 4.JPG (92.89 KB, 640x478 - viewed 796 times.)
Logged
Slateman
^
Bullpup Fanatic
****
Offline Offline

Posts: 924


« Reply #41 on: March 02, 2014, 09:34:30 PM »

What kind of ammo?
Logged
RoniRider
Member
**
Offline Offline

Posts: 15


« Reply #42 on: March 02, 2014, 11:00:40 PM »

 55gr FMJ armscorp.  I also used 55 gr tula before with same results. 
Logged
bluonyx
.
Member
**
Offline Offline

Posts: 6


« Reply #43 on: March 03, 2014, 12:45:01 AM »

Went to the range earlier this week and had good results with Fiocchi ammo.

It was Fiocchi 223A 55gr FMJBT. Overall I'm pretty happy with my placements since I've only been shooting for a year, so you could say I'm still a newb.

First shots were at 50 yrds to sight in the red dot.



These next ones were at 100 yrds.

Logged
Slateman
^
Bullpup Fanatic
****
Offline Offline

Posts: 924


« Reply #44 on: March 03, 2014, 09:06:09 AM »

55gr FMJ armscorp.  I also used 55 gr tula before with same results. 

That is some pretty meh ammo. Probably has more to do with your groups than the barrel being overheated.
Logged
RoniRider
Member
**
Offline Offline

Posts: 15


« Reply #45 on: March 03, 2014, 09:32:36 AM »

At this point, Point of Impact (POI) would not change with one brand of ammo without something else affecting it such as fouling or barrel heat. 

All these shots were in the sitting position so one would need to take that into consideration when looking at the group size.  The groups shot are intended to show that my particular IDF version Tavor shoots high and right after the barrel heats up (approx 3 mags).  I further believe that fouling is not an issue since I shot a dirty cold bore group.  To me it seems that the IDF version with just two mounting points has a greater potential of a shift in the POI from barrel heat than the Flattop versions for the following reason:
- Flattop rail is longer and has more points to stabilize it
- Flattop also act as a heatsink
- IDF version barrel directly mounts to the Mepro21 and transfer a lot of heat to the scope base.

I will shoot some heaver 69gr Nosler reloads just to remove all doubt that ammo is a factor with the POI shift.
Logged
clance
Member
**
Offline Offline

Posts: 14


« Reply #46 on: March 03, 2014, 10:29:31 AM »

I wonder if cryogenic treatment of the barrel would resolve a lot of the accuracy issues caused by the barrel warping during heating and cooling?

It is my understanding that the molecules of the metal aren't uniform in their structure but can be more or less dense randomly throughout the barrel due to the forging process. 

What the cryogenic process does as I understand it, is to condense the molecules forcing uniformity via attaining near absolute zero centigrade.  Then slowly reheating barrel allowing for a uniform expansion of the molecules, reducing causes for barrel warpage and uniforming the harmonics.

I would be interested in hearing from someone that has had this process done on another rifle and what the results were, and did it actually improve the overall accuracy of the weapon or had no effects?

One of the things that I would really like to see is Israel Weapon Industries (IWI) do is start offering for the civilian market heavier barrels at variable lengths, offering the option for stainless, and while I'm aware that they're talking about offering different calibers.  Actually start putting these options on the market...
Logged
Gunoil
Member
**
Offline Offline

Posts: 180



« Reply #47 on: March 03, 2014, 12:02:35 PM »

Good points Clance.Here is a good read on the different benefits of cryro barrel treatment.

https://nfa.ca/resource-items/cryogenic-treatment-rifle-barrels-0
Logged
clance
Member
**
Offline Offline

Posts: 14


« Reply #48 on: March 03, 2014, 01:44:50 PM »

Good points Clance.Here is a good read on the different benefits of cryro barrel treatment.

https://nfa.ca/resource-items/cryogenic-treatment-rifle-barrels-0


Interesting read Gunoil, thanks for sharing.
Logged
RoniRider
Member
**
Offline Offline

Posts: 15


« Reply #49 on: March 03, 2014, 03:58:38 PM »

Cryogenic treating was a big thing about 15-20 years ago but it has never been proven to be hugely effective.  It is like taking vitamins, it can't hurt, but you don't really know if it will help.   

Armalite doesn't seem to think cryo treatment is worth it: http://www.armalite.com/images/Tech%20Notes%5CTech%20Note%20103%20CRYOGENIC%20TREATING%20120206%20Rev%200%20Final.pdf
Logged
AZ2000
^
Sr. Member
***
Offline Offline

Posts: 329


« Reply #50 on: March 03, 2014, 08:46:02 PM »

Could be the temp difference between the barrel (steel) and the receiver (aluminum). Some will probably say, the AR is and can be very accurate, true but the barrel in an AR is held to the receiver by a torqued barrel nut.  The Tavor is mated by a pin. The aluminum will expand at an approximate 2 to 1 ratio, depending on the types of steel and aluminum. May be why the cold bore shots are more accurate? (just my  2 cents)
Logged
RoniRider
Member
**
Offline Offline

Posts: 15


« Reply #51 on: March 03, 2014, 09:36:58 PM »

AZ2000,  Excellent hypothesis!  I never thought about the pin locking the barrel to the receiver.  At least with a barrel nut on an AR there would be symmetrical heat transfer and pressure.  On the Tavor the pin cut out on the barrel might not allow an even heat transfer and cause the shift of impacts. 

The only reason I got wrapped around the axel with this is because for a combat rifle to shift an 1" @ 50yrds would yield a 6MOA off taget @ 300yrds....thats a big difference from aiming point when you are trying to hit a target shooting back at you. 
Logged
TDECK
Member
**
Offline Offline

Posts: 15


« Reply #52 on: March 03, 2014, 10:39:07 PM »

So is it a 6 moa rifle? It would surprise me if so after watching Hickok45. He puts the borrowed Tavor through its paces and it seems to hold 0. He has some small metal targets set out at a pretty good distance which he easily hits. He even hits a rolling watermelon which is not easy. Hickok45 does not want to like the Tavor but cant help himself after its fine performance.

I have a flat top 18 inch model and have not had any issues at all. I have only taken it out three times so my experience is limited.
« Last Edit: March 04, 2014, 01:22:51 AM by TDECK » Logged
RoniRider
Member
**
Offline Offline

Posts: 15


« Reply #53 on: March 03, 2014, 11:15:32 PM »

TDECK, scroll up and read my previous postings to see what I was referring to.
Logged
TDECK
Member
**
Offline Offline

Posts: 15


« Reply #54 on: March 03, 2014, 11:30:01 PM »

RoniRIder there seems to be different ideas on what is happening concerning the POI s***. Can you bottom line it for us? I am considering another Tavor purchase but will hold off until I know whats going on with the POI shift.
Logged
RoniRider
Member
**
Offline Offline

Posts: 15


« Reply #55 on: March 03, 2014, 11:33:46 PM »

Bottom line regarding my IDF version is that the group goes high and right after barrel heat up.  Seems everyone else is just fine with their Flattop Tavor tight groups.  I guess they can shoot 2" groups all day no matter how hot the barrel gets, but mine can't.  

Also I shouldn't have stated 6 MOA.  What I meant was that the accuracy would be of by 6" @ 300yrds from cold bore accuracy. 
« Last Edit: March 03, 2014, 11:39:58 PM by RoniRider » Logged
TDECK
Member
**
Offline Offline

Posts: 15


« Reply #56 on: March 03, 2014, 11:53:02 PM »

Ok, then that would explain the Hickok45 video since he is shooting a flat top.  It is impressive in case you havent seen it.
« Last Edit: March 04, 2014, 01:21:58 AM by TDECK » Logged
Gear Head
^
Bullpup Fanatic
****
Offline Offline

Posts: 3,686



WWW
« Reply #57 on: March 04, 2014, 01:20:05 AM »

At this point, Point of Impact (POI) would not change with one brand of ammo without something else affecting it such as fouling or barrel heat. 

All these shots were in the sitting position so one would need to take that into consideration when looking at the group size.  The groups shot are intended to show that my particular IDF version Tavor shoots high and right after the barrel heats up (approx 3 mags).  I further believe that fouling is not an issue since I shot a dirty cold bore group.  To me it seems that the IDF version with just two mounting points has a greater potential of a shift in the POI from barrel heat than the Flattop versions for the following reason:
- Flattop rail is longer and has more points to stabilize it
- Flattop also act as a heatsink
- IDF version barrel directly mounts to the Mepro21 and transfer a lot of heat to the scope base.

I will shoot some heaver 69gr Nosler reloads just to remove all doubt that ammo is a factor with the POI shift.


The flat top rail mounts to the gas block as does the IDF sight base. The rail may appear to be mounted more securely to the gun stock but that isn't really the case. The front of the rail just sits in a notch and the rear of it is just nestled in a pocket. Neither really add holding force. And if it did, it would probably just add to the POI shift when different forces act on the stock like changing shooting positions or using a sling.

Take a look at all the things that are attached to the barrel for a moment. Starting at the receiver working forward, the first thing that can apply pressure on it is the gas piston from the bolt carrier itself. It is in the gas block which is of course pinned to the barrel.

Then the gas block of course. While it doesn't apply pressure to the barrel in any particular direction by itself, it provides mounting for several things that can. Like the optics.

Both the IDF sight and flat top rail bolt to the top of the gas block. Any pressure applied to them transfers directly to your thin barrel. So if you try to do a "thumb over" grip on a flat top, guess what, your hand grip is pushing against the barrel indirectly.

The front sling socket also is attached through the gas block. Run tension on your sling, you have tension on your barrel. The sling mount also holds the charging handle assembly on in the rear.

Again, if you are holding the top of the gun somehow or have something attached to the factory side rail, that can all apply pressure to the barrel indirectly through the gas block. But that isn't the only place. The front hand guard screws pass through the forearm, stock body and upper part where the charging handle slots are. They thread into the "U" block that is wrapped over the top of the barrel and has a bushing inside of it that sorta pinches the barrel. That is why those mounting screws get hot when you shoot.

We aren't done though. The charging handle itself also rides along the top of the barrel and applies pressure to a ferrule they have pinned on the barrel. It is what gives it the leverage feel when you first start pulling back on it.

Similar to how an AK is, they used the barrel as a convenient place to mount several things to make it work.. It is the structure that keeps the front end of the gun rigid. If you have ever removed your forearm and charging handle assembly, you can easily feel how flimsy the front of the stock body is when nothing is attached to the barrel.

Logged

The second Amendment is the last line of defense for the 1st.

Gear Head Works' products are leading the way in innovative designs. Click the globe icon below my Avatar to visit www.gearheadworks.com
TDECK
Member
**
Offline Offline

Posts: 15


« Reply #58 on: March 04, 2014, 01:39:56 AM »

Gear Head, does this mean the Tavor platform is prone to POI shifts? I have had good luck with mine so far. I was just questioning how someone like Hickok45 could put on such an impressive display with a borrowed Tavor if the Tavor has such a problem with POI shifts. I think Hickok45 is at least 70 years of age and he just chews up targets of all sizes and distances with his borrowed Tavor. He even hits a target several times that is rolling down a hill. This and my own experience left me questioning the POI shift issue. The one thing I can say is I dont "ammo dump" because it is a complete waste of ammo in my opinion. I cant hit jack while ammo dumping so I dont see the point of this unless it is a function check. Could it be that this is what is causing the POI shift because of excessive heat from "ammo dumping"? 
Logged
Gear Head
^
Bullpup Fanatic
****
Offline Offline

Posts: 3,686



WWW
« Reply #59 on: March 04, 2014, 01:58:23 AM »

There is many factors that can affect POI. My personal gun doesn't shoot nearly as well as some of the groups I've seen posted here. I've shot it from rests, benches, supported etc. I've been competition rifle shooting for going on 30 years now too so I should have an idea of how to shoot.

I am just stating the facts. And every one of those factors can be a variable. And with any variable, your impact can change. That is why the most accurate guns have free floated barrels. The purpose is to eliminate as many variables as possible. The way the barrel attaches can be another factor as well as stated above. It is a slip fit with just a cam locking it in place. An AR gets torqued down with a nut against a flat surface, a DT rifle is a slip fit but then gets tightened down with several bolts too. Both are or can be very accurate. A difference in just a few tenths of thousandths can make a difference in accuracy in this spot. So I can easily see that there could be a difference in performance between guns. Manufacturing tolerances will play a major role in this.

The thinner barrel profile combined with the things attached to it can easily cause a change with heat as well.

Those are just factors involved with the gun design itself. Ammunition plays a key role in accuracy as well. Just because one rifle likes ammo "X", doesn't mean another gun of the same model will. That is true with any rifle. Barrel harmonics and ammunition factors are an entirely different subject that would take an whole thread by itself.
Logged

The second Amendment is the last line of defense for the 1st.

Gear Head Works' products are leading the way in innovative designs. Click the globe icon below my Avatar to visit www.gearheadworks.com
Pages: 1 2 [3] 4 5 Print 
Jump to:  



Login with username, password and session length

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
SimplePortal 2.3.5 © 2008-2012, SimplePortal
Valid XHTML 1.0! Valid CSS!