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Help! How does this crown look? - Printable Version

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Help! How does this crown look? - VikingCruze - 07-08-2018

I’m at the end of my rope here with the Grendel caliber. On paper the Grendel is everything I want it to be but I can’t seem to get a consistent load developed consistently. I’ve tried 7 bullets and 4 powders. I tried bumping the case shoulders back anywhere from .003” back to factory lengths. I’ve tried seating my bullets on the lands, if capable, and setting back from .010-.030”. I’ve tried three different primers. I’ve done extensive brass prep such as uniforming/ deburring flasholes, uniforming primer pocket depth, chamfering inside and outside, weight sorting brass, and trimming to equal lengths. I’ve tried AA, Hornady and Starline brass. I’ve tried using scopes from other guns that shoot sub 1/2MOA without luck. It seems like everything I shoot I’ll get something that looks promising but I’m never able to reproduce that load with the same results.

I’ve never had an issue before when loading for .223(AR15), 300BLK(AR15), .308, 6.5 Creedmoor, 7mm Remington Mag, 300 Win Mag, and 22-250. I’m using a Redding T7 press with a Redding sizing die (.286/.285). I’m using a Hornady seating die and get between .002”-.004” of runout if I turn the bullet 1/4 turn twice while seating.

My set up: Midwest Industries upper and lower. Midwest Industries 15” hand guard. SA clamp on adjustable gas block, black nitride gas tube, Giessele 2 stage trigger, JP bolt headspaced and purchased with high dollar barrel (unnamed). Luth AR rifle length Stock. 6-24 Vortex HST with Vortex AR Mount. I’ve tried with my Flash hider and SilencerCo Harvestor suppressor and without.

Today I looked closely at the crown and am wondering if this may be a problem. It’s not very smooth IMO but I’m not a gunsmith

Any suggestions would be greatly appreciated


Edit 7/11 to add link to a better picture below
https://www.flickr.com/photos/68382999@N05/43241191372/in/dateposted-public

Help! How does this crown look? - sneaky one - 07-08-2018

Pic is a bit blurry, but it looks like it needs to be re-cut. Who's the bbl maker? Did you put it together, if so did you Permatex it? You'll need Kroil to soak a few days to un assemble it- find a local picky G smith to re crown it.

Help! How does this crown look? - A5BLASTER - 07-08-2018

Who made the barrel?

What chamber is it?

100% sure you have the correct bolt headspace to it?

Have you tryed any factory ammo or just handloads?

How many rounds down barrel?

The pic is hard to make out but it does look kind of funky.

Help! How does this crown look? - VikingCruze - 07-08-2018

It’s a Criterion 22”. I torqued it to 40’ lbs after applying sleeve retainer per instructions. Anti seize to barrel nut. Unfortunately I had to resize the image in order to upload. I can email full size photos if that helps

Help! How does this crown look? - VikingCruze - 07-08-2018

Yes I’ve tried a box of factory Hornady Match Black with 123 ELD-M’s. Average size was alittle over an inch

Help! How does this crown look? - VikingCruze - 07-08-2018

I bought the JP bolt with the barrel and was told they headspaced it. I have about 350 rounds down this tube

Help! How does this crown look? - Kswhitetails - 07-08-2018

Sounds like you have an issue with some other kind of movement or fit. All fhinks beink ekual... choo shud git ekual wesults. Something is changing on you between trips.

Check everything, accessory mounts, optic mounts, (sounds like you've been over this road), handguard and barrel nuts, gas tube clearence, look for gas leaks (if there is a big enough leak, then your pressure could be spiking/curving differently on each trigger pull, changing lots of unusual things - like harmonics). If all else fails, a complete disassembly, heavy cleaning, bedding, reassembling, and torquing are my next bet. If that doesn't work, then the manufacturer of the barrel needs a call.

Best of luck, I know chasing rabbits down holes isn't the most fun you can have on Grendelback, but even if it's not the problem, the disassembly and reassembly process will kill a good afternoon, a cigar, and a few cold drinks. And then there's the fun of shooting to proof it again.

I'm with Sneaky, why no name on just the barrel?

Help! How does this crown look? - A5BLASTER - 07-08-2018

VikingCruze Wrote:I bought the JP bolt with the barrel and was told they headspaced it. I have about 350 rounds down this tube

Who did you buy this from?

I only know of two places to get a grendel barrel with a JP bolt and they don't sell that barrel makers products.

Help! How does this crown look? - VikingCruze - 07-08-2018

I bought it directly from the guys at Criterion. I live in Madison and work in Milwaukee so their shop is kind of on the way home. Really nice guys

Help! How does this crown look? - Kswhitetails - 07-08-2018

I see, so they make the barrel, and just don't put a name on it? Then they buy a JP bolt and match the headspace to it, or vise versa? That's Kosher; as long as the bolt and barrel are verified to chamber as they should together. I've just that I've never heard of it called "unnamed barrel" before.

There is a better way to post pics that are better for this. Flickr is my choice, by opening an account, I am able to share pics on message boards that come across in all their glorious size and resolution; a good thing when posting pics for others to look at to help diagnose potential problems.

[Image: 39868374050_c656a10ed2_b.jpg]Untitled by ., on Flickr

Help! How does this crown look? - grayfox - 07-09-2018

you say Criterion 22" but is it SAAMI, or "264 LBC" style?
Also, would you list your load ladders with powders/bullets and results?
Is it possible that you've tried too many combos and possibly muddied the waters... that's happened to me for sure.

Do you have chrony results from your loads? I work to get tight MV spreads before I worry about x.x MOA grouping.
Have you tried any SMK's like the 123?
Eldm's, 100 or 123 with CFE223, 8208 XBR or AA2520?

I would also agree that something somewhere could be loose... so the 2 areas I'd recommend concentrating on are
1) tightness all around, and
2) more specifics on load ladders and details

I'd hate to say that a Criterion barrel was a "dog that won't hunt" -- there are too many things to rule out before reaching that conclusion.

Help! How does this crown look? - StoneHendge - 07-09-2018

Do your groups pattern at all? That's usually a good sign that something is loose somewhere.

Help! How does this crown look? - VikingCruze - 07-09-2018

To clarify it’s not an unnamed barrel. I said that because I didn’t feel like listing the name at the time. Sorry for the confusion.

https://www.flickr.com/photos/68382999@N05/shares/R76Q57

Help! How does this crown look? - VikingCruze - 07-09-2018

https://c1.staticflickr.com/2/1807/42386899355_aaeef4df7d_o_d.jpg


https://www.flickr.com/photos/68382999@N05/43241085482/in/dateposted-public

Attached are results from today along with 6.5 Creedmoor groups as a control.

Help! How does this crown look? - VikingCruze - 07-09-2018

Gray fox,

I’m not sure of the specific chamber. I’ve tried 120/123 eld-m’s, 123SST’s, 123smk’s 130RDF’s and 120TTSX’s with TAC, Leverevolution, 8208xbr and blc2. I’ve gotten nice 5 shot single digit SD’s with 123 grainers.

I’ll work up a load in .3g/.4g increments and shoot until I see pressure which seems to be ejector marks with the Grendel more so than super flat primers. I’ll generally find at least one node and reload zoomed in that area. The problem is I’ll get to the range with loads in the sweet spot and they shot terribly as if I’m using a different batch/lot of everything which makes me want to pull my hair out.

Example: in the link below I had a good 120 Eldm load from a previous work up. The two upper left groups I shot to confirm came out like hot garbage. Also, in the new work with 123sst’s one would assume I found a node between 27.7 and 28.1 right? Similar tight grouping and POI. Next time out I shot in that range in .1g increments and all loads in that rang were junk.....averaging 1.25”. This doesn’t make sense and for what it’s worth the bottom 4 groups are store bought 123ELDm’s

https://www.flickr.com/photos/68382999@N05/41487237820/in/dateposted-public/
F

Help! How does this crown look? - 1Shot - 07-09-2018

Are you cleaning your bore between trips? Some rifles will just will not shoot well until the bore is well fouled. I have a 25-06 with a Shilen SS barrel that I thought was a dog when I got it. It did about what you are describing but I was cleaning the bore pretty good between range trips. Had a friend convince me to "NOT CLEAN", yes he had to yell it to me to get it to sink in. After shooting the rifle around 25 times it starts to shoot bug holes at 100 and average 1" at 300 yards on a calm day. The only time I clean the bore now is when accuracy starts to suffer a bit or if it has been raining while out hunting. I only use regular Hoppie's with a few patches and the accuracy returns.

Also if you live that close to the barrel maker take it to them and let them have a look at the crown.

I collect mil-surp rifles and I have turned some that have shot like a shotgun in to tack drivers by simply using a round head brass bolt chucked in a drill and use valve grinding compound and clean up the crown.

Help! How does this crown look? - VikingCruze - 07-09-2018

1Shot Wrote:Are you cleaning your bore between trips? Some rifles will just will not shoot well until the bore is well fouled. I have a 25-06 with a Shilen SS barrel that I thought was a dog when I got it. It did about what you are describing but I was cleaning the bore pretty good between range trips. Had a friend convince me to "NOT CLEAN", yes he had to yell it to me to get it to sink in. After shooting the rifle around 25 times it starts to shoot bug holes at 100 and average 1" at 300 yards on a calm day. The only time I clean the bore now is when accuracy starts to suffer a bit or if it has been raining while out hunting. I only use regular Hoppie's with a few patches and the accuracy returns.

Also if you live that close to the barrel maker take it to them and let them have a look at the crown.

I collect mil-surp rifles and I have turned some that have shot like a shotgun in to tack drivers by simply using a round head brass bolt chucked in a drill and use valve grinding compound and clean up the crown.


1 shot,

Yes, I used Butches bore shine to remove copper from the 120TTSX’s I shot after the groups pictured above. The TTSX’s all grouped about 1.25” which I was happy with for hunting as I’ve never had much luck with this type of solid bullet in other rifles. I usually don’t clean in between range trips as I have heard of similar situations.

I will defiantly hold off from cleaning my barrel and stick to lead core bullets and see if this helps. Thanks for the advice!

Help! How does this crown look? - VASCAR2 - 07-09-2018

Just curious if you bedded the gas block with Loctite and are you 100% sure there is sufficent clearance between the hand guard and the gas block. Some barrels just don’t shoot as well as others. Is your 6.5 Creedmor an AR-10 gas gun or bolt action?

Help! How does this crown look? - VikingCruze - 07-09-2018

Vascar2,

I did not bed my gas block to the barrel. I torqued it down to 15. I have this gas block:

https://suparms.com/collections/adjustable-gas-blocks-direct-impingement/products/750-adjustable-low-pro-clamp-on-gas-block-stainless-steel-finish

The Creedmoor work up on the right column above was shot with a Bergara BMP bolt action. I’ve never had an issue loading for bolt actions.

Help! How does this crown look? - A5BLASTER - 07-09-2018

If you think the crown needs reworking then it's best to do it because it will always bother you.

Probably best to tear it down to parts and
1 lap the upper
2 bed the barrel or shim it to upper
3 torque it to 5 pounds higher then you have it now
4 make double triple sure the gas tube isn't binding up on any of the parts
5 take good measurements and make sure the gas block is being seated over the port correctly and locktite the screws once they are torqued down to spec
6 install handguard and double triple check it isn't contacting the gas block or gas tube, try to flex it and see if you can make them touch if they do, find a different handguard.
7 check that your mags are somehow striking the bullet when loading and changing your bullets seating depth.
8 if your cleaning the barrel often stop let it get dirty and see if it settles in ( my tow jp barrels are like this they won't group unless they are dirty).

Just a question but what upper are you useing is it a mil spec or is it a nice 7075 t6 billet, could be the barrel is just to heavy if it's a mil spec upper and causing the group issues.

Just some food for thought hope it helps sir.

Edit to add, measure the gas port size and double triple check their isn't anything blocking flow in the port.