MSR 10 Barrel Swap - Extension Dimensions?

[Subwrx300]

Curious if any of the MSR owners cruising this site have pulled their barrel. I've got an MSR10 Hunter in 6.5 Creed and I'm exploring a custom barrel but running into road blocks from Savage CS team. The only info they give is "the upper and lower are proprietary" and promptly attempt to get me off the phone. After three calls and speaking with CS manager, he suggested I write letter to their engineering team in MA, because "they don't have email". Very very frustrating. I'll leave it at that...

What I'm hoping to know is whether the barrel extension is DPMS spec (Gen 1) or Armalite. With that info, assuming DPMS is the pattern for extension, I think barrel swap should be as simple as can be. Will still need to check bolt dimensions (for BCG fit), new gas block (low profile adjustable) and gas tube length (probably need custom gas tube). I roughly measured OD of barrel extension inside upper and it came out to 1.186+ (not a final or precise measurement as I haven't pulled barrel yet). Lilja has a blueprint of their barrels and it shows OD 1.188. My gut says it is a DPMS extension but don't know if the ring is proper distance from face of extension.

Any advice from this that have better knowledge on this rifle or checking barrel fit would be great. Ideally if someone can provide which dimensions (extension length, breech OD, breech to barrel nut flange, etc) are critical to check for cross application, I'd be super grateful!

 

[srt-4_uk]

If you are going to swap barrels, why not just take the extension off the barrel you have?

 

[Subwrx300]

Definitely an option. I did manage to get the barrel pulled and measure dimensions of the extension and barrel. It's very very close to what I believe is a DMPS extension. Virtually all measurements of the extension were within .001 but I'm not knowledgeable about which measurements provide go/no-go info.

I was able to swap with a friend's 308 barrel and all seemed to lock up correctly. So I took a leap of faith and ordered a Dracos 22" 6.5CM last night.

To my understanding (limited), please correct me if I'm off base here, don't the extension and barrel need to be fitted together at the same time to set proper headspace? I'm trying to learn the background behind AR10/lr308 style barrels so I can make better choices on future builds.

Any links to good info on this subject are appreciated. I have great knowledge of bolt gun mechanics/fitment but AR barrel dimensions and mechanics are newer to me. Thanks in advance for the replies!

 

[jonesturf]

https://rifleshooter.com/2014/05/building-machining-an-ar-15m16-m4-barrel-from-a-blank/

This is for an AR-15 barrel but its the same idea.

 

[Subwrx300]

https://rifleshooter.com/2014/05/building-machining-an-ar-15m16-m4-barrel-from-a-blank/

This is for an AR-15 barrel but its the same idea.

That's a good read! Helps immensely with how tenon is built to match extension and for bolt. Which leads to my next question and maybe I'm asking the question wrong: do all extensions have same (within reason) exterior dimensions?

For instance, do most barrels (AR10 style) use same exterior dimensions in the extension area? I'm asking because I keep reading that DPMS, Armalite and Knights barrels are different.

My research had not conclusively answered this question. It seems that most barrels will fit most receivers but the critical difference is in the bolt dimensions between the three and this leads to different headspace configurations. Is this accurate?

I'm hoping this is the case because it would allow me to choose any barrel and simply find the appropriate bolt to match.

 

[travgrif]

Did you end up getting your barrel swapped out? I'm looking to do the same to mine.

I got the same run around from Savage that you did, so couldn't get answer on what extension they use. I pinged Rainier Arms and they believed it to be DPMS, but weren't 100%.

 

[Subwrx300]

Did you end up getting your barrel swapped out? I'm looking to do the same to mine.

I got the same run around from Savage that you did, so couldn't get answer on what extension they use. I pinged Rainier Arms and they believed it to be DPMS, but weren't 100%.

I did! Have a Dracos 6.5CM installed and an also have an Aeroprecision 6.5cm. They are DPMS barrels and bolts.

The barrel nut is the only tricky part. I used a castle nut wrench on mine but it may mark up the barrel a bit as it's not quite the perfect diameter. If you find the actual barrel wrench, please post back.

I've got a few threads running around here with results from the Dracos barrel if you want to check out pictures and groups.

 

[travgrif]

Thanks for the info and quick reply!

I couldn't find any Savage MSR specific barrel nut wrench, but my Daniel Defense Lite wrench notches up much closer than my castle nut wrench. Plus is a lot beefier. It doesn't really look like it from this angle, but two of the tabs touch the notch sides and the third is very close. I think it should be good enough to get me to 50 ft lbs.

 

[Subwrx300]

Thanks for the info and quick reply!

I couldn't find any Savage MSR specific barrel nut wrench, but my Daniel Defense Lite wrench notches up much closer than my castle nut wrench. Plus is a lot beefier. It doesn't really look like it from this angle, but two of the tabs touch the notch sides and the third is very close. I think it should be good enough to get me to 50 ft lbs.

View attachment 6913166

That's awesome! I'll pick one up for sure! Good info! Sucks that Savage has their corporate ahoreholder bullshit to keep them from sharing information we need to tinker. Thankfully, we have The Hide!

 

[ZoneOne]

Anyone remember what ft lbs it took to remove the barrel nut? 50 no dice. 70 no dice. I’m a little reluctant to push it over 75. This thing seems like it was welded on. Feeling frustrated.

 

[Subwrx300]

Anyone remember what ft lbs it took to remove the barrel nut? 50 no dice. 70 no dice. I’m a little reluctant to push it over 75. This thing seems like it was welded on. Feeling frustrated.

Any luck on getting the barrel off?

 

[ZoneOne]

Any luck on getting the barrel off?

Negative - I'm going to sell it.

The whole point was attempting to switch it to 308 (I know, I know) but I just don't have the cash to feed it match grade ammo. I get match 308 issued to me by the case from work... so a 308 gas gun makes sense to me. Plus the dope/holds/etc will be way more similar from my gas gun to my bolt gun as opposed to shooting 6.5CM

 

[Subwrx300]

Maybe see if you can find a gunsmith to help you pull the barrel. Explain the situation and I'm sure he'd have some tools or at least experience to help spin it off. Otherwise, good luck with selling! How much do you want for it? May have buyer for right price. Send me a PM.

 

[Snuby642]

was probably rockset in place, boiling water will loosen it.
Costs nothing to try.