[3324]

I have been toying with this idea and have been reading customer reviews and other articles. One thing I see is the "conventional wisdom" that accuracy will suffer with a 1:8 rate of rifling twist in the 5.56 barrel vs. the 1:15 found in .22LR barrels. Can anyone give me an idea of about how much accuracy really suffers?

What I mean is I could live with a shot group that was twice the size as one from a 1:15 barrel. To me, that is not that much of a trade off for all the other benefits, principally cost savings and maintaining the basic platform I am using.

But a group that was four times as large -- eh, I wouldn't be happy with that.

If anyone has any experience with this, I'd be glad to hear your thoughts.

 

[Les]

I've tried both the conversion and a dedicated upper. With the conversion and a 1:9 twist I shot groups of 12" at 50 yards. With the dedicated upper I can shoot groups about 1 1/2". The conversion was a CMMG and malfunctioned regularly, was sent back to CMMG because of this, and the replacement unit malfunctioned regularly. This unit has since gone to another home. The dedicated upper is a DPMS bull barrel and has yet to malfunction. I went with the DPMS because it is built from the ground up as a .22 upper. I looked at the CMMG .22 upper and it's just a standard style upper with their conversion unit stuck in it. The DPMS was also the only dedicated upper I could find on the market that was NY compliant as delivered. Every other upper I looked at had to have a muzzle brake purchased and installed because they all came with flash hiders. By the time you do this you have spent as much or more than the DPMS costs. Hope this info is a help to you.

 

[Rico]

A second issue with the conversion kit is bore diameter.

the 22LR in a smaller diameter bullet/bore, when fired in the 556 it either has to expand to fit the larger bore or it bounces as it travels down the bore. Both accuracy suffers, and you can have a great deal of leading.

A dedicated upper avoids this but, if you're practicing drills at closer range, like from low ready to target one shot drills, or close range multiple target drills it's not as much of issue and the conversion kit may be a good low cost alternative.

Another plus to the conversion kit is you use your normal upper with your normal optics.

 

[3324]

You both cover pros & cons that I have been debating. I'm just a tad older than Les and my eyes told me to dig out one of my old Tasco tube dots to put on the M&P Sport I just bought, so as not embarrass myself too badly. So, yeah, would be nice to be able to stick with that configuration, as Rico says.

But 12" at 50 yards???? Many decades have passed since I first qualified with a rifle and I know I am not as good as I once was (although I maintain that I'm as good once as I ever was - lol). Still, I could not stand to shoot something that didn't give me better than a shotgun pattern at 50.

So I guess, in this case anyhow, conventional wisdom is right - the accuracy does suffer. And the unit can be unreliable, to boot. Well, I guess this option is off the table. Buying a dedicated upper or a M&P 15-22 takes away the ability to maintain the existing sight configuration. I guess I will have to stick with the old scoped 10-22 for plinking and shoot the Sport just enough to keep skills up while not depleting the retirement funds too much.

Thanks for the input, guys. I almost hit "go to checkout" on that CMMG. Glad I didn't.

 

[Les]

Glad to help. I interchange a Bushnell Micro red dot and a 4x scope on my conversion unit, depending on what and how far I am shooting. My Stag upper wears a Millett DMS 1-4x scope all the time. We had the red dot on for the boy scouts yesterday as we were at 50 feet shooting steel plates.

 

[3324]

I was looking at that DMS scope for the M&P but already had the old Tasco which is a 3 MOA (that's old) and decided to keep the money in my pocket for awhile.

I laid off shooting for about 7 years until my son got his permit and we started going to matches this year. So it had been awhile since I spent any money on guns or shooting in general. Then I decided I needed an AR and some essentials of course -- 2K of ammo (oh my), carry case, mags, other little stuff. Wife had forgotten how you have to pay to play. Been in a sticker shock coma for weeks now. I thought the scope would aggravate her condition so let that slide for now. But that does look like a nice scope.

 

[Chicken Shoot]

Just skimming through this and not sure I understand the OP BUT ... what is the cost difference between a conversion kit and buying the S&W M&P22? I know of two guys using those .22's in competition and they are brutal with them. They are weighted to about 13lbs and such as well though. With the rifling ... 1:14-1:17 twist on a .22 works best. I believe the Anshutz's are 1:14. But there is alot more to it. The slower the rate of twist, the warmer it must be to REALLY work well. (i.e-1:17 won't do squat in temps below 65-70 degrees or so.) 1:15 is pretty common in newer competition barrels and with good reason. Works well with subsonic target grade ammo and anything around the 1100fps range. Would I fire Hyper Velocity through it?? Probably not. Hope this info is somewhat helpful. I know you're not looking at full out competition rifles, but those rates are what's been used in the more consistent rifles at the shoots.

 

[Les]

Just skimming through this and not sure I understand the OP BUT ... what is the cost difference between a conversion kit and buying the S&W M&P22?

I bought my dedicated upper for $395 from Midway. The conversion unit was $190 IIRC. Both the dedicated upper and the conversion will run CMMG, Ciener, or Black Dog magazines. An M&P22 runs about $460 locally and you have to run dedicated S&W magazines.

 

[sr20sean]

You can run standard conversion mags in a m&p15-22

 

[Guest]

Reading this thread piqued my curiosity so I broke out one of my vintage sub caliber kits and stepped into the range for a little test.

I posted a reduced B-21 Police Silhouette with a white aiming point positioned to compensate for the mechanical offset of my Aimpoint sight.

Then, from a distance of 12-yards I fired ten shots from a rest. The resulting group was a ragged ½" hole pretty much where I expected to find it.

I was shooting CCI Green Tag ammunition through a 1/8 twist AR barrel.

For my uses I deem this "close enough for government use".

I don't shoot sub caliber enough to justify a dedicated upper. Besides I only use sub caliber for practicing my snap shots and point shooting so close is good enough for me.

 

[pmills]

KMUSSACK "I don’t shoot sub caliber enough to justify a dedicated upper."

Wait, we're supposed to justify our toys? I am screwed then.

All kidding aside i agree the conversion kit will be good enough in most cases. I did buy both, but because Rochester rifle club wont let you shoot conversions, the barrel has to be marked 22lr,

 

[3324]

Maybe I should just call S&W and suggest a .22 upper for the M&P. Something in the range of $200 would be nice. Just a suggestion.

 

[Guest]

KMUSSACK "I don't shoot sub caliber enough to justify a dedicated upper."

Wait, we're supposed to justify our toys? I am screwed then.

All kidding aside i agree the conversion kit will be good enough in most cases. I did buy both, but because Rochester rifle club wont let you shoot conversions, the barrel has to be marked 22lr,

Ok....I won't go there.....WTF?

 

[pmills]

WTF is correct. Not the most gun friendly range. Also have a 5 round mag limit. Fortunately i belong to several others.

 

[Les]

You can run standard conversion mags in a m&p15-22

Everything I have read says the BD and CMMG mags won't even fit in the mag well of a 15-22 but 15-22 mags will fit a standard lower running a conversion.