id say go and hit Underwood up for some good 10mm but if I remember the colt does not have a fully supported chamber so I believe they don't recommend it for that pistol.
I have a Glock 20 and like the 10mm round a lot.
If you find a good source for ammunition please share the information.

I have used the Winchester Silvertips 175 gr. in it for ages with no problems.


Bunch of 10mm at Hillsboro Sportsmans. HPR I think. I picked up a box to try. It is supposed to be full velocity loads (close to 1300). Other than that I love BB 200 grainers. When I load my own I go with 800x. I usually only load 8g with 180xtp's, but have been up to 10g. At 9g I get minor Glock smiles, at 10 I got pretty good Glock smiles and I had to toss the brass. You may be able to go up to 10g's using the 1911, perhaps better chamber support...
HPR ammo didn't feel as full powered as the Underwood to me but I don't chronograph, so sort of subjective. Underwood is awesome in my opinion. They seem to sell out pretty fast.
Underwood is good stuff, but read the warning at the top of the 10mm page first.

Cannot be used in Colt Delta Elite or any other firearms with rampless barrel due to complete lack of case support.

Safe for use in all 10mm firearms with a ramped feed barrel. (Examples: Glock, EAA Witness)

I recently picked up a Glock 20 Gen4. The reason I went with the Gen4 vs the SF is that the grip is .002 inches smaller with the backstrap that comes with it than the grip of the G20 SF and you get two larger backstraps and 3 magazines. The gun is a blast to shoot. I’ve shot Underwood, Double Tap, Buffalo Bore, Remington UMC and some Georgia Arms. I like Underwood the best, but it’s not cheap. This is a range and a woods gun for me, and I just ordered some Underwood 220 grain hard cast bullets to try out for woods carry. Looking forward to shooting them.
I have a EAA Witness and a Glock 29, both are 10 MM. If you have a Colt look carefully at Underwood's 10 mm page as only a few are recommended for a unsupported barrel. I think I'll take the Witness to the range today,
I have mixed feelings about the 10mm. I feel as though the only guns that can live up to the advantages of the 10mm over the .40S&W are the Glock 20 and steel framed EAA's(and the Ruger Blackhawk Buckeye, though quite rare.). I am sure fans of certain S&W models will disagree and that is fine. In the G20, it is the only autoloader I will carry that isn't a full size 1911. I find the Delta Elite to be a beautiful firearm and it has definitely seen great improvements since it's early days. I just wish it could handle the loads that validate the 10mm over the .40S&W.

While I have not used the Underwood 135gr. Nosler JHPs, I have handloaded them in both the .40 and 10mm and they are NASTY. I have used the Underwood 220gr. hardcast and a similar load from Buffalo Bore. I can also contend that as an everyday load, the Winchester Silvertip 175gr.(the 175 Silvertip in .41mag is the only factory round I use for that caliber.) is great stuff. I personally carry an assortment of Ruger Blackhawks(.357, .44spl. NM Flattop or .44mag SBH) for carry out here in the middle of nowhere. In the city I carry a 1911 in .45 and a Ruger LCP in .380. I would completely concede that a G20 can and will cover it all. Out here, carry the 220gr. hardcast(were I forced to shoot a bear with an autoloader this is the only load that would provide any confidence at all, of any caliber.) and in the city the 135gr. Noslers.

Does anyone have an opinion on the Magsafe 96gr. Defender(1,800fps from a Delta Elite) and 46gr. SWAT(2,400fps from Delta Elite) loads? In my nightstand sits a .44mag with 117gr. Defender loads(2,000fps from my SBH. It will truly go bump in the night.) and they definitely work as advertised. I picked some of the .44mag up from a forum member and was so impressed that I purchased more online. If the 10mm stuff is as advertised, it should be incredible.


Underwoods 155gr golddot load @1500fps is about as good as it gets for a CCW load.
I hand load 180gr bullets to 1300fps and they do alright for in the woods.


Arms Collectors of SW Washington Gun Show
Battleground Community Center
912 E Main St, Battle Ground, WA 98604, USA
Rimfire Challenge Dec 12th @ DRRC
Douglas Ridge Rifle Club
27787 OR-224, Eagle Creek, OR 97022, USA
Albany Rifle & Pistol Club (ARPC) Gun Show
Linn County Expo Center
3700 Knox Butte Rd E, Albany, OR 97322, USA


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