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55Gregg

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Reply with quote  #1 
Bear with me, I'm new to the wildcat world, that's partially why I picked the 277WLV it seemed to be well tested, data heavy and a safe place to start....

First run to the range with the new MDWS 20" 1:11 barrel and man were my velocities exciting....The gun is basic, Seekins Adj Gas Block, Mid Length, Aero Prec Hand guard and Upper, Anderson 223 Bolt, Anderson Carbine Buffer, Giselle Trigger....

The master load data sheet is limited on 20" data with 90g bullets (GD and Varminter)  using 1680 so I shot for the middle of the 18" data.  I shot a few 22.5 gr varminters to foul it and sight it in, and then started taking data.  I never adjusted the gas block and it was pretty well closed, I had to cycle the bolt after every shot.  The 23.2 and 23.4 loads grouped around an 1.5" but I wasn't really taking the time I should have.

All AA1680 All CCI 450 Primers, All COAL of 2.11", All new brass
90 Gr Varminter...23.0 gr...2730 FPS Brass Ok 5 rnds 
90 Gr Varminter ...23.2 gr...2780 FPS Very light ejector pin mark 5 rds 
90 Gr Varminter....23.4 gr ...2820 FPS ejector pin mark 5 rds
90 Gr Varminter....23.6 gr.... 2902 FPS heavy swipe primer holed 1 rd

I had another ladder built with GD using 23 to 23.8 gr 1680 everything the same as the varminter setup...but this time the brass had ejector marks at 23.0 and swiped and 23.2 so I decided this was just to hot for this setup, or I had made a measurement error.

My first question is, does the gas block being closed down increase muzzle velocities in any significant way?  

Second question... The 23.6 load had much more recoil and the muzzle velocity jump seemed to be unbelievably large..but the primer was solid black where firing pin hit it (no light through it) which seemed to confirm something bad wasn't far off.   So is there a threshold where a slight increase in charge results in a much greater increase in velocity or am I looking at something like bad data or an error in powder weight.  

Lastly, how should I adapt loads shown on the master data sheet for the 16" or 18" barrel to the 20" barrel?  Or should I even have to?

I'm going to pull all of the remaining  loaded rounds down and reload them starting at 22.4, but since this was a confusing experience I thought I'd put this out there for any words of wisdom.

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Pirate24

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Reply with quote  #2 
I'm no expert by any means and I would like to see others chime in on this subject,  I would definitely back off.  It appears that you already hit extreme max at 23.2 with 23.0 more likely with that particular combination with your barrel.   I can't answer your questions with any of the expertise available from others so I'll leave it to them but you can see major differences with minor changes in both velocity and PRESSURE! 
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BIGGDAWG

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Reply with quote  #3 
Yes, closed gas block will increase velocity - seen it many times and the block doesn't need to be closed to get the increase. I had one that was way over gassed, I turned the gas down so it would just lock bolt back and gained 80 to 100 fps that did surprise me. Your pressure signs surprise me at those charges but you don't say what brass you are using. If wolverine Starline it could be close because it has about .7 grain less capacity.
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mixednuttz

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Reply with quote  #4 
Looking at your data I'd guess the 23.0 to be your max. I would suggest backing off your load 2 grains and run another ladder. Might want to tune your gas block so the gun runs as well. Ejector swipes can be an early sign of pressure.
Your chronograph is valuable as well. You should see equal velocity increases for every charge increase. (Say 50 fps for every .2 gr increase as an example.) Once you see an irregular velocity result you are seeing things get unstable and you are likely above your max.
23.6 is way too hot in my opinion. I'm sure some of the others will chime in shortly.
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55Gregg

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Reply with quote  #5 
Great information!  The brass is all MDWS Starline, and now I know I have less capacity than some on the Master Load Data chart.

This is my first setup with an adjustable gas block so that threw a new variable into mix.  I appreciate BIGGDAWG sharing the brass volume and gas block knowledge, that really helps.  

This is all starting to make sense now...[thumb]

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RangerJoe

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Reply with quote  #6 
55Gregg: As BiggDawg already said, having the gas block nearly closed does affect the muzzle velocity and the pressure inside the case. Technically, it doesn't affect the peak pressure much, it mainly affects the dwell time, or how long the pressure has to act on the case.  Regardless, you would likely see a change in MV from shooting with the gas block closed versus open.

A longer barrel also provides more time for the pressure to act on both the bullet and the brass in the chamber (every action having an equal and opposite reaction).

Some "pressure" signs are actually signs of insufficient CARTRIDGE Headspace [HS] (not CHAMBER HS, which is different).  What brass did you use and how was it sized?  There are a lot of threads/posts on the forum discussing the importance of having your brass optimally fit your rifle's chamber... which typically is ~0.003" shorter Cartridge HS than Chamber HS.  We've seen the new Starline Brass average 0.007~0.010" less Cartridge HS than our Chamber specs.  If that is your situation too, your initial loads are fairly warm and the Cartridge HS is a bit short and your gas port is essentially closed... you are seeing compounding effects from multiple contributing factors.

You should measure the relative difference in Cartridge HS between your FIRED brass and your new prepared brass.  The absolute numbers are less important than the difference between the two.  Again, lots of information here in the forum (and the web) about how to do that.  A very "nice" way to accomplish that task is with Hornady's Cartridge HS Comparator kit.  An effective "Red Neck" method is to use an empty 9mm or .38 Special case (maybe a .380 ACP would work too).  The empty pistol case should ideally be resized.  Put the empty pistol case over the neck of the rifle brass, like a "hat".  Using calipers, measure the total length of the two cases, while keeping the pistol case centered on the rifle case's shoulder. Write down the length... do that with the fired brass and the new brass to see the difference.  Let us know.

My guess is you will find 0.008 or more difference between your new brass and fired brass. If that is the situation, don't panic... just load your first firings with the new brass not pushing max to "Fire Form" the cases to your chamber.  You also use this measurement method to set your resizing dies so that when you reload your fired brass, you only set the shoulder back (which determines Cartridge HS) the minimum amount necessary, typically about 0.003" for a semi-auto.

Hope this helps...


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55Gregg

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Reply with quote  #7 
Well that adds a new dimension to equation....and yes I'm using the Starline brass.  I don't know why I didn't think of headspacing before, but I've read enough about I should have.  I'll go grab that comparitor, I've seen it at store plenty of times.  

Fire forming is something I'll have to read up on more....up until the other day I thought is was something that involved a blowtorch.  But I guess its just firing new brass with a reduced load.

I know to the forum regulars must seem like groundhog day every time a new guy starts down the path from moderate to severe BRD, but we sure do appreciate the knowledge!


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RangerJoe

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Reply with quote  #8 
There are varying degrees of Fire Forming - sometimes changing the brass a lot, sometimes just a little.  But it all boils down to using the pressure of firing a round to form-fit the brass to your rifle's chamber.

With the Starline .277 WLV brass, it seems to average a bit short on Cartridge HS than ideal, however - I've seen much worse.  If your measurements confirm my suspicion, you don't have to fire the first load at some far reduced charge... just stay a good margin away from hot.  That will form the brass to your chamber. Using the comparator method to adjust your resizing dies will ensure you only set the shoulder back just enough for reliable functioning (again - typically around 0.003", +/- 0.0005).  Now your brass will last MUCH longer, it won't rattle around in the chamber, and won't show false pressure signs due to improper Cartridge HS.

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Cabob

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Reply with quote  #9 
Ranger Joe is 100% correct, as usual. I've just started prepping the starline brass that I received through the crowdfund project, and have found a couple of differences compared to LC brass.

1. The cartridge headspace is way short (1.251-1.252) compared to my chamber of 1.267.

2. The brass length is 1.523-1.525. A little short for initial fireforming, especially with the headspace being as short as it is.

3. The primer pockets are way tight... This is good and bad. Good because you should be able to get many, many firings before the pockets loosen up. Bad because I like to uniform all primer pockets and couldn't get my uniformer to go to the bottom of the pocket with many cases. (They should loosen up enough after one firing to perform this procedure).

All in all, though, this is good quality brass. It's not going to be plug and play for guys that have been using LC brass, but it's great to have a factory option!
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sleddoc

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Reply with quote  #10 
I agree with rangerjoe . I think its a head space issue. When I built my 277 all my loading was on mixed brass and I did have a few issues to figure out at first. I did buy a redding competition shell holder set that can be used on the cats based of the 223, 556 case. It does take a little extra time to figure out for your rifle ,but would be worth looking into if you are using specific brass for all your loads. ( starline )  It was a must for my goose build and the goose has been running flawlessly. 
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RangerJoe

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Reply with quote  #11 
Just for grins & giggles, I measured the Cartridge HS on 5 random fired .277 WLV cases in my bin.  These are a mix of LC cases fired from any one of 5 different WLV uppers - although most likely came from my 18" SS or my son's 18" Melonited tubes.  Cases are all decapped and washed, but NOT resized. 

I set the calipers at zero on the first case using Hornady's "A" comparator insert.  All 5 cases were zero +/- 0.0005".

I then measured 5 random new Starline cases right out of the bag.  Results as follows:
1) -.008
2) -.008
3) -.0075
4) -.008
5) -.007

That is pretty close to an average of 0.008" shorter Cartridge HS than my random mix of fired WLV brass.  It is also very consistent (for a small data sample).

This is not a knock against Starline; again, I've seen much worse. It is just something you need to be aware of...   If new brass is a tad short on Cartridge HS, don't load hot for the first firing. 

Again, as we've said several hundred times on this forum - LOAD TO YOUR CHAMBER.  Know what that means and how to measure / accomplish it.  Results will improve drastically and your brass will thank you for it!  [biggrin]

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55Gregg

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Reply with quote  #12 
Bought the Hornady Comparitor....

New Starline Brass is 1.250"+/-.001", I have 600 from 3 different orders, so I measured about 20 (its all in one bin) and it was all very consistent.  

My fired brass ranged from 1.262" to 1.265" milder loaded cases were generally shorter and hotter longer.  

I guess that means I need to fire form the brass to 1.262" to get the 0.003" from the longest fired case?

Thanks
 


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RangerJoe

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Reply with quote  #13 
Not exactly.  Shoot the new Starline brass with medium loads... not approaching HOT or Max, but not wimpy just getting the bullet out the muzzle either.  Then measure those cases.  Adjust your sizing die to give you approximately 0.003 (+/- 0.0005) LESS Cartridge HS.  The sizing die does that by how much it pushes (or sets) back the cartridge shoulder.  Screw the die in too far, you wind up with too much set back (sometimes called 'bump'), hence excessive Cartridge HS.  Have the die out too far and you get NO shoulder set back.  This is a game of thousandths of inches!

I'm a little surprised your fired brass has .003" difference... unless the mild loads were really mild.  Is all the fired brass the same? 

Also surprised your Starline brass was 0.011+ less Cartridge HS than your fired brass.  Although I only measured 5 cases, mine averaged right at 0.008 less than fired LC brass.  One-hundredth short HS is definitely enough to cause false pressure signs.

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55Gregg

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Reply with quote  #14 
Thanks and yes all of the brass that I have for the 277 is Starline. I used the "A" bushing to measure and checked the zero several times. The 10 rounds I used to sight and foul the bore were in the 22.4 to 22.5 range, I wasn't being too precise with those...The hottest ones were 23.4's and the one 23.6.  

I'm loading up 100 Varminters with 22.8 gr AA1680.  With 23 gr I was in the 2700's so I think they'll end up in the upper 2600's.  Hopefully that does the trick.

I'll get to the range with these, set the gas block, and hopefully get some brass formed and move on to the good stuff. 

Thanks for the advice and I'll post up when I get some good 20" barrel strings.  

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RangerJoe

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Reply with quote  #15 
Sounds great - and you are very welcome!

I also have a 20" 1:11 WLV barrel, 1 of several lengths in my WLV den.  Funny thing is, I've never done any load development specifically for it.  Anything that has shot well in my 18" 1:11 has also shot well (albeit a bit faster) in my 20".  Exactly the same is true for my 16" 1:11.  If it shoots well in the 18", it also shoots well in the 16" (albeit a tad slower) - at least for me.  Conversely, bullets/loads that shoot crappy in the 18" also shoot crappy in the 16" & 20".

Have fun - stay safe - and welcome to wildcat induced BRD!!  [crazy] 

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Cabob

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Reply with quote  #16 
Looks like you're on the right track, 55Gregg. My Starline brass pretty much mirrors yours. Good info.
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55Gregg

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Reply with quote  #17 
Got to the range and fired 76 rounds of identical 90Gr Varminter with 22.8gr of AA1680.  COAL was 2.11, Brass was all new Starline with CCI 450 Primers. 
  
This was primarily to fire form the brass and adjust the gas block.  Adjusting the gas block had immediate and obvious affects on velocity.  The last string is the only one that I didn't make adjustments to the block.  While it cycled fine I could never get it to lock back after the last round.  

Several of the primers backed out enough to notice but I guess that's related to 0.012" -0.014" of head space I'm trying to fire form out.  

Created: 01-15-2018 03:01:26 PM
Description: 277 varminter 90 aa1680 22.8
#     FPS        
5     2842           
4     2808            
3     2835            
2     2848            
1     2825            
Average: 2831.60
StdDev: 15.73
Min: 2808
Max: 2848
Spread: 40
True MV: 2831.60

Created: 01-15-2018 03:10:32 PM
Description: 277 varminter 90 aa1680 22.8
#     FPS       
5     2822        ADJUSTED GAS BLOCK AFTER THIS SHOT     
4     2768             
3     2789             
2     2771             
1     2725           
Average: 2775.00
StdDev: 35.25
Min: 2725
Max: 2822
Spread: 97
True MV: 2775.00

Created: 01-15-2018 03:11:31 PM
Description: 277 varminter 90 aa1680 22.8
#     FPS        
5     2736             
4     2794          
3     2831            
2     2803           
1     2743           
Average: 2781.40
StdDev: 40.69
Min: 2736
Max: 2831
Spread: 95
True MV: 2781.40

Created: 01-15-2018 03:13:33 PM
Description: 277 varminter 90 aa1680 22.8
#     FPS          
5     2752         Gas Block Set.   
4     2772           
3     2771             
2     2775             
1     2749            
Average: 2763.80
StdDev: 12.28
Min: 2749
Max: 2775
Spread: 26
True MV: 2763.80


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55Gregg

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Reply with quote  #18 
When I got back to the house I measured the fired cases, they were 1.264"- 1.2655".  Seems to confirm the assertion I have a head space issue when using new brass...Oh well, I get to fire form another 450 cases!  

I'm curious if I need to be worried about the primers protruding a little, or the black firing pin indentations.  The gun does seem unusually dirty so I'm chalking it up to head space.

20180115_191837.jpg 


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Cabob

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Reply with quote  #19 
With that many new cases, I'd try to find an accurate fire forming load with the combo that falls within your pressure parameters. That way you could use it for hunting or whatever you'd like, and it would make the fire forming process that much more enjoyable, and your fired cases would still come out with the correct headspacešŸ˜. Just a thought. I wouldn't worry too much about the primers backing out... A little soot, but not bad, just an undersized case issue. They won't do that now that you know your cartridge headspace and to set your dies for .003 bump. Looks good to me.
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wikster1983

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Reply with quote  #20 
The unusually dirty part could be the 1680- I had to clean my receiver lots more when I tested it, went to sw blk and haven't had to clean it yet. My sub loads are with 1680- that pistol is dirty as hell right now, going to switch over to swblk there too. Could be some of the fouling there as well as the pieced primers.
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REDs Reapers

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Reply with quote  #21 
Just my $.02 here 55Gregg... but I like running a longer O.A.L. of 2.200". This might help drop your pressure problem as there is more space in the case. I haven't got to fire any of my starline yet, so this is good info guys - THANK YOU!!!!
P.S.- I also have an adjustable gas block on a mid length, and it's wide open, with spotty last shot hold open running aa1680. Think I'm gonna try a slightly slower powder for my next set. I've noticed the 1680 works really good with pistol length gas systems. - RED
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RangerJoe

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Reply with quote  #22 
The above are correct - the primers backing out and little bit of soot are from "short" cartridge HS.  A1680 isn't a particularly dirty powder (compared to Unique or A5744), but not as clean as some others.  Cabob is also spot on regarding finding an accurate / fun fire-forming load.  You can achieve very respectable groups while forming your brass... no need to see it as throwing bullets & money away. 
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55Gregg

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Reply with quote  #23 
Hey guys this is all good stuff.  I'm gonna come up with a fun load to fire form these cases and try lengthening the COAL to 2.200".  I've got 2 lbs of 1680 to burn through but SW BO might be on menu next go round.  I figured the bolt lock back was probably something with the load because I couldn't find anything wrong with the gun.  

Lucky for you guys I have to go to work for a few days so I won't be bending your ears.  

I don't think I've been on a forum as factual and helpful as this one...its a rare and beautiful thing.

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REDs Reapers

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Reply with quote  #24 
Glad to help were I can - I've gotten plenty of help here too! Have fun and let us know how it goes. - RED
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17WSM

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Reply with quote  #25 
I've been on the fence about the Wolverine and have enjoyed watching and learning from your experience.  I need another wildcat AR like a hole in the head but the Wolverine just keeps calling me.

Good luck with your loads and please continue to post your results.  I find them very interesting.
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