New Year New Problem

Sounds like the length of the JP spring is just fine, then. If your rifle worked before the stock swap, it's either the buffer weight, spring rate or a combination of both. The other potential trouble area is the gas block being lined up. Usually, the opening into the gasblock is fairly generous so alignment doesn't need to be real precise. The last trouble area is ammo. It seems some M&P-10s don't like lower pressure ammo and using a higher spring rate/heavier buffer will only worsen that. I'm finding that's true with mine, but I need to do some more testing before drawing any conclusions.

With a good stock, I don't find the recoil of the M&P-10 objectionable. With the factory M4 style stock, it was uncomfortable for me because it dug into my flesh but the CTR with the thicker recoil pad took care of that. What I don't like about the CTR is the cheek weld I get when using a scope. It's half on the stock and half on the RE. This isn't a problem when using a taller mount & Aimpoint because I'm not pressing as much of my face on the rifle. The MagPul Moe Fixed will cover the whole RE. For me, that will be an improvement over the CTR. The choice is between saving weight, or getting a better cheek weld. Balance, even with the lighter M4 style stock is fine for me.

That doesn't mean I wouldn't install an UBR. It's just that I'm leaning more towards a lighter, less expensive option
 
apiccola,

Just wanted to let you know and other supporting members that today I shot over 100 rounds without a single malfunction, bolt locks back after last round each time running like a champ. The problem was indeed the gas rings and I should have addressed it prior but never knew it would lead to this, anyhow in conclusion and reply to 'vfin' my "dilemma" would have been forthcoming regardless whether or not I modified my rifle and it is disappointing that S&W would ship a brand new rifle with worn-out bolt rings. Again thank you for your support, now I am thinking of changing the buffer and spring and see what kind of trouble that will get me in.. :D

http://smith-wessonforum.com/smith-wesson-m-p10-rifles/346639-replacing-bolt-gas-rings.html

Is this the Troy 308 free float quad rail? If so, what bipod is that and do you have a link to it? Thanks. Great looking setup!
 
Range report with new upgrades

Since my last range day, I had changed my set-up with the following and here are my impressions: UBR Stock; JP Captured spring/buffer; Harris bipod (BRMS 6-9") and wished I could have the new trigger (SSA-E), but ran into problems installing it (with the bolt catch in the way and me unable to remove it) :o

The Magpul UBR, excellent no issues with LOP and provides me with a good cheek weld support and I simply love the tactical look.
JP Captured Spring, frankly disappointed, actually more felt recoil than with standard buffer/spring and I wouldn't claim that I get back on target quicker, may do a return and opt for Slash buffer/spring.
Harris bipod, excellent and quality product as compared to UTG.

No malfunctions and good groupings (as usual) @ 100 yards.

Now to figure this trigger install :confused:

http://www.flickr.com/photos/118379003@N05/13207480795/
 
You might want to look at buffer technologies (or at least I think that is the name of the site) for a hydraulic buffer. Work has it they do a pretty decent job. They have a AR10 specific buffer on there. I'm not sure who else sells them.
 
Buffer and Spring Replacement – Previously I had the JP Silent Captured Spring, although many reviews mention how well it works, none that I have come across address reduced recoil. The M&P 10 does not have significant recoil and it’s very manageable but for my taste I wanted the ability to stay on target for follow-up shots. Secondly, I noticed during my following range day the ejected brass had marks on the case head (similar to 2nd case from left in the link below) and after reading the article it concludes that a heavier buffer/spring or adjustable gas block should eliminate this.

Shooting Illustrated Mobile

JP Rifles offer heavier spring combinations but the complexity of changing the spring and my own intuition that it may not work, I believe if you have an adjustable gas block and JP’s own low mass BCG, then the captured buffer spring will be most beneficial. I went ahead and returned it and opted to try the CAR 10 buffer and modified spring. Most claim that a heavier buffer and spring is only Band-Aid for an over-gassed system and I believe that to be true, for my application replacing my gas block with an adjustable would not be an easy task plus I did not want to push my luck and run into problems with the block not seated correctly etc. at this stage, I may do so later. The CAR 10 buffer worked as advertised excellent recoil reduction (as compared to the JP and AR15 ST-2) for it shoots with zero kick and my ejected brass does not have CHS. This concludes my mods and experimentation with results I am more than happy with :) THANK YOU FELLOW FORUM MEMBERS FOR ALL YOUR HELP.

https://www.flickr.com/photos/118379003@N05/with/13770359755
 
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