'Freechex' range report.

[JeffinNZ]

Team.

Tested some of my own gas checks ex Charlie's "Freechex" TM gadget today in both my SMLE and No4 MkII. Checks made from 0.011 printing plates in aluminium. Results were at extremes IE; terrible and fantastic.

Good first:

SMLE pushing a CBE 313 220 over 41gr of H4350 for 2000fps - proven 2 MOA load. Threw the first round for some reason but 2-5 into 1 inches at 50.



Bad:

No4 MkII pushing a CBE 316 175 over 47gr of H4350 for 2390fps - recently proven 2 MOA load. Patterned like a shot gun.



Sooooo, what was the difference? Shank/check fit. The 316 175 bullet has a slightly stouter shank. Jim at CBE cut it bigger as he intended the bullet to be used in over sized .303 barrels. The 'Freechex' were a snug fit. On the 313 220 bullets the checks were very loose.

I surmise the checks are coming off the 313 220 loose shank uniformly however not so on the 316 175 and thusly causing the bullets to skew in flight. The top right bullet on the second photo actually appears to be yawing which reinforces my theory.

Tomorrow I am testing the CBE 313 215 in the No4 MkII and the Lyman 311316 in my .32-20. 'Freechex' loose on both. More later.

[copdills]

Thanks for the Report Jeff, keep us informed

copdills

[leftiye]

I kinda wondered if the aluminum cans were thick enough to make a good check. I see you used printing plate, maybe still too thin?

[JeffinNZ]

Team.

Shot the No4 MkII again today this time with CBE 313 215 bullet and 'Freechex' which was a loose fit on the shank. Load is 20gr of AR2205/H4227 for 1640fps and a proven sub 2 MOA load. Here is result at 50m.



The shoot to the right was an 'OIE' - Operator Induced Error. Other 4 measure just shy of an inch.

This appears to prove my theory that on a loose fit shank the 'Freechex' come off consistantly in flight and contribute to great groups. On the snug fit shank however they are no coming off consistantly AT ALL and blowing accuracy.

Also shot the .32-20 with the Lyman 311316 however the results were very poor. I fear this may be a reflection of the alloy however and I will disgard the target and heat treat some more bullets and retest.

[Bass Ackward]

This is interesting.

Looking at the second picture in the first post. It looks as if the check is being torn apart as it is the last thing to leave the muzzle, just when the torque from the RPMs is the highest. Maybe the aluminum is more brittle than copper and it breaks up along the lines cut into it by the rifling?

[45 2.1]

This interesting.

Looking at the second picture in the first post. It looks as if the check is being torn apart as it is the last thing to leave the muzzle, just when the torque from the RPMs is the highest. Maybe the aluminum is more brittle than copper and it breaks up along the lines cut into it by the rifling?

John-
I have used freechecs extensively. One pop can layer sized onto a Lyman 311241 PB boolit. They did not come off nor were they shredded or cut by the rifling. They engraved perfectly and usually were in the hole, in one piece, or still on the boolit when dug out for inspection and results. I also have the original 30 caliber GC freechec die from Hanned. It used three pop can layers for a normal GC boolit. No difference in results on that one either.

[Bass Ackward]

John-
I have used freechecs extensively. One pop can layer sized onto a Lyman 311241 PB boolit. They did not come off nor were they shredded or cut by the rifling. They engraved perfectly and usually were in the hole, in one piece, or still on the boolit when dug out for inspection and results. I also have the original 30 caliber GC freechec die from Hanned. It used three pop can layers for a normal GC boolit. No difference in results on that one either.

Bob,

If you look at his first attempt at lower velocity, (almost wrote RPMs) he has no problem at that level either. And I would therefore suspect that mounting a single layer of aluminum on a PB bullet would result in a tighter, (supported) thus stronger fit.

Maybe the problem ( if there is one ) comes in the layering process and at the higher pressure or wind resistance? That's what I was getting at.

If you look at the picture, I see two tails as if maybe the first two layers cut or tore. But the fact that they are still there would mean that they still held in place.

Be interesting to see anyway as his testing continues.

[Larry Gibson]

Bass

Well at least you mentioned "RPMS" which leads me to believe you suspect the real problem. I've been investigating getting one of the Freechec tools myself and reports from several users say what 45 2.1 is saying. Not sure how JeffinNZ made that load "proven" as the one he loaded for the match was with 40 gr of 4350 I believe. Attached is a target and M43 report on a load of 46 gr IMR4350 I recently fired in a .308 with a 171 gr 311291 (not that dissimilar from the bullet Jeff is using). The group is 3.77", the RPM is 180,000 and the psi (M43) is 50,900. I'd expect a little better accuracy with the rifle + 10X scope I was using vs Jeffs but you get the idea. There is little doubt that Jeff's load in his SMLE is way over the RPM threshold and the group shows it.

Larry Gibson

[Bass Ackward]

Bass

Well at least you mentioned "RPMS" which leads me to believe you suspect the real problem. Larry Gibson

Larry,

I avoided the use of the word RPMs in order to differentiate between torque forces in the bore that increase with acceleration and those that you claim outside the bore. I still believe in RPM forces, but more correctly in what happens as the bearing length exits the muzzle and less and less of the bullet is available to handle the still increasing force. The fact that I can have just one load at 200,000 fly well, tells me that RPMs in flight are not the issue. AS I have said before, RPMs can be your friend IF they bring about stabilization at an early enough state.

If this tearing problem occurs with multiple layers of aluminum, then one could make an argument against tapered GC shanks that are common on factory designs. The sole purpose of which is to keep down customer complaints for difficulty seating checks. Junior1942 claimed tails at 110,000 that he believed were lead, but may very well have been check as this picture looks as he described.

Jeff is having no adverse accuracy effects at velocities that you would refer to as in the zone. We already know from decades of research that crimp on checks benefited accuracy. But it was believed that this was a sole function of coming off in flight. I suspect that the real damage to accuracy is done long before muzzle departure is achieved. And once the GC shank stripped, removal in flight is a forgone conclusion. In other words, the checks coming off were a result of the problem, not the actual problem. Cause even in the zone, check removal caused .... RPMs. This can not be if RPMs is the be all, end all creating "the zone".

Remember, my two successful attempts at 200,000 were in a 6.5-06 that I used a 270 bullet sized down. That means that the tapered shank was reshaped under controlled sizing for what almost amounts to being swagged straight and true. My other was with an LBT bullet where the shanks are cut straight and large for STRONG check bite. This also explains slower twist rates too as the torque forces are lessened with a slower twist thereby making a stronger base.

THIS is why I wanted to test the 311291 and asked to borrow your mold. But I don't want to turn this test into another argument over RPMs.

[Larry Gibson]

Bass

Those are just my observations with comparable results at the same velocity with the same twist. We are discussing what occured here with Jeff's rifle and bullet and my rifle and comparable bullet. What happened with your swaged down 270 bullet and the custom mould are different as we've also discussed before. I've shot one hell of a lot of lyman non- crimp on GCs since '68 and I never found a consistant lessening of accuracy with the Lyman GCs. Actually except for the rare occasion where the Lymnas were a poor fit accuracy was very much the same. I still have some older Lyman GCs in .25 and .35 calibers. Tests a while back again showed no difference in 100 yard accuracy between them and Hornady crimp on GCs. Tests in very accurate rifles with custom moulds have shown the crimp on GC to be slightly more accurate, sometimes. The accuracy of the crimp on GC is most often better when the Lyman GC was a loose fit on the shank as you mention. With original Lyman moulds this is not the case and their accuracy is just as good with either GC. However I really doubt that Jeffs SMLE, even as nice as it is, can really tell the difference. I'm not arguing over the RPM issue. I do agree that the loose, thinner GC may have not sealed the bore and perhaps caused some additional damage to the bullet. However, that damage is then more noticeable in the adverse effect the high RPM has on the bullet during flight. I just stated the obvious and backed it up with a factual test demonstrating said inaccuracy. I'll not argue this issue further but will continue to present facts. This thread is not the place for further discussion of this.

I also agree with 45 2.1's post in that the several other shooters, all very competant cast bullet shooter, who use the GC making tool report the same as he does.

Perhaps Jeff could doublr up or triple up on the GC thickness as 45 2.1 mentions and then test this same load again? That might answer some questions.

Larry Gibson

[Bass Ackward]

I've shot one hell of a lot of lyman non- crimp on GCs since '68 and I never found a consistant lessening of accuracy with the Lyman GCs. Actually except for the rare occasion where the Lymnas were a poor fit accuracy was very much the same. Larry Gibson

Now see, isn't that something. I am just the opposite.

In fact, I can show you accuracy change just by changing check anneal, little alone changing check type. Some guys don't like the Gators for just that reason. My 35s can get another 100 fps before RPMitis sets in just going from a soft gator to a harder Hornady. Strange world huh?

[JeffinNZ]

All good stuff guys however I am using a SINGLE layer of 0.011 aluminium.

Not so sure about the forces 'tearing' the check material. If the lead is up to the job then surely the alloy is too??

Thanks for the interest though. I am just absolutely stoked they work so well up to the 2000fps load as 99% of my shooting is less or equal to this.

[Bass Ackward]

Not so sure about the forces 'tearing' the check material. If the lead is up to the job then surely the alloy is too??

Jeff,

Picture in your mind a bullet exiting the muzzle of a barrel. Eventually the GC is that last thing that leaves. That bullet is still accelerating. And the drive forces that were being shared by that entire bearing area is now solely on the check when forces are at their strongest point.

The check material and bite must be able to hold this force. The check material must form to the rifling as it enters the bore and simply not strip back. If it strips back, then there is less rifling shape imparted into the shank for the bite. In essence, you get the same effect as short rifling.

This is what I was considering. The fact that you are running a single piece of aluminum has me wondering 1. if it is ductile enough to conform to the rifling easily. And 2. if it is tearing upon exit. I would assume that not all aluminum is pure and some more flexible than others. A single layer of a beverage is so thin that it can can bite into a PB bullet maybe even better than a conventional check as it's tighter contact. Is that happening with your aluminum? That is what I was watching.

Don't misunderstand me here. I am not looking at this for pros or cons to aluminum. Shooting is a sizing and engraving operation done at high speed. What does this do to checks and bases in general. Is your aluminum showing us what ultimately has a copper check fail and causes what Larry refers to as the RPM effect? This train of thought can explain why harder lead is needed to hold this GCs bite in addition to surviving pressure as velocity increases. It would also explain PB failure at lower RPM levels. It would also explain paper patch success. It would also explain slower twist rates for lead. It would explain lower rifling height effects too. It could explain choking to a degree as more lead is being available for a tighter check bite as it sizes and elongates into lose space. Or why microgrooves do better with larger bullets. It would also explain the benefits to gentler leade angles on rifling for lead too. Many things as it relates to cast.

Then it would leave us with the question, how thick should a GC be before the inside rounds off enough that it negatively affects the bite on the shank? My mind off on another tangent.

Jeff: It would be nice if you could recover a few and report on them. Look to see if the aluminum maintained a square smooth base or if it turned back (created a sharp knife like edge) on the base.

[JeffinNZ]

Phewph! You're a thinking man alright. All good stuff. Pretty hard to recover checks but will try and find some. Pea metal on the range floor will make it a challenge.

Last evening a 'bumped' some 311316 bullets with a 'Freechex'. They bumped from 311 to 313-314 and the check is now a TIGHT fit. I have a load for the SMLE that produces just shy of 2400fps using these bullets over 18gr of 800X so will try them out and see what happens.

[Bigjohn]

I agree, I have spent many an hour digging in the backstop to recover boolits to confirm if the checks remained on or departed somewhere up range.

John.

[Larry Gibson]

Jeffin NZ

You've got to ask yourself howm many angels are dancing on the head of that pin? A lot of us don't buy off on the GC (let alone the bullet) being torn or even disturbed to any degree by the "torque) on exit from the muzzle. If you consider just how few fps in velocity the bullet may gain during the length of travel of the bearing surface on exit and the minimal twist in that distance then you'll see the torque applied to the front of the bullet is miniscule. What I'm pointing out here is there are other points of view.

Let us know what those bumped loads with the tight GCs do.

Larry Gibson

[leftiye]

Larry, It's not any fairy story. Many of the things we deal with aren't convenient or possible to observe. Bass's logic is still correct. All of the torque is still on the check at that point. Whether it tears or not is up to how thick, tough, etc the check is. It might tear (or have already torn) anyway regardless of trque, though torque would help.

As has been said, it may not be any better for the check to stay on, than it is for it to fall off, but if they fall off, they must all fall off, or it must be that none of them fall off, or else accuracy will be affected. AND if they fall off they must all fall off at the same point in their journey.

And (another of your favorites) let us not forget the effects of muzzle blast at exiting the muzzle. What happens to a torn gas check at this juncture, and what does that do to accuracy? It would seem that being intact at exit would be very important. Printing plates are a little brittle, if I'm not mistaken (my wife makes plates for a printing company). Not as soft as pop cans anyway.

[Bass Ackward]

Some people don't like to think. An that's OK. Pass this post then. Cause this is gonna be a twister.

I gave you the scenario of a GC exiting the barrel. What happens to a tapered GC shank in the beginning of the ignition cycle? Think of this as a bore sized bullet.

We know that pressure comes up incrementally if you can imagine slow enough. A GC is supposed to perform an early seal. It will size that way, but will it maintain it? And a GC is supposed to scrape the bore of fouling.

If only the front part of the check is making strong contact on the taper, then there is a hollow space between the check and the shank of the bullet. As the pressure comes up, the first thing that happens is that the check gives way to the pressure. It folds forward, forming to the shank of the bullet. In effect, it forms a boat tail bullet. As it slides forward, it breaks seal as the front of the check is closing up the GC groove as it extends forward. Since lube can not be compressed, it will follow the path of least resistance and flow back. So depending on the powder speed and how fast pressure came up, we could now only have full rifling contact on the front of the check. Plus we lost precious lube that supported and strengthened the base.

Now pressure comes up enough that the lead starts to deform. It's going to deform out until steel stops it. How is this deformation going to occur? From the back, but uniformly? I suppose if there are no air pockets in the base. But anytime you have uncontrolled deformation, it can do and go how it wants really. Now your GC groove is narrower than it was originally, and your lubrication for this highest obturating area has been reduced. How can this be a good thing?

What does choking do in this situation? We know that choking provides alignment. We also know that sizing bullets makes them longer. Choking also has to provide a back flowing of excess lead as the bullet sizes down that lead as it enters the bore. This conceivably happens before the check deforms, but most certainly before the base deformation occurs. So the space between the check and the shank is filled with lead coming back as opposed to the base folding forward. This process should also elongate the GC groove and the extra (excess) lube in this space that was filling the extra diameter, now fills a longer groove as volume remains the same. You might still lose some lube, but you had excess anyway. So lube pressure is maintained when the pressure seal is completed. And the base GC fit was formed before pressure had a truely deforming effect. Does this happen in every case? No. For really hard lead at low pressures, this may remain a boat tail bullet until it exits. But losing lube would not affect low velocities where you have plenty to work with. Having less rifling contact would have less effect at lower velocities too. It would show up as worse accuracy as velocity increased. Especially upon exit where it had to hold all the rotational force.

As a cast bullet increases in velocity, it requires more lube, and there is the likely hood that it will eventually lead at some point. This doesn't occur at lower velocities. So knowing how a GC removes fouling, under a narrow GC or wide GC scenario, which would have the more capability to remove more fouling and thus perform at a higher velocity level?

Possible? I certainly think so. Could explain why some guys have better HV success sizing with larger diameter bullets. Especially using factory designs. But I think that it's best to start with a solid and full check to base contact instead of having to rely on one occurring.

[Larry Gibson]

Bass and Lefteye

That's all well and fine in a theroretical world. There are lots of "logical" thoughts that have been proven false. To keep keep this short Bass, instead of the long drawn out process that you envision happening we can agree that obturation starts at the bottom of the bullet. Thus how about the base of the GC pushing on the base of the GC shank causing it to obturate and sealing the bore as the bullet moves forward? That is the most common thought process envisioning what happens when the old style Lyman GC were used on loose GC shanks. You make it sound like all sorts of horrible things happen when an old style Lyman GC is used. Isn't so, theyve been used quite successfully for many, many years.

Lefteye

As I told Bass, it is very doubtful if Jeff's SMLE, even as nice as it is, is able to tell the difference in accuracy between the two types of GCs. I've numerous similar milsurp rifles that have proven they can't tell the difference. I have a couple very accurate rifles that can tell the difference. However there is only a difference with certain types of loads out of those rifles. I can also state for a fact that the accuracy edge between the 2 types of GCs is very small. At no time did I ever have a group go from 2 moa to 5+ moa for example. Jeff's rifle can't tell the difference, especially based on one 5 shot sample. Maybe if Jeff shot ten 10 shot groups of each type of GC he might tell a difference. I don't think you or I are good enough to make that distinction on the one 5 shot group shown. To the contrary I can make an observation that that group of his as it matches the many hundreds of such almost identical groups I've fired and seen fired where the cast bullet exceeded the RPM threshold with identical type loads.

That's all I'm offering here is another view on what the cause of Jeff's poor group with his SMLE was. I am not going to get into another discussion of hypothetical causes with the two of you. I made a direct comparison with a very similar load, bullet, cartridge combination That gave a measured result. I'll leave it at that and to Jeff to take it or leave it. You two have your minds made up so let's just end it now.

Larry Gibson

[leftiye]

Larry, That's nice, but what does it have to do with what was said? Tis nother subject. You're probly right that the gun might not be able to tell the difference. But there was a difference that caused Jeff to post, and we were just trying to help out. You're still on another subject and therefore it shouldn't have been addressed to me as a response. If you're not interested in hypotheticals as you say, nor anyone else's thoughts then why argue with them?