I was asked about my 6.5CM Mega build, so I figured I'd detail not only the parts, but my modifications, problems and results over the last several hundred rounds.  At this point I have right close to 500 rounds through the rifle.

Here it is on my bench.


Build specs-
Mega MATEN Monolithic upper/lower
Kreiger 22" heavy profile barrel pre-chambered from Fulton Armory
Bolt from Shadow Ops Weaponry
JP Adjustable gas block
PRI 20MOA scope base
Leupold QD Low rings (didn't want QD, but needed low and that's what I found)
Geissele Hi-speed NM trigger
DPMS ambi selector
Norgon ambi mag release
Standard MEGA ambi bolt release (which I really like)
Slash's (Heavy Buffers.com) X-power spring and X-Heavy buffer
The brake I got from Damage Industries (sponsor here on Arfcom).  It's OK, but I'd like to revise the mounting away from the tapered washer.
Medium Gunfighter charge handle


Some details-



Notice the slight cutting on the rail so I can access the gas block without removing the rail


Shadow Ops bolt after 500 rounds or so-


Noveske sling stud through the hold of the keymod to provide a mount for the bipod without a riser




Reciprocating mass-


Detail of scope mounts and riser-


Now some details, first the mags.  I am using Fulton Armory branded ASC mags exclusively right now.  They are 10 rounders so I can keep the rifle lower to the ground,  I have also tried Magpul and DPMS mags, the DPMS suck sweaty donkey balls and the Magpul are smaller inside.  DMPS has a crappy follower, weaker spring and sharp edges.  And it only fits 19.  Magpul is also somewhat short inside but functions just as you would expect from a Magpul mag.  Definitely no problem there, and if I was shooting 123gr or 130gr I might stick with them anyway.

ASC/Fulton Armory mag loaded with 140gr Sierra




Comparison of the three mags-  I have the internal lengths written on a paper out in my shop, but I do remember the ASC is 2.885" and is about 0.050" longer than the Magpul.



Now for some of the bad results of what I've found-
#1- I couldn't get Berger 140gr or 130gr bullets to load.  At all.  This was prior to getting the ASC mags and I think it is partially due to the fact that the MEGA has no M4-style feed ramps, but the Kreiger barrel does.  So, I made them myself.  I have had very good results with Hornady and Sierra, at much less cost than the Berger, so I haven't tried any more Berger to see how they feed yet.  And my H4350 is running really low.  More on that later.



#2- After about 100 rounds I sheared off the buffer retainer.  I talked to Slash/Clint from Heavy Buffers and his first question to me was ‘it is a billet lower’.  According to him many billet lowers put the retainer slightly out of position so the retainer is always loaded when the buffer is forward.  Sure enough, after some close checking I found that the buffer was resting just a few thousandths away from the back of the bolt.  I think this also contributed to a phantom bolt seating problem I had at first.  The fix was pretty simple, cut a groove around the buffer to allow it to sit over the retainer and rest against the bolt.






#3- Not the rifle’s fault at all, but I can’t get powder for it.  I’ve tried a slew of powders and spent many hundreds of dollars on various powders to try to keep this thing shooting.  IMR 4350 is available, but not nearly as good as H4350 which I simply can’t get anymore.  I tried a bit of H4831, Superformance, Hybrid V-100, and a couple of others that I’m missing.  Hybrid V-100 is crap in a bottle, and I’ve still got 1 ½ bottles of it left.  I still think I might be able to get Superformance working, it started getting more flow than normal in the primers but that was using 123gr A-max and std primer, giving very high SD on velocity.  I’m hoping a mag primer and 140gr may settle it down, hopefully without more pressure signs which are very likely with this slower powder.  Almost all loads get some primer flow, just the way it goes.  And I’ve been getting loose primer pockets after 4 shots using Hornady brass.  I have never tried factory ammo, but eventually I might get a box just to see how it does.

#4- Related to the pressure issues noted above, I’d REALLLLY like to use a smaller firing pin diameter.  Somebody please tell me how I can make that happen without swapping extensions.

#5- Again not the fault of the gun, but this is an overall review so I will mention it here.  After two firings on new brass, the third wouldn’t chamber and I happened to have this problem at a match here in Utah.  I had to mortar the rounds out, inspected them close and couldn’t find any problems.  I already had a chamber gauge on backorder and a few days later it showed up, and I found that my ammo was ever so slightly out of spec.  The barrel/bolt is very intolerant of slight deviations from std.  A few small tweaks on the sizer die and I was back in business and have had no further problems since.  Wish I’d had the chamber gauge earlier.


Good results-
The rifle just plain shoots.  It’s been very reliable for the last 350 rounds without a single hiccup.  It took a while to get a few bugs worked out, but I’m pretty much there, assuming I can get some powder and don’t have to go back to load development and chasing my tail with velocity, accuracy and pressure signs.
This thing shoots.  Not sure if I mentioned that.  I’m a pretty crappy shooter compared to a lot of guys that are actually ‘good’, but I’ve found when I get in and do my job, I’ve had some incredible results.  I’m sorry that I don’t have pics of groups, but most of my shooting anymore is balloons at known or unknown distances.  My longest shots to date are 1300yds on 9” balloons.  It took three shots of watching vapor trail to get on my first balloon at that distance, the next two were one shot per balloon.














Things I'd like to change-
#1- I really like the A2 sized Magpul stock and I'd like to swap this stock with that one.  This one functions great, but I love the feel of the other after shooting my friends AR-10 with one on it.

#2- I like to figure out a smaller firing pin diameter.  This would really help in load development and is one of the reasons I'm dragging my feet on working up a new load.  I'd like to get this fixed first.

#3- I really should have gone with the large instead of a medium Gunfighter charge handle.  It's hard to get a good grip on it with that honking scope.

#4- It's a heavy pig.  Not sure what to do about that, but I'm already trying to figure out if my next big build (I'm just finishing up a sub-6lb AR) will be a GII DPMS rebuilt to 6.5CM or if I'll just go with the Grendel.  Decisions decisions.

my BCG is in the mail for my MATEN... how did you cut your buffer? I will check mine out before shooting, but that will kind of suck. I also have a slash buffer, but mine is the rifle length

Excellent and thorough review of your project.

I have a GAP .260 Rem AR10 built on DPMS receivers/BCG, with a Bartlein barrel that shoots extremely well.  I suffer the same issues with availability of H4350, which is my favorite powder so far.

I really prefer the 130gr VLD in it over 140's.  My chamber is cut to shoot VLD's from the mag, and it does.  Great rifle really.

I have to full-length size all my brass, even when new, since my .260 Rem uses a tighter neck than usual. Fired cases for me are .293" on the neck.

Most chamber diagrams show .297" for the .260 Rem.

For all the reasons you listed and more, I end up shooting 6.5 Grendel a lot more than .260 Remington.  The biggest reason is that every factory load is meant to work in a gasser, whereas you have to go to a custom loader to get decent 6.5CM or .260 Rem. loads that will run well in a gasser, even with RLGS.

Your pics definitely relate how Utah is a long range rifleman's paradise. Love it out here.

No problem, I'll do my dangdest to give you the straight of it, what's worked and what hasn't as well as what I would do different.  The hardest decision is 6.5CM or 260REM, and I still wonder if I made the right call.  Once I get the hang of reforming .308 brass into CM brass I'll be 100% happy with what I have as my opinion on Hornady brass isn't super high.  Primer pockets shouldn't be loose after 3 shots, 4 at the most, which is what I'm getting.  Lapua might be producing CM brass in the future, if so I'm raiding my kids piggy bank.



I chucked it up in a lathe and simply cut the height and thickness of the post of the retainer.  It kisses up against the bolt by several thousandths now, taking all the load off the retainer when closed but not so much that I have to nudge the buffer back to close the upper.  If you have trouble send it to me and I'll do the same thing and send it back to you, it took me 10 minutes on a lathe and I'm the world's second worst machinist.  Also, I wanted as much flexibility as I could get, not knowing just which stock I'd end up with so I have a spacer in the rifle tube allowing me to use the carbine spring/buffer.  Just thought I'd mention that.





Thanks, it's been my most fun project thus far, but I like the difficult ones.  I think I'm convinced that I'll do the Grendel next, I already have the dies for it and almost bought some brass the other day.  What powder are you using for it?  Maybe I'll start keeping an eye out and begin the frustration a year early.

My biggest problem right now is just training, and powder.  I've learned a lot here and there, but as I've found in all other parts of life you don't know what you don't know, till someone that does know tells you.  I shot for the UofU pistol team and learned what a good coach can do, I need to find one local.  Powder I have no answer for except to spend nearly $50/lb on Gunbroker, plus hazmat.

Utah is a great state for shooting, and I spend all day every day at work driving through the most barren wastelands of Utah, which is nice.  Let me know if you've got some time around central Utah and we can stretch out on some steel.  I'd love to see how well your Grendel does.

awesome thanks, i should know by wednesday

This is not a tag, honest.

One day I will start my build, I was looking at the Mega box in the safe today.

Are you in the Madison area?  I'll be in Madison in about 4 weeks or so.  I used to be able to your Wisconsin some when I went out there, but I think this trip I'll be more or less stuck in the city.  5 years ago I got Lyme Disease from a job I was working on in a swamp up near Portage.

I run courses frequently, and there are some good competition circuits here to keep you well on your way.

North Springs Range down in Price is awesome for shooting long range. You don't need to bring any steel at all, $7/day fee.  It's an amazing place.

I have a course in Sept. that will be applied violence with CCW, DM, and Close Quarters Marksmanship with the carbines over a very full 3 day/2 night schedule.  It's going to be a blast.

negative, Im near Appleton in the fox valley, I try to stay away from that liberal hippy town

You can use an Armalite ar10 bcg. The extensions are the same, a long as you use the entire bcg, you'll be good to go. They have a smaller firing pin, and are made very well. It's not coated with anything alleviates, but you can get the carrier chromed or melonited, not sure how much you can do with the bolt that won't screw up the heat treat our tolerances.

What's you barrel profile

Call and talk to JP. They have a high pressure bolt for the big AR's.  It is brand new and not on their website yet.  I emailed asking about one and got a prompt response.  I ordered one right off and it shipped quick.  It comes with the smaller diameter firing pin.  I haven't only shot about 35 rounds since swapping from the stock DPMS bolt, but not a single one shows the kind of primer cratering I was getting before.  Great customer service, and what appears to be a great product.

Thanks for the very detailed report, SCW.  I shoot a factory DPMS in 6.5CM.  

You mentioned that you hadn't tried factory ammo.  I have shot both the Hornady 140 grain and 120 grain Amax loads.  The 140s do sometimes show pressure signs;  I've had one pierced primer, and I almost always have ejector swipes.  The 120s don't exhibit the pressure signs.  My gun has a slight preference for the 140s.  It shoots in the neighborhood of 1.25 MOA with that load.  The 120s print about .25 MOA larger, on average.  The factory ammo does seem to be very consistent.

I finally got some powder, Reloader 17, so I'm going to see what I can do with the 123 grain pills.  I have some Amax, and I'm going to get some Lapuas as well.  I've read that the lighter bullets tend to prevent pressure issues like I see with the 140s, so perhaps that's the trade off to get longer brass life.  The Lapua 123 gives up only 3" of windage at 1000 compared to the Hornady 140, and it's 30 inches flatter, so there's not too much trade off.

I also prefer the ASC mags.  The fact that they use a butt-welded seam on the rear of the mag rather than overlapping sheets and spot welding, like on the front of the DPMS mag, does give one more OAL to work with.  However, I will say that I haven't had any feeding issues with either brand.  No idea if my gun has M4 ramps in the lower.

My gun is also one heavy beast, though as tough as it gets for me is trying to carry the gun, my cleaning kit, and an ammo can from the trunk of the car to the firing line without dropping anything.  Actually, I like that the weight helps mitigate recoil.  I shot the Grendel for a while, and I still vacillate about going back to the round.  Recoil was less than the Creedmoor, it used less powder, and the Les Baer barrel I shot was amazingly accurate.  I like the efficiency of the Grendel, but the extra oomph of the Creedmoor is easy to like when reaching way out there.

I do have one question for you.  What does the smaller diameter firing pin buy you?  If you're showing pressure signs and loosening primer pockets after 3 or 4 firings, how does a smaller diameter FP help with those issues?  

Oh, and Nosler now makes Creedmoor brass.  They're proud of it.

I just put a new SLR Rifleworks adjustable gas block on the gun to run different effective gas port sizes with the suppressor, but I haven't experimented yet.

I've got a 6.5CM Savage and it will put 3 rds of Hornady Match 140 A-Max through 4/10ths of an inch, if I do my part (which doesn't happen all that often.)  

What tripod is that you're using to shoot from?

North Springs I'm very familiar with, very nice place.
Interesting on the rest, IM will be headed your way.




THANK YOU!!!  I called but apparently they are only installing what they've got into their own rifles, he said to call back in a month and maybe then they would know when they would offer them for sale.  Maybe you got lucky and talked to the right guy?  Are you shooting a 6.5mm?  Creedmoor or Remington?  I owe you a beer, or two.




That's too bad, but not surprising.  I'll just stick with the ASC, maybe if I get a load for the 123gr that I find is just the cat's meow I can use some Lancers or Magpul, but I'm only getting 10 round mags too, the longer ones bring me up much too far in the prone.





I used to use R17 when I was shooting the Swede Mauser a lot (in a Savage action, Shilen Palma weight barrel).  Good powder and very good results, but not stable from summer to winter and I had to keep track of it.  I once had the dream of finding a good ball powder for the Creedmoor so I could load in bulk for this and my bolt action in the same caliber, but the only ball powder I found (Superformance) isn't working well in the gassers due to it's late pressure characteristics.  Too bad, velocities are great with it.

I use an Eberlestock  backpack for this rifle, I'll try to get some pics of how I have it set up posted for you.  I can haul my LRF, shooting sticks, tripod, rear bag, three french hens, two turtle doves and a chocolatey snack for a fat guy, along with water bladders and the like all pretty comfortably.  I like shooting from outcroppings and cliffs and you can see, and the backpack is nice for hiking around looking for a place to shoot.  It also has some pretty serous drawbacks that piss me off every time I use it.  I'm not sure that detail belongs in this forum, but WTH,right?

Smaller firing pin should provide improved support to the primer area, keeping the flow and piercings to a minimum. The Armalite firing pin is almost 40% (I think) smaller than the DPMS pin, but both of the work great in chamberings like the .308.  In the 6.5 where pressures are not tremendously higher at peak but build pressures late when the bolt is trying to cycle the pressures can still be high without as much support behind the primer.  I was trying to offset this problem by using a very heavy buffer and spring to keep the brass contained as long as possible to allow pressure to drop as much as possible, before extraction.  The adjustable gas block should also help with this, but it limits volume not pressure.  This still helps by not allowing the volume as quickly at the bolt and carrier where it would begin the cycling process.  The drawback is all the mass/energy moving forward can create a forward recoil and destroy optics, as well as be really annoying like in the case of the 11/87 and 1100 shotguns.  My 11/87 drives me nuts with the hesitation of the bolt at the back, then slamming forward- but that's beside the point.  And I've already got an SX2 to replace it, so all is right in the world.

I saw some Nosler brass locally a few months ago and laughed out loud.  Something like $1.50/case.  Ideally I'd like to figure out a good process to form .308 brass into CM brass and use some Lapua .308 Norma brass with a small primer.  I also think the Hornady brass is not fully supported/solid like the Lapua brass is, but I didn't have time to cut one of each open tonight for a comparison.  I'll try to do it in the morning before I head off to the salt mines.



Tripod is a Vortex that I painted.  I'll get some more shots of it when I get some of the rest of the setup.  There has been quite a learning curve with the support gear as well.  I broke a set of shooting sticks in 5 minutes while sitting in the living room seeing how I liked them.  $30 and they never even got dusty....

This is the barrel I used.  I would consider buying a blank and having it chambered to a specific bullet (Berger) if I was doing it again.  FA claims these are chambered to the Hornady 140gr A-Max and the way it shoots them I have no reason to doubt it.  However if you want a VLD bullet like the Berger, you should simply go that direction from the get-go.

FA Creedmoor Barrel

One Thing about it, the Berger is such a low-profile bullet that to be near the lands may end up with longer than magazine length, but I haven't looked.

I am shooting the 6.5 Creedmoor.  I was getting some pretty impressive cratering with loads that should not have been close to high pressure.  I have about 80 or so rounds through it since I got the JP bolt.  Night and day difference.  Primers look perfect after shooting the same loads that had me concerned about piercing a primer at some point.

Reducing the pin diameter and fitting it to the hole solves a lot of problems on the big guns.

Bumping this thread to say that JP is listing the high pressure bolt online for order. I just picked one up for my 6.5 CM that shows pressure issues.

Thanks guys!  It looks like they posted those just a few days after I called them  Would it have killed them to send one out a few days early?

I'll get one ordered and work up a load with it.  I'd REALLY like to be able to use 140gr bullets with Superformance powder.  

I forgot to highlight another feature I added, but will be glad to abandon when I move over to the Magpul MOE/A2 size stock.  This is a QR sling pocket I epoxied into the stock in two locations, on the side near the grip and on the bottom just in front of the std sling loop.  I used a #8 screw with a nut flush to the end of the screw (ie: not tight to the pocket), ground down the screw head till the sling would latch and shoved it into the hole filled with epoxy.  The screw with the net out on the end acts as an anchor and I have not had trouble at all, completely solid assembly thus far.




Front sling attachment is Noveske I think, there are several on the market and they are all about the same I think.



I do wish MEGA would provide built-in QR attachments like this MI rail-


Here are some additional pics of some of the rifle and crap I tote it around with.  It could probably use it's own axle and a hitch to my belt...

I'm using the Eberlestock Phantom backpack.  It's well made but has some serious design flaws that are really annoying.



It's comfortable enough that I can have the rifle in the pocket and loaded down, and still have a smaller gun slung and have good access.  Here is my CM with an AR pistol for size reference,



And how far down the pistol goes with the bottom of the scabbord fully deployed (it can be tucked up inside).


A nice rain barrier is provided with the backpack that zips into this pocket.  I'd like to get a multicam version of it, mine is brown, but it works very well when it's really wet outside and will even extend up enough to keep the gun dry.


Another shot of the pack with attached shooting rest (which only weighs a couple of ounces, but I never use it).


Side scabbard with my shooting sticks and tripod




It's a little tough to tell, but the legs are splayed at three different angles and deployed at three different lengths.  It maxes out at about 3'10", fully compressed is 1'4" (with home-made saddle attached) and weighs 2lbs 2oz, again with saddle attached.  I like it, fine purchase.


I have a mag pouch for a 10rd mag on the belt, but I'd like to find some larger pockets for LRF and stuff on the belt, and a pistol holster on the other side, but I'm not in a huge hurry for either.


Internal compartments and my first aid kit attached to the main flap


Here's the bad part of the pack-

The scabbard is attached to the pack such that the harness can be used with either or both.  That's kinda cool, and it works well enough.  But there is no compression on the pack and the scabbard in particular will flop around a lot, especially when empty.  The scabbard really needs a stiffener and the entire pack desperately needs compression.




The water bladder capability sucks.  I have to hang it off the zipper for the top pouch or it ends up in a pile at the bottom of the slot behind the side scabbards.



And another gratuitous shot of the shooting opportunity in Utah.  This was taken in the Dixie Nat'l Forest yesterday.



'

OP nice setup. I run Eberlestock GS2, biggest complaint is how difficult it is to get into main compartment. I may pick up one of those tripods.

What  kind of 100 yard accuracy you guys getting? I have gap10 in .260 rem and best I've done is a little over 1/2 moa; that was single loading each round. Still working on load development, but it's looking like lapua scenar 123s over h4350 in lapua brass is what I'll be shooting for a while. Tried 139s but got a lot of pressure signs; don't want to work this pricey brass too hard.

The tripod is awesome, but I may build a different saddle for mine with a little more padding.

Accuracy was GREAT with H4350.  I had several groups with both 123gr A-Max and 140gr A-Max that were about 1/2".  At 450yds I had a group at about 2" or so.  With the IMR 4350 I'm lucky to get 1" at 100yds, usually more like 1 1/2" and the velocities are about the same at 2750fps.  These are all fed from the magazine.  I did single load some Bergers when I first started shooting it, and those were stacking on top of each other, I imagine they will now feed using the ramps and ASC mags, once I get the new bolt and try some loads out with Superformance, if things work out I'll try some Bergers again.  I have an 8lb jug of Superformance and I love the velocities and the way it meters, so I'd really like to see the new bolt fix the other problems.

I may end up getting a bunch of Lapua .308 Norma brass and resizing that for use in this.  For some reason I haven't found the right combination for getting my brass to resize without crumpling the shoulder.


Pics of the GAP?

My 6.5 is just using a DPMS barrel I bought from Midway, but I shot a 10 round group yesterday that was under an inch including 2 that I called pulled left.  This was using 130 gr Berger and H4350.  I have some decent groups with 140 AMax and IMR 4350, but I think I need to swap primers.  My ES and SD are high which is my fault for using primers that I have had hanging around for longer than they should.

Oh pshaw....







Don't want to hijack your thread, but it's a GAP-10 in .260 Rem that was built by GAP a long time back (purchased 3rd hand); when I called them for info on it they couldn't tell me anything as that was when they basically built guns using part supplied by their customers. No idea who made the barrel or what twist it is (that's a pisser). Timney trigger, Horus/Bushnell optic w/Tremor 2 reticle (not my 1st choice, was on sale), Badger rings, Magpul CTR w/Larue RISR (me like), 3Bucc brass catcher (for not losing expensive Lapua brass), VLTOR muzzle device pictured has since been replaced.

Working well so far. Just wish I had the awesome Utah land to exercise on, I am envious of you Western guys...

OP you are quite the trooper if you are lugging that rifle and an AR pistol around...good workout I would guess.

SCW, which Vortex tripod is that?  They list several on their site, and with the mods you've made to yours, I'm not sure what model you have.

Summit.  I got it at a local shop for a bit less than this listed price.  They also had the Skyline and Ridgeview but the skyline is too heavy and the ridgeview was very flimsy.  I'm very happy with the Summit.  Do NOT get the Caldwell shooting sticks, they are the ones that lasted 5 minutes in the living room.  I now have some other brand (been trying to think of the name for a few days) and I like them quite a bit.  Much heavier and I can support the front of the rifle off the tripod and the back on the sticks with a bag.  Makes for a nice way to shoot in weird locations.

Vortex Summit

I like that scope quite a bit, I have it on my bolt action Creedmoor that collects dust and I haven't shot since I got this one running.  It's a very fine scope, I think I picked it up for about nine bills.  Weighs less than the NF, is more compact and it's just a damn fine optic.  I also like the new Vortex Razor II, but who doesn't?

Feel free to post up your Creedmoor and your experiences with it.  This is a good place to find out what's worked and what hasn't, it doesn't need to be my thread exclusively.
I hear you on the brass.  I have a few older posts in the Precision Rifle forum here that I did of shooting from some of the cliffs around me.  I think the biggest risk to my life isn't climbing them with all the crap on my back, but scrambling around afterwards trying to find all the $0.30 brass I can find.  I sometimes remember to use a jacket or something to try to limit brass flight.  I actually removed the ejector from my bolt action to make this easier, then made it 20x harder by getting a semiauto.  My mama raised a dummy

I don't get great SD with IMR4350 either, about 50fps or so.  With the H4350 and 123gr I was the lowest I had ever seen, right about 7 which is statistically nuthin.  With 140gr they were still low double digits.

Superformance was the worst, SD of about 80+ and showing pressure signs at starting loads.  I'd like to think that with 140gr (I was using 123) and a magnum primer I can get a better ignition and hopefully more consistent velocities.  It's a ball powder and duplex at that, so it might take a bit to get it cooking right.

I picked up a couple of boxes of those 130gr Bergers, haven't shot any yet.  Love the BC on them though, hopefully I can get them to work.

I'll dust off my notes tomorrow night if I have time.  I think the H4350 was just under max (in the newest Hornady book) and IMR was right about max.

I might not make it back in town tomorrow in time, and after that is the holiday, after that....

Mine likes 42.5 grains of H4350 under the 130gr Berger's.  Avg velocity of 2820 fps and using CCI primers an SD of 7.34.  I have my chrono sitting here as I type.  For the 140 AMax I have only really tried IMR 4350 and I got my best results at 41.0 gr.  That one I need to send over the chrono still.

24" pipe?

That's nice, it should be several pounds lighter than mine, after you get tired of that heavy boat-anchor stock and get something lighter!  LOL

What optics are you going to use?  That's a huge market for decisions anymore, lots of competition for quality stuff and with the 6.5CMs ability to really reach out there it's a shame to underscope it.

Can you also give me a detail of the Atlas mounting?  I'd consider moving to an Atlas if I could get a decent mount that didn't stand off much- if at all.

Yep.

Here's my 6.5 CM. I am waiting for the JP bolt and then I hope to do some load development with the limited components I've found.




 

R


to either   of you, since I am still doing my research, I was reading about BCG's today and one of the advantages to the Armalite design was the smaller firing pin diameter, and this less primer piercing. But with this new JP high pressure bolt is doing the same thing as the Armalite design, correct?

I was set on a 260 build but after (I believe it was Zairrifleman) posted some info in another thread I think it will be 6.5CM, since I truly need to roll my own with either rifle. Especially since it is a gas gun not bolt.

My understanding is that yes, the JP bolt does use a smaller diameter firing pin like the Armalite to help prevent primer cratering.  I do not know what other improvements there are, but my rifle seems to really like it and the quality is there with the JP bolt.

thanks

Wher di you pick up the handguard wrap.That would come in handy deer hunting out of my wood blind.

Apologies, I realize you posted this some time ago. But is there another thread or source that discusses this in more detail?

I do not have a specific source for more information.  While researching my 6.5 build I read about a  significant number of people having issues with primers cratering at what should be safe pressures.  The firing pin hole and firing pin size was discussed by a variety of sources that I felt in the end were most reputable.  When I was experiencing cratering at moderate charges I looked into the idea of getting my bolt sleeved and firing pin shaved but there were reports of problems with the firing pins breaking so I moved away from that.  After hearing about the JP bolt I gave it a shot and it did exactly what I wanted it to do.  Sorry I do not have more definitive sources.  While they are selling it I would imagine that the folks at JP would be willing to discuss it with you.

Load development continues.  Or will when I have the bolt issue resolved.

I managed to walk into a local (sorta, 80 miles from home but still the nearest shop) gunshop and found a 5lb jug of H4350 on the shelf, this was the first shot at 39.2gr with a 140gr Barnes Matchburner.

I've only used H4350 a little bit in the past with this rifle and didn't see this problem before, but hopefully I can get up and shooting soon with it again.  

You don't have a terribly pronounced ejector swipe (you'll always have a little with HRN brass) so you're load isn't what I'd call too hot.

Wanna see some ejector swipes?  I got a few of those too...

I agree with you though, not a hot load and that's was brand new brass and a magnum primer (Winchester).

Looking forward to getting that bolt back from you, I'll try this same exact load again and post results.

Awesome.   What's the new tip diameter?  Glad you were able to cut all of that crappy torched and ragged stuff on the bolt face out.  Maybe this time it won't be in such bad shape after 500 rounds.

Pretty funny that the chip of primer was still on the pin.