Question on Semi-auto accuracy and possible improvements

[Mark 1911]

Some of you may have seen my post a couple weeks back about the Belgium made Browning BAR I recently acquired.

I took it to the range for the first time last weekend and was getting poor accuracy even for a semi-auto. Once I got it on the paper, about the best 5-shot group I could claim at 100 yards was 6 inches, most of them more like 8 inches, and that was using a lead sled. I was using Federal Fusion 165 grain (30-06), which has a decent BC and a good reputation for consistency.

I took it home and cleaned it and noticed that it had probably never been disassembled before. The reason I believe that is because the gas cylinder was filthy, looked like several hundred rounds worth of powder residue, and dirty enough that the gas piston wouldn't drop out of the cylinder on its own, I had to coax it out with a piece of plastic tubing.

I've heard that a dirty action can impact a semi-auto's accuracy, but I am not too familiar with that because my guns NEVER get that dirty.

The gun is all cleaned up and the gas assembly including the piston and cylinder are like new clean. Everything is as slick as wet duck droppings.

The only other thing that might be impacting the the rifle's accuracy is that the scope is a low-end Bushnell, and I don't know how much putting a nicer scope on the rifle would make a difference. All of my rifles have either Nikon, Leupold, and even a few Swaro's, and all of them shoot way tighter than this rifle, no comparison, 1.75 or tighter at 100 yards, a couple my Remy 700s are consistently under 1 inch.

The first thing I will do is take the rifle back to the range and see how it does now that its all cleaned up. I'm wondering if that will tighten up the groups.

After I see the difference that makes, I may try a nicer mid-range scope like a Nikon Monarch or a Vortex.

Any ideas? Suggestions?

 

[actaeon277]

Scope might be shifting.

 

[Mark 1911]

Scope might be shifting.

The scope is mounted nice and tight as it should be, but when I look through the scope, it does some strange optical things, and I wasn't sure if that was just my old eyeballs playing games with me, or a defect in the scope. I am suspicious of the scope because the other two rifles I was shooting that morning were just fine.

 

[17 squirrel]

Now I'm old but I think that rifle has a 1 in 10 twist. And you most likely find better groups with heavier bullets, like 165 through 180 or even 200 grainers.

 

[Mark 1911]

Now I'm old but I think that rifle has a 1 in 10 twist. And you most likely find better groups with heavier bullets, like 165 through 180 or even 200 grainers.

The first rounds I put through it were reloads with 190 grain. I think I was getting better groups with those, but not consistent. I'd put one through the bullseye, then one 4 inches high, one three inches left. I think you're right about the heavier bullets shooting more consistent. The reason I went with the 165 for the final dial-in is because I might have an opportunity to hunt deer in Wisconsin with it so I thought 165 might be a better match for a deer.

 

[actaeon277]

The scope is mounted nice and tight as it should be, but when I look through the scope, it does some strange optical things, and I wasn't sure if that was just my old eyeballs playing games with me, or a defect in the scope. I am suspicious of the scope because the other two rifles I was shooting that morning were just fine.

Could be shifting internally.

 

[Mark 1911]

Could be shifting internally.

My hunch is you're right. Time to decide on a scope.

 

[17 squirrel]

The first rounds I put through it were reloads with 190 grain. I think I was getting better groups with those, but not consistent. I'd put one through the bullseye, then one 4 inches high, one three inches left. I think you're right about the heavier bullets shooting more consistent. The reason I went with the 165 for the final dial-in is because I might have an opportunity to hunt deer in Wisconsin with it so I thought 165 might be a better match for a deer.

Interesting .... I just talked to my kid brother because he owns a few old bar's that he hunts with. He told me his shoot almost moa.
I bet if you play with different bullet weights you will find what it likes. Maybe you'll get lucky and 180 rem coreloc's will be the shizzle, not to hard to find and reasonably priced.

 

[actaeon277]

My hunch is you're right. Time to decide on a scope.

You could borrow one. Maybe someone has one to loan out.
I thought I did, but I can't find it. Probably gave it away.

 

[Woobie]

Like Squirrel said, I would check that twist rate. If it's 1:10, heavier bullets will be your friend. Also, I'm guessing that scope doesn't have a parallax adjustment. I once used a scope that I could see roughly 3.5 to 4" of shift through the scope as I moved my head around. If you add something like 4 moa of parallax shift to the 2 moa you might be seeing out of overstabilized light bullets, throw in a really dirty gun and you are looking at some lousy groups. I hope this can be fixed with optics and bullets. I'd hate to think your barrel is FUBAR.

 

[actaeon277]

Like Squirrel said, I would check that twist rate. If it's 1:10, heavier bullets will be your friend. Also, I'm guessing that scope doesn't have a parallax adjustment. I once used a scope that I could see roughly 3.5 to 4" of shift through the scope as I moved my head around. If you add something like 4 moa of parallax shift to the 2 moa you might be seeing out of overstabilized light bullets, throw in a really dirty gun and you are looking at some lousy groups. I hope this can be fixed with optics and bullets. I'd hate to think your barrel is FUBAR.

Cheaper scopes usually have worse parallax.
That rule is not ironclad, but a guideline.

 

[Mark 1911]

Interesting .... I just talked to my kid brother because he owns a few old bar's that he hunts with. He told me his shoot almost moa.
I bet if you play with different bullet weights you will find what it likes. Maybe you'll get lucky and 180 rem coreloc's will be the shizzle, not to hard to find and reasonably priced.

I don't think its the rifle really, although the dirty gas piston might have been contributing. I'll change out the scope, I suspect that will tighten things up a lot. If that turns out to be true, then I'll focus on finding which ammo it likes the best.

You could borrow one. Maybe someone has one to loan out.
I thought I did, but I can't find it. Probably gave it away.

I am pretty sure you're right about the scope not holding true and that gives me a reason to upgrade a notch or two. Cabela's is currently having a sale that ends tomorrow, I'll take a look at their website and see what they're offering. Thanks for the input!

I'll let you know how the next range trip pans out.

 

[Woobie]

You might think about getting it re-crowned as well.

 

[actaeon277]

You might think about getting it re-crowned as well.

Probably the shooter.
He does shoot 1911s after all.

 

[Mark 1911]

You might think about getting it re-crowned as well.

This is starting to sound expensive. I'm still saving up for my next 1911.

Probably the shooter.
He does shoot 1911s after all.

Not as often as I'd like to!

 

[Yeah]

Name the base, rings, and the scope and how well it tracks. Start at the start.

 

[oldpink]

Nothing wrong with getting a new high quality scope (Leupold, Nikon, Swarovski, or Zeiss), even if it doesn't solve your problem.
That scope can always go on another rifle.
As Woobie suggested, definitely check your twist rate, a simple matter of running a very tight patch down the bore, marking your cleaning rod near the handle so mark depth and rotation, then pushing it until you see a full turn, then marking it for its depth again, then measure.
Choosing a bullet according to twist rate is part of it, but also the specific bullet itself could be part of the issue.
The BAR has a reputation for being one of the more accurate autoloaders, although not quite as accurate on average than an average bolt action, but you should certainly be able to get it within 2.5" and probably 1.5".

 

[Yeah]

Digging the idea that it is twist rate 'overstabilizing' the bullets, that is very interesting please expound!

 

[oldpink]

Digging the idea that it is twist rate 'overstabilizing' the bullets, that is very interesting please expound!

I would think more like understabilizing, especially when shooting the heavy 190 grain bullet he mentions having loaded.
I'd start at 150 or 165 grains.

 

[Woobie]

Digging the idea that it is twist rate 'overstabilizing' the bullets, that is very interesting please expound!

I said overstabilized. It's a poor term, but there is a reason we just don't make everything a 1:5 twist, and it's not just because we'd rip the jackets off the bullets. But my guess is you knew that already.