2 ARs - 2 different results

pilon

pilon

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Location
North of 9 in ON
Cartridge is hand loaded 25 gr. Varget, behind value priced Frontier 55 g. FMJ

AR #1 is a Colt Expanse with non chrome lined barrel. - 16 " barrel
AR # 2 is a CC MRR with chrome lined barrel. - 16" barrel

At 100 yards:

AR # 1 shoots a reasonable five shot group considering the less than premium bullet used.

AR # 2 shoots a sloppy 3 and sometimes 4 shot group out of 5 rounds fired. There is always one or two holes missing on the target after 5 shots. Yes, 5 sent downrange and only 3 or 4 reaching the target !!

I may not be the best bench rest shooter but I know I can hit a 10" X 10" target benched at 100 yards.

Need to chronograph each barrel for velocity I am guessing to see if the frangible bullet is just going too fast out of the chrome lined barrel.

Any one experience this?
 
Yes . Both 1 in 7

The chrome barrel had fired less than 50 rounds while the non chromed barrel had fired 200 or so if that is a significant variable.
 
Chromed barrels never shoot as well as a unchromed barrel, plus 1 in 7 might be over stabilized .
 
I had a similar issue with Frontier 55gr projectiles, they were CMJ “complete metal jacket” construction not FMJ.
Was Using a CC SA20 1:7 twist.
Couldn’t figure out what was going on.
Reset the target position to 25 yards.
Hmmm , looked like keyholing, but holes looked strange, thought maybe the projectiles were tumbling?
Took another shot on fresh paper then bang, one shot ,two holes.
The Frontier CMJ’s were coming apart mid flight.
I dug out a projectile from the backstop and found a remnant with the nose intact but missing the ass end.

Swore off the Frontiers and moved to Campro 55gr for cheap reloads. Never an issue with Campro 55gr .

Not sure why your chrome lined barrel would rip them up and not the non lined?
 
Try with Hornady 68gr HPBT bullets over Varget and get back to us before worrying about groupings after only trying some of the cheapest 55gr bullets on the market.
 
Ar180shooter said:
Try with Hornady 68gr HPBT bullets over Varget and get back to us before worrying about groupings after only trying some of the cheapest 55gr bullets on the market.
Click to expand...

OMG IT JUST MADE ONE BIG HOLE> WHAT"S GOING ON?

OP. The Colt MRR is a good rifle. As stated by others, is it possible you're getting one or two rounds going through the same hole? I would not be surprised at all. Are you shooting off the bench, with a solid rest/sandbags,or are you standing shooting off hand?
If you really want to check the accuracy of the barrel, shoot 1 round at a time at 5 different marked aiming points - that will tell you where the rounds are landing - one at a time and eliminate the possibility mentioned above. If they all land close to the POA, rifle is fine.
 
vrex said:
I had a similar issue with Frontier 55gr projectiles, they were CMJ “complete metal jacket” construction not FMJ.
Was Using a CC SA20 1:7 twist.
Couldn’t figure out what was going on.
Reset the target position to 25 yards.
Hmmm , looked like keyholing, but holes looked strange, thought maybe the projectiles were tumbling?
Took another shot on fresh paper then bang, one shot ,two holes.
The Frontier CMJ’s were coming apart mid flight.
I dug out a projectile from the backstop and found a remnant with the nose intact but missing the ass end.

Swore off the Frontiers and moved to Campro 55gr for cheap reloads. Never an issue with Campro 55gr .

Not sure why your chrome lined barrel would rip them up and not the non lined?
Click to expand...

I checked and mine are the CMJ ones as well. This weekend I want to see if results are replicated. I want to check velocities out of both barrels too.
Seems like the Frontier bullets are blowing apart in the chrome barrel. Might load some at slower speeds to see if they stay together. At least then I can make use of the 2000 Frontier bullets. Plinking tin cans at 25 yards with an AR has to be fun too! I have a few thousand of Western Metal bullets on hand (55 and 62 grainers) and if I have time will load them up too for the range this week end.
BTW
Factory loads produce nice 1- 1/4 inch or so groups so I know it's not the rifle. I'm sure I could improve on that with decent bullets and the right amount of powder driving them.

Thanks for the input.
 
Ar180shooter said:
Try with Hornady 68gr HPBT bullets over Varget and get back to us before worrying about groupings after only trying some of the cheapest 55gr bullets on the market.
Click to expand...
No worries at all. :0) I will pick up some Hornadys and give it a whirl.
Thanks

BioPace said:
OMG IT JUST MADE ONE BIG HOLE> WHAT"S GOING ON?

LOL

OP. The Colt MRR is a good rifle. As stated by others, is it possible you're getting one or two rounds going through the same hole? I would not be surprised at all. Are you shooting off the bench, with a solid rest/sandbags,or are you standing shooting off hand?
If you really want to check the accuracy of the barrel, shoot 1 round at a time at 5 different marked aiming points - that will tell you where the rounds are landing - one at a time and eliminate the possibility mentioned above. If they all land close to the POA, rifle is fine.
Click to expand...

I think I will need a bigger target for that. Maybe a table cloth with black dots. haha Rifle is fine. Bullets not so much. I'm pretty sure they are not going through the same hole but have seen that argument at a few pistol matches. hehe

Thanks everyone for input
 
Just wondering if your using the same lower (trigger, internals, etc) and swapping uppers or are these complete guns on their own? If they are different complete guns then maybe try swapping out uppers to see if the results change. I'm not a pro a determining accuracy differences but when possible I try the elimination first. Good luck. Phil.
 
P of PDent said:
Just wondering if your using the same lower (trigger, internals, etc) and swapping uppers or are these complete guns on their own? If they are different complete guns then maybe try swapping out uppers to see if the results change. I'm not a pro a determining accuracy differences but when possible I try the elimination first. Good luck. Phil.
Click to expand...
They are complete guns on their own. The upper of chrome barrel is all CC including BCG. The other is non chrome lined 16" and is entirely the original Colt Expanse rifle.

Had time out at the range this past week end and did manage better results after reducing powder charge to 25g. Varget behind the value Frontier 55g. projectile. Still the non chrome lined barrel shot better groups. 1 or 2 of 5 from the CC always opened the group up to around 5 inches at 100 yards.

Interesting is that same chrome barrel shot an average of 90fps faster than non chrome. Averages were around 2650 for chrome and 2560 for non chrome with load stated. Both guns functioned flawlessly.
Results are encouraging in that original loading of 26g. of Varget may have been pushing to hard and fast on the more fragile, it seems, Frontier bullet.

Next time out I'm thinking of dropping the powder charge to 24.5g. to see if even slower velocities with Frontier bullets results in tidier groups.
Not sure how much pressure is needed but hopefully it has enough jam to cycle the action :eek:)
Thanks Phil
 
pilon said:
Need to chronograph each barrel for velocity I am guessing to see if the frangible bullet is just going too fast out of the chrome lined barrel.
Click to expand...
I don't believe that the velocity is an issue, 25 grains of varget isn't exactly a hot load, I use 24.8 grains when I load up my 69gr SMK's in my ARbut I've heard of crazier things.
 
Have you tried different ammo?
Your twist rate has almost nothing to do with your groups at 100 yards, I've shot plenty of decent groups with a 7 twist and 55gr projectiles. You can not over stabilize a bullet but if your bullet jacketing is very thin the bullets may be coming apart once they leave the muzzle. Test this by moving closer and shoot at a large fresh target or just a large blank piece of paper, If you shoot at a large clean target from 25 yards away you should be able to account for all 5 of your shots and if the paper has some weird marks like it got hit by a bunch of shrapnel you've found why you can't find all 5 of your shots at 100 yards.

Every barrel is different so results will also be different. Same reason you typically have to develop a new load for every rifle if you want the best accuracy. Your 25gr of Varget may be a decent load for most 223 barrels but that doesn't mean it will perform in all barrels. This does not explain missing rounds on target though since even a bad group should still make a hole on the same paper as the other rounds.

Good luck, don't put much value in the posts from guys saying you can't shoot a 55gr through a 7 twist because they need heavier projectiles. The truth is that a heavier (longer) projectile needs a tighter twist to stabilize it properly, a 55gr can still shoot very well from a 7 twist, it just isn't optimal.
 
220 said:
Chromed barrels never shoot as well as a unchromed barrel, plus 1 in 7 might be over stabilized .
Click to expand...

Overstabilized? Have you ever personally experienced any such thing? No, because it isn't a thing anywhere but on the internet. You can spin a thin jacketed bullet so fast that it comes apart but you can't overstabilize a projectile.

mebiuspower said:
FN SPR A5M would like to have a word with you.

https://fnamerica.com/products/rifles/fn-spr-a5m-xp/
Click to expand...

1 moa from a bolt action "precision" rifle is pretty poor.
 
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