224 Valkyrie Forum

224 Valkyrie AR Platform => 224 Valkyrie Troubleshooting => Topic started by: Alaska_guy on July 11, 2018, 07:35:58 PM

Title: Measuring freebore.
Post by: Alaska_guy on July 11, 2018, 07:35:58 PM
This post is to help identify current barrels on the market and their freebore.  Due to the amount of people experiencing accuracy issues I would highly recommend checking your freebore.  This is an inexpensive and easy way to determine your barrels freebore.

This is most likely the easiest method I know of to measure freebore within
.010-.020.

Purchase cerrosafe to make a chamber casting.  Measure chamber casting to determine freebore.

http://www.midwayusa.com/product/462291/cerrosafe-chamber-casting-alloy-1-2-lb

Below is a quick video explaining how to make a cast.  Removal of your AR barrel will be required.

https://youtu.be/2AbOhlZVwAU

If you are a reloader, this method has worked very well for myself over the years.

https://youtu.be/faF2Im96K2U

Title: Re: Measuring freebore.
Post by: Constructor on July 11, 2018, 08:55:31 PM
Much easier way to do it posted elsewhere on this forum.
Title: Re: Measuring freebore.
Post by: Alaska_guy on July 11, 2018, 10:45:39 PM
Attaching Constructor's method here to keep everything compiled in one location.  Due to the scarceness of the SMK's I figured providing other methods to determine freebore might help people.


It seems there is a bunch of bad reamers going around. If you can load a 90gr SMK to 2.29 without jamming the bullet into the lands the reamer used to cut the chamber was out of spec.  The SAAMI spec for freebore is 1.676 from the base of the cartridge.
The easy and rough way to find the dimension -Turn a flat based .224 bullet around and seat it upside down in a 224 valkyrie case. Seat it so it barely touches the lands in your chamber. Measure from the base to the forward most part of the .224 diameter of the bullet. It should be very close to 1.676"

The correct reamer drawing that matches the SAAMI spec drawing is attached below. It's pretty easy to check your chamber. Don't wait for someone to prove it to you check it yourself. The 1.6767 dimension is the distance from the base to the start of the freebore.
The most accurate way to find the freebore dimension-  Take a .224" diameter inspection pin. Cut it in half, 1" long. stick it in a Hornady OAL gauge and adjust it in your chamber.  Measure from the front of the inspection pin to the base and there's your number.
ETA-7/3
The jump to the lands effects accuracy. If there is too much jump the accuracy may never be what it could be. The ARs mag length restricts us to how long we may load the cartridge. Most 6.8 mags allow loading to 2.295". If you load a 90gr SMK to 2.26" like the factory rounds and the barrel was chambered with a reamer that was not to spec the jump to the lands may be .060".  Most bullets shoot best when jumped .005-.020" or some VLDs shoot best when  jammed .005". 
  You may get lucky and find a sweet spot where the bullet jumps at .040 or .060 and it produce 3/4" groups. Mine did that with factory ammo but when I loaded the bullets out .010" off the lands the exact same barrel shot some 1/4" groups. If the barrels were chambered with a SAAMI spec reamer the jump with factory loaded 90gr SMKs is right there at .010".
  If your barrel was chambered with a out of spec reamer and you are happy with the accuracy don't worry about it.


(https://s15.postimg.cc/hp3yduewr/IMG_1049.jpg)

This thread will be used to identify what barrel you have and identify if the chamber is to SAMI spec or not.  It would also be nice to provide freebore measurements of barrel makers.
Title: Re: Measuring freebore.
Post by: Alaska_guy on July 21, 2018, 11:26:07 PM
Update on PSA barrel.

Well I had a chance to measure the PSA barrel using a hornady comparator gauge.  I consistently measured 1.763" to the lands using 75gr eld projectiles with a COAL of 2.313.  I also tried some 70gr gmx bullets and I measured 1.750 to the lands and 2.153 COAL.

If I flipped the 75gr eld around so the base was facing the lands I measured 1.880.  Turning the 70gr GMX around so the base was facing the lands I measured 1.840.

Hopefully that helps.  @Constructor, any thoughts?
Title: Re: Measuring freebore.
Post by: Constructor on July 22, 2018, 08:27:33 AM
If the measurement was to the forward most .224" diameter part of the bullet then I would say the freebore is long.
Title: Re: Measuring freebore.
Post by: Alaska_guy on July 22, 2018, 01:29:28 PM
Thanks.  I figured if I split the difference 1.880 and 1.840, lets call it 1.860 that would mean the PSA barrel is about 0.184 out of spec (long). Good thing your next batch of barrels is coming out soon.  Looking forward to trying a correct reamed barrel that has your blessing.  :D
Title: Re: Measuring freebore.
Post by: Retired on July 27, 2018, 07:08:59 PM
I see in a another forum, one of the members contacted Savage, said he had a rifle with a out of spec chamber [long freebore], when he told them it was the Valkyrie they asked for the rifle to be returned and they would correct the problem. Maybe some changes are starting to happen? 
Title: Re: Measuring freebore.
Post by: binazone on January 07, 2019, 06:58:06 AM
A bit late for a reply but I only just found this thread. I can confirm the PSA freebore dimension that Alaska guy found. I used both 88 and 75 ELDMs, base end first with my Hornady O.A.L. tool and got 1.890" and 1.893" respectively for results. Let's call it 1.892" or .216" over the SAAMI spec of 1.676".
Title: Re: Measuring freebore.
Post by: carnaby on April 20, 2019, 01:13:19 AM
The method described here to measure freebore is in error. It will not measure freebore.

The statement "The 1.6767 dimension is the distance from the base to the start of the freebore." is incorrect. This is the distance to the end of the freebore. Besides that, to measure freebore in this way you would need an inspection pin that was precisely the diameter of the freebore, which is not 0.224", but 0.2246", and then this is the minimum. The maximum can be as big as 0.2266" given the SAAMI diameter tolerance of +0.002".

So an inspection pin that was precisely 0.224" diameter with a 1.5 degree leade , with a freebore diameter at SAAMI minimum of 0.2246 would give an OAL of 1.6882". A flat based bullet with a diameter of 0.2238", with a perfectly sharp base edge (not going to happen unless you machine or file it flat) would measure 1.6920".

Note that none of these measurements with a .224" inspection pin or .2238" flat base bullet measure OAL to the freebore. They measure OAL to the point that is the same diameter as the pin or bullet IN THE LEADE, that is the section of the rifling that is cut at 1.5 degrees.

JGS reamers are made to a diameter tolerance of 0.0005", which means the freebore diameter could be .2246 + 0.0005 = .2251". In this case, a .224 inspection pin would have an OAL to the leade of 1.6977" and a 0.2238 bullet would be 1.7015".

At the SAAMI maximum of 0.2266" the OAL to the Leade would be 1.7263 for the pin and 1.7302 for the bullet. A chamber that measures in this way is still SAAMI spec.

If you want to make an attempt at measuring OAL to the end of the freebore, you need an inspection pin set. Find the largest pin that will actually slide into the freebore, then check the OAL of a Hornady OAL gage using that pin. It will stop at or near the end of the freebore. Suppose your freebore is 0.226" diameter, then take a 0.225" inspection pin (or machine a cutting edge bullet flat at the sealtite band which is approximately 0.2255". This will stop very close to the end of the freebore and give a much better measurement.

For example, if the freebore diameter is 0.226" and the diameter of the sealtite band is 0.2255" then you should measure an OAL around 1.6862". When I do this with my barrels I get an OAL of 1.6880" indicating that the diameter of the freebore is more like 2.2261". This assumes that the lands are perfectly at 0.219" and all other dimensions are MINIMUM SPEC, which is highly unlikely.

This bunk about out of spec chambers not helping the 224 Valkyrie. Nobody seems to know what they are doing when attempting to measure freebore, and it cannot be done accurately by the method described earlier in this thread.
Title: Re: Measuring freebore.
Post by: trianglevelvet on May 09, 2019, 10:49:40 PM
I just went through a giant process of trying to figure out using tapers and pins and calibrated ball bearings to get full chamber dimensions.......

And decided that this is why Cerrosafe was invented.
 :o
 
And these:

https://www.hornady.com/reloading/precision-measuring/precision-tools-and-gauges/lock-n-load-bullet-comparator#!/

https://www.sinclairintl.com/reloading-equipment/measuring-tools/bullet-seating-depth-tools/length-gauge-prod70272.aspx
Title: Re: Measuring freebore.
Post by: Ryan_otto on July 28, 2019, 06:20:58 PM
Have used constructors backwards bullet method before to determine if a barrel was 6.8 SPC or 6.8 spc II. Great method! Very easy!
Title: Re: Measuring freebore.
Post by: Constructor on September 04, 2019, 08:47:37 AM
The method described here to measure freebore is in error. It will not measure freebore.

The statement "The 1.6767 dimension is the distance from the base to the start of the freebore." is incorrect. This is the distance to the end of the freebore. Besides that, to measure freebore in this way you would need an inspection pin that was precisely the diameter of the freebore, which is not 0.224", but 0.2246", and then this is the minimum. The maximum can be as big as 0.2266" given the SAAMI diameter tolerance of +0.002".

So an inspection pin that was precisely 0.224" diameter with a 1.5 degree leade , with a freebore diameter at SAAMI minimum of 0.2246 would give an OAL of 1.6882". A flat based bullet with a diameter of 0.2238", with a perfectly sharp base edge (not going to happen unless you machine or file it flat) would measure 1.6920".

Note that none of these measurements with a .224" inspection pin or .2238" flat base bullet measure OAL to the freebore. They measure OAL to the point that is the same diameter as the pin or bullet IN THE LEADE, that is the section of the rifling that is cut at 1.5 degrees.

JGS reamers are made to a diameter tolerance of 0.0005", which means the freebore diameter could be .2246 + 0.0005 = .2251". In this case, a .224 inspection pin would have an OAL to the leade of 1.6977" and a 0.2238 bullet would be 1.7015".

At the SAAMI maximum of 0.2266" the OAL to the Leade would be 1.7263 for the pin and 1.7302 for the bullet. A chamber that measures in this way is still SAAMI spec.

If you want to make an attempt at measuring OAL to the end of the freebore, you need an inspection pin set. Find the largest pin that will actually slide into the freebore, then check the OAL of a Hornady OAL gage using that pin. It will stop at or near the end of the freebore. Suppose your freebore is 0.226" diameter, then take a 0.225" inspection pin (or machine a cutting edge bullet flat at the sealtite band which is approximately 0.2255". This will stop very close to the end of the freebore and give a much better measurement.

For example, if the freebore diameter is 0.226" and the diameter of the sealtite band is 0.2255" then you should measure an OAL around 1.6862". When I do this with my barrels I get an OAL of 1.6880" indicating that the diameter of the freebore is more like 2.2261". This assumes that the lands are perfectly at 0.219" and all other dimensions are MINIMUM SPEC, which is highly unlikely.

This bunk about out of spec chambers not helping the 224 Valkyrie. Nobody seems to know what they are doing when attempting to measure freebore, and it cannot be done accurately by the method described earlier in this thread.
1.6267" IS the start of the freebore and  END of the cone. "Freebore is the area in front of the cone where the  bore is bullet diameter but has no lands...free bore.   The end of the freebore is where the lands start ramping up to full height. 1.6767" As the spec shows it should be .2246" as most are .0005 large diameter than the bullet, just enough to allow the bullet or pin to slide in without an interference fit.   If your freebore is larger diameter than that they ground the reamer wrong. Yes they have tolerances but it's the difference in a good reamer and a bad one and all of this started because of the poorly ground PTG reamers.   They were ground with an extra long freebore so long that no one could seat the 80-95gr bullets out to where they were close to the lands to get decent accuracy.  Some bullets may shoot okay with a .060 jump but some will not. The 90gr bullets set to a max allowable mag length of 2.295 shot poorly but when set out to 2.345 they were shooting under .5 MOA.
The barrels chambered with the JGS reamers were much more accurate with the bullets seated to max mag length 2.295 and under. That is the goal, produce barrels that are accurate.
The bullet is .224" and where the bullet touches the lands is .224" so that is the only measurement that matters and a .224" inspection pin is what should be used to figure out at what length  a .224" diameter bullet will touch the lands.
  All of this about the correct freebore length is important for the 80-95gr bullets. Bullets like the 77TMK and all bullets shorter may work better with the long freebore. At least it will allow loading the short bullets to a longer OAL for more powder capacity.
Title: Re: Measuring freebore.
Post by: Hammerhead on September 08, 2019, 05:07:51 PM
All of the arguments weather a chamber is in spec or not and how to measure it should be overshadowed by the fact that the "spec" for the Valkyrie is suspect at best.
Title: Re: Measuring freebore.
Post by: carnaby on September 08, 2019, 09:55:14 PM
All of the arguments weather a chamber is in spec or not and how to measure it should be overshadowed by the fact that the "spec" for the Valkyrie is suspect at best.

Why do you say that? What are your reasons? What makes a cartridge spec suspect?
Title: Re: Measuring freebore.
Post by: carnaby on September 08, 2019, 10:11:53 PM
Freebore is the area in front of the cone where the  bore is bullet diameter but has no lands...free bore.   
Not quite, it is typicall greater than bullet diameter but yes free bore.

Quote
The end of the freebore is where the lands start ramping up to full height.
Sort of. The freebore ends where the constant diameter ends and the chamber leade starts at 1.5 degrees or whatever shallow angle is chosen for the particular chamber.

Quote
1.6767" As the spec shows it should be .2246" as most are .0005 large diameter than the bullet, just enough to allow the bullet or pin to slide in without an interference fit.
Bullet = .224 but .224 + .0005 = .2245, so this isn't right, it's not even minimum spec. JGS cuts their chamber reamers to +0.0005 greater than spec, so I would expect a JGS freebore diameter to be .2246 + .0005 = .2251 or greater. If you grind your reamer to absolute minimum spec you won't get many barrels out of it before your chambers are less than minimum spec from reamer wear.

Quote
If your freebore is larger diameter than that they ground the reamer wrong.
Wrong = you don't like them? That doesn't make any sense. You are free to dislike a certain amount of bullet jump, but a reamer that is in spec is hardly "wrong". Unless of course you asked for a particular reamer grind with a particular tolerance, and the company agreed to that exact thing and did not deliver. Then you may also be able to claim that a reamer is ground wrong. Otherwise claiming that a reamer is wrong or out of spec when it is clearly in spec is incorrect.

Quote
Yes they have tolerances but it's the difference in a good reamer and a bad one and all of this started because of the poorly ground PTG reamers. They were ground with an extra long freebore so long that no one could seat the 80-95gr bullets out to where they were close to the lands to get decent accuracy.


You still have not shown that the freebore, which is the cylindrical section , i.e. constant diameter, that is at least .2246" in diameter is long in any chambers. It might be in some chambers but I've not found one. Your method of measuring freebore doesn't measure freebore, it just measures the point in the throat that is .224" in diameter.
Title: Re: Measuring freebore.
Post by: Hammerhead on September 09, 2019, 08:18:15 AM
Hey I can see this from multiple points of view. Even yours Carnaby. Like Some folks I can seat a 95 SMK to out to the lands and shoot well under .5 but who wants to hand feed an ar is beyond me. The fact the the designed freebore was wayyyy too much has done more to hurt the  valkyrie  than anything ever posted in this forum.
Title: Re: Measuring freebore.
Post by: carnaby on September 11, 2019, 03:18:17 PM
Hey I can see this from multiple points of view. Even yours Carnaby. Like Some folks I can seat a 95 SMK to out to the lands and shoot well under .5 but who wants to hand feed an ar is beyond me. The fact the the designed freebore was wayyyy too much has done more to hurt the  valkyrie  than anything ever posted in this forum.
That's an interesting assertion. Chambers are tricky though because as we've seen, the chamber spec has to work with the cartridge specification at all tolerances. To get the bullet jump you want in an AR-15 can be done but then you are close to a minimum spec chamber which is a challenge in its own right. If I could go back in time I would increase the length and width of the AR-15 magazine well to work with cartridges loaded to 2.35" OAL. Wouldn't that be nice.

I will give you one thing though... it does seem that the neck diameter of the chamber specification was messed up and should have been 0.255" as in the original prints. My new chambers are run at 0.255" and I like them a lot better. When I neck bushing size 2/3 of the length of the neck from brass fired in the old chambers and compare with the new, the old shows a noticeable bulge and definitely cannot be chambered in the new barrels.

And a final word on bullet jump... I'm getting 0.75" 5-shot groups with ammo loaded to 2.285" OAL with a OAL to the lands around 2.34" or so. Personally I consider that quite good from an auto loader.
Title: Re: Measuring freebore.
Post by: KRC on September 11, 2019, 04:15:03 PM
I'm with Hammerhead on this one.

I think this cartridge was designed on a cocktail napkin during the last few cold ones of a long Happy Hour. (Hey, since AR shooters are buying bucketloads of CHEAP (non-Federal) ammo, let's make a cartridge that'll sorta fit in all those AR's out there that we can sell high priced ammo for. - it will (maybe/sometimes) shoot a heavy bullet and we can HYPE UP THE LONG DISTANCE ballistics (numbers anyways) performance!) This was followed by the Happy Hour design napkin being sent to the Legal department, where a couple of non-shooting marshmellow lawyers (safetysafetysafety!!!) further stretched out the freebore. (Hey, we're designing this to sell high-priced Federal ammo, not for reloaders who might stupidly want to load into the lands (or anyone that might want to HIT anything at long distance). Then, off to the R&D department where they refined and tested the cartridge on their apparently ONE SINGLE in-house AR barrel (which was likely a premium lapped barrel and COMPLETELY unlike the rough, mass-produced, unlapped button rifled barrels on most AR's). Then quickly off to Marketing to refine the HYPE and product launch.

Ooops! Doesn't shoot?
BLAME THE BULLET!       (or alternately the reamer guy)
Waitdahminnit - design a cartridge and ammo around a specific bullet, then when it fails in the market, blame the BULLET???
(Get someone at Sierra to talk - "there was nothing wrong with that bullet") So after you pull your product, have your vendor reconfigure their bullet (thicker jacket) to compensate for your (lack of) engineering, and some dumbass builds a BOLT rifle to demo how good the cartridge REALLY is, and some (SOME! but not many) hard-working, meticulous load developing, handloading, precision shooters get this abomination to actually shoot, it's now legit?

Not freakin' likely. This baby will die a slow lingering death.

PS - I fell better now . . . . 


Let the flaming begin . . .
Title: Re: Measuring freebore.
Post by: Hammerhead on September 11, 2019, 06:30:15 PM
Kinda seems like the marketing dept. got way out ahead of r&d for sure. Heck I looked thru my records and  a 90 SMK that was the original marketing bullet they stated was supersonic to 1300yds with killer accuracy and so on, touched my lands at an OAL of 2.415. couldn't hit the broad side of a barn with it.  >:(
Title: Re: Measuring freebore.
Post by: 1000 yrd guy on September 12, 2019, 04:40:45 AM
Lets not forget that almost all new cartridges that come out have early issues. This one in particular is a bit diff in that it is a supposed to be a long range AR cartridge .I dont see all the fuss not to say a lot of guys are struggling to find consistent accuracy, I myself have loaded almost every bullet under the sun for my cheap PSA and zeroing in on my final loads. I can now work my way right out to 1000 no problems and I am not that good of a shooter with my old eyes and shaky hands. I enjoy the challenge of working through load development since I enjoy reloading as much as I enjoy shooting. Give it time, my feeling is this puppy is here to stay and I cant wait to take down some yotes this winter with it instead of the boring ole .223 . ;)
Title: Re: Measuring freebore.
Post by: Hammerhead on September 12, 2019, 05:35:18 AM
The Val on coyotes hits like Thor's hammer no doubt. The old ones that hang up a half mile out are still in grave danger. I'm still very optimistic about the success of the cartridge with the new shorter bullets arriving on the market it's going to help all the non handloaders out and in turn the Val. It's just such a handloader only round right now for the people that want the high precision that was hyped up in the beginning.

I did speak via email with Berger a week or so back and they indicated that the 82BT's that are the holy grail for my rifle are not coming back from being discontinued but a replacement will likely be around sometime close to Christmas.
Title: Re: Measuring freebore.
Post by: 1000 yrd guy on September 12, 2019, 03:59:43 PM
Hammer I agree with alot of your thoughts ,however as I remember when the Valk was hyped up (shot show 18) and else where it was more about long range that accuracy. The accuracy will come with time, its takin me a full summer and a lot of different powders and bullets but I am def zeroing in now.And im sure that loads im getting good results with prolly shoot like hell in your gun .Its def a challenge .
Title: Re: Measuring freebore.
Post by: carnaby on September 13, 2019, 01:25:52 AM
The new 90 smk load from federal has given me consistent sub moa accuracy when their initial offering would barely hold 3" at 100 yards. The new bullet may be a factor. They are also loading a lot lighter, as muzzle velocity is down over 100 fps and is surprisingly consistent shot to shot.
Title: Re: Measuring freebore.
Post by: Flygrimm on September 13, 2019, 08:36:17 AM
Carnaby

Does the new load have the guts to consistently make it to 1K?

Took my Valkyrie out for the first time a couple of weeks ago.  Got it on paper at 100 with flawless function.  Was using the Federal 75 grain.  Iím going to use the Hornady 88 factory on my next trip. 

Hopefully I can do it justice.

Stuart
Title: Re: Measuring freebore.
Post by: carnaby on September 13, 2019, 01:51:51 PM
Does the new load have the guts to consistently make it to 1K?

Yes it does. At 2650 fps at the muzzle that puts it over 1.2 Mach at 1000 yards, and that's at sea level. Even at 2500 fps out of the muzzle from a shorter barrel at say 500 feet above sea level and 60 F it's at 1275 fps which is around 1.17 Mach.

The claims of supersonic performance to 1300 yards are of course baloney. The 90 SMK needs 2700 fps at the muzzle to get to 1300 yards above 1.0 Mach, and transonic flow is typically accepted to start around 1.2 Mach so performance at 1300 yards is likely to be poor. The only real way to get there is with a 24"+ barrel and 95 SMK bullets, and even then the bullet will likely be in the transonic flow region by 1100 to 1200 yards.

But yeah, 1000 yards, no problem. I've shot the 80 SMK and 88 ELD at 1000 yards with good results from a 24" barrel. 
Title: Re: Measuring freebore.
Post by: Flygrimm on September 13, 2019, 06:54:36 PM
That sounds good.  1000 is my eventual goal.  Maybe the reduction in MV will lead to better brass (primer pocket) life.  Itís good to know that I donít have to take the velocity to extremes to get the distance I want.

Thanks

Stuart
Title: Re: Measuring freebore.
Post by: 1000 yrd guy on September 14, 2019, 04:29:19 AM
Carn,Im glad to see that Im not the only one who says velocity numbers from the bullet makers are BS. Sure if you have a 28 inch barrel you can get close but who the hell shoots that but a few, the valk was designed for AR so why they dont publish the data for 20-22 even the 16 inch barrels that are AR common is beyond me. I have 20 inch and wish I had at least 22 maybe Ill bump up this winter, and am anywhere from 2500 fps to 2700 in most of my heavies, the Nosler rdf 85 that I really like cause I can get to a 1000 easily still is border line slow in my opinion. Even at max powder on the Hornady 88s i was well under 2650 fps. And the powders that gave the highest velocity's for me shot like poop. You hear guys on forums chirping numbers like 3000-3400 fps WTH they shooting.
Title: Re: Measuring freebore.
Post by: Danno_ on September 14, 2019, 12:01:21 PM
I'm loading 85 RDF's through a 22" 6.5t at 2700 fps with 26.9 gr of PP2000MR. Using Federal brass with no primer pocket issues. It shoots sub moa. SD around 10 ES around 25. I've only been able to shoot out to 600 and it shoots great.