The question that often rears it's head - "What should I use as a trainer" or "What rimfire caliber makes the better trainer". Usually this is followed by a somewhat heated debate that leaves the original question somewhat unanswered. I would have to submit that the choice of caliber for a trainer depends on what the questioner is looking to accomplish. Many use the "train with waht you use" slogan, however economics usually point to the rimfire calibers as a suitable training platform.
Some ancillary questions that branch off of the original question is what model firearm? Bolt or semi?
What optic? etc. No one answer can be given without taking first into consideration a few things:
Probably the most important question: <span style="text-decoration: underline"><span style="font-weight: bold">What do I want a training rifle for?</span></span>
Just to put holes in paper?
To learn and compensate for bullet drop and wind drift?
To learn proper shooting form?
To save money as compared to more expensive centerfire cartridges?
Considering the amount of shooting I will be doing, do I go with the economical .22lr or the more expensive .22mag and .17hmr?
To build a training rifle so I have the same feel as my centerfire, and also be able to do all of the before mentioned?
What distances will I be collecting data so I can learn from the practice shooting sessions?
Because a physical disability doesn't allow me to fire a centerfire repeatedly?
Because it's fashionable?
In the end, I'm sure it's to become a better marksman, but still the question remains, what rimfire caliber? let's take a look (by definition) from Webster's dictionary of some terms:
<span style="text-decoration: underline"><span style="font-weight: bold">TRAINER</span></span>
Main Entry: train·er
Pronunciation: \ˈtrā-nər\
Function: noun
Date: 1598
1 : one that trains
2 : one (as a machine or vehicle) used in training
3 : a person who treats the ailments and minor injuries of the members of an athletic team
<span style="text-decoration: underline"><span style="font-weight: bold">TRAIN </span></span> (some removed as they don't pertain)
Main Entry: 2train
Function: noun
Etymology: Middle English, from Anglo-French, from trainer to draw, drag
Date: 14th century
4 a : order of occurrence leading to some result —often used in the phrase in train <this humiliating process had been in train for decades — Paul Fussell> b : an orderly succession <a train of thought> c : accompanying or resultant circumstances : aftermath <consequences the discovery will bring in its train>
8 : a series of parts or elements that together constitute a system for producing a result and especially for carrying on a process (as of manufacture) automatically
<span style="font-weight: bold"><span style="text-decoration: underline">TO TRAIN</span></span> (verb)
Main Entry: 3train
Function: verb
Etymology: Middle English, from Anglo-French trainer, from Vulgar Latin *traginare; akin to Latin trahere to draw
Date: 15th century
transitive verb
3 a : to form by instruction, discipline, or drill b : to teach so as to make fit, qualified, or proficient
4 : to make prepared (as by exercise) for a test of skill
5 : to aim at an object or objective : direct <trained his camera on the deer> <training every effort toward success>
intransitive verb
1 : to undergo instruction, discipline, or drill
synonyms see teach
<span style="text-decoration: underline"><span style="font-weight: bold">TRAINING</span></span>
Main Entry: train·ing
Pronunciation: \ˈtrā-niŋ\
Function: noun
Date: 1548
1 a : the act, process, or method of one that trains b : the skill, knowledge, or experience acquired by one that trains
2 : the state of being trained
<span style="text-decoration: underline"><span style="font-weight: bold">PRACTICE</span></span>
Main Entry: 1prac·tice
Variant(s): also prac·tise \ˈprak-təs\
Function: verb
Inflected Form(s): prac·ticed also prac·tised; prac·tic·ing also prac·tis·ing
Etymology: Middle English practisen, from Middle French practiser, from Medieval Latin practizare, alteration of practicare, from practica practice, noun, from Late Latin practice, from Greek praktikē, from feminine of praktikos
Date: 14th century
transitive verb
1 a : carry out, apply <practice what you preach> b : to do or perform often, customarily, or habitually <practice politeness> c : to be professionally engaged in <practice medicine>
2 a : to perform or work at repeatedly so as to become proficient <practice the act> b : to train by repeated exercises <practice pupils in penmanship>
intransitive verb
1 : to do repeated exercises for proficiency
2 : to pursue a profession actively
4 : to do something customarily
<span style="text-decoration: underline"><span style="font-weight: bold">TEACH</span></span>
Main Entry: teach
Pronunciation: \ˈtēch\
Function: verb
Inflected Form(s): taught \ˈtȯt\; teach·ing
Etymology: Middle English techen to show, instruct, from Old English tǣcan; akin to Old English tācn sign — more at token
Date: before 12th century
transitive verb
1 a : to cause to know something <taught them a trade> b : to cause to know how <is teaching me to drive> c : to accustom to some action or attitude <teach students to think for themselves> d : to cause to know the disagreeable consequences of some action <I'll teach you to come home late>
2 : to guide the studies of
3 : to impart the knowledge of <teach algebra>
4 a : to instruct by precept, example, or experience b : to make known and accepted <experience teaches us our limitations>
5 : to conduct instruction regularly in <teach school>
intransitive verb
: to provide instruction : act as a teacher
usage see learn
synonyms teach, instruct, educate, train, discipline, school mean to cause to acquire knowledge or skill. teach applies to any manner of imparting information or skill so that others may learn <taught us a lot about our planet>. instruct suggests methodical or formal teaching <instructs raw recruits in military drill>. educate implies development of the mind <more things than formal schooling serve to educate a person>. train stresses instruction and drill with a specific end in view <trained foreign pilots to operate the new aircraft>. discipline implies training in habits of order and precision <a disciplined mind>. school implies training or disciplining especially in what is hard to master <schooled the horse in five gaits>.
<span style="text-decoration: underline"><span style="font-weight: bold">LEARN</span></span>
Main Entry: learn
Pronunciation: \ˈlərn\
Function: verb
Inflected Form(s): learned \ˈlərnd, ˈlərnt\; learn·ing
Etymology: Middle English lernen, from Old English leornian; akin to Old High German lernēn to learn, Old English last footprint, Latin lira furrow, track
Date: before 12th century
transitive verb
1 a (1) : to gain knowledge or understanding of or skill in by study, instruction, or experience <learn a trade> (2) : memorize <learn the lines of a play> b : to come to be able <learn to dance> c : to come to realize <learned that honesty paid>
2 a nonstandard : teach b obsolete : to inform of something
3 : to come to know : hear <we just learned that he was ill>
intransitive verb
: to acquire knowledge or skill or a behavioral tendency
synonyms see discover
<span style="text-decoration: underline"><span style="font-weight: bold">SUBSTITUTE</span></span>Main Entry: 1sub·sti·tute
Pronunciation: \ˈsəb-stə-ˌtüt, -ˌtyüt\
Function: noun
Etymology: Middle English, from Anglo-French substitut, from Latin substitutus, past participle of substituere to put in place of, from sub- + statuere to set up, place — more at statute
Date: 15th century
: a person or thing that takes the place or function of another
— substitute adjective
<span style="text-decoration: underline"><span style="font-weight: bold">SIMULATION</span></span>
Main Entry: sim·u·la·tion
Pronunciation: \ˌsim-yə-ˈlā-shən\
Function: noun
Etymology: Middle English simulacion, from Anglo-French, from Latin simulation-, simulatio, from simulare
Date: 14th century
1 : the act or process of simulating
3 a : the imitative representation of the functioning of one system or process by means of the functioning of another <a computer simulation of an industrial process> b : examination of a problem often not subject to direct experimentation by means of a simulating device
Whew, ok, we see what the terms mean, so let's put it into perspective, and I humbly submit my own take on the definition of a training rifle:
<span style="text-decoration: underline"><span style="font-weight: bold">A TRAINING RIFLE</span></span> - A firearm that allows the act, process, or method of one that trains to gain the skill, knowledge, or experience acquired by one through instruction, discipline, or drill and that teachs so as to make fit, qualified, or proficient in the use of the firearm, by using practice to learn the skill of marksmanship, safety, and familiarize one's self with the operation and feel of a firearm. To use the training rifle as substitution or simulation for another primary firearm for training purposes or learn balistic data from, or practice to become more proficient in using a primary firearm.
Once again, the major questions should be considered first, but the different characteristics of .22lr, .22 mag, .17hmr, offers different reasons for choosing a caliber for training.
<span style="text-decoration: underline"><span style="font-weight: bold">.22lr</span></span> - Numerous ammos to choose from, many models of firearms to choose from. Ammos are usually readily available. Slower speed, range, lower cost and noise levels (as compared to .22 mag / .17hmr) allows for better understanding of bullet drop / wind drift and how to adjust to it, one can practice not too far away from urban areas, the availability and economy of the ammo allows for more rounds to be used in a practice session. Subsonic and match grade ammo allows for traditionally a higher grade of consistancy / stability which helps to determine results on target while experimenting with shooting form.
<span style="text-decoration: underline"><span style="font-weight: bold">.22 mag</span></span> - Several ammos to choose from (not as many as .22lr). Availability may be an issue in some areas, and is more expensive to shoot than the .22lr. Flatter trajectory and energy allows for longer shots than the .22lr. No Subsonic or match grade ammo avialable, and is louder than the .22lr. Plenty of models of firearms to choose from, but not as much as the .22lr. The flatter trajectory may not allow for as much deviation as the .22lr at shorter ranges and may may not allow a shooter the oppurtunity to explore and learn adjusting for bullet drop and weather conditions as the .22lr does. Will usually have to use it at further ranges to accomplish this.
<span style="text-decoration: underline"><span style="font-weight: bold">.17 HMR</span></span> - Several ammos to choose from (not as many as .22lr or .22 mag). Availability may be an issue in some areas, and is more expensive to shoot than the .22lr and usually slightly more than the .22 mag. Flatter trajectory and energy allows for longer shots than the .22lr and .22 mag. No Subsonic or match grade ammo avialable, and is louder than the .22lr and .22 mag. Plenty of models of firearms to choose from, but not as much as the .22lr. The flatter trajectory may not allow for as much deviation as the .22lr or even the .22mag at shorter ranges and may may not allow a shooter the oppurtunity to explore and learn adjusting for bullet drop and weather conditions as the .22lr does, and is much more flat shooting than the .22mag, however succumbs to wind easily, to almost a fault.
If one is not interested in analizing the ballistics of bullet drop / windage, and are mostly interested in putting groups on paper and muscle memory, the .22 mag and .17hmr, (at short to mid range), allows for less adjustments due to their flatter trajectory and higher velocity as compared to .22lr, but is pricier to shoot. On the other side of the coin, the .22lr offers a many more ammo options at short to midrange, has match grade ammo for great consistancy, is usually more economical to shoot, but not quite as effective at longer ranges as the .22 mag and .17 hmr.
So there is a quick rundown of the three popular rimfire cartridges, the .17machII is limited in production rifles as compared to the above, and was left out. From the three, you can derive which one would better suit your goals when considering a training rifle caliber.
<span style="text-decoration: underline"><span style="font-weight: bold">BOLT OR SEMI AUTO</span></span>? - Again it depends on what your goals are. Traditionally, bolt actions offer better accuraccy and dependability, however modern machining and manufacturing processes have made many semi autos tack drivers the function well. Is your primary rifle a bolt action? - might as well have a bolt action trainer to match the fit form and function of the primary, the same goes if your primary is a semi auto. With the popularity of the AR styled rifles, there are many .22 caliber uppers, conversion units, and full blown rifles in that caliber and configuration that will serve well as trainers.
If you are just out to punch holes in paper or cans at 25 yards and don't have much interest in bullet drop or windage adjustments, either bolt, semi, pump or a lever action will do.
once you've chosen your caliber and it's time to choose your model of rifle, (and if you want a trainer that is a good SUBSTITUTE for your primary) try to find one that has the ability change out performance enhancing parts such as barrels, triggers, and availablity of stocks that best mimic your primary rifle's one. This will allow you to have the same or similar feel of your trainer to your primary. The same weight, thickness, length, etc. will contribute to getting the most out of your trainer. A regular sized or bull barrel is another consideration, with the bull barrel being the better (traditionally) the more accurate of the two, as it handles harmonics and reduces warp, whip and heat better. It is also heavier in weight, and usually is more expensive than a regular sized barrel.
<span style="text-decoration: underline"><span style="font-weight: bold">OPTICS </span></span>- Now that you have your caliber and rifle model picked out, it's time to put an optic on it. Just like when choosing a rifle model, try to mimic the optic (if not make the same) as your primary rifle. The same measurement of adjustment, turrets, length, weight, additional adjustments, and most improtantly the reticle should match what is on your primary rifle. This will allow that familiarity with the trainer (which should be the goal) that you are looking for, with similiar formulas for adjustments, and also any ranging procedures.
In the end, to be a "True" trainer, the rifle and the optic combination should be as close as possible to the primary firearm in fit, form, and function as to build familiarity on the feel of the rifle and develop the muscle memory to transition to the primary rifle easly, including making adjustments.
Even if not being a duplicate of the primary firearm, a rimfire used for shooting practice / training is a valuable tool, that is, if the lessons that it provides is learned and able to be applied to the intended "Big Brother". This is where a more affordable budget concious rifle comes into play, as one's budget may not allow them to build a rimfire calibered clone of a custom centerfire primary firearm.
<span style="text-decoration: underline"><span style="font-weight: bold">In closing </span></span>- the caliber, model, optic, and any accessories of the rimfire trainer should encompass the goals that the shooter is trying to achieve and any limitations of both the trainer rifle and the shooter fits into the equation. To build a serious trainer is something not to go into lightly, and research must be done to provide the best platform for you to learn in with and to suit your training objective.
Hopefully this longwinded rambling will help someone who is contemplating a rimfire "trainer" to consider their goals, what their budget will alow them to build, what type of shooting their "trainer" is set up to simulate, and what type of research they have to do to make the right selection for them.
Some ancillary questions that branch off of the original question is what model firearm? Bolt or semi?
What optic? etc. No one answer can be given without taking first into consideration a few things:
Probably the most important question: <span style="text-decoration: underline"><span style="font-weight: bold">What do I want a training rifle for?</span></span>
Just to put holes in paper?
To learn and compensate for bullet drop and wind drift?
To learn proper shooting form?
To save money as compared to more expensive centerfire cartridges?
Considering the amount of shooting I will be doing, do I go with the economical .22lr or the more expensive .22mag and .17hmr?
To build a training rifle so I have the same feel as my centerfire, and also be able to do all of the before mentioned?
What distances will I be collecting data so I can learn from the practice shooting sessions?
Because a physical disability doesn't allow me to fire a centerfire repeatedly?
Because it's fashionable?
In the end, I'm sure it's to become a better marksman, but still the question remains, what rimfire caliber? let's take a look (by definition) from Webster's dictionary of some terms:
<span style="text-decoration: underline"><span style="font-weight: bold">TRAINER</span></span>
Main Entry: train·er
Pronunciation: \ˈtrā-nər\
Function: noun
Date: 1598
1 : one that trains
2 : one (as a machine or vehicle) used in training
3 : a person who treats the ailments and minor injuries of the members of an athletic team
<span style="text-decoration: underline"><span style="font-weight: bold">TRAIN </span></span> (some removed as they don't pertain)
Main Entry: 2train
Function: noun
Etymology: Middle English, from Anglo-French, from trainer to draw, drag
Date: 14th century
4 a : order of occurrence leading to some result —often used in the phrase in train <this humiliating process had been in train for decades — Paul Fussell> b : an orderly succession <a train of thought> c : accompanying or resultant circumstances : aftermath <consequences the discovery will bring in its train>
8 : a series of parts or elements that together constitute a system for producing a result and especially for carrying on a process (as of manufacture) automatically
<span style="font-weight: bold"><span style="text-decoration: underline">TO TRAIN</span></span> (verb)
Main Entry: 3train
Function: verb
Etymology: Middle English, from Anglo-French trainer, from Vulgar Latin *traginare; akin to Latin trahere to draw
Date: 15th century
transitive verb
3 a : to form by instruction, discipline, or drill b : to teach so as to make fit, qualified, or proficient
4 : to make prepared (as by exercise) for a test of skill
5 : to aim at an object or objective : direct <trained his camera on the deer> <training every effort toward success>
intransitive verb
1 : to undergo instruction, discipline, or drill
synonyms see teach
<span style="text-decoration: underline"><span style="font-weight: bold">TRAINING</span></span>
Main Entry: train·ing
Pronunciation: \ˈtrā-niŋ\
Function: noun
Date: 1548
1 a : the act, process, or method of one that trains b : the skill, knowledge, or experience acquired by one that trains
2 : the state of being trained
<span style="text-decoration: underline"><span style="font-weight: bold">PRACTICE</span></span>
Main Entry: 1prac·tice
Variant(s): also prac·tise \ˈprak-təs\
Function: verb
Inflected Form(s): prac·ticed also prac·tised; prac·tic·ing also prac·tis·ing
Etymology: Middle English practisen, from Middle French practiser, from Medieval Latin practizare, alteration of practicare, from practica practice, noun, from Late Latin practice, from Greek praktikē, from feminine of praktikos
Date: 14th century
transitive verb
1 a : carry out, apply <practice what you preach> b : to do or perform often, customarily, or habitually <practice politeness> c : to be professionally engaged in <practice medicine>
2 a : to perform or work at repeatedly so as to become proficient <practice the act> b : to train by repeated exercises <practice pupils in penmanship>
intransitive verb
1 : to do repeated exercises for proficiency
2 : to pursue a profession actively
4 : to do something customarily
<span style="text-decoration: underline"><span style="font-weight: bold">TEACH</span></span>
Main Entry: teach
Pronunciation: \ˈtēch\
Function: verb
Inflected Form(s): taught \ˈtȯt\; teach·ing
Etymology: Middle English techen to show, instruct, from Old English tǣcan; akin to Old English tācn sign — more at token
Date: before 12th century
transitive verb
1 a : to cause to know something <taught them a trade> b : to cause to know how <is teaching me to drive> c : to accustom to some action or attitude <teach students to think for themselves> d : to cause to know the disagreeable consequences of some action <I'll teach you to come home late>
2 : to guide the studies of
3 : to impart the knowledge of <teach algebra>
4 a : to instruct by precept, example, or experience b : to make known and accepted <experience teaches us our limitations>
5 : to conduct instruction regularly in <teach school>
intransitive verb
: to provide instruction : act as a teacher
usage see learn
synonyms teach, instruct, educate, train, discipline, school mean to cause to acquire knowledge or skill. teach applies to any manner of imparting information or skill so that others may learn <taught us a lot about our planet>. instruct suggests methodical or formal teaching <instructs raw recruits in military drill>. educate implies development of the mind <more things than formal schooling serve to educate a person>. train stresses instruction and drill with a specific end in view <trained foreign pilots to operate the new aircraft>. discipline implies training in habits of order and precision <a disciplined mind>. school implies training or disciplining especially in what is hard to master <schooled the horse in five gaits>.
<span style="text-decoration: underline"><span style="font-weight: bold">LEARN</span></span>
Main Entry: learn
Pronunciation: \ˈlərn\
Function: verb
Inflected Form(s): learned \ˈlərnd, ˈlərnt\; learn·ing
Etymology: Middle English lernen, from Old English leornian; akin to Old High German lernēn to learn, Old English last footprint, Latin lira furrow, track
Date: before 12th century
transitive verb
1 a (1) : to gain knowledge or understanding of or skill in by study, instruction, or experience <learn a trade> (2) : memorize <learn the lines of a play> b : to come to be able <learn to dance> c : to come to realize <learned that honesty paid>
2 a nonstandard : teach b obsolete : to inform of something
3 : to come to know : hear <we just learned that he was ill>
intransitive verb
: to acquire knowledge or skill or a behavioral tendency
synonyms see discover
<span style="text-decoration: underline"><span style="font-weight: bold">SUBSTITUTE</span></span>Main Entry: 1sub·sti·tute
Pronunciation: \ˈsəb-stə-ˌtüt, -ˌtyüt\
Function: noun
Etymology: Middle English, from Anglo-French substitut, from Latin substitutus, past participle of substituere to put in place of, from sub- + statuere to set up, place — more at statute
Date: 15th century
: a person or thing that takes the place or function of another
— substitute adjective
<span style="text-decoration: underline"><span style="font-weight: bold">SIMULATION</span></span>
Main Entry: sim·u·la·tion
Pronunciation: \ˌsim-yə-ˈlā-shən\
Function: noun
Etymology: Middle English simulacion, from Anglo-French, from Latin simulation-, simulatio, from simulare
Date: 14th century
1 : the act or process of simulating
3 a : the imitative representation of the functioning of one system or process by means of the functioning of another <a computer simulation of an industrial process> b : examination of a problem often not subject to direct experimentation by means of a simulating device
Whew, ok, we see what the terms mean, so let's put it into perspective, and I humbly submit my own take on the definition of a training rifle:
<span style="text-decoration: underline"><span style="font-weight: bold">A TRAINING RIFLE</span></span> - A firearm that allows the act, process, or method of one that trains to gain the skill, knowledge, or experience acquired by one through instruction, discipline, or drill and that teachs so as to make fit, qualified, or proficient in the use of the firearm, by using practice to learn the skill of marksmanship, safety, and familiarize one's self with the operation and feel of a firearm. To use the training rifle as substitution or simulation for another primary firearm for training purposes or learn balistic data from, or practice to become more proficient in using a primary firearm.
Once again, the major questions should be considered first, but the different characteristics of .22lr, .22 mag, .17hmr, offers different reasons for choosing a caliber for training.
<span style="text-decoration: underline"><span style="font-weight: bold">.22lr</span></span> - Numerous ammos to choose from, many models of firearms to choose from. Ammos are usually readily available. Slower speed, range, lower cost and noise levels (as compared to .22 mag / .17hmr) allows for better understanding of bullet drop / wind drift and how to adjust to it, one can practice not too far away from urban areas, the availability and economy of the ammo allows for more rounds to be used in a practice session. Subsonic and match grade ammo allows for traditionally a higher grade of consistancy / stability which helps to determine results on target while experimenting with shooting form.
<span style="text-decoration: underline"><span style="font-weight: bold">.22 mag</span></span> - Several ammos to choose from (not as many as .22lr). Availability may be an issue in some areas, and is more expensive to shoot than the .22lr. Flatter trajectory and energy allows for longer shots than the .22lr. No Subsonic or match grade ammo avialable, and is louder than the .22lr. Plenty of models of firearms to choose from, but not as much as the .22lr. The flatter trajectory may not allow for as much deviation as the .22lr at shorter ranges and may may not allow a shooter the oppurtunity to explore and learn adjusting for bullet drop and weather conditions as the .22lr does. Will usually have to use it at further ranges to accomplish this.
<span style="text-decoration: underline"><span style="font-weight: bold">.17 HMR</span></span> - Several ammos to choose from (not as many as .22lr or .22 mag). Availability may be an issue in some areas, and is more expensive to shoot than the .22lr and usually slightly more than the .22 mag. Flatter trajectory and energy allows for longer shots than the .22lr and .22 mag. No Subsonic or match grade ammo avialable, and is louder than the .22lr and .22 mag. Plenty of models of firearms to choose from, but not as much as the .22lr. The flatter trajectory may not allow for as much deviation as the .22lr or even the .22mag at shorter ranges and may may not allow a shooter the oppurtunity to explore and learn adjusting for bullet drop and weather conditions as the .22lr does, and is much more flat shooting than the .22mag, however succumbs to wind easily, to almost a fault.
If one is not interested in analizing the ballistics of bullet drop / windage, and are mostly interested in putting groups on paper and muscle memory, the .22 mag and .17hmr, (at short to mid range), allows for less adjustments due to their flatter trajectory and higher velocity as compared to .22lr, but is pricier to shoot. On the other side of the coin, the .22lr offers a many more ammo options at short to midrange, has match grade ammo for great consistancy, is usually more economical to shoot, but not quite as effective at longer ranges as the .22 mag and .17 hmr.
So there is a quick rundown of the three popular rimfire cartridges, the .17machII is limited in production rifles as compared to the above, and was left out. From the three, you can derive which one would better suit your goals when considering a training rifle caliber.
<span style="text-decoration: underline"><span style="font-weight: bold">BOLT OR SEMI AUTO</span></span>? - Again it depends on what your goals are. Traditionally, bolt actions offer better accuraccy and dependability, however modern machining and manufacturing processes have made many semi autos tack drivers the function well. Is your primary rifle a bolt action? - might as well have a bolt action trainer to match the fit form and function of the primary, the same goes if your primary is a semi auto. With the popularity of the AR styled rifles, there are many .22 caliber uppers, conversion units, and full blown rifles in that caliber and configuration that will serve well as trainers.
If you are just out to punch holes in paper or cans at 25 yards and don't have much interest in bullet drop or windage adjustments, either bolt, semi, pump or a lever action will do.
once you've chosen your caliber and it's time to choose your model of rifle, (and if you want a trainer that is a good SUBSTITUTE for your primary) try to find one that has the ability change out performance enhancing parts such as barrels, triggers, and availablity of stocks that best mimic your primary rifle's one. This will allow you to have the same or similar feel of your trainer to your primary. The same weight, thickness, length, etc. will contribute to getting the most out of your trainer. A regular sized or bull barrel is another consideration, with the bull barrel being the better (traditionally) the more accurate of the two, as it handles harmonics and reduces warp, whip and heat better. It is also heavier in weight, and usually is more expensive than a regular sized barrel.
<span style="text-decoration: underline"><span style="font-weight: bold">OPTICS </span></span>- Now that you have your caliber and rifle model picked out, it's time to put an optic on it. Just like when choosing a rifle model, try to mimic the optic (if not make the same) as your primary rifle. The same measurement of adjustment, turrets, length, weight, additional adjustments, and most improtantly the reticle should match what is on your primary rifle. This will allow that familiarity with the trainer (which should be the goal) that you are looking for, with similiar formulas for adjustments, and also any ranging procedures.
In the end, to be a "True" trainer, the rifle and the optic combination should be as close as possible to the primary firearm in fit, form, and function as to build familiarity on the feel of the rifle and develop the muscle memory to transition to the primary rifle easly, including making adjustments.
Even if not being a duplicate of the primary firearm, a rimfire used for shooting practice / training is a valuable tool, that is, if the lessons that it provides is learned and able to be applied to the intended "Big Brother". This is where a more affordable budget concious rifle comes into play, as one's budget may not allow them to build a rimfire calibered clone of a custom centerfire primary firearm.
<span style="text-decoration: underline"><span style="font-weight: bold">In closing </span></span>- the caliber, model, optic, and any accessories of the rimfire trainer should encompass the goals that the shooter is trying to achieve and any limitations of both the trainer rifle and the shooter fits into the equation. To build a serious trainer is something not to go into lightly, and research must be done to provide the best platform for you to learn in with and to suit your training objective.
Hopefully this longwinded rambling will help someone who is contemplating a rimfire "trainer" to consider their goals, what their budget will alow them to build, what type of shooting their "trainer" is set up to simulate, and what type of research they have to do to make the right selection for them.
