Colt M4 LE6920 to 6.5 Grendel

[Jakegsxr11]

I have a colt M4 I'd like to convert to 6.5 Grendel. I've done some research but still have a few questions. Do I only need to purchase a bolt and barrel and all the other parts will be able to be reused?

What bolt/barrel combo do you recommend. I was thinking between:
JP 18" with JP enhanced bolt
PF Criterion 18" with PF supermatch bolt
I'm open to other suggestions also but those two seem some of the best for the money.
I'm in no hurry to receive the parts and am willing to wait for quality.

[VASCAR2]

The Colt 6920's I've seen have a fixed front sight integrated with the gas block. Were you going to use your current gas block/front sight. If your going to use an 18" barrel were you going to change hand guards? If you plan on using a suppressor in the future I'd recommend an adjustable gas block. If your going to use a suppressor with 18" barrel I'd get a midlength gas system.

Don't forget for best performance you'll need 6.5 Grendel mags and I like E-Lander 6.5 Grendel mags best.

Personally I think your best option is to build another complete upper in 6.5 Grendel. I'd suggest you keep your Colt 6920 upper as is. In full disclosure any spare upper I owned morphed into a second complete rifle but prices are pretty affordable right now. By converting your Colt upper over 6.5 Grendel compared to building a seperate upper is not that much money. An upper receiver can be purchased for $50-$70, another bolt carrier $100 or less. If your replacing the gas block I'd get a new gas tube and if your buying a new hand guard your looking $100-$200 difference in building a new upper compared to converting your Colt.

[LRRPF52]

Welcome aboard.

My advice pretty much mimics VASCAR2's.

Keep the Colt upper complete and just build another complete Grendel upper.

Do you have an AR15 armorer wrench and vice?

[Jakegsxr11]

Thanks for the input so far. I plan on buying an AR 15 armorer wrench and I have a standard bench vise. Do I need a specific specialized vise? I didn't realize the site and gas block were one piece. I don't really want to keep the front iron sight. I suppose I'll start looking into building or purchasing a complete upper. I don't see myself ever using a suppressor.

[VASCAR2]

A normal shop vise will work. Depending on the hand guard will determine whether you'll need an armorers wrench. As an example ALG/Geissele free float hand guards come with a supplied wrench for installation. I bought a Rousch Sports hand guard and a 10" cresent wrench was needed for the barrel nut. If you use the delta ring with an A-2 hand guard you'll need an armorers wrench. A lot of barrel nuts should be tightened using a torque wrench to ensure the nut does not come loose.


There is a handy tool for tightening the castle nut on the buffer tube but I used a punch and mallet before buying a castle nut wrench.

[Jakegsxr11]

Ok, I've decided to build a complete rifle. I've had my local shop order me a Vision Defense stripped upper and lower and if I don't like them on sight I'm then going to order the Aero Performance upper and lower. I am also going to pick up a Giessele SSA trigger and a standard mil spec LPK. I'm not sure on what to use for a bolt and barrel. I'm torn between a:
JP enhanced bolt and barrel at 18" ($530)

PF Criterion 18" barrel and PF Supermatch bolt ($440)

Brux Barrels, make me a custom 1:8 twist contoured to my liking to the bolt of my choosing, their barrel charge is $410 for barrel only. I'm really wanting to try this option because they seem like a great local shop but am unsure what bolt to use.

Does anyone have any other options I should consider or want to help me choose between the 3?

[VASCAR2]

Any of three barrels sound good. If you opt for the Brux I'd buy a .136 bolt face depth Grendel bolt from JP, Precision Firearms, AA hard use bolt or a Group buy bolt from the forum. I got a group buy bolt and it looks really good but I haven't used it yet. I have a PF 6.5 Grendel BCG and it has been gtg. My other two 6.5 Grendel bolts are AA.

I've not read of any problems with bolts from AA, PF or JP and my Group Buy bolt looks like it has very good quality.

[Jakegsxr11]

What do you guys recommend for a gas system on a 18" barrel? I'm thinking a rifle length with a .094 gas port. Will this be optimum? What buffer would you run?
Thanks

[A5BLASTER]

My JP barrel is 18 inch with rifle gas length and I'm running a JP scs and have a rifle length buffer and spring for back up works great for me.

Also have adjustable gas and a cheap muzzle brake off eBay on it and it is very flat shooting and very lil recoil.

Hope this helps sir.

[ricsmall]

I would go with the brux barrel. Just be sure they are using a saami spec reamer. They're barrels are superb. Get a bolt from whoever has it ready to ship, either PF or JP I would imagine. You could check with AA.

I would go with rifle length gas personally, very soft shooting and easy on components. Start with a .094" gas port and if it needs more it's easy to enlarge it. Buffer will depend on whether you plan to run a collapsible carbine stock or a rifle length stock. If carbine, run a 5.2 oz carbine length buffer. H3 I believe it is. If using a rifle length stock run a rifle buffer

Richard

[Jakegsxr11]

Thanks, I'm going to go with the brux. I ordered a bolt from the group buy. I really just wanted to confirm my gas port of rifle length at .094 will work and what buffer to use. I would prefer a carbine length buffer but didn't know if I would require rifle length or what weight to run.