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7mm or .300 WSM in AR10/SR25 platform?

Nukes

Sergeant
Full Member
Minuteman
Jul 12, 2012
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Central Coast of AZ
Does anyone have experience with a 7mm WSM or .300 WSM build in an AR10/SR25/DPMS platform? If so, I am most interested in your observations.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

I have what I feel to be the more common and better suited, 300 SAUM AR10 and I love the beast. It's a factory rifle, that's been upgraded to suit but I do intend on building a 7mm SAUM upper for it in the very near future.

Right now I'm shooting 190 VLDs at a drop confirmed 2915 fps, but I've ran 210s at almost that same speed before experienceing pressure sighs.
In my experience, and adjustable gas block is a must...and that MAY have been the reason why you don't see many of these around.
I know sales by DPMS and Armalite were pretty slow, and that's why it was dropped...but the ability to better tune the gas system is a big advantage in my opinion.

Right now, from my research, you're limited to one supplier and thats Accuracy Systems. Trying to get your hands on a bolt is where all the problems lie, especially if you want to build one yourself.
I haven't found anyone else besides Accuracy Systems that's still building them...but I have seen that POF had one at SHOT a few years back that apparently never made it to market...and another builder was suppose to have one released last year, but I guess that hasn't made it either.

Here's mine.

9593.jpg
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

What mags are you using in your 300saum ? I have a lr-308 that I am thinking of getting work done to it. This sounds very interesting to me. Who can turn my POS DPMS into a 300 wsm ?
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

I use standard Armalite mags. The original that came with the upper was a Gen 1 mag with a modified follower from Armalite...but they advised me that all their Gen II mags should work just fine.
If that's true, I see no reason why any DPMS or Pmags wouldn't work with your DPMS platform, but I have no way to test this theory.


Accuracys Systems could do it...because I like I said. DPMS isn't willing to let the last of their bolts out the door for people to build with.
They have to hold onto them in case one of their older rifles has a warranty issue.
If you call and ask about a bolt, you'll get the "WE DON'T HAVE ANY, or WE DON'T MAKE THOSE ANY MORE"
Which is BS because I've had two other forum get their hands on one AFTER I called to check.J

I believe the DPMS models that were made came with a 20" barrel which is a complete waste of the calibers potential IMO.
My Armalite has a 24" 1:10 twist that handles anything I want to feed it.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

Yahoo!

Thank you, c_bass16. Now THAT is what I am talking about. Very nice @ 1105yds with can!

Why do you say "...the more common and better suited, 300 SAUM..."? Please excuse my ignorance, but it is not obvious to me why the SAUMs would be better suited than the WSMs to a semiauto platform.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

The reason is because the SAUM (case length of 2.015) is just a fraction shorter than the WSM (case length of 2.100), yet the SAUM has a longer neck (SAUM neck length of .3115 compared to WSM neck length of .2979...depending of course on how you trim your cases) which some can argue, will help prevent causing or increasing runout as your bullets engage the feed ramps in a semi-auto, and has been argued that it offers longer barrel life and substantially less powder necessary to achieve velocities that are MAYBE only 50 fps slower. In some cases, equal.

It also means, that you can use a longer heaver bullet, seat them to mag length, and still be closer to the lands, than you would be able to get with a WSM. It's not much...but when you're trying to get a few thousandths closer for accuracy, it means a lot.

Now you can always modify a magazine, and as much as people bitch about doing that. I've been doing it for years with my 243WSSM in my AR...and I've seen no negative effects.
I'll be re-testing 210 VLDs with a modified mag next spring I think. It should allow me to keep my velocity up, and reduce some pressure.

In a semi auto...ESPECIALLY FOR THE 7mm...the SAUM is a no brainer, unless you're content shooting medium weight bullets.

I've taken mine to a mile on 13" steel, and although I don't shoot 100% out there...I have no doubt that the caliber capabilities greatly increase my chances.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

Oh' god, looks like a am going to spend a lot of money. I really want to have a semi auto 300 saum now.
Do you have any idea on barrel life? I am guessing it will be short, and sweet.
Is there a difference in the buffer? What about the carrier, is it the same ?
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

I don't think you will have ANY problem with barrel life.
Carrier is the same, buffer is the same, but I upgraded to a Tubbs flat spring and added an adjustable gas block.
Was it needed? I have no idea, but it sure doesn't hurt.

I read a post buy a guy that owned a DPMS version, and he said the recoil was WAY to much for him.
With the adjustable gas block and the suppressor...it's VERY easy to control and see impacts.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

Thanks.

Is it equally difficult to find SAUM and WSM brass?

Whose adjustable gas block did you use?
 
Re: 7mm or .300 WSM in AR10/SR25 platform?


RND Manufacturing builds (or used to) a WSM. Call him on the phone. He'll talk to you.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

I happen to have one of the dpms 300 saums, and it is a shooter. A good friend has an identical one, and it shoots the exact same loads as mine. The 20" barrel does seem silly and I'm sure it costs a lot of velocity. I have not modded any part of the upper on mine, though I'm thinking of making the gas block adjustable. It came with 2 mags, and one works perfectly and one does not. I shoot 110 vmax at 3500 fps, and 178 amax at 2770 fps, the only two bullets I've tried.

I did break an extractor last spring, and though dpms at first said they didn't have one, after a little pressure they looked and came up with a new one for me, no charge. Considering that I found it barely used for $725 for the complete rifle, it's one of the very best firearms deals I've ever done. Brass has been easy to find on the web and seems to last for numerous firings. I definately recommend snagging one if you happen to find it.

BTW, pmags do not work with it for some reason.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Nukes</div><div class="ubbcode-body">Thanks.

Is it equally difficult to find SAUM and WSM brass?

Whose adjustable gas block did you use? </div></div>

I've never had issues finding brass, IF I LOOK. In fact, "Precision Reloading" is local to me, and I just bought two bags of 50 Rem Brass when I first got started and I've still got about 90% of them left.
I picked up 40 pieces of Nosler once fired but it was nothing but a head ache. It's much more consistent as far as weight and case capacity...but the capacity is so much smaller, that I had to drop my charges by almost 2 full grains or I would rip the rims off.
I trashed it all and just shoot Rem brass now.
Places like Cabelas rarely have it in stock, but if you have one close to you...just order it online and they will ship it to your local store for no charge.

The gas block I went with is a Low Profile PRI Adjustable. It fits PERFECTLY inside my 13.8" Troy MRF rail.



<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Casey Simpson</div><div class="ubbcode-body">
RND Manufacturing builds (or used to) a WSM. Call him on the phone. He'll talk to you. </div></div>

Yes, RND Manufacturing builds them...but they aren't based off the DPMS or Armalite pattern. It's a 100% proprietary design that does NOT even share a carrier or bolt. It's all unique and expensive to boot.
I'm sure it shoots great, but for that price tag, it sure as hell better.
 
Re: 7mm or .300 WSM in AR10/SR25 platform?

They pop up from time to time, RARE but it happens. As rare as they are, they are going to cost ya...you'd probably be better off having one built the way you want.
 
Seems like I remember the ar-10 saum barrel extension having different feed ramps. Anybody know if a regular extension works? Also I think the AR-10 has a smaller firing pin hole than the dpms. Is there any problems with the dpms pin size for the saum application?
 
Seems like I remember the ar-10 saum barrel extension having different feed ramps. Anybody know if a regular extension works? Also I think the AR-10 has a smaller firing pin hole than the dpms. Is there any problems with the dpms pin size for the saum application?

IDK if it's caused by the larger pin size, but I have had pierced primers with my DPMS Saum. I was thinking it's probably overgassed and am planning on putting on an adjustable gas block.
 
The Armalite bolt has a smaller fp and should fix your problem. Also there is a chart somewhere of the different cup thicknesses of different primers. I think the cci military has a thicker cup and may be less likely to blow out.