So I Made These Inserts

[USMCDOC]

i made a couple of inserts for my old Stoney Point.. i made one to measure the rim thickness and another to measure from the base of the case to the front of the driving band on the bullet.. What were my conclusive test with CCI SV was this.. the deviation in the thickness on rims for the Standard Velocity was minimal.. a spread from 39.5 to 40.5 was it. But the base to driving band was different... it was wide spread.. but what only proved was that i forgot to clean the excess lube off and shooting the ammo that way didn't show any significant improvement.. and with the rims being very close.. i didn't see any improvement there either. So in the end, i found that at least with this ammo, just shooting it was the only thing a person needs to be concerned with.. good trigger control. I have a good tune on the 10/22 now and it is shooting good.. even a person (i let two people shoot it today, one adult and on younger teenager.. and both were able to keep everything within the 9 ring on a IR50/50 target. Not being use to how the rifle is shot and not knowing wind deflections of the bullet, this turned out pretty good.. and the wind was not being kind today.. If you have a look at this test, you will see that CCI SV fared well in that test considering some of the other contenders..
http://www.accurateshooter.com/guns-of-week/22lr-rimfire-ammo-comparison-test/

 

[Outrider27]

We have found that measuring rim thickness with bulk ammo so that it can be sorted into batches of a little over 1thou variation makes a significant improvement in accuracy. Of course 1 brick of bulk 22 ammo will have a range with a few under 0.035" and a few over 0.041". My experience with quality ammo,starting the same place you did - CCI SV, was the same as yours; as you go up in price/quality rim thickness tends to be thicker and the range of variation smaller, making rim thickness sorting unnecessary. One thing that was interesting with bulk ammo is that the batches with the thickest rims (0.039" and up) shot smaller groups than the batches (much larger batches, unfortunately) with thinner rims. Best guess, rims 0.039" and up give more consistent ignition.

 

[USMCDOC]

We have found that measuring rim thickness with bulk ammo so that it can be sorted into batches of a little over 1thou variation makes a significant improvement in accuracy. Of course 1 brick of bulk 22 ammo will have a range with a few under 0.035" and a few over 0.041". My experience with quality ammo,starting the same place you did - CCI SV, was the same as yours; as you go up in price/quality rim thickness tends to be thicker and the range of variation smaller, making rim thickness sorting unnecessary. One thing that was interesting with bulk ammo is that the batches with the thickest rims (0.039" and up) shot smaller groups than the batches (much larger batches, unfortunately) with thinner rims. Best guess, rims 0.039" and up give more consistent ignition.

yeah, all of my Lapua Center-X is running at 0.039 - 0.0395

i don't remember what the numbers were for Wolf Match Target, but it would end up being in like 6 different piles. Back then i as using one of those Bald Eagle rim gauges. i will be honest, i like the way i am doing it how over the Bald Eagle one!

 

[USMCDOC]

i don't know why the website wants to post the pics upside down.. it is making me dizzy looking at em.. but i forgot to upload these on the first post.

 

[Tim s]

You can measure till you drop,the real answer is scrap the CCI and Wolf and shoot either Lapua and/or ELEY which require zero measuring with the exception of perhaps OAL lot testing for ELEY.
This is, of course, unless you're just screwing around shooting againt yourself.
Rule #1 for .22 benchrest rifles.... don't spend decent money on a good gun then try and feed it sub par ammo.

 

[USMCDOC]

You can measure till you drop,the real answer is scrap the CCI and Wolf and shoot either Lapua and/or ELEY which require zero measuring with the exception of perhaps OAL lot testing for ELEY.
This is, of course, unless you're just screwing around shooting againt yourself.
Rule #1 for .22 benchrest rifles.... don't spend decent money on a good gun then try and feed it sub par ammo.

No.. this is about my experimenting.. i shoot matches with Center-X. But the SV is good for working on being consistent on the trigger.. esp a 10/22 that don't like to be touched and don't like total free recoil either.. it is a fine line.. but the rifle will shoot the SV well enough for a good day of practice..

 

[holstil]

I thought the keys to 22 ammo were freebore and velocity. I assumed headspace was important but how much so? Interesting to look at test results. Maybe a relationship between freebore and headspace per gun is a worthy test?

 

[USMCDOC]

I thought the keys to 22 ammo were freebore and velocity. I assumed headspace was important but how much so? Interesting to look at test results. Maybe a relationship between freebore and headspace per gun is a worthy test?

I would gather to say that the rifle has a Bentz chamber in it, as to freebore, i am not sure, i have not looked to see where the bullet is getting engraved at on the driving bands. As for the 10X-III that i have.. it is a Eley chamber in it from what i am told, but engraves on the second band. I know that both rifles like Center-X 328m/s ammo pretty darn good. And Standard Plus as well as Standard Velocity.. i am thinking of going to the range today.. not sure.. conditions look pretty good..

 

[USMCDOC]

i did measure the rims on the Center-X, but did not separate them by rim thickness (.037 - .0385), but did measure the base to driving band on a partial box this morning and separated them by that.. here are the results


Whereas the CCI SV was real close in the rim thickness considering it's price point, .039 - .0415 (with the center of the bell at .040), the base to driving band numbers are very wide. from .770 to .778, but as you can see, the CCI SV is significantly longer. I measured one of each for over all length.. CCI SV was .994 and the Center-X was .974.

So today.. if all goes well, i will have a good test..

 

[holstil]

Have fun. You have some nice toys
I'm gonna try to do some plinkin this weekend.

 

[Outrider27]

As an afterthought, I don't know how others came to measuring rim thickness of bulk .22 ammo to improve accuracy; 10-12 years ago I had never heard of it, then one day a book on Ruger 10/22s and modifying them caught my eye, and I bought it. In one chapter they talked about modifying a 10/22 and discussed the improvements in accuracy they achieved by sorting according to rim thickness when using cheaper ammo. What I have done ever since tracks with their findings: ammo grouped by rim thickness shoots more consistent groups than that not sorted by rim thickness (remember that we're talking bulk ammo here, where in one brick, you will have groups from under 0.034/35" - the fouler pile- to 0.042"), and that the best groups come from the ammo in the 0.039" and up pile(s). In general, our finding was that once you got to 0.039" rim thickness and above, they reached the smallest group size, just as the Ruger book had said. We generally made 2 piles, 0.039-0.041" and over 0.041", but at that thickness it didn't seem to change group size if we did it that way or just pitched anything over 0.039" all in one pile. When we advanced to measuring more expensive ammo (Eley, Lapua and some others), we quickly quit measuring them, as they always seemed to fall into the 0.039+" to 0.0415" range; since that was what we were looking for anyway, no need to measure.

 

[USMCDOC]

What i found yesterday with the Center-X and separating by base to ogive was that seemed to make the ammo just a tad more consistent on the target. So for the future, i will do that with my Center-X.. But what i have found with the CCI SV, is that the way that bullet is made, is what hurts the potential of the ammo being a bit more accurate. i didn't see any improvement from separating the ammo by rim thickness. But because of the wide differences in base to ogive, i can see a difference on the target and now understand why so much vertical with it. i have shot some good groups with it, but i have not shot consistantly rows of dots with it.

 

[USMCDOC]

The other day i had been shooting some SK Standard Plus.. it was showing good results in the 10/22.. so i ordered a case of it today.. i will try them with separating them by rim thickness (this worked for me with Wolf Match Target) and then i will if i can also then separate it by base to ogive.. i am looking forward it this.. if it proves to be worth while.. i will order a bunch more of it!

 

[Trophy 2000]

Doc, I truly enjoy reading your work , interesting and polite to others.

 

[USMCDOC]

Doc, I truly enjoy reading your work , interesting and polite to others.

Thank you sir!

 

[Trophy 2000]

I'm new to this rimfire benchrest shooting. So if my questions sound a little dumb it's because on this subject I am. Do you smoke the bullets to see where they hit the rifling or are you just measuring overall length. Or don't the bullets reach the lands . Perhaps that is what goes into a custom.22 cal. Rifle. Maybe I'm doing too much reading and not enough thinking. In any event I appreciate your writings.

 

[Trophy 2000]

Another question , I noticed at KSS the Eley ammo had a lot of different velocity. Can accuracy be improved by a increase or decrease on a specific rifle? I'm thinking that perhaps a group size could shrink with a little slower bullet.

 

[USMCDOC]

Another question , I noticed at KSS the Eley ammo had a lot of different velocity. Can accuracy be improved by a increase or decrease on a specific rifle? I'm thinking that perhaps a group size could shrink with a little slower bullet.

It isn't the velocity they say that matters.. it is the harmonic distortion or waves that the ammo produces.. but i don't think that it totally is all that.. Because of the notion that once a barrel is tuned.. it is tuned.. but even then, some ammo isn't going to shoot as well as others, due to the "impulse" that is created by the round going off that sets the harmonic timing of the barrel, and the use of the tuner is to hopefully help that barrel stop in the same place all the time..

 

[USMCDOC]

I'm new to this rimfire benchrest shooting. So if my questions sound a little dumb it's because on this subject I am. Do you smoke the bullets to see where they hit the rifling or are you just measuring overall length. Or don't the bullets reach the lands . Perhaps that is what goes into a custom.22 cal. Rifle. Maybe I'm doing too much reading and not enough thinking. In any event I appreciate your writings.

Not smoking the bullets.. i am measuring the base to the front edge of the driving band on the bullet.. but rounds have to be separated by rim thickness before doing the base to driving band measurement

 

[Trophy 2000]

Ok, got it. Then my next question is how is ammo sorted for different shooting temps and wind. I would think that on a windy day a faster bullet could minimize drift. Or is it the burn rate of different ammo powders? I read somewhere that a specific top shooter has a variety of ammo that he may change from card to card as the match progresses. What is the variable that a shooter is chasing in ammo?