Help! How does this crown look?

[grayfox]

Several thoughts here that might help, for you to consider.

Biggest thing is I am a big proponent of using chrony to isolate good vs so-so barrels. Nodes will show up at pretty much known MV ranges for barrel length and have small SD's. So if you have one of those low-SD loads concentrate on that load, and re-check its MV/SD data in a couple of shooting sessions. If the low SD remains, then play with coal by 0.010's to see what length gives the best group. If that will not group then something is loose, either mechanically or with your hold technique on that gun. (Are you shooting w/ bipod on a bench? I've stopped using bipod at the bench and use only benchrest and sandbag now for bench. Maybe you've already covered this but I'm listing things to think about with no assumption on your techniques.) Since you tried several scopes I'm thinking it is not internal to the scope.

The bottom row of shots seems to be about 1" give or take. I think I see some what I would call flyers in some of the other groups... the latest issue I've been working on, and at least some flyers come from "cheek weld" -- never understood what that was until I started fitting stocks with some sort of riser so I could get a solid perch for my fat head (LOL!!), and steady sand bag underneath the stock at the rear. So if the scope rings are torqued, the base is torqued, the barrel is torqued, gas block sealed well/tight and the trigger is consistent with clean break, the rifle should shoot consistently and we're back to the load workups.

Me personally I'm not fond of TAC for heavier pills, find some use for it in the 90-100 ranges. I'd try as mentioned, XBR or H335 with some 100 gr eldm's, maybe even XBR with the 123's but be keenly aware it can spike on 123's at ~28.5 or a bit less. CFE 223 or even AR-comp with the 123's like sst or eldm, ARC not above 28.0 in an AR, CFE is listed for sst up to 31.2


In case I missed it, do you have some chrony data on any load ladders? not just a single load but a range, one bullet, one powder, one case/primer for each of a couple ladders. I'd like to plug it into my spreadsheets and give a look-see.
What MV/SD data did you get on the 123 Black rounds?

[VASCAR2]

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/adjustab...eel-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.

I’ve read where accuracy on a gas gun like an AR-15 improved after someone used thread locker to bed the gas block. All the gas blocks I’ve assembled myself I’ve used Blue Permatex thread locker. I also put blue thread locker on the gas block screws. If your sure there is clearance between the gas block and hand guard I’d probably still bed the gas block to remove one more variable.

Honestly for me I don’t think your 6.5 Grendel AR-15 shoots that bad. I find it more difficult to consistently shoot tight groups with an AR-15 compared to bolt action rifles. The only way I can help eliminate my shooting error is to use a Caldwell lead slead on a solid bench. If I’m shooting off a bipod with a rear bag I’m just not consistent as I used to be when I was younger. Every bodies expectation of accuracy is different and each barrel is unique. I’m not qualified to say if your barrel’s accuracy is sub standard for a Criterion AR-15 barrel.

[Crusty]

I think that the imprecision which many see is due to inconsistent cheek welds and eye alignment to the scope picture. Parallax can be reduced but never eliminated in a scope and simply having your eye in a different place than where it was in previous shots can make your shot go somewhere else due to parallax. I think that many barrels get the blame for what is really operator error.

[VikingCruze]

I think that the imprecision which many see is due to inconsistent cheek welds and eye alignment to the scope picture. Parallax can be reduced but never eliminated in a scope and simply having your eye in a different place than where it was in previous shots can make your shot go somewhere else due to parallax. I think that many barrels get the blame for what is really operator error.

Crusty,

Sorry to disappoint. My .223 shoots just fine when used with the same lower as the Grendel. I shoot off of a solid bench rest and rear bag as pictured while verifying scope level is level before each shot. Also, my Bergara has the same AR 15 pistol grip and shoots fine.

https://www.flickr.com/photos/68382999@N...ed-public/

[VikingCruze]

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.

Blaster thanks for the help! I did lap the face of my reciever with Brownells lapping tool. I bedded the barrel with sleeve retainer; the fit was pretty tight before hand. Here is the upper I have. It looks to be inline with what you listed:

https://www.midwestindustriesinc.com/MI-...frs-15.htm

[A5BLASTER]

Blaster thanks for the help! I did lap the face of my reciever with Brownells lapping tool. I bedded the barrel with sleeve retainer; the fit was pretty tight before hand. Here is the upper I have. It looks to be inline with what you listed:

https://www.midwestindustriesinc.com/MI-...frs-15.htm

Yea that's a forged upper, I have read here and other places for a long heavy barrel it's best accuracy wise to use a billet upper.

How much truth there is to it in not sure but I know I don't use anything but billet uppers now, they are a lil thicker and less likely to flex when shot.

Not saying that is what the problem is but best to look at all angles when problems arise.

Since the place you got it is so close I would get with them and see what they think and will do about the issue your having.

[VikingCruze]

Several thoughts here that might help, for you to consider.

Biggest thing is I am a big proponent of using chrony to isolate good vs so-so barrels. Nodes will show up at pretty much known MV ranges for barrel length and have small SD's. So if you have one of those low-SD loads concentrate on that load, and re-check its MV/SD data in a couple of shooting sessions. If the low SD remains, then play with coal by 0.010's to see what length gives the best group. If that will not group then something is loose, either mechanically or with your hold technique on that gun. (Are you shooting w/ bipod on a bench? I've stopped using bipod at the bench and use only benchrest and sandbag now for bench. Maybe you've already covered this but I'm listing things to think about with no assumption on your techniques.) Since you tried several scopes I'm thinking it is not internal to the scope.

The bottom row of shots seems to be about 1" give or take. I think I see some what I would call flyers in some of the other groups... the latest issue I've been working on, and at least some flyers come from "cheek weld" -- never understood what that was until I started fitting stocks with some sort of riser so I could get a solid perch for my fat head (LOL!!), and steady sand bag underneath the stock at the rear. So if the scope rings are torqued, the base is torqued, the barrel is torqued, gas block sealed well/tight and the trigger is consistent with clean break, the rifle should shoot consistently and we're back to the load workups.

Me personally I'm not fond of TAC for heavier pills, find some use for it in the 90-100 ranges. I'd try as mentioned, XBR or H335 with some 100 gr eldm's, maybe even XBR with the 123's but be keenly aware it can spike on 123's at ~28.5 or a bit less. CFE 223 or even AR-comp with the 123's like sst or eldm, ARC not above 28.0 in an AR, CFE is listed for sst up to 31.2


In case I missed it, do you have some chrony data on any load ladders? not just a single load but a range, one bullet, one powder, one case/primer for each of a couple ladders. I'd like to plug it into my spreadsheets and give a look-see.
What MV/SD data did you get on the 123 Black rounds?

Gray fox,

Thanks for the solid advice. Unfortunately I don’t log data into my book until I can repeat and verify a load so I don’t really have much to share except a few index cards on my bench that haven’t made it into the trash. I didn’t have the Crono setup for the factory loads; that’s probably worth doing so I’ll pick up another box. On my last index card I have 27.9G of TAC and 123SST’s yielding the lowest SD of 11.5 with an ES of 30 for a 5 shot grouping. This was with the SST held .010” off the lands. I used CCI450’s and the average velocity was 2450. If I remember correctly the COAL was about 2.2525”.

I have XBR but I get ejector marks at 28 grains. Have you ever noticed less accuracy when reloading brass with pressure signs vs those without? This week I’ll pick up a pound of CFE223 and ARC for the 123 I would prefer to shoot for long distance. We shoot out to 1300 yards on my buddies farm. We’ve got 12 - 16” steel targets spread out with hit indicators on all steel past 800.

I tried flexing my handguard and I can get the screws on the clamp on gas block to touch which was surprising so I’ll get that fixed by Dremeling part of the heads off. I’ll have better data this Sunday. I’ll also try another lower I have to see if it’s a cheek weld problem but I’ve have three friends that all shoot sub 1/2MOA try it as is.

Thanks

[VikingCruze]

I’ll reach out to the boys at Midwest Industries and ask. Their very helpful and I would recommend.

[grayfox]

I've settled on MI handguards myself, I like them.
On that 2450 ft/sec load... sst's as I recall don't really like to be up close to the lands, they shoot better at about 2.245, which is not even the 2.260 standard. You might try that. Also it might just be me but 2450 for a 22" barrel sounds kinda slow. nothing wrong with slow if it's accurate. If you're at the TAC limit then for sure get one of the better powders. I'd kind of expect sst's to get more like 2500+ even up to 2550+ for a 22", depending of course on the barrel specifics. My 20" Howa gets 2525 easily on sst's, 2510 on eldm's, no pressure signs, accurate, single digit sd's. I don't consider it a fast barrel more like a medium one.

Ejector marks (did I write about this?) sometimes are a result of being scraped by the sharp edge of the ejector during bolt rotation and may not be pressure signs per se. The Grrr is a mild pressure cartridge so a better way to see about over pressure is to measure the case diameter just above the web, use a mic, a caliper won't be fine enough... compare to unfired. It's after 10 pm so my brain is shutting down but there are some threads that talk 0.001's on this for info. LRRPF52 and JAS and I think Sneaky did a lot of pressure tests on Grendel loads maybe they might chime in.

On the record-keeping, record them all, good bad or indifferent. Xls rows in a spreadsheet are cheap after all! dates, MV, loads, brass, SD, etc etc. You'll want to go back thru them at some point so go ahead and write them down. Heck I even have a separate tab for each grendel, again Xls space is cheap.

Hornady black 123 is a sort of "regular guy-proof load" commercially, in 20" about 2400-2425 ft/s so yours should be higher, but SD ought to be good, anyway it's a chance to get some independent data/verification on your barrel. not foolproof but a definite data-point on performance, that's what you want to look for. Once we get some MV/SD performance data we should be able to narrow down where to look for MV-nodes -- that's when you'll find accurate loads.

[bj139]

The only things I can suggest:
-True the face of the upper
- Apply grease to face of barrel extension and inside nut as well as threads.
- You could try a brass round head screw in a drill and lapping compound on the muzzle. If you are going to get it lathe crowned anyway, it would not hurt to try first. People have reported it works.

[1Shot]

One other thing to note. 123 SSTs are not the most accurate bullet in some rifles and in others they just will not shoot. I have one rifle that has a BCA 20" that I thought just HATED these. Could not get it to shoot under 1 1/2" with anything and averaged 2". Then I gave some IMR 4895 a try and BINGO just under 1" with 3 of the 5 in one hole. Now this was just one group and I have not been able to get to the range to give it another try but just goes to show you that barrels can be VERY picky about bullets and powders they want. If you can get some 120 Sierra Pro Hunter bullets they seem to shoot very well in everything I have tried them in. I have also done a little testing with Speer 120 Gold Dots and they are showing lots of promise also and should make a great hunting bullet. I know the 120 Sierra is a good hunting bullet also.

[Lastrites]

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

Your questioning the quality of the crown and the shop of sort of on the way home from work, why haven't you just stopped into the shop and ask them to check it out?

[bj139]

Your questioning the quality of the crown and the shop of sort of on the way home from work, why haven't you just stopped into the shop and ask them to check it out?

I smiled when I read this. Yes. They will probably want to see it.

[VikingCruze]

Your questioning the quality of the crown and the shop of sort of on the way home from work, why haven't you just stopped into the shop and ask them to check it out?

The 30-40 extra mins of driving isn’t what’s keeping me from taking it in. Right now I’m afraid to leave my rifle in my truck even if it’s locked up because I’m building low income apartments on Milwaukees north side. Theirs been 5 shootings within a block of my job site since I started. I carry an HK VP9 or an LC9 daily. Sleeve retainer Is the only thing preventing me from easily taking the barrel In

[BCHunter]

Just take the upper then? I understand not wanting it stolen off job site, people looking for easy opportunities there. Should be able to hide an upper in a truck, heck chain it to the seat mount?

[VikingCruze]

I've settled on MI handguards myself, I like them.
On that 2450 ft/sec load... sst's as I recall don't really like to be up close to the lands, they shoot better at about 2.245, which is not even the 2.260 standard. You might try that. Also it might just be me but 2450 for a 22" barrel sounds kinda slow. nothing wrong with slow if it's accurate. If you're at the TAC limit then for sure get one of the better powders. I'd kind of expect sst's to get more like 2500+ even up to 2550+ for a 22", depending of course on the barrel specifics. My 20" Howa gets 2525 easily on sst's, 2510 on eldm's, no pressure signs, accurate, single digit sd's. I don't consider it a fast barrel more like a medium one.

Ejector marks (did I write about this?) sometimes are a result of being scraped by the sharp edge of the ejector during bolt rotation and may not be pressure signs per se. The Grrr is a mild pressure cartridge so a better way to see about over pressure is to measure the case diameter just above the web, use a mic, a caliper won't be fine enough... compare to unfired. It's after 10 pm so my brain is shutting down but there are some threads that talk 0.001's on this for info. LRRPF52 and JAS and I think Sneaky did a lot of pressure tests on Grendel loads maybe they might chime in.

On the record-keeping, record them all, good bad or indifferent. Xls rows in a spreadsheet are cheap after all! dates, MV, loads, brass, SD, etc etc. You'll want to go back thru them at some point so go ahead and write them down. Heck I even have a separate tab for each grendel, again Xls space is cheap.

Hornady black 123 is a sort of "regular guy-proof load" commercially, in 20" about 2400-2425 ft/s so yours should be higher, but SD ought to be good, anyway it's a chance to get some independent data/verification on your barrel. not foolproof but a definite data-point on performance, that's what you want to look for. Once we get some MV/SD performance data we should be able to narrow down where to look for MV-nodes -- that's when you'll find accurate loads.

Gray Fox,

I was able to make it to the range today and try out CFE223 and AR Comp for the first time with 123SMK’s at 2.260” COAL. All of the CFE223 groups were terrible with an average groups size of 1.30” so I didn’t upload a picture. The AR Comp had two great groups with low standard deviations. Well see if I can reproduce these loads next time out. If history repeats itself I will not but I’m remaining hopeful.

The groups on the top row were shot with a $100 Bear Creek 16” 300 Blackout using Hornady 150 soft points and Lil Gun powder as a comparison. These groups can be repeated and this budget barrel shoots sub MOA.

The links below show the groups and crono data

https://www.flickr.com/photos/68382999@N...ted-public

https://www.flickr.com/photos/68382999@N...ted-public

[VikingCruze]

Just take the upper then? I understand not wanting it stolen off job site, people looking for easy opportunities there. Should be able to hide an upper in a truck, heck chain it to the seat mount?

If I can’t get the latest good groupings with AR Comp to repeat them I will take the barrel in to have them assess.

[VikingCruze]

Thanks 1 shot. I tried SMK’s today as I always have good luck with them in other calibers

[VikingCruze]

The only things I can suggest:
-True the face of the upper
- Apply grease to face of barrel extension and inside nut as well as threads.
- You could try a brass round head screw in a drill and lapping compound on the muzzle. If you are going to get it lathe crowned anyway, it would not hurt to try first. People have reported it works.

I did true the face of the reciever with Brownells tool. I’m afraid using a brass screw may void the warranty. I’m sure the Criterion guys will make it right if I can’t get it to shoot.

[-Justin-]

That crown looks rough.. if tool marks that bad made it through QC I'd be questioning how much attention was spent on the rest of the barrel... I wouldn't bother with reworking the crown, for the $$$ you spent I'd be looking for a replacement.