Question Project: What are the qualities of a Competitive Service and/or Precision Rifle

[Frgood]

This is the planning stage of putting together a competition Service Rifle. The first of the two projects is to be sourced from one of my 80% AR-15 build. The second, to be a .308 hopefully from a completed 80% lower. I am beginning this project with the braintrust of this forum as I do not have the knowledge or experience. So first, some questions for all to get this project thread started.

My current assumptions - I think the conversation where 'accuracy' and 'precision' are the subjects is a non-starter. If my goal is to hit an 'X' ten out of ten times at 200, 400, and 600 yards, then accuracy and precision is required. We have no need to overthink this requirement with long-winded rambling. This requirement assumes 1 MOA which would translate to a six-inch ten ring at 600 yds. This is the goal.

1) Considering we're starting with an 80% lower, Is the goal stated achievable?

2) What are the critical factors of the build that need to be addressed?
For example: Does the lower have any critical dimensional tolerances that need to be met and, if so, which companies sell workable lowers?
How does the quality of my cuts affect this type of build? In one of my lower's, the safety holes are off by the slightest amount to cause drag on the safety.

3) Should my uppers align with the lowers with a particular variance that impacts the goal.

4) What is the impact of the BCG and Bolt selection? There are far too many in the market and there has to be measurable metrics to determine which will satisfy our requirement.
Honestly, finish is the most talked about aspect. But, I haven't found a discussion on the impact of a finish on accuracy. Most talk about lubricity feeling.
And staking the gas key should be a given and not a discussion point.

5) Barrel selection and installation will be discussed when we get to that point as this builder can only go by recommendation of manufacturers as I do not have unlimited funds to create a test suite.


I realize this is a long start with a lot of topics. To simply my first task is to determine if any of my current lowers are sufficient to start or if I need to begin anew.
Let's start with that.

How do I determine if my lowers and uppers can be used to create a competitive (CMP/NRA) Service / Precision Rifle?

 

[no4mk1t]

This is the planning stage of putting together a competition Service Rifle. The first of the two projects is to be sourced from one of my 80% AR-15 build. The second, to be a .308 hopefully from a completed 80% lower. I am beginning this project with the braintrust of this forum as I do not have the knowledge or experience. So first, some questions for all to get this project thread started.

My current assumptions - I think the conversation where 'accuracy' and 'precision' are the subjects is a non-starter. If my goal is to hit an 'X' ten out of ten times at 200, 400, and 600 yards, then accuracy and precision is required. We have no need to overthink this requirement with long-winded rambling. This requirement assumes 1 MOA which would translate to a six-inch ten ring at 600 yds. This is the goal.

1) Considering we're starting with an 80% lower, Is the goal stated achievable?

Yes, quite achievable.

2) What are the critical factors of the build that need to be addressed?
For example: Does the lower have any critical dimensional tolerances that need to be met and, if so, which companies sell workable lowers?
How does the quality of my cuts affect this type of build? In one of my lower's, the safety holes are off by the slightest amount to cause drag on the safety.

It's not like it was in the 80's before widespread use of CNC. Things are much better now in terms of dimensional tolerances and fit. Only my builds from the 80's had sloppy fit issues between the upper and lower. All my builds using currently manufactured uppers and lowers have had zero fitment issues. I don't think you should worry about this aspect of the build whether you use 80% or 100%.

3) Should my uppers align with the lowers with a particular variance that impacts the goal.

You want minimum play between the upper and lower when assembled. A little wiggle isn't going to have a negative impact on anything, but most peeps OCD is better satisfied with none. But none is harder to do. I've only ever had one upper/lower combo that required had fitting to go together, and that was in the 90's. The easiest way to get a zero wiggle fit is use an Accu-wedge or the two piece rear pin that screws together to make things tight. But that isn't legal for Service Rifle.

4) What is the impact of the BCG and Bolt selection? There are far too many in the market and there has to be measurable metrics to determine which will satisfy our requirement.
Honestly, finish is the most talked about aspect. But, I haven't found a discussion on the impact of a finish on accuracy. Most talk about lubricity feeling.
And staking the gas key should be a given and not a discussion point.

The upper is where most of your focus should be on component selection.
I would choose a bolt made from Carpenter 158 steel AND High Pressure Tested, (HPT) AND magnetic particle inspected (MPI) This weeds out any inferior bolts and is part of the mil-spec. Yes, you can use a bolt made form 9310, and a lot of us did when that's all that could be had at the time, but C158 is the current mil-spec.

The BCG is going to be made from 8620, so your choices are going to be whether to get phosphate, Nitrided, or NB. Phosphate used to be the only game in town and is mil-spec, but technology marches on and the latter two offers advantages in lubricity and ease of cleaning. I don't think you can go wrong picking either one. Nitrided is what has been furnished in the last few uppers I've bought, and I've been happy with them.

5) Barrel selection and installation will be discussed when we get to that point as this builder can only go by recommendation of manufacturers as I do not have unlimited funds to create a test suite.

At this point in your High Power career, it would be a case of the best choice would be to wait on buying that Kreiger until you are in the Master class. I would buy a White Oak barrel and spend the difference on powder, primers, and bullets for practice. If you stick with the sport and advance in skill, most shooters eventually wind up with two uppers. One upper will have a new or nearly new barrel and will be held for use in important matches and Camp Perry. The second upper will have previously been the best upper, but now has reached the mid point in barrel life. This upper is used for practice and local matches. When accuracy falls off, it will get re-barreled and the #1 and #2 place of the uppers will swap. In this scenario, do not try to save money by using the same BCG in both uppers. THe bolt lugs wear in and you want them to wear into just one barrel. When you change barrels, I always bought a new bolt. The lugs on either side of the extractor carry more load than the others and are where cracks will form eventually. Usually take many more rounds than it does to wear out a barrel, but I have had buds who had a lug break off if they loaded their ammo hotter than prudent. I always used to sell the removed barrel and bolt and sold them together for someone who only shot reduced course matches or wanted a blaster barrel for their kid.

I realize this is a long start with a lot of topics. To simply my first task is to determine if any of my current lowers are sufficient to start or if I need to begin anew.
Let's start with that.

How do I determine if my lowers and uppers can be used to create a competitive (CMP/NRA) Service / Precision Rifle?

The rules have changed a lot since I played the game. It used to be the Service Rifle had to outwardly resemble the issue M16A2. Now, optics and other changes are allowed such as rails in place of the issue style handguards. Read up on the rules before you buy your parts.

Parting thoughts:
Price an upper from White Oak and see if that fits the budget. Not up on current prices, but building may or may not save money.

If you decide to build the upper yourself, pay close attention to gas tube fit. With a striped bolt carrier, you should barely be able to feel the gas key slip over the tube when slid into the upper. If you feel resistance when the key meets the tube and it takes a little push to make it go forward, tweak the tube or nudge the barrel nut to achieve perfect alignment. I had a bud that experienced short stroking on an upper with about 1000 rounds on it. The gas key had worn down one side of the tube until it leaked enough to short stroke.

Check the gas key screws every now and then. I had mine come loose even though they were staked. Doesn't take much until the gun short strokes.

Do the RTV silicone mod to the charging handle to prevent "gas eye". There's a thread here I posted about it.

See if there is a club hosting a High Power clinic or reduced course match. Go to it and be a sponge. One of the best clubs in GA hosts a monthly 100 yd. reduced course match that serves two purposes. For the aspiring new shooters, it's a place to learn from more experienced shooters. For the experienced shooters, it's a chance to shoot their CLE rimfire uppers in match conditions for meaningful practice. You will always shoot better in competition than in solo practice.

That's enough for now. They'll be more questions, ask away, that's what we're here for.

 

[Racer88]

If my goal is to hit an 'X' ten out of ten times at 200, 400, and 600 yards, then accuracy and precision is required.... This requirement assumes 1 MOA which would translate to a six-inch ten ring at 600 yds. This is the goal.

@no4mk1t covered the technical stuff very well, it seems... since I know nothing about Service Rifle competition. A friend of mine competes on a national level and has earned the Distinguished Rifleman medal.

The question raised for me when I read the quoted above is: Can YOU shoot <1-MOA at 200, 400, and 600 yards? In my limited precision rifle experience, many rifles (even relatively inexpensive ones) are capable of that precision. So, it depends more on the shooter.

At 400 and especially 600 yards... wind becomes a major factor. Also, good ammo.

 

[Mako 13]

Unless the NMC has really changed, the M1As we competed with were sub MOA with optic or you weren't going up the classes very fast.
A deer rifle will shoot 1 MOA these days. Can a 7.62 X 51 AR platform be built to sub MOA?

 

[Frgood]

Unless the NMC has really changed, the M1As we competed with were sub MOA with optic or you weren't going up the classes very fast.
A deer rifle will shoot 1 MOA these days. Can a 7.62 X 51 AR platform be built to sub MOA?

That is going to be my next question after I tried this with a 5.56 platform first. I have an DaVinci ar-10 lower and matching upper sitting in a box waiting to be built. But first there are 4 AR-15's sitting in my safe I built with the 5D jig and the hope is to rebuild one suitable for quality target shooting.

 

[Racer88]

My AR-15 (223) built by above-referenced friend is sub-MOA. And, it's a relative "economical" build. Nothing special or expensive.

A recent 5-shot group at 100 yards by my 17 year old daughter with this rifle:

I did this with it at 600 yards, and I'm not especially talented.

 

[Frgood]

It looks like White oak has a 1:8 twist .223 Wylde 20 inch barrel that is reasonable in price.

As I have several uppers, I'd like to know if there is a definitive method of evaluating their competency for this build.
I just checked all three for movement between their lowers and cannot find any movement. although my test was to place the gun in a vise and wiggle the barrel while watching the rear hinge point of the upper and lower. I recall all three rear pins are holding tight and require a punch and light tap to remove.

With this is mind, I'm guessing that just the barrel needs to be ordered. Once it arrives, I'll start a thread/discussion on barrel installation as that would be the next can of worms we can collectively tackle.

For everyone's reference, I'm confident with no4mk1t advice and am ordering Shop Barrels | White Oak Armament .

Additional reference from this discussion - 5.56 Twist Rate Chart & Recommendations

A final though before ordering. BCG and Bolt matching to the barrel. As in bolt rifles and 1911s, there is the effort on ensuring proper lock-up and headspacing. I see White Oak has complete BCGs and individual bolts. How would one determine optimal bolt lock-up?

Again this question seeks to answer can I use my existing budget BCG's or order a new one from White Oak given that I don't see any notes on matching the bolt to the barrel.

 

[Frgood]

My AR-15 (223) built by above-referenced friend is sub-MOA. And, it's a relative "economical" build. Nothing special or expensive.

View attachment 2687
A recent 5-shot group at 100 yards by my 17 year old daughter with this rifle:
View attachment 2688

I did this with it at 600 yards, and I'm not especially talented.
View attachment 2689

Thanks for the interesting addition and I think others can use the build spec. In the spirit of this forum I'd like to demonstrate, if possible, if one can get a quality result from an 80% lower. I know I would be very curious of the result from taking your upper and placing it on someone's homebuilt lower. It would really raise the bar for 80% builders so that we'd see folks doing more than creating a bunch of soda can and milk jug shooters.

 

[Racer88]

Thanks for the interesting addition and I think others can use the build spec. In the spirit of this forum I'd like to demonstrate, if possible, if one can get a quality result from an 80% lower. I know I would be very curious of the result from taking your upper and placing it on someone's homebuilt lower. It would really raise the bar for 80% builders so that we'd see folks doing more than creating a bunch of soda can and milk jug shooters.

I would expect a well-finished 80% to perform well.

 

[no4mk1t]

It looks like White oak has a 1:8 twist .223 Wylde 20 inch barrel that is reasonable in price.

That would be a good choice for your first build.

As I have several uppers, I'd like to know if there is a definitive method of evaluating their competency for this build.
I just checked all three for movement between their lowers and cannot find any movement. although my test was to place the gun in a vise and wiggle the barrel while watching the rear hinge point of the upper and lower. I recall all three rear pins are holding tight and require a punch and light tap to remove.

If you have a few to choose from, just pick the one that has the least wiggle on the lower.

With this is mind, I'm guessing that just the barrel needs to be ordered. Once it arrives, I'll start a thread/discussion on barrel installation as that would be the next can of worms we can collectively tackle.

Are you building a "classic" upper with iron sights, A2 handgaurds, and A2 FSB? Or are you going with an optic, rail type handguard, and low profile gas block?
I ask that because the classic build will require a float tube under the handgaurd, and a gas tube with bends in it for the float tube. The handguards also need to be modified to fit the float tube. If you're going this route, I can post pics to illustrate.

For everyone's reference, I'm confident with no4mk1t advice and am ordering Shop Barrels | White Oak Armament .

Additional reference from this discussion - 5.56 Twist Rate Chart & Recommendations

Thanks. Was on my states rifle team for 15 years. I hope I learned a thing or two in that time.
Either 1/7 or 1/8 will work fine. I've shot both and there's no difference. And a fast twist barrel will shoot the 52 SMK like a laser. Don't ;et the armchair warriors tell you it won't. "Over stabilization" is a buzz word you'll hear and it is technically true that the light bullets in a fast twist barrel do not require that much twist. It doesn't mean they won't shoot good though. Now the thin jacketed bullets for prairie dog hunting will self destruct at about 60-70 yds, but Sierra or Hornady match bullets won't.

A final though before ordering. BCG and Bolt matching to the barrel. As in bolt rifles and 1911s, there is the effort on ensuring proper lock-up and headspacing. I see White Oak has complete BCGs and individual bolts. How would one determine optimal bolt lock-up?

If you already have a bolt carrier, go ahead and use it. When you ordered the barrel, ask if they can furnish a bolt matched to the barrel. With modern tolerances, this isn't a big deal like it was with say an M1 where the tolerances were more generous.

Again this question seeks to answer can I use my existing budget BCG's or order a new one from White Oak given that I don't see any notes on matching the bolt to the barrel.

In a new barrel, I would start with a new bolt. If the one you have is new, use it. If you are worried about head space, that is pretty easy to verify with a gage.

 

[no4mk1t]

Thanks for the interesting addition and I think others can use the build spec. In the spirit of this forum I'd like to demonstrate, if possible, if one can get a quality result from an 80% lower. I know I would be very curious of the result from taking your upper and placing it on someone's homebuilt lower. It would really raise the bar for 80% builders so that we'd see folks doing more than creating a bunch of soda can and milk jug shooters.

Yes you can.
The lower is basically just a housing for the trigger and a mounting platform for the stock and grip. It contributes little to the accuracy of the finished weapon.

And a well built AR with even a Colt factory chrome lined HBAR barrel can shoot 1/2 MOA with hand loads it likes. It can literally take you all the way to Master class. I know guys that have done just that.

Do not evaluate any AR for accuracy using M193, M855, or any FMJ type bulk ammo. Use quality match bullets and tune the load to the gun.

 

[Frgood]

 

[no4mk1t]

Also read my post on using the M1907 sling as a shooting aid.