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PC4 to 10mm conversion?

5253 Views 28 Replies 12 Participants Last post by  fubar
I'm interested in a 10mm carbine. Would it be practical to re-bore the chamber in a Ruger PC4 to accept a 10mm round. Ruger has not responded to my inquiries. I understand there is a significant increase in pressure in the chamber and recoil when firing. I believe that modern firearms are designed for safety and as such significantly over designed for chamber pressure and would remain safe with this conversion. As to recoil, a more powerful spring and possibly a butt pad would probably suffice.

Does anyone have any information or feelings on the subject?
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Col.

I know Olympic Arms is making uppers and guns in 10mm. I think you ought to talk to a competent gunsmith to see if the PC4 conversion is feasible.

Mike
Since the Ruger is blowback operated the heavier recoil of the 10mm would be a very bad thing. It is almost sure to beat itself up and unless you are able to craft a bolt that's about twice as heavy it's not a good idea.

Mike you are correct about Olympic Arms but the 10mm unit I tested was gas operated. That was a long time ago and they may have changed it but I wouldn't think so.
This link will take you to Olympic Arms pistol caliber uppers.

http://www.olyarms.com/usa.html

Click "Retail Catalog" in left sidebar then click "Pistol Caliber Uppers" in top right hand column of the page. They do have 10mm listed but are A2 types rather then M4 flat-tops.
Two more issues. One, what to do for magazines? Two, would a magazine big enough to hold 10mm fit in a PC4 mag well?
Thanks to all. The magazine well on the PC4 has sufficient walls to allow cut and fill modification for a 10 mm mag. Feed angle would be the biggest concern but could be managed. I currently have a EAA Witness compact and used one of my magazines to size it up.

I've looked at the Olympic Arms concept but was really looking for somthing with a rifle stock not a pistol grip.

Finally, does the blowback operating system really require a heavier bolt? I was issued a Thompson back in my days with 2dForce and hated the weight. Can a beefier spring handle the recoil but still be light enough to charge the weapon? I had two officers in Baghdad over the last year that couldn't cycle their pistols and I made them stay in the Palace until we took them back to the airport.
The recoil of full charge 10mm ammo is almost twice that of the .40 S&W and the best and safest way to manage that is to increase the mass of the slide. Springs are given way too much credit and increasing spring weight is rarely a complete solution.
Good to see you, Colonel… you didn't waste any time getting here.
Colonel G said:
…does the blowback operating system really require a heavier bolt? I was issued a Thompson back in my days with 2dForce and hated the weight.
Willikers, most do/did… it was helpful in absorbing recoil, of course, in witness whereof is a photo that most who've been to the High Desert Dojo may recall, of former USMC Colonel Jeff Cooper firing a Thompson SMG off his chin!

But I'm confused about one thing, and perhaps you could illuminate us… when did the Force have Thompsons? I was under the impression that when Force stood up in the late '50s they used the SMG, Cal. .45, M3A1, which they continued with 'til '65/'66 when they moved over to M14s and then the M16A1s.

As for the Corps, after replacing the M50 and M55 SMGs in '42, primarily with M1 Carbines and a smattering of Thompsons in all models, I believe that they all were replaced circa '44/'45, yes?
I had two officers in Baghdad over the last year that couldn't cycle their pistols and I made them stay in the Palace until we took them back to the airport.
Officers unable to cycle their slides? Ye Gawds and little brass buttons, man, what does that say about the Proud and the Few of today?!? (And these were what pistols, BTW?)

Sounds like you're been around for a while… what's your FRA number?
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Colonel G said:
...I had two officers in Baghdad over the last year that couldn't cycle their pistols and I made them stay in the Palace until we took them back to the airport.
Was that from lack of strength or from sand & grit?

I had a customer come into the shop after returning from a tour in Afghanastan with a similar complaint. He had a standard issue Beretta M9 & didn't get to clean it for a couple of days. On the night he finally did get to pull it down, the slide locked up half way back from the sand & crud in it.

After that, he "aquired" a 1911 like everybody else in his unit had.

Troops unofficially aquiring 1911's, FBI HRT getting 1911's, LAPD SWAT getting 1911's, & according to an article in the new issue of American Handgunner, some recon Marine outfits have 1911's. The more things change, it seems the more they stay the same. Perhaps someone somewhere someday will finally get a clue & push for the best handgun ever issued to troops, to be re-issued.

Dean, I think there may still be some non-standard weapons issued in different units & commands. I was in the Navy in the 80's & one ship I was on, the armory had about 8 M14's, 2 Grease Guns & 2 Thompson M1's, as late as 1986. True I never saw the Thompsons removed from the locker for pratice or drill, but they were there.
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I was in 2dForce in the early 80's and Platoon Cdrs carried the SMG's. We had Thompson's, Uzi's and MP-5's.

I made sure all our weapons in Baghdad were clean; the joint officers sent to me were just unable to pull back the slide on their Berretas. I also had them empty and reload their magazines every week. I'd heard several stories of the magazine springs fouling and not feeding the weapon properly. Reloading 15 rounds in a magazine was a chore for most of us.

On issuing a new weapon I must say the 10mm is what it was intended to be-an excellent replacement for the .45. All the ammo produced for the .45 must be compatible with ALL .45's (lest the lawyers get invoved), and let's face it some are approaching 100 years old. The new 10mm weapons are made with much better, more consistent materials and consequently the ammo can be made consistently more powerful.

And that brings us back to the topic of a 10mm carbine. I like the idea of common ammo and magazines. I've read about M1 Carbine conversions to 10mm. I like the feel of the M1 Carbine and thought the PC4 in 10mm could serve a similar role.

One more note, no matter what weapon is issued the Armed Forces still need more live training. At the CPA HQ in Baghdad, the Marines at the gates keep score at the clearing barrel. The "O's" have far outpaced the "E's" and the contractors in the number of rounds fired into the barrel.

Know the condition of your weapon, train with a round in the chamber and magazine in the well, and be safe. Enough said!
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The new 10mm weapons are made with much better, more consistent materials and consequently the ammo can be made consistently more powerful.
I'm a little lost here sir. To my knowledge there are no "new" 10mms with the exception of a special run of Kimbers and the aforementioned Olympic Arms tops that you dismissed.

And in terms of "power" why in the world would you want a pistol cartridge when you can have the 5.56 NATO with ever so much more "power"?

The 10mm is very much on the wane and while it still appears in ammo catalogs, choices are limited.

But the thing that worries me most is the idea of making this out of that and then going into a possible combat situation. Unless you are able to test the thing for thousands of rounds- and possibly wear it out in the process- my ass would feel better with something off the shelf.

As a Marine O-6 I would bet that you can have your choice of anything with an FSN (or whatever they are called now) and our benevolent uncle will handle the logistics and give you all the ammo you want.

The M-4 has a flat top, collpasable stock and can be hung with several cool optical sights.

But that's just my opinion and I could be wrong :D
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Colonel G said:
I made sure all our weapons in Baghdad were clean; the joint officers sent to me were just unable to pull back the slide on their Berretas. I also had them empty and reload their magazines every week. I'd heard several stories of the magazine springs fouling and not feeding the weapon properly.
The "feeding problems" had much more to do with the fine grit sands of SWA preventing the 9 X 19mm rounds "rolling" into place at the juncture where the M9s' magazine "funnel" down from double-stack to single column. I reported on this in an Industry Intelligencer column at the time of DS/DS.
On issuing a new weapon I must say the 10mm is what it was intended to be-an excellent replacement for the .45. All the ammo produced for the .45 must be compatible with ALL .45's (lest the lawyers get invoved), and let's face it some are approaching 100 years old. The new 10mm weapons are made with much better, more consistent materials and consequently the ammo can be made consistently more powerful.
Except that, save the Winchester 175-grain STHP, it's not… as both Br'er Petty and I have noted on numerous occasions, the original "Bren Ten standard" Norma ammunition specs were, in the case of the 170-grain PCs, completely abandoned circa '88-'89, and as for the 200-grain FMJs, they simply fell into "disuse."
And that brings us back to the topic of a 10mm carbine. I like the idea of common ammo and magazines.
That may have been "practical" in the latter 19th Century when those who carried arms on the frontier had to cast and reload their own rounds, and certainly didn't have a Guns 'R Us every ten blocks to re-up their munitions, but at this stage of the game I think that "practical logs" finishes w-a-a-a-a-y up the track to personal conceit, because one would still be firing a pistol-caliber round from a shoulder-fired weapon, and the external ballistics would still pale beside those of a 5.56mm even from the shortest-barreled carbine.

In my never-quite-humble-enough-opinion, of course….
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I am not quite sure that I would want to issue the 10mm to the troops on a force wide basis, Unfortunetly, they don't receive the training necessary to become profecient with the round. In a handgun, with a full house round, not the FBI "lite" load, its a bear for most people to shoot well. If you are going to lite load it, why bother with a 10 at all? Stick with a 9 or preferably 45.

In a carbine, I don't see that either. The M4 is almost perfect for the job. If you want something less powerfull than the 223, it needs to be a sub gun, there again, why fiddle with what works? The M3's & MP5's have worked for years without many complaints.

Don't get me wrong, I love the 10, I have 2 of them & shoot them on a regular basis. But it takes ALOT of pratice to shoot well with the load as originally conceived. Loaded down does not make sense. Just shoot the 40 S&W.

Several depts around here are issued the .357 Sig, & there are grumblings about that round for the same reason as the 10mm, scores on the range went way down, female officers found it difficult to control, etc. About the same complaints of the 10mm years ago.

I am but a peon & nobody at the Pentagon asked me, but if they did, I don't see anything better for our boys in uniform than the M16 family of rifles, the M4 version in particular, & a single stack 45 for a sidearm.

And with all due respect to Col. Cooper & the rest of the "mousegun" haters who want a return to the M14, if it was so good, then why was it replaced so soon after introduction? And if the M16 is so bad, why is it still in use after 40 years, the longest issued service rifle in our nations history.

Things that make you go hmmmmmmmm.
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Charlie Petty said:
As a Marine O-6 I would bet that you can have your choice of anything with an FSN (or whatever they are called now) and our benevolent uncle will handle the logistics and give you all the ammo you want.
FWIW: FSN (Federal Stock Numbers) were replaced with NSN (NATO/National Stock Numbers) starting September 30, 1974.

Trivia: Did you know that the Ruger Super Blackhawk has its own NSN? :shock:
Alarmed said:
And with all due respect to Col. Cooper & the rest of the "mousegun" haters who want a return to the M14, if it was so good, then why was it replaced so soon after introduction? And if the M16 is so bad, why is it still in use after 40 years, the longest issued service rifle in our nations history.
Why has the USMC & the Army re-commisioned the M14 for Afghanistan and Iraq duty? Could it be Mattel's black gun is okay up close and personal but not worth a dern at distance?

As to Alarmed two whys? Politic$ and dollar$. If it wasn't for politic$, we'd be fielding the XM8 in 6.8mm instead of 5.56mm.
csmkersh said:
If it wasn't for politic$, we'd be fielding the XM8 in 6.8mm instead of 5.56mm.
If it wasn't for politics we would be fielding a SIG instead of the pizza pistola!

Ed
Both true although the 6.8 doesn't go back very far does it?

Top can probably answer this better, but it seems to me as if the one size fits all concept of the M-16 has always been range-limited. I know there were tests back in the early 60s which showed that the round would penetrate a standard GI helmet at 600 yards... hitting it was a whole different ball game.

The gripe about the M-14 was weight wasn't it? But Nam was an entirely different battlefield. There most infantry combat was at relatively short ranges and troops needed to carry lots of ammo so the lighter weight of the 5.56 cartridge was a plus. There were even experimental aluminum cased 5.56 rounds that were roughly half the weight so troops or aircraft could carry twice as much. I don't know if those ever made it into combat though.

Today's desert setting makes long range capability much more desireable, although I wonder though if the M40 (or replacement) plus the M240 and 249 light machineguns wouldn't meet most of those needs.
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Wasn't part of the M14's problem that it was virutally uncontollabe on full auto? I imagine the semi-auto version would certainly come in handy in some situations but certainly not for everyone.

Ed
If you fired it in 2-3 shot bursts it wasn't too bad but much better in semi mode.
When DoD first fielded the black rifle, it had a 1:14 twist rate. This limited its range but almost guaranteed the bullet would tumble on impact. But there were a number of problems with the early ammo. But it wasn't long the Army decided that the ammo feed problems the gun was having could be solved with a forward assist and while we're at it, let's change the twist to 1:12. This did lengthen the range so they changed it once again to 1:9.

But like CP said, 'Nam was an entirely different world. shotguns would have made more sense a lot of times. And you could pact double the number of 5.56 than the 7.62 NATO. Today a "sporting rifle" has turned out to be the distance king in Afghanistan - the Barrett .50 BMG and Sen Fineswine wants to outlaw them for the guys who made them popular to start with; long range sports shooters.

In comparision, the M14 is much harder to control full-auto than the M16, but even the M16 is a 3 round burst mode gun in its current M16/M4 versions. Aim at their crotch and stitch 'em up through the torso as it climbs. But if you need full auto, where's your M249 SAW or M240 LMG?
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