EAA Witness 10mm to 40 S&W

PapaBSRPapaBSR Member Posts: 25 ✭✭
edited August 2012 in Ask the Experts
Has anyone tried just a barrel and mag swap on the EAA Witness with out replacing the slide? I have done this on other handguns with success.


  • cavman 69cavman 69 Member Posts: 654 ✭✭✭✭
    edited November -1
    i think you can shoot .40s&w out ot a 10mm barrel. the 40 is the same caliber, just shorter brass. like shooting .22cal out of a .22LR barrel. i could be wrong, hopefully someone else will confirm or not.
  • catpealer111catpealer111 Member Posts: 10,695
    edited November -1
    Contact EAA, you can buy a conversion kit that comes with a slide, barrel, guide rod and spring, and a magazine to properly convert your 10mm to .40 S&W. Trying to shoot a .40 out of a 10mm barrel/chamber is risky at best. Both of these rounds headspace off the mouth of the case. With the .40, you'd be relying on the extractor to keep the round in place.
  • 62fuelie62fuelie Member Posts: 1,036 ✭✭✭
    edited November -1
    The 40 S&W headspaces on the case mouth so the function may suffer in the longer 10 mm chamber. You may be able to use the 10 mm magazines even though they are for the longer round, just seat your bullets a little longer. You may need to use a lighter recoil spring for reliability. I would start with a BarSto barrel and a Wolff recoil spring for 40S&W then replace other parts if required for function.
  • beantownshootahbeantownshootah Member Posts: 13,137
    edited November -1
    I've heard of people just running .40SW through stock 10mm guns with NO modifications whatsoever, but I've never tried this myself (nor would I).

    From my perspective, a "minimal" 10mm to .40SW conversion would entail at least swapping in a proper .40SW barrel for headspace, and an appropriate .40SW weight spring to ensure good reliability.

    You might be able to get away running .40SW through a 10mm magazine, though IMO .40SW EAA witness mags are pretty easy to get, and so that's probably a better way to go.

    Now in fact, its possible (and maybe even likely) that the EAA 10mm shares the exact same slide as the .40SW, so this might actually be "the" conversion, but I don't know that for sure. You could contact EAA and ask them, they might tell you.

    Edit: In other words, I'm saying the EAA "10mm" slide and the "40SW" slide might be otherwise identical. Don't know. . .but given the barrels are the same caliber, and likely to be the same external diameter it seems likely to me.
  • fl23infl23in Member Posts: 404 ✭✭✭
    edited November -1
    quote:Originally posted by cavman 69
    i think you can shoot .40s&w out ot a 10mm barrel. the 40 is the same caliber, just shorter brass. like shooting .22cal out of a .22LR barrel. i could be wrong, hopefully someone else will confirm or not.

    Big diff young one. you talking about Hunderds of in pressure diff. i sure as hell would not ever listen to your line of thinking. that is like sayin oh u can shoot .308 out of 30-06, they are both .30 cal head spacing IS VERY IMPORTANT [V]
  • PapaBSRPapaBSR Member Posts: 25 ✭✭
    edited November -1
    I seen this on a website....think it's credible?
    Note, I have large frame .40 barrels in stock which are used to convert a 10mm Witness pistol to .40 with no other parts needed for the caliber conversion. You can use your 10mm slide and magazines with this barrel to run .40 ammo in a 10mm pistol. Same cost as standard barrels and probably not available from any other EAA/Tanfoglio parts vendor in the USA.
  • ToploaderoneToploaderone Member Posts: 4 ✭✭
    edited November -1
    IF you have the 'large' frame (barrel dia .590) you CAN convert your 10mm frame to shoot .40 S&W by only changing the barrel (and spring). I have one, a 10mm complete pistol, with a 40S&W barrel, 9mm barrel, and this weekend a .357 Sig barrel. They all use the same extracter, slide etc. All the 10mm clips work fine, all the 40S&W clips work fine. 357 Sig should work fine with the 40S&W clips too. The barrel being used for the 357 Sig fits the slide better than the original 10mm and the 40S&W was a drop in (it came from EAA, 9mm from Numrich). I got a spring assortment from Wolff because the original 10mm would throw the brass almost as far as the distance to the target (25 yards). Now use a 20lb for the 10, 18 for the .40 and probably an 18 for the Sig.
  • gunnut505gunnut505 Member Posts: 10,290
    edited November -1
    Not sure about the Witness line, but my Sig Pro 2340 swaps from 40S&W to 357Sig with only a barrel and spring change.
    I don't have any 10mm stuff since I got rid of my Delta Elite; but my Witness in .40 will chamber a 10mm empty.
  • rsnyder55rsnyder55 Member Posts: 2,626
    edited November -1
    I know this is a different manufacturer and may not apply, but I am shooting 10mm, 40S&W, and 357sig out of a Glock 20C and only change the barrel. The 10mm magazine feeds all three calibers fine. I do not have the change the springs.
  • CS8161CS8161 Member Posts: 15,418 ✭✭
    edited November -1
    I have an EAA Witness 10mm and I had to give it a try. The 40 S&W ammo fed thru the gun flawlessly. I fired about fifty rounds of 40 caliber ammo thru the stock 10mm barrel, using the 10mm magazines. No problem. I don't think I would do this on a regular basis, but it did work fine. I may invest in a 40 caliber barrel, no need to buy 40 caliber mags or even change the recoil spring in the pistol.
  • tsr1965tsr1965 Member Posts: 8,682
    edited November -1
    The 10mm slide will work ok, but you need a barrel, for headspace reasons(and don't let anyone tell you otherwise), most likely a magazine, and lastly a recoil spring. you should be able to get all this for $150.00-200.00.

    quote:(and don't let anyone tell you otherwise),

    Yes, a 40 S&W, can be fired in a 10mm Norma chamber, safely, and reliably. Yes, pistols with tight extractors, might hold the round in place for the firingpin to detonate the primer. However, with just the extractor holding the case, you are asking a lot.

    The most proficient means of firing a 40 S&W, in a 10mm Norma chamber, is the S&W 610, 10mm Norma revolver, which uses moon clips to hold the cartridges by the rim, for extraction. This method has been used in revolvers for 45 Colt/45 ACP, and 357 Magnum/38 special. On a side note, the 38/357 are rimmed cartridges, and will headspace on the rim also, but some speed shooters have their revolvers cut specifically for use of the moon clips, wwith the 38/357, for speed loading/reloading purposes.

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