Accuracy of a semi?

[Epoxy7]

Jard 180, 1.1 moa at 100m
Total all rounds 1.5 moa

IBI 18.6 stainless barrel,
Mid - grade trigger,
Leupold Mk 5 3-18x,
bipod and bag,
M855 62 grain ammo,
10 groups of 5 rounds each, slow fire and cooling between groups, average of 1.1 moa with an SD of .2 moa.
3 round called fliers and additional rounds fired to make each group full 5 rounds each.

1.5 moa when all rounds (50 total) combined (overlaid onto a single group).

Note; While 100m precision is interesting, remember that MV extreme spread (ES) is a geater determining factor for hit percentage at range.
i.e. at 600m a small ES will give you more hits than a small group.

This post aligns with my own, more limited, data;

Applied Ballistics​

** Tech Tuesday **
Today's message is for long-range shooters who might feel frustrated by inconsistent group sizes at 100 yards. While we all aim for the best possible groups, it’s important to be realistic about how much this truly matters compared to other factors. The reality is, we have limited time and resources, so it’s wise to consider the trade-offs when deciding which variables to focus on. In this case, we're comparing precision with muzzle velocity standard deviation (MV SD) for a load intended for long-range shooting.
Imagine you’re developing loads for your rifle and have one that produces tight groups at 100 yards but shows poor MV SD, versus another that gives average groups but has excellent SD. At 100 yards, one load clearly performs better, but what about at long range, where you actually intend to use the rifle?
Counterintuitive as it may seem, for long-range work, it's better to choose the load that produces larger groups at 100 yards but has a significantly lower MV SD. The reason is that MV SD leads to considerable vertical dispersion at long distances, far outweighing the short-range advantage of smaller group sizes.
Ultimately, consider your objective and prioritize the variables that will be most important in achieving it. While some factors are obvious, there are subtle trade-offs that may defy initial expectations. These unexpected realities, however, are just as important.
Follow for more long range shooting tips and visit https://thescienceofaccuracy.com/ to learn more!
#AppliedBallistics #TheScienceOfAccuracy #ballistics #longrangeshooting

Interesting and a good read.

 

[rugbydave]

An accurized Semi auto is capable of sub .5 moa from the bench. 5 round groups at 100 yards. Most of my AR10 rifles accomplished this with ease. Some of my AR15s as well. All had target triggers and precision barrels. Unfortunately they have been political prisoners for years now.

Currently the HK SL8 is your best bet. Not sure if any of the 308 rifles not banned are capable of this.

I will say that I disagree with the 10 round group theory. If the rifle has a semi heavy/varmint barrel and shots 5 rounds under .5 moa at 100 then it’s very accurate. If it’s a hunting rifle like a TC icon 308 and it shoots 3 rounds in the same hole before opening up. Then it’s a very accurate rifle.

The reason for this is testing the rifles accuracy vs heat dissipation of the barrel. A cold barrel is an accurate barrel. An M24 sniper rifle has an #8 barrel contour. You’re getting into sewer pipe barrels if you want those 10 round + consistent groups. While the 5R with a recontoured varmint profile from the same barrel will open up the groups faster as it heats up a lot faster. However the barrel and gun aren’t any less accurate. The barrel just heats up faster.

Anyways. All god fun. It will be a great day when our political prohibs get freed.

The reasoning behind 10 rnd groups for .223 gas guns is more that it gives you a better indication of how precise the rifle will shoot as it will be actually employed. In my experience, once you're shooting past 400 or so yards, you need roughly twice the ammo expenditure to make the same amount of impacts as you would with a short action (.308, 6.5 etc) bolt gun. This comes down to the increased wind drift as well as added difficulty in spotting splash from the lighter bullets. This is less evident on manicured ranges with proper berms than it is in field conditions with partially obscured targets, longer veg, wet ground, etc. For this reason I prefer to have a good grasp on how the rifle will print over 10 rnds as group size relative to target size very much affects the decision making matrix for correcting when you get little feedback.

If a semi can put together multiple 5 rnd groups (letting the barrel cool between strings) that are .5 moa and all to the same poi, then yes, it's a very precise rifle. On the flip side, if the gun prints multiple .5 moa groups but poi is all over the place and the composite of the groups is closer to 2 moa, that's a different story. Either the shooter has poor fundamentals or the rifle tends to string rounds.

I think (based on your posts over the years) that you have a solid grasp of what a precise rifle is but I also think lots of people cherry pick the one anomalous group that is much smaller than the average to say that their rifle is "sub-moa as long as I do my part". It just strikes me as incredibly unlikely that so many of these budget Canadian made rifles are sub-moa rifles and yet despite having handled many myself and run many students through classes I've yet to see one. Obviously I'm talking about factory guns, not about accurised rifles with aftermarket barrels.

 

[Epoxy7]

The reasoning behind 10 rnd groups for .223 gas guns is more that it gives you a better indication of how precise the rifle will shoot as it will be actually employed. In my experience, once you're shooting past 400 or so yards, you need roughly twice the ammo expenditure to make the same amount of impacts as you would with a short action (.308, 6.5 etc) bolt gun. This comes down to the increased wind drift as well as added difficulty in spotting splash from the lighter bullets. This is less evident on manicured ranges with proper berms than it is in field conditions with partially obscured targets, longer veg, wet ground, etc. For this reason I prefer to have a good grasp on how the rifle will print over 10 rnds as group size relative to target size very much affects the decision making matrix for correcting when you get little feedback.

If a semi can put together multiple 5 rnd groups (letting the barrel cool between strings) that are .5 moa and all to the same poi, then yes, it's a very precise rifle. On the flip side, if the gun prints multiple .5 moa groups but poi is all over the place and the composite of the groups is closer to 2 moa, that's a different story. Either the shooter has poor fundamentals or the rifle tends to string rounds.

I think (based on your posts over the years) that you have a solid grasp of what a precise rifle is but I also think lots of people cherry pick the one anomalous group that is much smaller than the average to say that their rifle is "sub-moa as long as I do my part". It just strikes me as incredibly unlikely that so many of these budget Canadian made rifles are sub-moa rifles and yet despite having handled many myself and run many students through classes I've yet to see one. Obviously I'm talking about factory guns, not about accurised rifles with aftermarket barrels.

That makes sense. I always wondered why the fascination with 10 round groups.

 

[Gunnerlove]

I think Dave Oakie told me something like "All matches are 10 rnds minimum so that is the minimum group size that matters"

Made sense to me.

 

[deadman]

It's a pencil barreled SP1 as I've said before. So if a lighter barrel profile is more susceptible to poi shift due to shooting/heat, I should take that into account.

I picked up a couple different boxes of various but similar ammo to try out. From some old norinco yellow box to the smk I use in my bolt rifle. Will try to get out tomorrow to run some through and see how it does.

 

[beltfed]

That makes sense. I always wondered why the fascination with 10 round groups.

I would define or break down accuracy as the combination of three fundamental elements within the shooting 'system' - those elements are:
- Mechanical
- Environment
- Human / Shooter
The rifle & ammunition combine to make the mechanical element, and together form the mechanical accuracy (and for all intents could be interchanged with 'mechanical precision').
The Shooter and the Environment combine with mechanical accuracy to perform as a 'system' and make the practical accuracy.

The biggest variables to performance of the system in most cases of use of semi-auto rifles are the human and environmental elements.

We can place little in the way of controls on the environment, at least outdoors, but some strides like shooting on a known distance range, shooting from prepared positions, shooting on calm days in good weather or shooting indoors can mitigate much of that, at least at short ranges in the pursuit of determining the mechanical accuracy.
Likewise, we can reduce and almost eliminate the human element in determining the mechanical element by bench-resting or shooting from a mechanical rest.

The rifle and ammunition are mechanisms within the system that are easily controlled (in comparison to the environment or shooter/human element) and we can determine the baseline of what this element can achieve through statistical analysis of results down range on paper.
The more rounds down range to form that statistical analysis, the better.

We know that quite often 5 rounds doesn't accurately indicate mean point of impact, never mind the mechanical accuracy potential of a rifle/ammo combination, and 10 rounds or stacking of multiple 5 round groups is a reasonable compromise of getting sufficient statistical data vs. getting into an endless loop of testing. I'm of the opinion that statistically 3/5 round groups have very little meaning, most of the time. As with everything, there are exceptions to the rule, such as truly precise rifles/ammo combinations, and distances from target.

Knowing what that mechanical accuracy/precision is, will help the shooter work on the mental and physical fitness that combine with the principals of marksmanship (PoM) that define the shooter element and helps them overcome the environmental element.

A 5 round group might be sufficient to show MPI for a 3-gunner that rarely competes past 100m and is shooting at a 6 moa gong or an IDPA/IPSC target, but it likely won't suffice for someone that is shooting a sport that depends on more precision from the mechanical element.

If I know my mechanical component is capable of 2 moa, and I am loosing points on a 4 moa target at any given range, I know that me as the shooter needs to work on PoM to overcome a >2moa deficit and get it down to <2moa.
If I'm capable of 1moa and I'm loosing points on that same 4 moa target, my mechanical component has to be +3moa

 

[Machine1507]

I get that, I'm just looking for feedback from others about their experience. I've got a real itch for a mk12 mod 0, and started thinking about how well my own old rifle would fare.

I have real mk12 mod o from states. Its a 1inch gun with factory ammo. I haven't but you can easily get .5 with handloads.
Most accurate SA from atrs build 6.5cm. It was .5 inch with S&B 140. Best group I had with was 136 Lapua sceners .20000 from the lands. Feel free to message me for anything Mk12 related.

 

[rugbydave]

It's a pencil barreled SP1 as I've said before. So if a lighter barrel profile is more susceptible to poi shift due to shooting/heat, I should take that into account.

I picked up a couple different boxes of various but similar ammo to try out. From some old norinco yellow box to the smk I use in my bolt rifle. Will try to get out tomorrow to run some through and see how it does.

View attachment 838305

If I didn't say so before, that's a real beaut of a rifle. I'm curious to see how it prints. I think the non-free-floated handguard will be the weak link with regards to how precise the rifle can shoot and the twist of the barrel will limit you to lighter weight bullets.

I saw your comment about being very interested in a Mk12 Mod 0 and to be honest, your rifle is only a new match barrel, gas block and free-float handguard away from attaining the performance level of a Mk12 (which despite looking very "cool" is a pretty old design) without having to go down the crazy expensive rabbit hole of building a "clone-correct" rifle with the PRI handguard, correct gas block, Douglas barrel, etc.

 

[deadman]

Well I wasted about 500 dollars worth of ammo today. I'm sure part of it was my error, I had a few jenky shots that I know were me but a quick breakdown goes like this:

10 shot groups (4 groups of each different ammunition)

Warmup/sighter with American Eagle 55gr fmj

Norinco 55gr fmj 5"

AE 55gr fmj 4" (gave up after one, was no better than Norinco and wanted to see if groups could improve)

Fed 50gr jhp 3"

Fed 53gr vmax 2.5"

Hornady 53gr vmax 2.5"

Hornady 55gr vmx 2"

Fed 69gr smk 2"

These were rough averages of the groups, I didn't feel the need to take notes on exact numbers.

Each group was shot at a pace of around 4 seconds between shots, with only time to reload my magazine between. I walked to the target between ammunition types, so maybe 5 minutes between types.

Barrel never got extremely hot but never really cooled down to cold bore temp either. I didn't see any particular stringing patterns, just nothing impressive. I had a couple groups with the 55gr vmax that were in the 1" territory but completing the 10 rd groups always got me. The 69gr smk was similar actually but going to 10 killed them.

This was all at 100 yds though, no idea if either bullet would have been consistent at 2 or 300. If I had been able to get 1" groups with any of it I would have pushed out further to see if it was repeatable. As it is, I don't feel it's worth the effort.

Anyway, not surprising but still disappointing. I'm not the best shooter out there, some of it could very well be my error. In someone else's hands the results may have been different.

 

[rugbydave]

Well I wasted about 500 dollars worth of ammo today. I'm sure part of it was my error, I had a few jenky shots that I know were me but a quick breakdown goes like this:

10 shot groups (4 groups of each different ammunition)

Warmup/sighter with American Eagle 55gr fmj

Norinco 55gr fmj 5"

AE 55gr fmj 4" (gave up after one, was no better than Norinco and wanted to see if groups could improve)

Fed 50gr jhp 3"

Fed 53gr vmax 2.5"

Hornady 53gr vmax 2.5"

Hornady 55gr vmx 2"

Fed 69gr smk 2"

These were rough averages of the groups, I didn't feel the need to take notes on exact numbers.

Each group was shot at a pace of around 4 seconds between shots, with only time to reload my magazine between. I walked to the target between ammunition types, so maybe 5 minutes between types.

Barrel never got extremely hot but never really cooled down to cold bore temp either. I didn't see any particular stringing patterns, just nothing impressive. I had a couple groups with the 55gr vmax that were in the 1" territory but completing the 10 rd groups always got me. The 69gr smk was similar actually but going to 10 killed them.

This was all at 100 yds though, no idea if either bullet would have been consistent at 2 or 300. If I had been able to get 1" groups with any of it I would have pushed out further to see if it was repeatable. As it is, I don't feel it's worth the effort.

Anyway, not surprising but still disappointing. I'm not the best shooter out there, some of it could very well be my error. In someone else's hands the results may have been different.

Honestly there's nothing disappointing about 2" 10rnd groups. That's what I'd expect from a good factory barrel. You'd most likely see things tighten up with a free-floated handguard. If you want to go that route and keep the same aesthetic, I believe DPMS make a free float handguard that looks like a regular A2 handguard.

2 moa with those 69gr rounds means your rifle should be effective out to 600yds on reasonable sized targets like a 2/3 IPSC (12" wide by 18" tall). I don't know if you have that kinda range available to you but you should give it a go.

 

[deadman]

What I would really like is the pri handguard and sights....

I know it's a retired system but always liked it. I do have a heavier profile 18.6" barrel (1:8) that I wanted to use for a mk12-ish type build but haven't ever been able to get my hands on the other parts needed.

As for how far I can shoot to test the 69gr, I can shoot about 600 yds to the treeline from where I have my bench sitting.

If I want to shoot further, I just need an elevated shooting position and I could shoot a mile. Not that I have a rifle or the skill capable of that though....

 

[rugbydave]

Well, you can get the PRI handguard direct from PRI, it's $338 USD, they also have the gas block with the flip-up sights for about $180 USD. If that's the path you want to go. As long as your heavier barrel is setup for rifle length gas, that's all you'd need (+ a gas tube which you already have) to setup something very similar to a Mk12 Mod 0 (minus the Swan sleeve which I think is quite hard to source). Just get one of the importers to bring all that in for you. Personally I'd just do a high end free-float handguard and an adjustable gas block and get the same performance for way cheaper but I get why you'd want to copy the aesthetic of the Mk12, they look damn cool.

If I had been smart and bought a MS receiver set before the OIC bull####, I'd build up something similar to a "modernised Mk12/SPR". I'm tempted to do so on a Crypto but just don't have a ton of faith in Crusader. None of the current AR-180 variants really scratch the precision gas gun itch...

 

[deadman]

Pri told me they couldn't guarantee a shipped package wouldn't get pinched by cbsa, and two importers told me the same thing. They said I could order through them but again no guarantees.

I'd have bought the complete builders kit for a mk12 if not for that uncertainty.

 

[tessy2ton]

What I would really like is the pri handguard and sights....

I know it's a retired system but always liked it. I do have a heavier profile 18.6" barrel (1:8) that I wanted to use for a mk12-ish type build but haven't ever been able to get my hands on the other parts needed.

As for how far I can shoot to test the 69gr, I can shoot about 600 yds to the treeline from where I have my bench sitting.

If I want to shoot further, I just need an elevated shooting position and I could shoot a mile. Not that I have a rifle or the skill capable of that though....

Nice ammo comparison, Deadman, you fart more knowledge about ar's than any of these posters. You know your ####, they are all envious you get to play and they dont ha ha.

 

[beltfed]

Interesting results with the 69smk. Are you positive your barrel is a 1:12 twist?

The reason I ask, is I have put a healthy amount of them down range with the Swiss Arms Classic Green and Black Special HBar both of which were 1:10 twist. They always did ok to around 300m. Anything past that they fell apart.

At the end of the day, if they are shooting ok for you that's great.

 

[deadman]

I wouldn't say they are shooting great, I'm not satisfied with the results. I won't be using that combination to get 2" groups when I can grab my M700 and get a quarter of that size with the same ammo.

You weren't wrong when you predicted it wouldn't perform.

 

[Epoxy7]

I think you might want to temper your expectations. With a SP1 barrel and non free float handguard you can’t expect match grade accuracy. The really accurate semis are all using bull barrels with free float handguards and match triggers.

One possibility to bring the group size down a bit is to give PMC 55 bronze a try. I know it sounds funny. But at 100 metres, I’ve had some surprisingly good results in some firearms.

A buddy of mine had one of the Norinco AR-15 rifles CQA I think. The ones that looked like they had BBQ paint for a finish. But, the handguard was changed and free floated along with a good trigger. These actually had hammer forged barrels. 1:12, 14.5” if zi recall correctly. Anyways we were able to get 1 moa at 100 yards, 5 round groups. Using a bipod and rear bag. 2 moa red dot that was turned down to make it a bit finer of a dot. To say we were surprised would be an understatement.

No guarantees but it might help out. Good luck.

 

[deadman]

With a barrel/handguard swap, maybe I'll revisit this.

I do know this: after comparing ammo, it's sure going to be hard using all the 55gr fmj I have. When it groups over twice the size as some of the other stuff, the only consolation is that it's 30 cents a round.

Good enough for ringing plates but won't be using it for coyotes etc.

 

[rugbydave]

With a barrel/handguard swap, maybe I'll revisit this.

I do know this: after comparing ammo, it's sure going to be hard using all the 55gr fmj I have. When it groups over twice the size as some of the other stuff, the only consolation is that it's 30 cents a round.

Good enough for ringing plates but won't be using it for coyotes etc.

With somethinglike a good quality Hbar and. free float handguard, I bet you'll get solid results.

I just use the 55gr stuff as blaster ammo for close range drills and unsupported positional out to 2 or 300 hundred (on decent sized plates). Keep my .223s all zeroed for 75gr stuff and know the offsets for the 55s.

 

[Epoxy7]

With a barrel/handguard swap, maybe I'll revisit this.

I do know this: after comparing ammo, it's sure going to be hard using all the 55gr fmj I have. When it groups over twice the size as some of the other stuff, the only consolation is that it's 30 cents a round.

Good enough for ringing plates but won't be using it for coyotes etc.

yup, keep some for ammo testing as another firearm might like it. The rest for steel, plinking and carbine practice,

Funny thing. I bought RUAG ammo for a Swiss Arms PE90 target and it shot very poorly. Turns out the 556 and 223 versions of the ammo were different. Of course I bought the wrong one.

However 62 grain American Eagle was shooting 1 moa, 5 shots at 100. I was just going to use it for plinking but decided to do some ammo testing. Worked out well.