SOC's AR10-TU Magnum 300 RSAUM

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11 years 6 months ago #25729 by OleCowboy
Replied by OleCowboy on topic SOC's AR10-TU Magnum 300 RSAUM
Good stuff, been wondering about that rd...

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11 years 6 months ago #25737 by SOC
Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM

Lizardette wrote: My experience with adjustable gas systems in general has not been good.

My complaints about set screws (in no particular order) are thus:

1. Requires a tool to adjust.

This isn't a big deal to a lot of people. I really prefer things that can be adjusted without tools, especially when you anticipate needing to change it.

I stash an allen key for the gas block inside the MIAD grip. I also have all my firearm related bits in my Leatherman.

2. Continuous adjustability.

The fact that it is continuously adjustable isn't the problem. The lack of definite settings makes it harder to exactly repeat a given adjustment. That's not to say it's impossible to do. I'm just lazy about some things and this is one of them. I'd rather have definite settings that lock into place, even if it's just with a ball detent.

I record in number of turns in 1/4 increments from fully closed the ammo cycles best at in my dope book. Just another data point.

3. The screw isn't captured in any way.

I'm not worried about it falling out completely so much. My experience has been that non-captured screws back out under recoil though, changing your gas setting, possibly throwing off your accuracy, and possibly decreasing reliability. Blue lock-tite can help alleviate this problem, when the screw does not get heat applied to it with every shot. In my experience blue lock-tite goes liquid pretty quickly when it's applied to a screw holding anything attached to a gas system. It heats up and the screw backs out, unless...

In this application the ceramic based rock-set is best. Takes up to 1100 degrees and doesn't hinder adjustments or require re-application. (Tell you clean out the gas system)

4. Fouling.

Oh my dear lord... Fouling. When the passage through a gas system is partially obstructed (as this is how set screws "adjust" gas flow), powder residue builds up on it. If you don't remove it and clean it often, eventually it will build up to the point that the screw gets stuck in place and the passage through the gas tube starts getting considerably smaller. It's a real... thing, to get enough torque on one of those small allen wrenches to un-stick a carbon-ed in screw.

On my MGI I've fired 1000's of rounds and never noticed fouling causing the allen to stick or have more resistance than when it was new. That may have to due with quality clean burning ammo. If I noticed a change I'd clean it out. (I suspect my AR-10TU would have even less of this problem)

... I think that's it.


I'm not saying any of your opinions are invalid, but most of your concerns are easy to overcome. For me being able to tune the rifle in the field, to the ammo and to environmental conditions aids reliability. Like any other firearm modification your going to have to consider the pros and cons and how you plan to use it.

A PRI (or other infinitely adjustable) gas block on my AR10-TU is a must. I couldn't reliably fire ammo from 110gn V-max to 210gn Berger VLD without sacrificing reliability or excessive recoil and ware for one or the other, or needing combinations of weighted buffers and buffer springs.

You see more and more high end AR type rifles with adjustable gas systems for a reason.
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11 years 6 months ago #25794 by Lizardette
Replied by Lizardette on topic SOC's AR10-TU Magnum 300 RSAUM
You make very good points.

Most of my reasoning is based on personal preference. For the time being, I'm not quite motivated enough to keep detailed records. It sounds like you, on the other hand, keep very detailed records - out of necessity. Because of the number of different loads that you use, it makes sense to keep track of everything. For me though, I basically use one bullet weight (168), loaded to roughly the same velocity regardless of the powder used. When I do change bullet weights, it's never a drastic change. Twelve grains up or fourteen grains down. It's easy to keep track, in my head, of the necessary changes in elevation between these loads.

As far as tools go, I desperately want a Leatherman Surge with their bit kit. It would make life much easier. Recording the number of quarter turns is a good system. I would prefer something where there are marks around the circumference of the piece that the screw goes into and a notch or something on the screw that you can index with said marks.

That's totally me being picky though.

If that's the case, I may have to invest in a supply of rock-set. I had a small packet of it that came with my AAC Blackout Flash Hider, but I'm not sure how much I have left. That seriously sounds like good stuff though. Thank you for pointing it out.

Cleaner burning powder could have a lot to do with a lack of carbon build-up. I'm curious, what powders are you using?

If the screw is stainless steel, that could have a big impact on it as well. The last set screw adjustable gas system I used had a parkerized chrome-moly adjustment screw and gas block. If they'd been stainless, I may not have had a problem.

As far as more AR's coming equipped with adjustable gas blocks, I'm not sure. Market demand drives pretty much everything that's offered. If there are more available, there's obviously a demand. The question is whether that demand is based on an actual need that the majority of consumers have, or whether the majority of consumers just think it's "cool." I honestly have no idea which it is.

You've given me some things to think about. :)

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11 years 6 months ago #25795 by SOC
Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM
I shoot almost entirely mil-surp or commercial ammo in the MGI. The Russian ammo is pretty dirty but due to possible use of corrosive primers I "wash" them out including the gas system.

I did initial load development for the AR10-TU using RL-17 with very good results (Consistent, more velocity, less pressure sign). Right now I'm burning up the factory ammo for it. Remington uses what I assume is some proprietary double base powder for the 300 RSAUM.

The PRI blocks are also treated inside and out with something similar to nickel boron but its very non stick as are the allen screws.

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11 years 6 months ago - 11 years 6 months ago #25802 by OleCowboy
Replied by OleCowboy on topic SOC's AR10-TU Magnum 300 RSAUM

Lizardette wrote: You make very good points.

Most of my reasoning is based on personal preference. For the time being, I'm not quite motivated enough to keep detailed records. It sounds like you, on the other hand, keep very detailed records - out of necessity. Because of the number of different loads that you use, it makes sense to keep track of everything. For me though, I basically use one bullet weight (168), loaded to roughly the same velocity regardless of the powder used. When I do change bullet weights, it's never a drastic change. Twelve grains up or fourteen grains down. It's easy to keep track, in my head, of the necessary changes in elevation between these loads.

As far as tools go, I desperately want a Leatherman Surge with their bit kit. It would make life much easier. Recording the number of quarter turns is a good system. I would prefer something where there are marks around the circumference of the piece that the screw goes into and a notch or something on the screw that you can index with said marks.

That's totally me being picky though.

If that's the case, I may have to invest in a supply of rock-set. I had a small packet of it that came with my AAC Blackout Flash Hider, but I'm not sure how much I have left. That seriously sounds like good stuff though. Thank you for pointing it out.

Cleaner burning powder could have a lot to do with a lack of carbon build-up. I'm curious, what powders are you using?

If the screw is stainless steel, that could have a big impact on it as well. The last set screw adjustable gas system I used had a parkerized chrome-moly adjustment screw and gas block. If they'd been stainless, I may not have had a problem.

As far as more AR's coming equipped with adjustable gas blocks, I'm not sure. Market demand drives pretty much everything that's offered. If there are more available, there's obviously a demand. The question is whether that demand is based on an actual need that the majority of consumers have, or whether the majority of consumers just think it's "cool." I honestly have no idea which it is.

You've given me some things to think about. :)

I have a box full of Leathman, literally, been getting these for Christmas, Fathers day, B day for years. If I have that model its yours, the bit kit you would have to buy, I have a bit kit that I use with my Skeletool CX and going to keep it...

Yes SS could be an advantage. Unless the screw is some weird set of threads you should have no problem finding a SS one and if you have to cut to length
Last edit: 11 years 6 months ago by OleCowboy.
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11 years 6 months ago #25815 by Lizardette
Replied by Lizardette on topic SOC's AR10-TU Magnum 300 RSAUM
Cowboy, that would be awesome. Let me know if you have one and I'll pm you my address. :)

SOC: Nickel-Boron would probably do the trick. Might be more expensive, but it sounds like it's more than worth it. Also, I've wanted to try the Reloader series of powders for quite awhile, but just never got around to it. I've heard good things about them though.

Most of what we load with are IMR branded powders: 4895 and 4064 (both safe for the Garands that we load for), 4198, 3031, 8208 (I have ONE rifle that likes this powder and only with one bullet weight at that), and 4350.

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11 years 6 months ago #25817 by OleCowboy
Replied by OleCowboy on topic SOC's AR10-TU Magnum 300 RSAUM

Lizardette wrote: Cowboy, that would be awesome. Let me know if you have one and I'll pm you my address. :)

SOC: Nickel-Boron would probably do the trick. Might be more expensive, but it sounds like it's more than worth it. Also, I've wanted to try the Reloader series of powders for quite awhile, but just never got around to it. I've heard good things about them though.

Most of what we load with are IMR branded powders: 4895 and 4064 (both safe for the Garands that we load for), 4198, 3031, 8208 (I have ONE rifle that likes this powder and only with one bullet weight at that), and 4350.

I certainly will, got to find that box, bet I have a good dozen in there and I have given some away over the years...

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11 years 4 months ago - 11 years 4 months ago #27474 by SOC
Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM
Here is my load data on my 300 RSAUM.

210 Burger VLD Hunting bullet
New Remington brass (2.004" length)
Reloader RL-17 Powder
Federal 215 Primers
COL (2.860) 2.168 to Ogive


Velocity was as follows from my 24" AT-10TU

Shot 5 rounds of factory Rem 175gn Core-lokt (about 2900 FPS) to compare pressure sign on brass and confirm chronograph was working.

54gn

#1-2580.7 FPS
#2-2589.5 FPS
#3-2614.8 FPS
#4-2617.3 FPS
#5-2615.7 FPS

SD: 17.2 FPS
CV: .7%

MAD: 14.8 FPS
CV: .6%

AV: 2603.6 FPS
ES: 36.6 FPS


55gn

#1-2661.8 FPS
#2-2654.2 FPS
#3-2664.4 FPS
#4-2649.9 FPS
#5-2636.4 FPS

SD: 11.1 FPS
CV: .4%

MAD: 8.1 FPS
CV: .3%

AV: 2653.3 FPS
ES: 27.9 FPS


56gn

#1-2694.7 FPS
#2-2719.4 FPS
#3-2723.9 FPS
#4-2726.6 FPS
#5-2716.0 FPS

SD: 14.6 FPS
CV: .4%

MAD: 10.7 FPS
CV: .4%

AV: 2716.1 FPS
ES: 31.9 FPS


57gn

#1-2793.6 FPS
#2-2753.7 FPS
#3-2778.6 FPS
#4-2750.1 FPS
#5-2766.6 FPS

SD: 18.0 FPS
CV: .6%

MAD: 14.1 FPS
CV: .5%

AV: 2768.5 FPS
ES: 43.5 FPS


58gn

#1-2780.5 FPS
#2-2819.3 FPS
#3-2821.2 FPS
#4-2828.9 FPS
#5-2790.8 FPS

SD: 21.1 FPS
CV: .8%

MAD: 18.0 FPS
CV: .6%

AV: 2808.1 FPS
ES: 48.4 FPS


59gn

#1-2859.1 FPS
#2-2830.8 FPS
#3-2862.1 FPS
#4-2856.1 FPS
#5-2863.0 FPS

SD: 11.1 FPS
CV: .4%

MAD: 13.4 FPS
CV: .5%

AV: 2854.2 FPS
ES: 32.2 FPS


60gn

#1-2922.6 FPS
#2-2892.0 FPS
#3-2910.3 FPS
#4-2903.1 FPS
#5-2928.8 FPS

SD: 14.8 FPS
CV: .5%

MAD: 11.5 FPS
CV: .4%

AV: 2911.3 FPS
ES: 36.8 FPS

When comparing the 60gn load brass to the factory ammo brass I saw no difference in pressure sign, no extractor or ejector marks no swelling at the web.

The factory Rem ammo uses a brass colored primer vs my Federal 215 Primers.

I noticed LESS pressure sign on the Fed 215 primers less flattening less firing pin crater. I am assuming this is due to the Fed 215's being a harder primer.

I plan to do accuracy testing and based on that data I may go up or down in .1gn increments to fine tune accuracy.

I also have some 208gn A-max on hand and am looking for 210gn Sierra Match King and will work up load data for those.
Last edit: 11 years 4 months ago by SOC.
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11 years 4 months ago #27475 by Siscowet
Replied by Siscowet on topic SOC's AR10-TU Magnum 300 RSAUM
Good data. You obviously took great care in assembling your handloads to get such low variations in MV. Look forward to your accuracy data.

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11 years 4 months ago #27626 by SOC
Replied by SOC on topic SOC's AR10-TU Magnum 300 RSAUM

Siscowet wrote: Good data. You obviously took great care in assembling your handloads to get such low variations in MV. Look forward to your accuracy data.


These loads cost me a bit over $2.50 each so I'm very intent on getting the most out of them.

Factory ammo runs $55-$65 a box of 20 if I can find it and it is giving nowhere the performance of my handloads.

I think the biggest hindrance to accuracy testing will probably be me.

Another shooter with their own handloads was getting .6 MOA from this rifle before it became mine.

I eventually plan to shoot 1000yds once I have finalized my load development and developed the ability to shoot that far.

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