17 ccm primer pocket expansion, hope you find this interesting

[foxhunter]

a while back trcuda posted in a thread that he re swaged his 17 ccm case heads back to hold a primer, done enough it would work harden the heads to handle more pressure and save cases.
fired some loads with the cases ed donated a while back (thanks again ed) here is how the experiment went.

factory case heads measured .3025 primer pocket hole measured .1725
fired; using 20 gr vmaxes
7.2 gr aa 1680, loose primer pocket
7.4 gr aa 1680, loose primer pocket
7.6 gr aa 1680, loose primer pocket
7.8 gr aa 1680, gas leak around the primer, would not hold new primer.

case heads measured .305 on all give or take .0005

swaged 4 cases down to .300 with p-pockets at .1695
fired 4 rounds each with 7.2, 7.4,7.6 and 7.8 gr aa 1680

here are the results;
7.2, case head .300, p-pockets measured .169 tight
7.4, case head .3015 p-pockets measured .170 tight
7.6, case head, 302, p-pockets measured .1705 tight
7.8 case head .3025 p-pockets measured, .1735, .1735, .174,
.175 , .1735, .174 still help primers but not snug, .175 pocket had slight tension on the primer , next time fired it would have leaked

re-swaged the case head back to .300 and the pockets to .1695 and pockets were factory + snug

note the last load of 7.8 gr aa 168 did not leak gas around the primer

[Skypilotbc]

Not owning one, I still find your efforts and results with the .17 CCM to be potentially very useful. Thanks for posting it, Bob!!
Bob

[Rodgervich]

That is indeed interesting Bob BUT be cautious. It is true that the brass will work harden and tend to hold shape and size but repeated work hardening will also cause the brass to become brittle, just like case necks. If you load them hot and repeatedly swage the heads eventually they will crack, most likely right up the side of the head rather than loosening the pockets.
These are my thoughts based on academia and not experience, I would nevertheless advise you to use care with this practice. I selfishly want to keep you around in good health to answer my future questions.

[foxhunter]

thanks paul, maybe that's why trcuda never answered my post, i hope he didn't blow himself up.
i thought it was interesting that all the loads from 7.2-7.8 expanded the primer pocket equally but not so once the case head was re swaged. 7.8 caused gas leak all the way around the primer but didn't on the second firing of the same case.
just wonder how many times the head would have to be worked before it would reach the same hardness of good factory brass? and how long the cases would last with a moderate load?
7.2-7.6 gr seemed to retain the primer pocket tension quite well and probably could be used several times without further swaging.

[Monted]

That is interesting and I think I will play with it some myself. What are you useing to re swage the base of the case? I at one time fooled areound with swaging the base of a 223 case useing an old arber press and a plate with a hole of the proper size that had been polished. It worked OK but it did not affect the primer pocket any that I recall. Did you get a chance to run any of those loads thru a crono. to see what kind of speed you were getting?
10 Pm and it is 52 deg. outside. Is this winter in Mont. Ed

[foxhunter]

ed, used a rcbs collet bullet puller in .30 caliber, the case will fit thru the shell holder hole to keep the case centered and square, once the collet tightens down 1/4 turn does the trick.

it was 54 here today and no i did not use the chronograph yet but i think they are pretty slow due to the brass being soft. watch your case length on the 17 ccm, some cases were .020 to long before firing.

[Larry in VA]

[quote=foxhunter;5457]ed, used a rcbs collet bullet puller in .30 caliber, the case will fit thru the shell holder hole to keep the case centered and square, once the collet tightens down 1/4 turn does the trick.quote]

Hey Bob:

I’ve been following your posts with a good deal of interest since I have a Cooper in 22CCM that’s doing the same thing. Primer pockets are getting real loose after only a couple of firings which should be fairly light loads, also my primers are popping out about 1/32 to /18 of an inch. Either I have a head space problem on the gun or Schroeder cut the rims way to thin.

Is there any reason why the method of using a RCBS 30cal. bullet puller wouldn’t work to swage down a primer for a 22CCM? Also how are you measuring the primer pocket diameters?

PS
Bob; Still looking for that bullet straightening thingy. I know I have it some where. I’ll let you know when I find it. Wify straitened up my gun room while I was healing from my MC accident and am still looking for stuff. She was well meaning, but there was order to the chaos.

Larry

[tim simbari]

Bob, unless I missed it ,What are you using for primers? I neat idea I was told way back in the early days of the CCM was to use Winchester pistol primers. With 1680 the accuracy is very good, nice ES and they seem to be a bit larger and seat well. Give them a shot. Altough 1680 varies considerably, I use 9.2gr with 20gr Bergers with no serious issues.

[trcuda]

Bob,

Your test results mirror mine very close. However there are a couple of places that you have mistaken my original intentions. First, I have only swaged the pockets of my cases one time. I think that repeated swageing might eventually cause over hardening and possibly splits if used at high preassures. Not sure that this would happen at CCM preassure levels but who wants to find out! Second, the whole reason for this project on my end was to salvage CCM brass that had developed loose pockets from ONE SHOT (HMR Equiv) power level loads. My brass was NEVER loaded with a load hotter than 20 Vmax with 7.1 gr of WC 680 (slightly slower than 1680, equiv to 6.8 gr of 1680) with CCI 500 primers. This is my proven load for my rifle with ONE SHOT brass and is the load I intend to use with the reswaged cases as well. This was NEVER done with the intention of being able to use hotter loads, only to salvage expensive, hard to find, overly soft brass that was only used with rimfire level loads. I would not try this project with a case that ran at 50-60,000 PSI although there is a tool out there for reswaging primer pockets in small rifle cases. To me it is not worth the effort for cases that are commonly available.

One test I did not see that you had done was repeated firings at the 7.2 gr.level with the same case. This was the test that was most important to me. I think that you will find that you can get at least 5 more firings before the pocktets loosen up. My oringinal tests had one case that was at 10 and still going strong.

Your idea of the bullet puller is a good one. I may have to try that somethime. My method is to use a .301 (IIRC) TiN coated neck bushing pushed over the case untill it bottoms out on the rim. The case is then pushed out with a knock out rod. I can do several a minute with this method, but your way may be faster if it is consitant enough.

Hope this clears up some of the confusion.

Tim

[foxhunter]

tr, been waiting to hear from you on this subject, 6.9 gr of aa 1680 produces 17 hmr velocity with 20 gr vmaxes, should have more knock down power.
now to chronograph a few of these loads to see how fast they are going.
haven't put the rifle on the bench yet to test for accuracy, may do that today.