View Full Version : .22lr accuracy: Glenfield Model 60 vs CMMG 20" AR-15 upper?

October 11, 2012, 11:18 AM
I have an older Glenfield Model 60 with a 3-9 scope on it that works flawlessly. By older, I mean 1975, when it had 18 rounds of capacity and a longer barrel than today, it seems. I haven't been able to shoot it enough to use it's full capability for accuracy.

[I also have a Marlin Model 39a from the 1950s that is more accurate than I am, and holds 19 rounds.]

I have an AR-15 and was recently toying with the idea of a CMMG upper for it, in the 20" A2 configuration. Keep in mind, I live in california and am limited to 10 round magazines for it, but the tube-fed ones I have hold 18 and 19 rounds, respectively.

So, the AR-15 upper would be fun, but I am trying to figure out if it will provide me with any accuracy advantage over what I already have, before I shell out $500 for the upper, and a LOT more for all the mags I'd need to keep up with the Glenfield.

Again, the Glenfield has the mag advantage of 8 more rounds per loading, and I use the Spee-D-Loader so I can do 8 magazines worth very quickly, while I'd have to buy 18 AR-15 magazines to shoot the same amount of ammo [180 rounds] down range in a rapid fashion.

There are only two things that would make me buy the CMMG upper: Improved accuracy and I WANT IT.

Thus, my question: which would be more mechanically accurate, the CMMG AR-15 upper or the Glenfield Model 60? And by how much?

I am fully aware that the skill of the operator is the biggest factor. I am not focused enough to achieve quarter sized groups at 25 yards or 50 yards. I am happy with half-dollar sized groups at 25 yards, and ecstatic at half-dollar sized groups at 50 yards. I just want my skills to limit my accuracy, not the firearm I am using.

Thanks for helping me make a decision.

October 11, 2012, 02:54 PM
I have a CMMG dedicated .22LR upper with a 16" barrel. In my experience, it is VERY accurate - I would say equal or better than a stock Model 60. You mention "half-dollar sized groups at 50 yards." That is pretty easy to accomplish with the CMMG upper.

Personally, I would recommend the 16" carbine upper over the 20" A2 configuration. The 20" barrel offers no benefit over 16" for the .22LR (since muzzle velocity on that round tops out in a 16"-18" barrel, and falls off after that). If anything, the 20" barrel may be less accurate due to the fact that it is less stiff, and there is a greater chance for movement to affect accuracy.

Also you mention a price of $500. That is considerably more than the CMMG 16" .22LR upper, which runs about $360-$370.

Here is a link to my experience with a CMMG dedicated .22LR upper:


October 11, 2012, 04:49 PM
Also you mention a price of $500. That is considerably more than the CMMG 16" .22LR upper, which runs about $360-$370.

If I get the CMMG Upper I like [that is most like my A2 style AR-15], it costs $479 [with the SS bolt set-up]. In addition to that, I'd want at least 10 magazines, so that I had 100 rounds ready to fire at once. I would probably only buy 5 magazines to start, but that alone is $29.95 per magazine, which equals $149.75 for 5 of them, or $299.50 for 10 of them. This puts me at $628.75 to $778.50, not counting shipping and any sales tax applied. Shipping would probably run around $20, so now I'm up to $648.75 at least.

I live in California, where we are limited to 10 rounds in a magazine. If I could, I'd rather have 4 25-round magazines, but that isn't an option here for me.

So, for the type of CMMG I'd want, it would cost me over $500, even if I found all the parts on sale.

I did want the A2 20" barrel, but only because I wanted the CMMG to look just like my existing A2-style 20" upper. If it will cause a decline in accuracy or in velocity, due to the extra length, then I'd probably consider the shorter barreled M4 style 16". I am just partial to the longer stuff.

October 11, 2012, 11:13 PM
Whoever quoted you $30 for a 10-round magazine is overcharging you:


I have found the Black Dog Machine magazines to be very well-made and reliable, but they don't hold the bolt open on the last round. But neither do the CMMG mags, unless you buy the optional bolt hold-open adapter.

If you really want the 20" rifle-length barrel, that is your decision to make, but I can tell you from experience that the 16" length is very accurate, and that seemed to be your primary concern from your first post. Also, think about the SS bolt. The premium you pay just buys a bolt that is (in theory) slightly easier to clean. My upper came with the phosphate-finished bolt with SS collar, and it is not difficult to clean at all.

Anyway, no matter what you get, I have a feeling you are going to really like it!

October 13, 2012, 04:39 PM
you can get 1"-2" groups at 50 yds with a ciener .22lr unit and the 223 upper, so you can have the (20 second parts swap) choice of 223 or .22lr, while hiking.

The "conversion kits" are a fun diversion, but they are no substitute for a proper .22LR upper in accuracy (your standard AR barrel twist of 1:7 or 1:9 is far from ideal for .22LR) or reliability, and they will dirty up your AR gas tube very quickly.

October 13, 2012, 05:33 PM
I own a CMMG Sierra 22lr upper that I use on my S&W M&P-15T lower.

It is very accurate for a hunting and plinking rifle, although I doubt it would win any championships, and was very reliable until I installed a 3# Timney trigger.
Wouldn't hardly work at all after that.

I fixed the problem by sharpening the CMMG's firing pin and cutting 1.5 coils from the firing pin return spring.

With the 3# trigger I find this set up very accurate, reliable and a joy to shoot.

I would buy it all over again.