Can a rifle really be this sensitive to ammo?

I have rifles that go from 4moa to 1moa depending on load with the same bullets.

I don't understand why it doesn't work like it does in video games.

There is an upside to this. I got a 1903a4 and its shooting 4moa with off the shelf ammo. I know it will shoot better once I find a load it likes, so having some faith that it will get better, I can start some load development.

J.

A co-workers .223 AR is a very very picky rifle. We have tried 6 different bullets and as many powders with all of them. It usually shoots everything 3 MOA or worse. The ONLY bullet and powder combo it's shoots is a 69gr Sierra and CFE223 it is MOA with that load.

I doubt many rifles would like those first two brands.

Geez, even my 16", 7lb DPMS G2 AP4 punches 2moa groups with bulk FMJ. There's something wrong with the rifle, scope or ammo if you are getting 8moa groups...

I've never experienced differences quite that large. But, I have had 3-4" swings between factory and hand loads. When that happens, I keep the factory loads for fouling rounds.

If you still have some of the poor performing ammo, might be interesting to test again, but reverse the order they are fired.

Ha! I went shooting with a guy who had a 308, a Savage target rifle of some sort. He couldn't stay on paper at 100 yards with the 150 gr FMJ's he had.

I gave him some of my 180 reloads I was using, he shot a 1/4" group, about a two feet low. We thought the barrel was bad before that, especially since the few hits he had had had gone through the paper sideways.

My M1A

Totally believable. I have a .308 that is that picky. Here's what I've found out. The cheaper ammunition is not concentric from round-to-round.

I purchased a concentricity gauge and started looking at the individual rounds and there could be as much as 0.004-inch difference in where the center of the bullet was located from round-to-round.

While that doesn't look like much, you need repeatability between rounds for consistent accuracy. When the bullet goes into the forcing cone at different angles, do to the bullet being off center - the rounds aren't engaging the rifling in the same way and you get inconsistent results.

When I used Federal Match ammunition and QC'd the rounds, they were all within 0.0005 of each other - and the groups were less than 0.4-inch at 100 yards.

Yes. Every rifle I own from my 11" 10mm . SBR , 5.56 and 6.8SPC AR's to all my lever actions to my Savage Lightweight hunter in 308 are very ammo dependent for very tight groups. And just like you I always first doubt myself. I think this is a healthy thing, that for me at least makes me step through the fundamentals.

It certainly happens, and in my experience is more common with gas guns. Generally they have pretty light barrels (even with 'HBAR' profiles) and tend to have lots of harmonics. They also often have pretty generous chamber dimensions. And of course all the issues associated with gas ports. All that adds up to a lot of pickyness and inconsistency.

They also tend to have garbage triggers, which makes distinguishing shooter issues from gun issues much harder.

Many accurate heavy barrel bolt guns with tight chambers I've shot will at least group anything with a reasonably consistent powder charge.

Rifle good,ammo poor.I have a 308 bolt gun that will usually run in the .6's or .7's with good handloads with anything but 748 powder-put that stuff in it and it's 4 MOA and worse,even with the same bullets,primers and brass.

Here's my Savage model 12 BVSS .223

69g SMK vs. 55g AMAX

4"-5"-6" with low cost 308 ammo is not surprising out of an AR-10, but 8" groups are encroaching on mosin nagant territory. Anyone who has worked up handloads has seen their fair share of headscratcher groups because they've shot them!

10 people shooting the same rifle and ammo will produce 10 different accuracy assessments.

How do we subtract/separate our own variables from that of the rifle and ammo?

How do we subtract/separate our own variables from that of the rifle and ammo?

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I wish I knew Bart.

How do we subtract/separate our own variables from that of the rifle and ammo?

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I can tell you how I do it.

The gun club I belong to has a 100 yard tunnel so there can be no wind drift.

The house for the tunnel has a poured concrete table that is level for the gun support.

When I check a gun / load combination for accuracy, I put sandbags under the gun for support, and on top of the barrel to help stabilize the gun. I have a rifle sled, but I've found the sandbags to be better for absolute gun stability.

I try to eliminate or reduce variables that I can affect or control to the greatest extent possible.

Heck, I get variables of more than 2 MOA with my own reloads. My rifle has a sweat spot in the middle of the min to max load range and that's that.

buckhorn_cortez:

When I check a gun / load combination for accuracy, I put sandbags under the gun for support, and on top of the barrel to help stabilize the gun. I have a rifle sled, but I've found the sandbags to be better for absolute gun stability.

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If that's not how you shoot your stuff hunting or some other discipline, the barrel won't behave the same way as it's natural vibrating while the bullet goes through the barrel will be different. The barrel will shoot to a different place relative to the point point of aim.

The barrel is no longer at its normal position and fit to the stock with that sand bag's weight pushing down on it. It won't whip and wiggle the same way as it does without the bag.

Here's how some match rifle competitors test their match rifles and ammo for accuracy eliminating all human variables. This free-recoiling machine rests holds a rifle much like people do. It recoils back and up just hand held rifles do. Several have been used for decades by different competitors. This one belongs to David Tubb; his Dad had it built back in the 1960's.



This machine rest cannot be used to get zeros on sights for a given lot of ammo. If done, it'll be different by 1 or 2 MOA from that of a zero established hand held on a bench top or a field position without artificial support. But the accuracy level doesn't change any significant amount.

It's my opinion that using the position used by F-class competitors do shooting from prone with rests under the stock fore end and stock toe; with or without a sling. It's proved more repeatable from shot to shot than shouldering a rifle as it rests atop something on a bench. A totally free recoiling rifle on bags on a bench top is also good, as long as its recoil doesn't shove it off the bags and it falls to the ground; traditional benchrest way in matches.

Can a rifle really be this sensitive to ammo?

Seeing is believing I guess and absolutely yes. My .308 bolt gun as well as my AR 10 can give similar results and likely the M1A. This is why I like to roll my own.

Ron

I think a lot depends on the rifle. I've owned some that would shoot very well with specific loads, poorly with others. All of them will do better with some ammo, but I've owned several rifles that would do pretty darn good with most anything you put in them.

bikemutt said:

I decided to take my AR10 to the range today with a variety of ammo to see what it likes. Up until now I've run Norma match .308 through it with excellent results but, I've run out of that ammo so, time to try new stuff.

First up at 100 yards was 5 rounds of HPR 168 gr match. I just about lost it figuring everything from the scope must be loose to I'm drunk (I was sober). 8" or worse group from a Rainier Arms Select barrel?

Next up was Aquila 150 gr plinker ammo which I had very low expectations of; it's regularly 4 moa ammo for me, regardless of rifle.

Finally I fired 5 rounds of Hornady 168 match, low and behold that's what I expect from this rifle; sub-moa.

I guess I'm posting this because I've never seen a rifle so picky. I don't mind that as I'll feed it what it likes. Anyone here at THR noted this sort of ammo preference from a rifle?

Picture runs from top left, clockwise.

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Short answer - yep.
And I have found 22s to be even pickier.

cougar1717 said:

4"-5"-6" with low cost 308 ammo is not surprising out of an AR-10, but 8" groups are encroaching on mosin nagant territory. Anyone who has worked up handloads has seen their fair share of headscratcher groups because they've shot them!

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If one of my MNs turned in 8" groups I'd used it for a boat paddle. Mostly they are in the 4 ~ 5" range with surplus ammo, and 3 ~ 4" with better surplus, and 2 ~ 3" with new commercial. At 100 yds, that is.