View Full Version : 14.5 Sabre Middy oddball behavior
I was given a 14.5 middy Sabre barrel by Gunz here a few weeks back. So I compiled the parts and assembled the upper half.
We took it out and put a 6.5 power variable Bushnell scope on it and got some really decent groups about MOA with both 77 gr and 55 gr Gamekings.
But some of our bulk ammo is loaded with those Hornady 50 grain Flat based soft points with 25.3 grains of Benchmark. (It's just a standard load for throttlin' ammo so we don't run ball powder in the good stainless barrels)
To the point... this barrel only hit the entire cardboard target (18"X24") twice at 50 yards. I had to move the target to 15 yards and this round shot about a 10-12" group. :confused:
WTF??? The bullets aren't keyholing, and there's no signs that they're coming apart. I've never shot a gun/ammo combo so horrendous. The barrel is a nominal 1/7 chrome lined 556 chamber GI profile.
Any theories?
That's hard to try and diagnose without being able to be there.
So your getting moa at a 100 or 50 with the 77's and gamekings. Then you switch to the soft points.and you are having trouble hitting a 18x24 piece of cardboard. You move it in to 15 and your getting shotgun like groups.
Is everything with the scope tight? Have you tried to run some iron sights/carry handle to see if you can rule out the scope and the mount. The optics setup would be my first place to check, a.barrel shooting moa then groups that are larger than 00buck at the same distance.
Are the bullets the 55 sp w/can or is it a 50? Im having a hard time trying to wrap my head around this problem.
Do you have any of the same bullets loaded with different powder? Are you running the wolf primers with this load?
Sorry for all the questions just trying to get as much info as i can. I have seen some barrels not like certain combos, but never that bad. I don't think its load related, because i could grab just about any powder, primer, bullet combo i have available and get accuracy at least on par with m855. With no load work up just a minimum load. From the loads i have seen you and pappabear post Im highly doubtful its the load.
No scope any more. Just irons. I went out Saturday with the specific goal of checking this out as we observed it shooting steel the week prior.
The bullets are the 50 gr SP with no canalure. And they shoot fine in other guns.
I haven't tried a different powder yet.
When you ran the irons were the problems just as bad? A little better? Worse?
I highly doubt its the powder causing that big of problems. I would ask if you ran it through a chrono, but that load would did the chrono even though it can't find an 18x24 piece of cardboard.
Was there anything abnormal about the bullet impacts on the target? Do you have any theories
I shot 3 mags in a row. 5 rounds each of 77s, gameking 55s, and the SPs.
The 77s shot poi at 50, the gamekings shot 1" below those, and then the SPs on hit the target twice. ?
My theory is that the barrel twist is somehow too fast for the light bullet. :confused: I mean... if it shot 4" groups at fifty, I'd be like WOW! It doesn't like that load... but this is crazy.
The holes that do hit the paper appear normal. You'd about have to shoot this thing to believe how dramatic it is.
thopkins22
03-11-13, 13:01
My theory is that the barrel twist is somehow too fast for the light bullet. :confused: I mean... if it shot 4" groups at fifty, I'd be like WOW! It doesn't like that load... but this is crazy.
People always say that generally the twist rate is approximate and that outside of cut barrels and hammer forging, it can vary. How true that is, or to what degree is something I don't know. Hence the reason that some 1/9 barrels shoot heavy bullets and some don't.
I would guess that you're right about the twist and you have something like a 1/6...or faster or slower(I don't know how fast it would have to be too really screw things up.)
Why don't you measure it with a Dewey rod or some other nice rod?
Here I always thought it was a myth that you could over stabilize a bullet short of spinning it so fast that it came apart.
Here I always thought it was a myth that you could over stabilize a bullet short of spinning it so fast that it came apart.
It would actually be "de-stabilizing" it... ;)
I need to shoot that batch of ammo in at least one other gun to make sure I didn't do something goofy with the powder setting or seating die.
I think I need to check the feedramps for any weird surface that could be grabbing the soft point.... and I'm going to chamber and eject a live round to see what the round looks like.
steyrman13
03-11-13, 15:47
Did you shoot a string of the accurate loads after the 50s to confirm zero still?
I was starting to think the twist rate was to fast as well. Then i thought that the 5 grain difference should not be to light unless your barrel is closer to a 1 in 6.5.
I have never checked the actual twist on a 1 in 7, because everything has always been stable. I checked a 1 in 9 i had, and it was actually 1 in 8.5.
I think your right about the bullet being spun to fast. You should check the actual twist rate along with trying the rounds in a different firearm. At this point i think it has to be to many rpm's. It is the only reason (i can think of) why you are having success with the first two loads and the third lighter one is giving you problems.z
It is just to odd that a 50grain bullet is doing this. I was reluctant to think your problem was that the bullet is being spun to fast, because i have shot 45 grain bullets out of my 1 in 7 with no problems. The groups were not great, but they were not near what your getting. I think your barrel has an actual twist rate that is a little faster than its claimed twist.
Edit: even if you made a mistake with the charge or mixed anything up in the loading process, i do not know of a mistake that could cause groups like your getting.
A weak SWAG is bullet setback. Do the feed ramps in the receiver match up will with the barrel? I would hard chamber a half dozen (from the same magazine if possible), maybe twice - and take a look at COL and/or damage to the bullets.
uncle money bags
03-11-13, 23:03
A weak SWAG is bullet setback. Do the feed ramps in the receiver match up will with the barrel? I would hard chamber a half dozen (from the same magazine if possible), maybe twice - and take a look at COL and/or damage to the bullets.
My bet is with this theory, specifically regarding bullet damage.
If bullet damage was causing the problem it would more than likely happen while the bullet is in the barrel. Like a burr tearing the jacket. If the feed ramps deform the tip it is not going to cause the bullet to be off like it is. The tip of the bullet does not have anything to do with how it flies.
I would think if the bullet was being damaged so bad that at 15ft groups open up to 10-12 inches the other bullets would be damaged as well. I doubt they would be near moa if the other bullet can not maintain 10-20moa.
I think the set back would be more likely of the two swag's shootist posted. Im sticking with the swag of the bullet not being stable, because its being spun to fast. If markm provides proof it is not Im coming up blank. Without being able to witness everything makes trying to diagnose the problem very hard. I have never had this happen to the extent markm is experiencing. I have had some loads that did not perform, but switching out a component fixed the problem. My groups were like m855 and they would not get better with any change in charge weight i tried. I actually had to change the powder or primer.
Checked the weapon and chamber last night. Nothing at all unusual about the feedramps. No build up or anything.
I dropped a few live rounds down into the chamber and closed the bolt onto them by hand. Nothing at all unusual there.
It's really looking like some sort of twist rate issue.
thopkins22
03-12-13, 11:31
Checked the weapon and chamber last night. Nothing at all unusual about the feedramps. No build up or anything.
I dropped a few live rounds down into the chamber and closed the bolt onto them by hand. Nothing at all unusual there.
It's really looking like some sort of twist rate issue.
You can get a rough measurement of the twist rate using a cleaning rod, jag, and tight fitting patch. Just mark the starting point on your rod, and push it through being sure to let the rod spin freely as the rifling grabs the patch. Stop when you get one full revolution and mark that point and then measure.
You can get a rough measurement of the twist rate using a cleaning rod, jag, and tight fitting patch. Just mark the starting point on your rod, and push it through being sure to let the rod spin freely as the rifling grabs the patch. Stop when you get one full revolution and mark that point and then measure.
I need to get a jag. I usually just run slotted tips.
thopkins22
03-12-13, 12:47
I've got so many lying around from various .22 caliber rods over the years.... I'll send you one for free if you want. I kind of feel invested in learning what's going on now.
I think Pappabear has one. I'll give you a shout though.
Loaded up some of these bullets with TAC last night. 25.5 grains. We'll shoot them tomorrow morning. :p
Remember, twist rate has to do with bullet LENGTH, not weight. Longer bullets just generally weigh more (tracers being a notable exception).
I've also had stabilization issues with 45 and 50gr flat base bullets in 1:7 barrels, they're simply not long enough to stabilize properly. My problems were not quite as bad as what MarkM is describing, but shotgun patterns for sure.
I reload with Varget only, so no comment on powder.
Galaxy Note II + Tapatalk 2
I've also had stabilization issues with 45 and 50gr flat base bullets in 1:7 barrels, they're simply not long enough to stabilize properly. My problems were not quite as bad as what MarkM is describing, but shotgun patterns for sure.
It's got to be a twist rate issue. I'm just stunned at how bad the bullets shoot but still make round holes in the target.
It's got to be a twist rate issue. I'm just stunned at how bad the bullets shoot but still make round holes in the target.
My issues were with a Sabre 16" 1:7 middy barrel too.
Check the condition of the crown and pin gage the bore diameter at the muzzle.
.219- should go
.220 should not
Check the condition of the crown and pin gage the bore diameter at the muzzle.
.219- should go
.220 should not
I don't have pin guages. :(
I'd love to have those for 30 and 22 cal applications. Pin guaging a Krieger will make you want to throw all your other barrels in the trash can. :p
I don't have pin guages. :(
I'd love to have those for 30 and 22 cal applications. Pin guaging a Krieger will make you want to throw all your other barrels in the trash can. :p
$20 from McMaster
I bet your muzzle is flared and that's why the 50gr flat base bullets don't group.
$20 from McMaster
I bet your muzzle is flared and that's why the 50gr flat base bullets don't group.
Interesting... I couldn't care less about this barrel, but I can't let go of the challenge of cracking the mystery.
What sizes should I order? We'd like these for inspecting .30 bolt gun barrels too. Can you get away with just one per caliber?
BUMPING this one... Revisited this Barrel/Bullet combo.
I'm now convinced that the bullets are coming apart. I re-installed this barrel.... I shot this gun Saturday and on an IPSC sized cardboard at like 25 yards, could only get two holes out of 10 rounds.
I noticed dirt kicking up a little down range BEYOND the reach of the muzzle blast. I'm almost certain that bullet frags are trinkling all over the place after the bullet exits the barrel.
(A 5 shot group of longer/heavier Matchkings as a control group shot fine.)
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