The Skinny on Gas Checks - Al. vs Copper

[quicksylver]

A little back ground first....

I have been an avid user of copper checks...had to 'cause that's all I had..

I have been watching the treads posted by those who do use Al checks...and found them to be very interesting..but there was no real side by side comparisons that I could find...

I got to conversing with Josh and he ultimately offered to send some of his along so I could compare them to copper checks myself....THANK YOU JOSH...

The checks arrived Monday... Josh was kind enough to supply me with both the Al checks he makes as well as some copper ones....

I have to say I am impressed with the quality of both..

My first impression was that they looked a little more cupped than the Gator checks I have been using...BUT
in the end they square off very nicely...

Next ..I tried finger seating them on some bullets...THAT turned out to be a joy!!! See Picture..

I then fully seated them in my 450 and ran the bullets through my Lee Push through sizer..
I noted the gas check shank size of the different bullets in the photo...both fit fine..

I then lubed them with the 450..Good looking. RIGH !....

For velocity and accuracy testing I decided to use my Remington 700 in 308 Win...the bullets I choose were
the NOE 314466...sized down to .310, lubed with Ben's Red and BLL, pushed by 17.5 grs of 2400 and sparked with WLRP...

The 314446 are first pushed through a .313 or .312 die and then finial sized by being pushed through a .310 die.

This these pictures show the process of double sizing and lubing....

So here is the preliminary results folks...the chrony data comes after the photo...

DATA....

String/Group 1- copper
1 1749
2 1740
3 1747
4 1740
5 1756
H 1756
L 1740
Av 1746
Es 16
Sd 6

String/ Group 2 - Al
1 1773
2 1782
3 1763
4 1782
5 1777
H 1782
L 1763
AV 1775
ES 19
SD 7

String/Group 3 - Copper
1 1756
2 1742
3 1749
4 1740
5 1766
H 1766
L 1740
A 1759
ES 16
SD ( forgot to reset)

Srting/Group 4 - Al
1 1780
2 1787
3 1756
4 1782
5 1766
H 1787
L 1756
AV 1774
ES 31
SD 12

So there were several surprises waiting for me...
1. The Al checks afford a slightly higher velocity with the same powder charge
2. I did not think I would ever consider 1/2" groups sort of Ho-Hum..
3. There wasn't.... at this time a duplication in accuracy..
4. SD..MAY not have all that much to do with accuracy potential..

Next trip will be for additional accuracy testing..I think I may have been a little off because I am always concerned about hitting the chorno...

Dan

 

[Josh]

As I noted in our PM's you may need to adjust your powder charge by a few 1/10ths of a grain to get back in the node. There seems to be just enough difference to change things up.

 

[quicksylver]

As I noted in our PM's you may need to adjust your powder charge by a few 1/10ths of a grain to get back in the node. There seems to be just enough difference to change things up.

My thoughts exactly...I was going to drop down to 17.3 on that load....and see what happens....

 

[Ian]

#4, quite true.

 

[Ian]

My thoughts exactly...I was going to drop down to 17.3 on that load....and see what happens....

I fought people on this very thing regarding bullet lube testing. I'd send out something, or someone would duplicate a promising experimental recipe we were working on, and I'd get "this lube sucks, my finest-tuned benchrest tack driver won't group with it", and at the same time be told the velocity was as much as 200 fps higher....Well DUH!!!! Re-tune the load! Glad you gentlemen are on the ball with these things.

 

[quicksylver]

#4, quite true.

Ian...I did not come to this conclusion because of this testing..but rather through the last 8 yrs or so after running loads over the chrony for my match buddies...each and everyone of them said.."SREW THIS I AM GOING TO SHOOT THE LOAD THAT GROUPS THE BEST"..

 

[quicksylver]

Two other comments;

1. Since the AL. checks have less springback ..one does not need to flair the case mouths as much...

2. I have mentioned this before...but the bullets with AL .checks seat easier...

 

[Ian]

Ian...I did not come to this conclusion because of this testing..but rather through the last 8 yrs or so after running loads over the chrony for my match buddies...each and everyone of them said.."SREW THIS I AM GOING TO SHOOT THE LOAD THAT GROUPS THE BEST"..

I didn't come to that conclusion over night, either. Internal ballistics relates to barrel harmonics, but "harmonious burns" do not always sing in tune with "harmonious vibrations". I think getting the rifle to vibrate in a happy zone, even if it's a large zone, is more important than nailing the internal ballistics down to a single-digit number. At least that's what my targets have told me.

 

[fiver]

but when you get that near single digit deviations and the accuracy both......... oh yeah.
the groups stay tight out there as far as the targets will allow.

 

[35 shooter]

Interesting experiment and i'll be watching your results. Over the course of a year working up loads for my 35 whelen my AL. checks out grouped Hornady copper checks with every load.
The loads were all first worked up with the copper checks.

I did have to do some experimenting to find the perfect thickness of al.
.010" was supposed to be perfect, but .014" worked best with my material, but only after annealing for best fit.
On the other hand, i tried some .010" half hard al. checks from Sage's and they shoot as good as my .014" al.

I'm working up loads with hornady copper checks in my new .308 now and can't wait to try some of Josh's 30 cal. al. checks in it. The material he describes sounds like a winner to me.
I have come to view gc's and gc material and thickness as just as important as any other component in a load.
It pays to experiment with gas checks and that's part of the fun.

 

[kenneth]

thank you! informative and very interesting.

 

[KHornet]

Good and interesting thread. I have been using both Al and copper depending on availability for a long time and have been satisfied with both. Things change over time.

 

[quicksylver]

I have come to view gc's and gc material and thickness as just as important as any other component in a load.
It pays to experiment with gas checks and that's part of the fun.

Right on !!!....
Choices come with consequences ...now that we have more choices in check material they are definitely something to pay attention to...it's an eye opener to me...

Along with additional accuracy testing of the 466 w/ Al. checks and 2400..I am going to go to the other end of the spectrum and see what happens with the 299 and AA4064...probably will be using my '03 for that...

 

[quicksylver]

OK Guys!!!!....dang I can't hold myself back anymore!!!

One of the reasons I chose the 314466 was because it had to be sized down so far....from .315 to .310

I was expecting at least one comment on how that was supposed to be such a bad move ..

Oh well!!!....

 

[KHornet]

My only comment is: If that is what it takes and it works, don't fix it! Have gone down that far a couple of times myself!

 

[Tony]

Since you already "know" it's a bad move I did not see any point in mentioning it. LOL

 

[quicksylver]

You guys used to be a lot more fun...

 

[fiver]

I got no room to say anything.
I use a super similar bullet in my 30-30 and also in the 7.7 jap.
I push the checks on and dip lube the two bottom grooves, then size to 310.
for the 7.7 I used to run them through the 312 sizer which I gave away [not thinking] and had to replace.

 

[S Mac]

So, what a novice CB shooter might take away from this is with aluminum check you can expect a slight velocity increase? Maybe because they have slightly less friction down the bore?

 

[quicksylver]

So, what a novice CB shooter might take away from this is with aluminum check you can expect a slight velocity increase? Maybe because they have slightly less friction down the bore?

So far that is correct. ..I am going to run some heavies with a slow powder over the chrony to see how they compare. ...

I did run four more 5 shot groups using the AL checks and two different charges to see if accuracy would improve...it did not.....
I will post pictures......

Just remember this trial is being done with my gun ...you may get different results with yours....