User Panel
User Panel
User Panel
|
Posted: 4/18/2019 8:00:50 AM EDT
12.5" KAK bbl. Factory Win 145gr FMJ, ejection is 4 o'clock at 8'
Recoil a bit more than 5.56, less than 7.62x39. Just threw the PA red dot on there till I figure out what optic I want. 1-8 or 1-6, not sure yet. KAK can on it because the 12" Larue rail I ordered turned out to be too long, going with a 10" I think. Only problem so far is it will not reliably extract a live round, extractor slips over case lip. Needs a extractor donut upgrade. Older hard chrome Aim Surplus BCG  350 Legend recoil is mild.  350 Legend pistol 12.5" Magpul 10rd, remove inner shoulder ribs, load to full capacity, feeds fine. If you do not want to mod a poly mag you can get three rounds to feed from a 7.62x39 5rd or 10rd mag  350 Legend magazine prep.  Attached File Attached File Attached File Attached File |
|
|
|
Posted: 4/18/2019 9:36:44 AM EDT
[#1]
If the bolt is retracting too fast and the extractor is slipping - think about it - the brass hasn't relaxed from the chamber wall and is getting dragged out too early. If the brass isn't pushing the bolt face the unlock timing is too early.
Timing and gas pressure. Harder brass isn't always an option so adjustable gas and a heavier buffer are often preferred. And yah, the leftover parts of a previous build are sitting in the box sending telepathic messages . . . BRD is setting in again . . . they warned me this would happen. . . Is there no cure? |
|
|
|
Posted: 4/18/2019 9:54:51 AM EDT
[#2]
The extractor hook may not be far enough forward, or you have excessive head space. It works when you fire it, because the case backs up a hair and the extractor can then snap over the rim.
Don't forget, that's a straight wall case with a .010" tolerance range between the Go and No-Go Gauges. The brass is probably .003" or so shorter than the Go-Gauge, so if KAK has the chamber cut at the deep end of the range, you've got quite a bit of head space there. All that space means the extractor hook must be positioned accordingly. The head space range should have been more like .005", similar to the 450 Bushmaster. If a barrel manufacturer is smart, they will use the standard Go-Gauge, but make their own No-Go gauge that is only .005" out. We'll probably be seeing some light primer strikes with the 350 Legend as well. I'm curious to see how long the fired and un-fired cases are. You may not be aware, but the 450 Bushmaster had it's share of light primer strikes in the early days. That was due to Bushmaster cutting the chambers too deep, coupled with Hornady making the brass a bit shorter than need be. They later lengthened the brass a hair. Tony |
|
|
|
Posted: 4/18/2019 11:00:34 AM EDT
[#3]
Tag for comments, interesting build.
|
|
|
|
Posted: 4/18/2019 11:55:15 AM EDT
[#4]
 Attached FileShows primer hit  Attached File^ Did not measure before firing^ A single unfired round measures "1.7025. |
|
|
|
Posted: 4/18/2019 12:02:07 PM EDT
[#5]
Very cool. But where did you get the Ammo?
|
|
|
|
Posted: 4/18/2019 12:15:16 PM EDT
[#6]
With a case length of 1.7025, if the chamber is cut to the minimum depth you'll have about 8 thousands head space. If it's at the max in-spec depth, you'll have about 17 thousands head space.
You would need quite a bit of extractor reach to grab the rim if it's sitting 17 thousands off the bolt face. It would have been nice if Winchester had made the brass a bit longer. Tony |
|
|
|
Posted: 4/18/2019 12:27:24 PM EDT
[#7]
Quote HistoryQuoted:
Very cool. But where did you get the Ammo? |
|
|
|
Posted: 4/18/2019 1:02:28 PM EDT
[#8]
Can you measure the bullet diameter, and the case diameter of a loaded round at the very top of the case.
Tony |
|
|
|
Posted: 4/18/2019 1:13:44 PM EDT
[#9]
Tony
Would not the case fireform to the chamber length? The pre-fired is 1.7025 and post-fired is 1.7020, doesn't add?? |
|
|
|
Posted: 4/18/2019 2:39:27 PM EDT
[#10]
Quote HistoryQuoted:
Can you measure the bullet diameter, and the case diameter of a loaded round at the very top of the case. Tony  Attached FileCase  Attached File |
|
|
|
Posted: 4/18/2019 3:48:41 PM EDT
[#11]
Seeing that the bullet measured .354" I wonder what your bore slugs? I see Winchester shows on their website the bullet diameter is listed at .357".
Winchester 350 Legend I have heard the correct bullet diameter is .355"? Have you done any accuracy testing? |
|
|
|
Posted: 4/18/2019 4:46:51 PM EDT
[#12]
Assuming the bullet is really .355, if you tried to shoot a .358 rifle bullet in that case, the diameter would end up .379". The chamber reamer is .3789" at that point, so you could probably slam it into the chamber, but it would be difficult to extract by hand.
I've seen a lot of straight walled cases get shorter after the first firing, so the head space increases a bit with fired cases versus new. If you're lucky, when you size it, it may grow a bit in length, but maybe not. The case would fire-form to the chamber only if the side walls of the case stuck to the chamber and the case head backed up, thus stretching the case. If the whole case slides back, it's not going to stretch the case. Tony |
|
|
|
Posted: 4/18/2019 5:05:10 PM EDT
[#13]
Donut and buna fairly worn. Got a refresh on the way.
 Attached FileAlso no accuracy testing yet, just wanted to put a few down range to get the feel of the round. Chrono coming too. |
|
|
|
Posted: 4/18/2019 5:27:42 PM EDT
[#14]
How 'bout a pic of the back side of the extractor? Straight down from directly above.
Tony |
|
|
|
Posted: 4/19/2019 6:41:52 AM EDT
[#15]
|
|
|
|
Posted: 4/19/2019 8:57:27 AM EDT
[#16]
See that shiny spot at the front of the extractor (top), that is where the back of the extractor was dragged across the barrel extension when you tried to manually extract a live round. It did that, because the hook wasn't snapped over the rim of the case.
Tony |
|
|
|
Posted: 4/19/2019 10:17:47 AM EDT
[#17]
You mean the clean spot, lol
I appreciate your forensic attention and input to this thread man. This bolt came out of a 16" 5.56 that I run a Hybrid on, that is why so dirty. Also the NiB really shows crud. Have not talked to you in many years. I remember some conversation on assaultweb with you and one of my friends. '99 or '00 You were trying to figure out something case-wise about the not yet named 458 SOCOM Have not checked on AW in many years. Also, @tirod what are you doing hanging out in the fringe forums? We need some cover fire in the Saudi Purge thread man. Frickin_under_scores are running rampant. Dial up a rant tor two plz 
|
|
|
|
Posted: 4/27/2019 9:43:40 AM EDT
[#18]
Switched the rail to a 10" Larue, fits better with the Mystic X
 Attached FileAlso swapped in a fresh ejector spring/buna/donut. Seems to have fixed unfired round extraction. Hoping to get in some trigger time today. |
|
|
|
Posted: 4/27/2019 5:16:13 PM EDT
[#19]
Finally a few groups.
50yds, rested. 1-6 PA ACSS reticle. Nice glass actually. 145gr factory fmj, their intentional blaster ammo. With Mystic X on it. Certainly minute of deer. Hand loads will tell more. It's no threat to the benchrest community but it does shoot well enough to get game. Love this round.  Attached FileSomething weird happened and I had a case head separation. Shows high pressure indications.  Attached File Attached FileHammered that primer flat. NIB BCG from Aim surplus |
|
|
|
Posted: 4/27/2019 6:25:10 PM EDT
[#20]
I'd check your headspace.
|
|
|
|
Posted: 4/27/2019 7:54:53 PM EDT
[#21]
look at the case mouth of that failure.
definitely a headspace issue ETA: please more pictures |
|
|
|
Posted: 4/28/2019 8:24:36 AM EDT
[#22]
Quote HistoryQuoted:
look at the case mouth of that failure. definitely a headspace issue ETA: please more pictures Magnifying glass shows a slight ring line around the mouth. The case failure was from the 2nd shot out of a 10rd mag. Barrel was clean before first shot. Found the head and went to my gun bench and picked out the case body with a dental pick. Went back out and fired the 8rds in the mag fine. Then fired the 4 five shot groups in the pic. Still have not found the first case fired.  Attached File Attached File Attached File Attached FileThe other 20 fired cases/primers all look normal. @moleman Only place I can find with gauges is PTG @$37ea for GO or NOGO or FIELD. Ah, the joys of a new round 
|
|
|
|
Posted: 4/28/2019 9:33:22 AM EDT
[#23]
Let's talk about these case mouths.
Attached FileWere they crimped? Were they overly deburred? Or were they too long in the chamber? |
|
|
|
Posted: 4/28/2019 11:09:43 AM EDT
[#24]
Quote HistoryQuoted:
Let's talk about these case mouths. https://www.ar15.com/media/mediaFiles/1147/cases2_jpg-927195.JPG Were they crimped? Were they overly deburred? Or were they too long in the chamber? |
|
|
|
Posted: 4/28/2019 11:18:33 AM EDT
[#25]
Not really the right answer.
From that picture it looks like brass was pinched down in the chamber because it was too long. I may be wrong. Take a look at this picture below I found.  If there is an interference fit the case mouth will be crimped and unable to release the bullet creating extra high pressure. |
|
|
|
Posted: 4/28/2019 11:54:31 AM EDT
[#26]
Looks like a light crimp on the new ammo.
 Attached FileI measured the ID of the failed case mouth at .0350-0.352. The other spent cases measure up to 0.355 |
|
|
|
Posted: 4/28/2019 12:57:19 PM EDT
[#27]
Great thread fellas!
This thread is relative to one of my ARs...the 45 Raptor. Same style cartridge that is headspaced on the case mouth. Here's my questions on ARs that have headspacing that is set off of the case mouth vs. what you see in a standard headspaced cartridge. What are the biggest problems in regards to keeping these ARs running smoothly? Headspacing is absolutely critical? (as it should be) But with the case shrinkage/growth from firing and resizing it seems like we have to be super careful when reloading for these guns. Bullet crimp tightness is extremely important? I only reload for my 45 Raptor, but with the availablilty of over the counter ammo for a 350 Legend or 45 Raptor, do we need to be putting the micrometer to every brand/style of ammo we use in these casemouth headspaced guns? What are some of the other important factors we need to pay attention to when shooting these straight walled case mouth headspaced cartridges? Such as the 350 Legend and the 45 Raptor Thanks |
|
|
|
Posted: 4/28/2019 2:20:47 PM EDT
[#28]
After seeing the 2nd set of pics, I'd do a chamber cast first to see what the case mouth step to freebore is and measure the case head against a new and the other fired cases. It almost looks like the case mouths are slipping up past the case mouth step in the chamber. If that's the case it could very well pass a headspace check. That would explain why your rifle wouldn't grab unfired cartidges and your case head separation where if it were solely from high pressure you'd expect more flow into the ejector hole and likely the primer would fall out. Seen reports of similar looking case mouths where guys were using a heavy roll crimp into the cannelure on a 357AR instead of the recommended gentle taper crimp not into the cannelure. Can't seem to find the pic of that at the moment, but the case mouths looked to have a slightly thinner stepped thickness look to them from getting pinched against the case mouth step by the bullet as it passed by. Different causes, but same end result.
Cerrosafe is easy to melt and use. I use a metal jig and a tight fitting patch to block the bore, and plumbers putty to block off the locking lugs and make a little funnel in the barrel extension down to the chamber. You can use thin carboard trough to direct the McDonalds hot coffee temp metal into the chamber so you don't need to take the upper off. Roto metals has more than enough for $10 https://www.rotometals.com/chamber-casting-alloy-ingot/ Brownells, midway and other places will have it also. If you get another case head separation it can be used to grab onto the case so it can be knocked out, melted and reused. While I'd do the chamber cast first, do you have access to a lathe? Straight wall case gauges are easy to make out of O1 or pin gauges but you need to be able to cut them perfectly square and to a precise length. |
|
|
|
Posted: 4/28/2019 3:11:43 PM EDT
[#29]
Thanks everyone especially moleman, yeah I already have the entire set of gages coming from PTG will let you know what it does.
No problem pulling the bbl. Never used cerrosafe but knew of it. |
|
|
|
Posted: 4/28/2019 9:35:41 PM EDT
[#30]
When you get the gauges, you need to check the length to make sure they are correct. And make sure PTG didn't chamfer the front edge too much, or they will drop too deep.
And while you're at it, you better check the diameter of the gauges as well. |
|
|
|
Posted: 4/28/2019 10:51:41 PM EDT
[#31]
Quote HistoryQuoted:
I measured the ID of the failed case mouth at .0350-0.352. The other spent cases measure up to 0.355 |
|
|
|
Posted: 4/29/2019 10:42:47 AM EDT
[#32]
Happy2shoot,
Except that it is smaller. The case failure it the other point of information. It tells you that the cartridge did not headspace on the case mouth. |
|
|
|
Posted: 5/3/2019 2:13:58 AM EDT
[#33]
interesting.
I know the KAK barrels are threaded to 5/8 instead of 1/2. Does that seem to be better? I can't quite comment on the possible short comings of the new cartridge. Or the case seperation, case mouth damage. Maybe things are just a little too new at this point? |
|
|
|
Posted: 5/3/2019 7:03:21 AM EDT
[#34]
My pic but edited by moleman [thanks]
Dosen't look good guys. Anyway, some measurements. Chamber mouth 0.3785" Whatever the next thing is 0.3685" [a mini step? Help me moleman] Leade 0.3565"  Attached FileContacting KAK, will keep updating. |
|
|
|
Posted: 5/3/2019 8:31:11 AM EDT
[#35]
The .3685" step shouldn't be there and is what is causing your issues. My best guess after talking with a buddy who's a top notch machinist is that the rougher was fed in too far and left that shoulder. I'd stop shooting it and send it back.
|
|
|
|
Posted: 5/4/2019 9:46:13 AM EDT
[#36]
Send the pictures to KAK, they should take care of you.
Yikes though, how did that even happen? Would the reamer be cut improperly like that? |
|
|
|
Posted: 5/4/2019 2:04:34 PM EDT
[#37]
That doesn't make me feel real great about my KAK barrel I just got. Think I will start with the CMMG 16" first.
Actually I might get some cerrosafe before I put either together |
|
|
|
Posted: 5/4/2019 4:07:52 PM EDT
[#38]
I got a GLFA 18 inch barrel last week. 40 rounds absolutely no issues. All brass looks good. Haven’t checked accuracy yet but functional test was 100%. I’m going to cancel my cmmg order.
|
|
|
|
Posted: 5/4/2019 9:23:38 PM EDT
[#39]
Quote HistoryQuoted:
Yikes though, how did that even happen? Tony |
|
|
|
Posted: 5/5/2019 6:55:16 AM EDT
[#40]
Quote HistoryQuoted:
Send the pictures to KAK, they should take care of you. ...snip... |
|
|
|
Posted: 5/7/2019 7:46:38 AM EDT
[#41]
A friend at work bought a 16" KAK 350L bbl same time I did. Told of my issues, decided to check his with a chamber cast, same problem. Identical dimensions too.
 Attached File |
|
|
|
Posted: 5/7/2019 12:45:28 PM EDT
[#42]
Ran too deep with boring bar on rough or if using a rouging reamer. Either way, you figured it out. Good for you on not assuming.
|
|
|
|
Posted: 5/7/2019 3:04:39 PM EDT
[#43]
One more thing. My gauge numbers for my Manson 1.711" Go 1.7205" No, PTG 1.711" Go 1.7142" No
SAAMI 350 LEG is 1.710"(min) - 1.720"(max). With most "in stock" gauges ive used since '94 they have always have had a 0.0000" - +0.0010" on the Go. The No is Max and this number has swayed a couple tenths to as much as -0.0040" short of SAAMI max with different manufactures. You will typically find "field" at max SAAMI headspace for rimless cases with a shoulder. Now all that said it depends on the gauge manufacture. They have their own tolerances and ideas where they think certain gauges should be held too in the SAAMI standard. All four of the big reamer gauge companies have always been helpful, just ask them where their gauge dimensions ad tolerances are. |
|
|
|
Posted: 5/7/2019 3:28:25 PM EDT
[#44]
One more thing. My gauge numbers for my Manson 1.711" Go 1.7205" No, PTG 1.711" Go 1.7142" No
SAAMI 350 LEG is 1.710"(min) - 1.720"(max). With most "in stock" gauges ive used since '94 they have always have had a 0.0000" - +0.0010" on the Go. The No is Max and this number has swayed a couple tenths to as much as -0.0040" short of SAAMI max with different manufactures. You will typically find "field" at max SAAMI headspace for rimless cases with a shoulder. Now all that said it depends on the gauge manufacture. They have their own tolerances and ideas where they think certain gauges should be held too in the SAAMI standard. All four of the big reamer gauge companies have always been helpful, just ask them where their gauge dimensions ad tolerances are. |
|
|
|
Posted: 5/7/2019 9:16:24 PM EDT
[#45]
You gotta be really careful when dealing with straight wall cases and chamber gauges. You can measure the gauge end-to-end all you like, but if the diameter of the gauge is a bit undersize and the leading edge is chamfered, it will blow your reading all to hell when in actual use.
The above poster did not mention the diameter of the gauge or the chamfer on the leading edge, which is extremely critical with a straight wall cartridge gauge. Tony P.S. For the Cliff Notes...the Manson gauge has a ten thousands swing and the PTG has three. |
|
|
|
Posted: 5/7/2019 10:01:07 PM EDT
[#46]
Here's a pic for you guys. This is a pair of 450 Bushmaster No-Go Gauges from the same manufacturer. Both of them are the exact same length, but they are both undersize in diameter.
A loaded 450 Bushmaster cartridge is about .478" at the case mouth and the chamber reamer is .481" at that point. But these gauges are both only .474" in diameter which is 7 thousands under the chamber diameter. The gauge would still work even though the diameter is undersize, until you factor in the chamfer on the leading edge of the right hand gauge. It drops too deep and ends up being at the same depth position as the Go-Gauge. The manufacturer of the gauges should have looked at the chamber reamer drawing or measured a loaded round, and made the gauges about .479" in diameter. Then they could de-bur or give them a light chamfer on the leading edge and all would have been good. I've been in this business 20 years and it's pretty clear, there is a serious disconnect between the guys that make barrels, make reamers/gauges, and make ammo. Tony 
|
|
|
|
Posted: 5/8/2019 7:01:31 AM EDT
[#47]
Besides the two barrels I personally chamber cast I know of another on a local Michigan forum, same problem. My 12", friends 16" and local forum guys 18" barrels.
Anybody with a KAK 350 Legend barrel please check your chamber. |
|
|
|
Posted: 5/9/2019 9:27:15 AM EDT
[#48]
Did the roughing reamer go in too far? Or, did the finish reamer not go in far enough?
According to SAAMI. 
|
|
|
|
Posted: 5/11/2019 6:15:09 AM EDT
[#49]
Barrel refunded, search for new one begins.
|
|
|
|
Posted: 6/12/2019 7:18:10 PM EDT
[#50]
Quote HistoryQuoted:
Barrel refunded, search for new one begins.  Failed To Load Title This guy had a 9mm barrel reamed and gas port drilled to spec. Sounds like there is a lot of confusion regarding what Winchester is claiming that this is and what it's spec actually is. While the bore is supposed to be .357. It looks like they actually went with .355 and chocked it up to tolerance. 
|
|
|
Win a FREE Membership!
Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!
You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.
AR15.COM is the world's largest firearm community and is a gathering place for firearm enthusiasts of all types.
From hunters and military members, to competition shooters and general firearm enthusiasts, we welcome anyone who values and respects the way of the firearm.
Subscribe to our monthly Newsletter to receive firearm news, product discounts from your favorite Industry Partners, and more.
Copyright © 1996-2024 AR15.COM LLC. All Rights Reserved.
Any use of this content without express written consent is prohibited.
AR15.Com reserves the right to overwrite or replace any affiliate, commercial, or monetizable links, posted by users, with our own.
Attached File